JP7824376B2 - ethanol - Google Patents

Description

The present invention relates to ethanol, and more specifically, to ethanol with an adjusted content of specific trace elements. Furthermore, the present invention relates to a new resource-recycling type of ethanol that uses a gas containing carbon monoxide and hydrogen as a substrate, rather than being derived from conventional petroleum resources or biomass resources.

Petrochemical products are used in many aspects of our lives. However, because they are such familiar products, mass production and mass consumption are causing a variety of environmental problems, which has become a major global issue. For example, polyethylene and polyvinyl chloride, which are representative petrochemical industry products, are consumed in large quantities and thrown away, and this waste is a major cause of environmental pollution. In addition, the mass production of petrochemical industry products has raised concerns about the depletion of fossil fuel resources and the global environmental issues of increased carbon dioxide in the atmosphere, which are also being discussed.

With growing global awareness of such environmental issues, methods for producing various organic substances from raw materials other than naphtha, which is a raw material for petrochemical industry products, have been investigated in recent years. For example, a method of producing bioethanol from edible raw materials such as corn through sugar fermentation has attracted attention. However, such sugar fermentation methods using edible raw materials have been criticized for their potential problems, such as causing food prices to rise, as limited agricultural land is used for non-food production.

To solve this problem, the use of non-edible raw materials that would traditionally have been discarded is also being considered. Specifically, methods have been proposed in which non-edible raw materials such as cellulose derived from waste wood or used paper are used to produce alcohols through fermentation, and methods have been proposed in which the above-mentioned biomass raw materials are gasified and the synthesis gas is used to produce alcohols using a catalyst, but these methods have not yet been put into practical use. Furthermore, even if various petrochemical products could be produced from these non-petroleum raw materials, they would ultimately end up as waste plastics that do not decompose naturally, so they cannot be said to be effective as a fundamental solution to environmental problems.

Currently, approximately 60 million tons of combustible waste are disposed of in Japan per year. The amount of energy is equivalent to approximately 200 trillion kilocalories, far exceeding the amount of energy contained in naphtha, a raw material for plastics in Japan. This waste is also a valuable resource. Converting these waste resources into petrochemical products would enable the realization of an ultimate resource-circulating society that is not dependent on petroleum resources. From this perspective, Patent Documents 1 and 2, etc., disclose technologies for producing synthetic gas (a gas primarily composed of CO and _H2 ) from waste and then producing ethanol from the synthetic gas by fermentation.

However, as pointed out in Patent Document 3, synthesis gas produced from waste contains a wide variety of unidentified impurities, some of which are toxic to microorganisms, making productivity a major challenge when producing alcohol from synthesis gas through microbial fermentation. Furthermore, alcohol obtained by microbial fermentation of synthesis gas also contains various components resulting from the impurities in the synthesis gas, and these components cannot be completely removed even by purification processes such as distillation. Therefore, developing derivatives from alcohol obtained by microbial fermentation of synthesis gas has been a major technical challenge.

JP 2016-059296 A International Publication No. 2015-037710 Japanese Patent Application Laid-Open No. 2018-058042

According to the inventors' research, while C2 raw materials, such as conventional ethanol, are known to be starting materials for various chemical products, as described above, it has been found that alcohol produced from resources other than petroleum or biomass resources (recyclable resources) contains trace amounts of various unknown substances, unlike naphtha-derived chemical raw materials. However, with conventional technology, the properties of the substances are unknown, and there has been insufficient consideration to date as to whether it is necessary to remove all substances or only specific substances. Therefore, even though the above patent documents propose alcohol produced from recyclable resources, there is still room for technological improvement before such alcohol can be put to practical use.

On the other hand, while the above-mentioned documents disclose general fermentation and distillation methods and the optimal composition of synthetic gas, they do not provide detailed descriptions of the processes, nor do they even identify the alcoholic substance obtained.

The present invention was developed in light of this background technology, and its objective is to provide practical new alcohols and their derivatives that are more industrially valuable than existing petrochemical raw materials.

As a result of intensive research aimed at solving the above-mentioned problems, the inventors have identified the wide variety of trace substances contained in alcohol produced from recycled resources, and have further found that it is possible to control the content within a specific range using a new production method. Furthermore, they have discovered that various derivatives of this substance exhibit superior effects compared to existing petroleum-derived alcohol. For example, in the process of synthesizing butadiene from ethanol, they have found that the ethanol conversion rate is improved compared to when conventional petroleum-derived ethanol is used, and that alcohol of a practical level equal to or better than petroleum-derived alcohol can be obtained, leading to the present invention.

More specifically, when ethanol is produced from a gas substrate containing carbon monoxide and hydrogen using waste as a carbon source, the researchers discovered that synthesizing butadiene from the ethanol improves the ethanol conversion rate. After detailed investigation into the reason for this, they found that trace amounts of inorganic substances are present in ethanol derived from recycled resources using a gas containing carbon monoxide and hydrogen as a substrate. The present invention is based on this finding.

That is, the present invention includes the following gist.
[1] Ethanol containing inorganic components and having a sodium content of 150 mg/L or more and 1000 mg/L or less.
[2] The ethanol according to [1], wherein a gas containing carbon monoxide and hydrogen is used as a substrate.
[3] The ethanol according to [1] or [2], which is derived from microbial fermentation.
[4] The ethanol according to [1], wherein the gas containing carbon monoxide and hydrogen is derived from waste.
[5] converting a carbon source into a synthesis gas comprising carbon monoxide and hydrogen;
a microbial fermentation step of supplying the synthesis gas containing carbon monoxide and hydrogen to a microbial fermenter and obtaining an ethanol-containing liquid by microbial fermentation;
a separation step of separating the ethanol-containing liquid into a liquid or solid component containing microorganisms and a gas component containing ethanol;
a liquefaction step of condensing and liquefying the gas components;
a purification step of purifying ethanol from the liquid obtained in the liquefaction step;
Including,
A method for producing ethanol, wherein the purified ethanol has a sodium content of 150 mg/L or more and 1000 mg/L or less.
[6] The method according to [5], further comprising a step of purifying the synthesis gas.
[7] The method according to [5] or [6], wherein the carbon source is derived from waste.
[8] The ethanol according to any one of [1] to [4], which is for use in chemical products.
[9] The ethanol according to any one of [1] to [4], which is for use as fuel.
[10] The ethanol according to any one of [1] to [4], which is used as a polymer raw material.
[11] A chemical product made from the ethanol according to any one of [1] to [4].
[12] A fuel comprising the ethanol according to any one of [1] to [4] and/or ethyl t-butyl ether obtained from the ethanol according to any one of [1] to [4].
[13] A polymer raw material obtained by using ethanol as a raw material according to any one of [1] to [4].
[14] The polymer raw material according to [13], selected from the group consisting of ethylene, propylene, butadiene, ethyl acetate, isobutene, methyl (meth)acrylate, acrylic acid, aminohexanoic acid, and diethyl carbonate.
[15] A polymer made from the polymer raw material according to [13] or [14].
[16] A molded article made of the polymer according to [15].

According to the present invention, by producing ethanol containing specific trace amounts of inorganic components, various unique effects can be achieved compared to commercially available industrial ethanol. For example, the present invention can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as fuel. In addition, it is expected that similar effects can be achieved even with existing alcohols by adding specific amounts of specific inorganic components.

The ethanol produced by the present invention can be used as a raw material for the production of, for example, butadiene, ethylene, propylene, isobutene, acetaldehyde, acetic acid, ethyl acetate, methyl (meth)acrylate, ethyl t-butyl ether ethylene glycol, ester compositions, polyesters, acrylic acid, aminohexanoic acid, diethyl carbonate, polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polyisobutylene, polymethyl methacrylate (PMMA), ethylene propylene diene rubber (EPDM), polybutylene terephthalate (PBT), polyethylene furanoate (PEF), polyurethane (PU), and the like. The ethanol produced by the present invention can also be used in a variety of applications, including cosmetics, perfumes, fuels, antifreeze, disinfectants, disinfectants, cleaning agents, mold removers, detergents, hair washes, soaps, antiperspirants, facial cleansing sheets, solvents, paints, adhesives, diluents, and food additives.

The following describes one preferred embodiment of the present invention. However, the following embodiment is merely an example for explaining the present invention, and the present invention is not limited to the following embodiment in any way.

<Definition>
In the present invention, "ethanol" does not mean pure ethanol as a compound (ethanol represented by the chemical formula: _CH3CH2OH ), but rather means a composition containing impurities ( _contaminant components) that are inevitably contained in ethanol produced through synthesis or purification.

<Ethanol>
The ethanol according to the present invention contains 150 mg/L or more and 1000 mg/L or less of Na (sodium) as an inorganic component. Sodium may be contained in the ethanol as sodium ions or as a sodium compound.

The sodium content in ethanol can be measured using conventional methods. For example, one method for measuring sodium content is to use an inductively coupled plasma mass spectrometry (ICP-MS) analyzer. In an ICP-MS analysis, a calibration curve is created by adjusting the concentration of a standard atomic absorption solution, and the sodium content is determined by analyzing the sample to be measured based on this calibration curve.

The ethanol used in the present invention is preferably ethanol produced from a gas containing carbon monoxide and hydrogen as a substrate, or ethanol derived from microbial fermentation. This is because adding sodium to these ethanols at the above concentrations simplifies the production process. Here, ethanol that is 100% pure, i.e., contains absolutely no impurities, does not contain sodium at the above concentrations. Furthermore, commercially available industrial ethanol derived from fossil fuels does not contain sodium at the above concentrations. Furthermore, commercially available industrial ethanol derived from fossil fuels and ethanol produced by fermentation using biomass feedstocks such as cellulose typically do not contain sodium at the above concentrations, but sodium can be added to achieve the above concentrations.

Without being bound by theory, it is believed that the synthesis gas used in the production process of ethanol derived from microbial fermentation using a gas containing carbon monoxide and hydrogen as a substrate contains various trace components in addition to carbon monoxide and hydrogen. Therefore, even when alcohol is obtained through purification processes such as distillation, it is difficult to remove all impurities such as inorganic substances, and it is believed that inorganic substances are inevitably contained in the alcohol. In the present invention, the inclusion of these unavoidable substances in ethanol is believed to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

The Na (sodium) content in ethanol is preferably 170 mg/L or more, more preferably 190 mg/L or more, even more preferably 500 mg/L or more, and preferably 400 mg/L or less, more preferably 300 mg/L or less. The Na content is the amount of Na compounds converted into elemental Na. Having a Na content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as fuel.

The ethanol of the present invention may contain inorganic components other than Na. For example, it may contain inorganic components such as Si, K, Fe, and Cr. Compounds containing these elements may be inorganic compounds or organometallic compounds.

When ethanol contains Si, the Si content is preferably 10 mg/L or more, more preferably 20 mg/L or more, even more preferably 30 mg/L or more, and preferably 100 mg/L or less, more preferably 90 mg/L or less, and even more preferably 80 mg/L or less, relative to the ethanol. The Si content is the amount of Si compounds converted into elemental Si. Having a Si content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as fuel.

When K is contained in ethanol, the K content is preferably 1.0 mg/L or more, more preferably 1.5 mg/L or more, even more preferably 2.0 mg/L or more, even more preferably 2.5 mg/L or more, and preferably 10 mg/L or less, more preferably 7 mg/L or less, and even more preferably 5 mg/L or less, relative to the ethanol. The K content is the amount of K compounds converted into elemental K. Having a K content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

When ethanol contains Fe, the Fe content is preferably 2.0 mg/L or less, more preferably 1.5 mg/L or less, even more preferably 1.0 mg/L or less, and even more preferably 0.5 mg/L or less, relative to the ethanol. The Fe content is the amount of Fe compounds converted to elemental Fe. Having an Fe content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as fuel.

When ethanol contains Cr, the Cr content is preferably 0.6 mg/L or less, and more preferably 0.5 mg/L or less, relative to the ethanol. The Cr content is the amount of Cr compounds converted to elemental Cr. Having a Cr content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as fuel.

The ethanol of the present invention is obtained by extracting and further purifying the ethanol-containing liquid obtained from the microbial fermenter, as described below. In addition to the unavoidable substances mentioned above, other components may be included. For example, trace amounts of aromatic compounds may be included. Examples of aromatic compounds include toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene. Only one of these may be included, or two or more may be included. Ethylbenzene is preferably included as the aromatic compound.

The total content of aromatic compounds contained in ethanol is preferably 0.4 mg/L or more, more preferably 0.5 mg/L or more, even more preferably 0.7 mg/L or more, even more preferably 1.0 mg/L or more, and preferably 10 mg/L or less, more preferably 7 mg/L or less, even more preferably 5 mg/L or less, and even more preferably 3 mg/L or less, based on the total ethanol content. Having an aromatic compound content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

When ethylbenzene is contained in ethanol, the ethylbenzene content, relative to the total ethanol, is preferably 0.1 mg/L or more, more preferably 0.2 mg/L or more, even more preferably 0.3 mg/L or more, even more preferably 0.5 mg/L or more, and preferably 5 mg/L or less, more preferably 3 mg/L or less, even more preferably 2 mg/L or less, and even more preferably 1 mg/L or less. Having an ethylbenzene content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as fuel.

When ethanol contains toluene, the toluene content, relative to the total ethanol, is preferably 0.01 mg/L or more, more preferably 0.02 mg/L or more, even more preferably 0.03 mg/L or more, even more preferably 0.05 mg/L or more, and preferably 1 mg/L or less, more preferably 0.5 mg/L or less, even more preferably 0.2 mg/L or less, and even more preferably 0.1 mg/L or less. Having a toluene content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

When o-xylene is contained in ethanol, the o-xylene content, based on the total ethanol, is preferably 0.1 mg/L or more, more preferably 0.2 mg/L or more, even more preferably 0.3 mg/L or more, even more preferably 0.5 mg/L or more, and preferably 5 mg/L or less, more preferably 3 mg/L or less, even more preferably 2 mg/L or less, and even more preferably 1 mg/L or less. Having an o-xylene content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

When m-xylene and/or p-xylene is contained in ethanol, the total content of m-xylene and/or p-xylene is preferably 0.2 mg/L or more, more preferably 0.3 mg/L or more, even more preferably 0.4 mg/L or more, even more preferably 0.5 mg/L or more, and preferably 5 mg/L or less, more preferably 3 mg/L or less, even more preferably 2 mg/L or less, and even more preferably 1 mg/L or less, based on the total ethanol. Having an m-xylene and/or p-xylene content within the above ranges can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

The ethanol of the present invention may further contain a trace amount of aliphatic hydrocarbons. Examples of aliphatic hydrocarbons include n-hexane, n-heptane, n-octane, n-decane, n-dodecane, n-tetradecane, and hexadecane. Only one of these may be contained, or two or more may be contained. It is preferable that the aliphatic hydrocarbon contain one or more of n-hexane, n-decane, and n-dodecane.

The total content of aliphatic hydrocarbons in ethanol is preferably 0.16 mg/L or more, preferably 0.2 mg/L or more, more preferably 0.3 mg/L or more, even more preferably 0.5 mg/L or more, and 10 mg/L or less, preferably 7 mg/L or less, more preferably 5 mg/L or less, and even more preferably 3 mg/L or less, based on the total ethanol content. Having an aliphatic hydrocarbon content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

When n-hexane is contained in ethanol, the n-hexane content, relative to the total ethanol, is preferably 0.1 mg/L or more, more preferably 0.2 mg/L or more, even more preferably 0.3 mg/L or more, even more preferably 0.5 mg/L or more, and preferably 5 mg/L or less, more preferably 3 mg/L or less, even more preferably 2 mg/L or less, and even more preferably 1 mg/L or less. Having an n-hexane content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

When n-heptane is contained in ethanol, the n-heptane content, relative to the total ethanol, is preferably 0.01 mg/L or more, more preferably 0.02 mg/L or more, even more preferably 0.03 mg/L or more, even more preferably 0.05 mg/L or more, and preferably 1 mg/L or less, more preferably 0.5 mg/L or less, even more preferably 0.2 mg/L or less, and even more preferably 0.1 mg/L or less. Having an n-heptane content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

When n-octane is contained in ethanol, the n-octane content, relative to the total ethanol, is preferably 0.01 mg/L or more, more preferably 0.02 mg/L or more, even more preferably 0.03 mg/L or more, even more preferably 0.05 mg/L or more, and preferably 1 mg/L or less, more preferably 0.5 mg/L or less, even more preferably 0.2 mg/L or less, and even more preferably 0.1 mg/L or less. Having an n-octane content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

When n-decane is contained in ethanol, the n-decane content, relative to the total ethanol, is preferably 0.01 mg/L or more, more preferably 0.02 mg/L or more, even more preferably 0.03 mg/L or more, even more preferably 0.05 mg/L or more, and preferably 1 mg/L or less, more preferably 0.5 mg/L or less, even more preferably 0.2 mg/L or less, and even more preferably 0.1 mg/L or less. Having an n-decane content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

When n-dodecane is contained in ethanol, the n-dodecane content, relative to the total ethanol, is preferably 0.01 mg/L or more, more preferably 0.02 mg/L or more, even more preferably 0.03 mg/L or more, even more preferably 0.05 mg/L or more, and preferably 1 mg/L or less, more preferably 0.5 mg/L or less, even more preferably 0.2 mg/L or less, and even more preferably 0.1 mg/L or less. Having an n-dodecane content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

When n-tetradecane is contained in ethanol, the n-tetradecane content, relative to the total ethanol, is preferably 0.01 mg/L or more, more preferably 0.02 mg/L or more, even more preferably 0.03 mg/L or more, even more preferably 0.05 mg/L or more, and preferably 1 mg/L or less, more preferably 0.5 mg/L or less, even more preferably 0.2 mg/L or less, and even more preferably 0.1 mg/L or less. Having an n-tetradecane content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

When hexadecane is contained in ethanol, the hexadecane content, relative to the total ethanol, is preferably 0.01 mg/L or more, more preferably 0.02 mg/L or more, even more preferably 0.03 mg/L or more, even more preferably 0.05 mg/L or more, and preferably 1 mg/L or less, more preferably 0.5 mg/L or less, even more preferably 0.2 mg/L or less, and even more preferably 0.1 mg/L or less. Having a hexadecane content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

The ethanol of the present invention may further contain a trace amount of a dialkyl ether. Examples of dialkyl ethers include dimethyl ether, diethyl ether, dipropyl ether, dibutyl ether, and dipentyl ether. Only one of these may be contained, or two or more may be contained. It is preferable that the dialkyl ether contains dibutyl ether.

The total content of dialkyl ethers in ethanol is preferably 0.001 mg/L or more, preferably 0.01 mg/L or more, more preferably 0.1 mg/L or more, even more preferably 1.0 mg/L or more, and 100 mg/L or less, preferably 80 mg/L or less, more preferably 50 mg/L or less, and even more preferably 30 mg/L or less, based on the total ethanol content. Having a dialkyl ether content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as a fuel.

When dibutyl ether is contained in ethanol, the dibutyl ether content is preferably 1 mg/L or more, more preferably 2 mg/L or more, even more preferably 5 mg/L or more, even more preferably 10 mg/L or more, and preferably 50 mg/L or less, more preferably 40 mg/L or less, even more preferably 30 mg/L or less, and even more preferably 25 mg/L or less, relative to the ethanol. Having a dibutyl ether content within the above range can improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and improve combustion efficiency when using ethanol as fuel.

The ethanol of the present invention contains the inorganic components described above and, if desired, trace amounts of organic components such as aromatic hydrocarbons and aliphatic hydrocarbons. However, the concentration of ethanol (pure ethanol as a compound), which is the main component of the ethanol, is 75% by volume or more, preferably 80% by volume or more, more preferably 90% by volume or more, even more preferably 95% by volume or more, still more preferably 98% by volume or more, and preferably 99.999% by volume or less, more preferably 99.99% by volume or less, even more preferably 99.9% by volume or less, and still more preferably 99.5% by volume or less.

The ethanol concentration in the ethanol of the present invention can be set according to the intended use. For example, 90% by volume or more is preferred for cosmetics, and 75% by volume or more is preferred for disinfectant ethanol. The upper limit can also be set appropriately depending on the use. In terms of transportation costs, etc., a higher ethanol concentration is preferable for the product.

<Ethanol production method>
As a method for producing ethanol having the above-described characteristic gas chromatographic peak, for example, ethanol can be produced by microbial fermentation of carbon monoxide-containing synthesis gas derived from waste or exhaust gas. In such a method, the content of aromatic compounds and the like in the raw material gas derived from waste or exhaust gas and the purification conditions can be controlled to control the amount of aromatic compounds and the like contained in the final product. Below, as an example, a method for producing ethanol by microbial fermentation of carbon monoxide-containing synthesis gas derived from waste or exhaust gas will be described.

The ethanol production method includes the following steps: a step of converting a carbon source into a synthesis gas containing carbon monoxide and hydrogen; a microbial fermentation step of supplying the synthesis gas containing carbon monoxide and hydrogen to a microbial fermenter and obtaining an ethanol-containing liquid by microbial fermentation; a separation step of separating the ethanol-containing liquid into a liquid or solid component containing microorganisms and a gas component containing ethanol; a liquefaction step of condensing and liquefying the gas component; and a purification step of purifying ethanol from the liquid obtained in the liquefaction step. If necessary, the method may also include a feedstock gas generation step, a synthesis gas preparation step, a wastewater treatment step, etc. Each step is described below.

<Material Gas Generation Process>
The raw material gas generation process is a process in which a carbon source is gasified in a gasification section to generate raw material gas. A gasification furnace may be used in the raw material gas generation process. A gasification furnace is a furnace that combusts (incompletely combusts) a carbon source, and examples include a shaft furnace, a kiln furnace, a fluidized-bed furnace, and a gasification reforming furnace. A fluidized-bed gasification furnace is preferred because partial combustion of waste enables high hearth load and excellent operability. Gasification of waste in a fluidized-bed furnace at low temperatures (approximately 450 to 600°C) and in a low-oxygen atmosphere results in decomposition into gases (carbon monoxide, carbon dioxide, hydrogen, methane, etc.) and char containing a high carbon content. Furthermore, since non-combustible materials contained in the waste are separated from the furnace bottom in a hygienic and low-oxidation state, valuable materials such as iron and aluminum can be selectively recovered from the non-combustible materials. Therefore, such waste gasification enables efficient resource recycling.

The gasification temperature in the raw material gas generation process is not particularly limited, but is typically 100 to 2500°C, preferably 200 to 2100°C.

The gasification reaction time in the raw material gas generation process is typically 2 seconds or more, preferably 5 seconds or more.

The carbon source used in the raw gas production process is not particularly limited, and various carbon-containing materials can be suitably used for recycling purposes, such as coke ovens in steelworks, blast furnaces (blast furnace gas), coal used in converters and coal-fired power plants, general waste and industrial waste introduced into incinerators (particularly gasifiers), and carbon dioxide by-products from various industries.

More specifically, the carbon source is preferably waste, and specific examples include plastic waste, food waste, municipal solid waste (MSW), industrial solid waste, discarded tires, biomass waste, household waste such as futons and paper, waste from construction materials, coal, petroleum, petroleum-derived compounds, natural gas, shale gas, etc. Of these, various types of waste are preferred, and unsorted municipal solid waste is more preferred from the standpoint of sorting costs.

The feed gas obtained by gasifying a carbon source contains carbon monoxide and hydrogen as essential components, but may also contain carbon dioxide, oxygen, and nitrogen. The feed gas may also contain other components such as soot, tar, nitrogen compounds, sulfur compounds, phosphorus compounds, and aromatic compounds.

In the above-mentioned raw material gas generation process, the raw material gas may be generated by performing a heat treatment (commonly known as gasification) to combust (incompletely combust) the carbon source, i.e., by partially oxidizing the carbon source, resulting in a gas containing, although not particularly limited, 0.1% by volume or more, preferably 10% by volume or more, and more preferably 20% by volume or more of carbon monoxide.

<Synthetic gas refining process>
The synthesis gas purification process is a process for removing or reducing specific substances, such as various pollutants, dust particles, impurities, and undesirable amounts of compounds, from a feed gas. When the feed gas is derived from waste, the feed gas typically contains carbon monoxide at 0.1% to 80% by volume, carbon dioxide at 0.1% to 70% by volume, and hydrogen at 0.1% to 80% by volume. It also tends to contain nitrogen compounds at 1 mg/L or more, sulfur compounds at 1 mg/L or more, phosphorus compounds at 0.1 mg/L or more, and/or aromatic compounds at 10 mg/L or more. Other environmental pollutants, dust particles, impurities, and other substances may also be present. Therefore, when supplying synthesis gas to a microbial fermenter, it is preferable to reduce or remove substances and undesirable amounts of compounds from the feed gas that are undesirable for stable microbial cultivation, so that the content of each component in the feed gas falls within a range suitable for stable microbial cultivation.

In particular, in the synthesis gas purification process, a pressure swing adsorption unit filled with the above-mentioned regenerated adsorbent is used to adsorb carbon dioxide gas in the synthesis gas onto the regenerated adsorbent (zeolite), thereby reducing the carbon dioxide gas concentration in the synthesis gas. Furthermore, the synthesis gas may be subjected to other conventional treatment processes to remove impurities and adjust the gas composition. Examples of other treatment processes include gas chillers (moisture separators), cryogenic separation (cryogenic) separators, particulate (soot) separators such as cyclones and bag filters, scrubbers (water-soluble impurity separators), desulfurization units (sulfide separators), membrane separation units, deoxygenation units, pressure swing adsorption (PSA) separators, temperature swing adsorption (TSA) separators, pressure temperature swing adsorption (PTSA) separators, separators using activated carbon, and separators using deoxygenation catalysts, specifically, separators using copper or palladium catalysts.

The synthesis gas used in the ethanol production method of the present invention contains at least carbon monoxide as an essential component, and may further contain hydrogen, carbon dioxide, and nitrogen.

The synthesis gas used in the present invention may be obtained by generating a raw material gas by gasifying a carbon source (raw material gas generation process), and then adjusting the concentrations of the carbon monoxide, carbon dioxide, hydrogen, and nitrogen components from the raw material gas, as well as reducing or removing the substances and compounds described above.

The carbon monoxide concentration in the synthesis gas is typically 20% by volume or more and 80% by volume or less, preferably 25% by volume or more and 50% by volume or less, and more preferably 35% by volume or more and 45% by volume or less, based on the total concentration of carbon monoxide, carbon dioxide, hydrogen, and nitrogen in the synthesis gas.

The hydrogen concentration in the synthesis gas is typically 10% by volume or more and 80% by volume or less, preferably 30% by volume or more and 55% by volume or less, and more preferably 40% by volume or more and 50% by volume or less, based on the total concentration of carbon monoxide, carbon dioxide, hydrogen, and nitrogen in the synthesis gas.

The carbon dioxide concentration in the synthesis gas is typically 0.1% by volume or more and 40% by volume or less, preferably 0.3% by volume or more and 30% by volume or less, more preferably 0.5% by volume or more and 10% by volume or less, and particularly preferably 1% by volume or more and 6% by volume or less, based on the total concentration of carbon monoxide, carbon dioxide, hydrogen, and nitrogen in the synthesis gas.

The nitrogen concentration in the synthesis gas is typically 40% by volume or less, preferably 1% by volume or more and 20% by volume or less, and more preferably 5% by volume or more and 15% by volume or less, based on the total concentration of carbon monoxide, carbon dioxide, hydrogen, and nitrogen in the synthesis gas.

The concentrations of carbon monoxide, carbon dioxide, hydrogen, and nitrogen can be adjusted to a specified range by changing the elemental composition of the hydrocarbons (carbon and hydrogen) and nitrogen in the carbon source during the raw gas generation process, or by appropriately changing combustion conditions such as the combustion temperature and the oxygen concentration of the gas supplied during combustion. For example, if you want to change the carbon monoxide or hydrogen concentration, you can change the carbon source to one with a higher ratio of hydrocarbons (carbon and hydrogen), such as waste plastic, or if you want to lower the nitrogen concentration, you can supply a gas with a higher oxygen concentration during the raw gas generation process.

In addition to the components described above, the synthetic gas used in the present invention may contain, without limitation, sulfur compounds, phosphorus compounds, nitrogen compounds, etc. The content of each of these compounds is preferably 0.05 mg/L or more, more preferably 0.1 mg/L or more, even more preferably 0.5 mg/L or more, and preferably 2000 mg/L or less, more preferably 1000 mg/L or less, even more preferably 80 mg/L or less, even more preferably 60 mg/L or less, and particularly preferably 40 mg/L or less. Setting the content of sulfur compounds, phosphorus compounds, nitrogen compounds, etc. at or above the lower limit has the advantage of allowing microorganisms to be cultured optimally, while setting the content at or below the upper limit has the advantage of preventing contamination of the culture medium with various nutrient sources not consumed by the microorganisms.

Examples of sulfur compounds include sulfur dioxide, _CS2 , COS, and _H2S , and among these, _H2S and sulfur dioxide are preferred because they are easily consumed as a nutrient source for microorganisms. Therefore, it is more preferable that the sum of _H2S and sulfur dioxide contained in the synthesis gas is within the above range.
As the phosphorus compound, phosphoric acid is preferred because it is easily consumed as a nutrient source for microorganisms, and therefore it is more preferred that the synthesis gas contain phosphoric acid in the above range.
Examples of nitrogen compounds include nitric oxide, nitrogen dioxide, acrylonitrile, acetonitrile, and HCN, and HCN is preferred because it is easily consumed as a nutrient source for microorganisms. Therefore, it is more preferable that HCN is contained in the synthesis gas in the above range.

The synthetic gas may also contain aromatic compounds in an amount of 0.01 mg/L or more and 90 mg/L or less, preferably 0.03 mg/L or more, more preferably 0.05 mg/L or more, and even more preferably 0.1 mg/L or more, and preferably 70 mg/L or less, more preferably 50 mg/L or less, and even more preferably 30 mg/L or less. A content equal to or greater than the lower limit tends to enable favorable cultivation of microorganisms, while a content equal to or less than the upper limit tends to prevent the culture medium from being contaminated by various nutrient sources not consumed by the microorganisms.

<Microbial fermentation process>
The microbial fermentation step is a step of producing ethanol by microbial fermentation of the synthesis gas in a microbial fermenter. The microbial fermenter is preferably a continuous fermentation apparatus. Generally, any shape of microbial fermenter can be used, including stirred, airlift, bubble column, loop, open bond, and photobio types. In the present invention, a known loop reactor having a main tank section and a reflux section can be suitably used as the microbial fermenter. In this case, it is preferable to further include a circulation step of circulating the liquid medium between the main tank section and the reflux section.

As long as the synthesis gas supplied to the microbial fermenter satisfies the above-mentioned synthesis gas component requirements, the gas obtained through the feed gas production process may be used as is, or another specified gas may be added to the gas obtained by reducing or removing impurities from the feed gas before use. As the other specified gas, at least one compound selected from the group consisting of sulfur compounds such as sulfur dioxide, phosphorus compounds, and nitrogen compounds may be added to produce the synthesis gas.

Synthesis gas and microbial culture medium may be supplied continuously to the microbial fermenter, but they do not need to be supplied simultaneously; synthesis gas may be supplied to a microbial fermenter that has already been supplied with microbial culture medium. Certain anaerobic microorganisms are known to produce ethanol and other substances from substrate gases such as synthesis gas through fermentation, and these types of gas-assimilating microorganisms are cultured in a liquid medium. For example, a liquid medium and gas-assimilating bacteria may be supplied and housed, and synthesis gas may be supplied into the microbial fermenter while the liquid medium is stirred in this state. This allows gas-assimilating bacteria to be cultured in the liquid medium, and ethanol to be produced from synthesis gas through the fermentation process.

In the microbial fermenter, the temperature of the culture medium (culture temperature) may be any temperature, but is preferably around 30 to 45°C, more preferably around 33 to 42°C, and even more preferably around 36.5 to 37.5°C. The culture time is preferably 12 hours or more in continuous culture, more preferably 7 days or more, particularly preferably 30 days or more, and most preferably 60 days or more. There is no specific upper limit, but from the perspective of regular equipment maintenance, it is preferably 720 days or less, and more preferably 365 days or less. The culture time refers to the time from when the seed culture is added to the culture tank until the entire culture medium in the culture tank is discharged.

The microorganisms (species) contained in the microbial culture solution are not particularly limited, as long as they are capable of producing ethanol through microbial fermentation of syngas using carbon monoxide as the main feedstock. For example, it is preferable that the microorganisms (species) produce ethanol from syngas through the fermentation action of gas-utilizing bacteria, and that they are microorganisms that have a metabolic pathway for acetyl-COA. Among gas-utilizing bacteria, the genus Clostridium is more preferable, and Clostridium autoethanogenum is particularly preferable, but is not limited to these. Further examples are provided below.

Gas-assimilating bacteria include both eubacteria and archaea. Examples of eubacteria include bacteria of the genus Clostridium, Moorella, Acetobacterium, Carboxydocella, Rhodopseudomonas, Eubacterium, Butyribacterium, Oligotropha, Bradyrhizobium, and the aerobic hydrogen-oxidizing bacteria of the genus Larsotonia.

On the other hand, examples of archaea include bacteria of the genus Methanobacterium, bacteria of the genus Methanobrevibacter, bacteria of the genus Methanocalculus, bacteria of the genus Methanococcus, bacteria of the genus Methanosarcina, bacteria of the genus Methanosphaera, bacteria of the genus Methanothermobacter, Metha Examples include bacteria of the genus Nothrix, bacteria of the genus Methanoculleus, bacteria of the genus Methanofollis, bacteria of the genus Methanogenium, bacteria of the genus Methanospirillium, bacteria of the genus Methanosaeta, bacteria of the genus Thermococcus, bacteria of the genus Thermofilum, bacteria of the genus Arcaheoglobus, and the like. Among these, as archaea, bacteria of the genus Methanosarcina, bacteria of the genus Methanococcus, bacteria of the genus Methanothermobacter, bacteria of the genus Methanothrix, bacteria of the genus Thermococcus, bacteria of the genus Thermofilum, and bacteria of the genus Archaeoglobus are preferred.

Furthermore, due to their excellent ability to assimilate carbon monoxide and carbon dioxide, archaea of the genus Methanosarcina, Methanothermobactor, or Methanococcus are preferred, with Methanosarcina or Methanococcus being particularly preferred. Specific examples of Methanosarcina bacteria include Methanosarcina barkeri, Methanosarcina mazei, and Methanosarcina acetivorans.

Among the gas-utilizing bacteria described above, bacteria with high ethanol production ability are selected and used. For example, gas-utilizing bacteria with high ethanol production ability include Clostridium autoethanogenum, Clostridium
Examples of suitable bacteria include Clostridium ljungdahlii, Clostridium aceticum, Clostridium carboxidivorans, Moorella thermoacetica, and Acetobacterium woodii, and among these, Clostridium autoethanogenum is particularly preferred.

The medium used to cultivate the above-mentioned microorganisms (species) is not particularly limited as long as it has an appropriate composition for the bacteria, but is a liquid containing water as the main component and nutrients (e.g., vitamins, phosphate, etc.) dissolved or dispersed in the water. The composition of such a medium is prepared so that gas-assimilating bacteria can grow well. For example, when using Clostridium as the microorganism, reference can be made to paragraphs "0097" to "0099" of U.S. Patent Application Publication No. 2017/260552, etc., for the medium.

The ethanol-containing liquid obtained from the microbial fermentation process is obtained as a suspension containing microorganisms, their remains, and proteins derived from the microorganisms. The protein concentration in the suspension varies depending on the type of microorganism, but is usually 30 to 1,000 mg/L. The protein concentration in the ethanol-containing liquid can be measured using the Kjeldahl method.

<Separation process>
The ethanol-containing liquid obtained by the microbial fermentation process is then subjected to a separation process. In the present invention, the ethanol-containing liquid is heated to room temperature to 500°C under conditions of 0.01 to 1000 kPa (absolute pressure) to separate it into a liquid or solid component containing microorganisms and a gaseous component containing ethanol. In conventional methods, the ethanol-containing liquid obtained by the microbial fermentation process is distilled to separate and purify the desired ethanol. However, because the ethanol-containing liquid contains microorganisms and proteins derived from microorganisms, distilling the ethanol-containing liquid as is can cause foaming in the distillation apparatus, hindering continuous operation. In addition, the use of a membrane evaporator is known as a method for purifying foamable liquids, but membrane evaporators have low concentration efficiency and are not suitable for purifying liquids containing solid components. In the present invention, before separating and purifying the desired ethanol from the ethanol-containing liquid obtained by the microbial fermentation process by distillation or the like, the ethanol-containing liquid is heated to separate it into a liquid or solid component containing microorganisms and a gaseous component containing ethanol, and the desired ethanol is separated and purified from only the separated gaseous component containing ethanol. By carrying out the separation step, foaming does not occur in the distillation apparatus during the distillation operation for separating and purifying ethanol, so that the distillation operation can be carried out continuously. Furthermore, since the ethanol concentration contained in the ethanol-containing gas component becomes higher than the ethanol concentration in the ethanol-containing liquid, ethanol can be separated and purified efficiently in the purification step described below.

In the present invention, from the viewpoint of efficiently separating the liquid or solid component containing microorganisms, their carcasses, and proteins derived from microorganisms from the gas component containing ethanol, the ethanol-containing liquid is heated preferably under conditions of 10 to 200 kPa, more preferably under conditions of 50 to 150 kPa, and even more preferably at atmospheric pressure, at a temperature of preferably 50 to 200°C, more preferably 80 to 180°C, and even more preferably 100 to 150°C.

There are no particular restrictions on the heating time in the separation step, as long as it is long enough to obtain the gaseous components. However, from the standpoint of efficiency and economy, it is usually 5 seconds to 2 hours, preferably 5 seconds to 1 hour, and more preferably 5 seconds to 30 minutes.

The above-mentioned separation process can be carried out using any device that can efficiently separate the ethanol-containing liquid into liquid or solid components (microorganisms, their carcasses, proteins derived from microorganisms, etc.) and gaseous components (ethanol) using thermal energy. For example, drying devices such as rotary dryers, fluidized bed dryers, vacuum dryers, and conduction heating dryers can be used. However, from the perspective of efficiency in separating an ethanol-containing liquid with a low solid component concentration into liquid or solid components and gaseous components, it is preferable to use a conduction heating dryer. Examples of conduction heating dryers include drum dryers and disk dryers.

<Liquefaction process>
The liquefaction step is a step of liquefying the gaseous components containing ethanol obtained in the separation step by condensation. The apparatus used in the liquefaction step is not particularly limited, but it is preferable to use a heat exchanger, particularly a condenser. Examples of condensers include water-cooled, air-cooled, and evaporative types, with water-cooled types being preferred. The condenser may be a single-stage or multi-stage type.

It is preferable that the liquefied product obtained by the liquefaction process does not contain components that were contained in the ethanol-containing liquid, such as microorganisms, their remains, or proteins derived from microorganisms. However, the present invention does not exclude the inclusion of proteins in the liquefied product. Even if the liquefied product contains proteins, the concentration is preferably 40 mg/L or less, more preferably 20 mg/L or less, and even more preferably 15 mg/L or less.

The heat of condensation of the gaseous components obtained by the condenser may be reused as a heat source in the purification process described below. By reusing the heat of condensation, ethanol can be produced efficiently and economically.

<Refining process>
Next, ethanol is purified from the liquefied product obtained in the liquefaction step. If components such as microorganisms have already been removed, the ethanol-containing liquid obtained in the microbial fermentation step can be supplied to the purification step without undergoing the above-mentioned separation step. The purification step is a step in which the ethanol-containing liquid obtained in the liquefaction step is separated into a distillate having an increased concentration of the target ethanol and a bottoms liquid having a decreased concentration of the target ethanol. Examples of equipment used in the purification step include a distillation apparatus, a treatment apparatus including a pervaporation membrane, a treatment apparatus including a zeolite dehydration membrane, a treatment apparatus for removing low-boiling substances having a boiling point lower than that of ethanol, a treatment apparatus for removing high-boiling substances having a boiling point higher than that of ethanol, and a treatment apparatus including an ion exchange membrane. These apparatuses may be used alone or in combination of two or more. Thermal distillation or membrane separation may be suitably used as a unit operation.

In thermal distillation, a distillation apparatus is used to obtain the desired ethanol as a distillate with high purity. The temperature inside the distillation apparatus during ethanol distillation is not particularly limited, but is preferably 100°C or below, and more preferably approximately 70-95°C. Setting the temperature inside the distillation apparatus within this range ensures separation of ethanol from other components, i.e., ethanol distillation. In particular, the ethanol-containing liquid obtained in the liquefaction process is introduced into a distillation apparatus equipped with a heater using steam at 100°C or higher. The temperature at the bottom of the distillation column is raised to 90°C or above within 30 minutes, and the ethanol-containing liquid is then introduced into the middle of the distillation column. High-purity ethanol can be obtained by performing the distillation process with a temperature difference between the bottom, middle, and top of the column within ±15°C. The distillation temperature difference is preferably ±13°C, more preferably ±11°C. This distillation temperature difference ensures separation from other components, i.e., ethanol distillation.

The distillation apparatus preferably uses multiple distillation columns. In this case, it is preferable to use a treatment device containing an ion exchange membrane between the distillation columns. In the present invention, by passing the ethanol through an ion exchange membrane, the concentrations of sodium ions and potassium ions can be controlled, thereby adjusting the sodium and potassium contents in the final ethanol to within a suitable range.

The pressure inside the distillation apparatus during ethanol distillation may be normal pressure, but is preferably below atmospheric pressure, and more preferably approximately 60 to 95 kPa (absolute pressure). Setting the pressure inside the distillation apparatus within this range improves the ethanol separation efficiency and ultimately the ethanol yield. The ethanol yield (the concentration of ethanol in the distillate after distillation) is preferably 90% by volume or more, and more preferably 95% by volume or more.

For membrane separation, known separation membranes can be used as appropriate, and zeolite membranes, for example, are suitable.

The concentration of ethanol contained in the distillate separated in the purification step is preferably 20% by volume to 99.99% by volume, and more preferably 60% by volume to 99.9% by volume.
On the other hand, the concentration of ethanol contained in the bottoms is preferably 0.001% by volume to 10% by volume, and more preferably 0.01% by volume to 5% by volume.

The bottoms separated in the purification process are substantially free of nitrogen compounds. Note that, in the present invention, "substantially free" does not mean that the nitrogen compound concentration is 0 mg/L, but rather that the bottoms obtained in the purification process have a nitrogen compound concentration low enough that a wastewater treatment process is not required. In the separation process, the desired ethanol is not purified from the ethanol-containing liquid obtained in the microbial fermentation process, but rather the ethanol-containing liquid is separated into a liquid or solid component containing microorganisms and a gaseous component containing ethanol, as described above. During this process, the nitrogen compounds remain in the liquid or solid component containing microorganisms, and the gaseous component containing ethanol contains almost no nitrogen compounds. Therefore, the bottoms obtained when ethanol is purified from a liquid obtained by liquefying the gaseous component are considered to be substantially free of nitrogen compounds. Even if the bottoms contain nitrogen compounds, the concentration of nitrogen compounds is 0.1 to 200 mg/L, preferably 0.1 to 100 mg/L, and more preferably 0.1 to 50 mg/L.

Furthermore, for the same reasons as above, the bottoms separated in the purification process are substantially free of phosphorus compounds. Note that "substantially free" does not mean that the phosphorus compound concentration is 0 mg/L, but rather that the bottoms obtained in the purification process have a phosphorus compound concentration at a level that does not require a wastewater treatment process. Even if the bottoms contain phosphorus compounds, the phosphorus compound concentration is 0.1 to 100 mg/L, preferably 0.1 to 50 mg/L, and more preferably 0.1 to 25 mg/L. Thus, according to the method of the present invention, the bottoms discharged in the ethanol purification process are substantially free of nitrogen compounds and phosphorus compounds, and are considered to contain almost no other organic matter, thereby simplifying the wastewater treatment process that was previously required.

<Wastewater treatment process>
The bottoms separated in the refining step may be supplied to a wastewater treatment step. In the wastewater treatment step, organic matter such as nitrogen compounds and phosphorus compounds may be further removed from the bottoms. In this step, the bottoms may be subjected to anaerobic or aerobic treatment to remove the organic matter. The removed organic matter may be used as fuel (heat source) in the refining step.

The treatment temperature in the wastewater treatment process is usually 0 to 90°C, preferably 20 to 40°C, and more preferably 30 to 40°C.

The bottoms obtained through the separation process have had liquid and solid components, including microorganisms, removed, so the burden of wastewater treatment and other processes is reduced compared to bottoms obtained by supplying the bottoms directly from the microbial fermentation process to the purification process.

In the wastewater treatment process, the nitrogen compound concentration in the treated liquid obtained by treating the bottoms is preferably 0.1 to 30 mg/L, more preferably 0.1 to 20 mg/L, and even more preferably 0.1 to 10 mg/L, and it is particularly preferable that no nitrogen compounds are contained. Furthermore, the phosphorus compound concentration in the treated liquid is preferably 0.1 to 10 mg/L, more preferably 0.1 to 5 mg/L, and even more preferably 0.1 to 1 mg/L, and it is particularly preferable that no phosphorus compounds are contained in the bottoms.

<Uses of ethanol>
The ethanol of the present invention can be used as a raw material for producing various organic compounds. For example, the ethanol of the present invention can be used as a raw material for producing butadiene, ethylene, propylene, isobutene, acetaldehyde, acetic acid, ethyl acetate, methyl (meth)acrylate, ethyl t-butyl ether ethylene glycol, ester compositions, polyesters, acrylic acid, aminohexanoic acid, diethyl carbonate, polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polyisobutylene, polymethyl methacrylate (PMMA), ethylene propylene diene rubber (EPDM), polybutylene terephthalate (PBT), polyethylene furanoate (PEF), polyurethane (PU), and the like. Below, a method for synthesizing butadiene using the ethanol of the present invention as a raw material and a method for producing polyethylene and polyester are described as examples, but it goes without saying that the ethanol of the present invention can also be used as a raw material for other chemical products and polymers.

<Method for synthesizing butadiene>
Butadiene is primarily produced by refining the C4 fraction, a by-product of synthesizing ethylene from petroleum (i.e., naphtha cracking), and is a raw material for synthetic rubber. However, in recent years, there has been a strong demand for technology that converts ethanol (ethanol derived from microbial fermentation) that is not derived from fossil fuels into 1,3-butadiene, instead of using petroleum-derived chemical raw materials. Known methods for synthesizing butadiene using such ethanol derived from microbial fermentation as a raw material include a method using MgO as a catalyst, a method using a mixture of Al ₂ O ₃ and ZnO, and a catalyst having a magnesium silicate structure. In addition to the above, vanadium, manganese, iron, cobalt, nickel, copper, zinc, gallium, niobium, silver, indium, cerium, etc. are also used as catalysts.

By contacting the ethanol of the present invention with the above-mentioned catalyst and heating it, an ethanol conversion reaction occurs, allowing the synthesis of 1,3-butadiene. By synthesizing butadiene using the ethanol of the present invention as a raw material, it becomes possible to realize an ultimate resource-circulating society that is not dependent on petroleum resources.

The heating temperature required to promote the conversion reaction is, for example, 300 to 450°C, preferably 350 to 400°C, within the reaction system. If the temperature within the reaction system falls below this range, the catalyst activity will be insufficient, resulting in a slower reaction rate and reduced production efficiency. On the other hand, if the temperature within the reaction system exceeds this range, the catalyst may be more susceptible to degradation.

The reaction can be carried out by conventional methods such as batch, semi-batch, or continuous. Using a batch or semi-batch system can increase the ethanol conversion rate, but with the ethanol of the present invention, even when using a continuous system, ethanol can be converted more efficiently than conventional methods. The reason for this is unclear, but it is thought to be due to the fact that ethanol derived from recycled resources, such as that of the present invention, which uses gas containing carbon monoxide and hydrogen as substrates, exhibits a unique peak in a gas chromatogram measured by gas chromatography-mass spectrometry that is not seen in ethanol derived from fossil fuels.

Methods for contacting the raw materials with the catalyst include, for example, a suspension bed method, a fluidized bed method, and a fixed bed method. Either a gas phase method or a liquid phase method may be used. From the viewpoint of easy catalyst recovery and regeneration, it is preferable to use a fixed-bed continuous gas phase flow reactor in which the catalyst is packed into a reaction tube to form a catalyst layer and the raw materials are circulated as a gas to carry out the reaction in the gas phase. When carrying out the reaction in the gas phase, the ethanol of the present invention may be gasified and supplied to the reactor without dilution, or it may be appropriately diluted with an inert gas such as nitrogen, helium, argon, or carbon dioxide and supplied to the reactor.

After the ethanol conversion reaction is complete, the reaction product (1,3-butadiene) can be separated and purified using separation methods such as filtration, concentration, distillation, extraction, or a combination of these.

<Polyethylene>
The ethanol of the present invention can also be suitably used as a raw material for polyethylene, a versatile general-purpose plastic. Conventional polyethylene is produced by synthesizing ethylene from petroleum and polymerizing the ethylene monomer. By producing polyethylene using the ethanol of the present invention, it becomes possible to realize an ultimate resource-circulating society that is not dependent on petroleum resources.

First, ethylene, a raw material for polyethylene, is synthesized using the ethanol of the present invention as a raw material. The method for producing ethylene is not particularly limited, and it can be obtained by conventionally known methods. As an example, ethylene can be obtained by the dehydration reaction of ethanol. A catalyst is typically used to obtain ethylene by the dehydration reaction of ethanol, but this catalyst is not particularly limited, and conventionally known catalysts can be used. A fixed-bed flow reaction is advantageous from a process standpoint, as it allows for easy separation of the catalyst and the product; for example, gamma-alumina is preferred.

Since the dehydration reaction is an endothermic reaction, it is usually carried out under heated conditions. There are no restrictions on the heating temperature as long as the reaction proceeds at a commercially useful reaction rate, but temperatures of 100°C or higher are preferred, more preferably 250°C or higher, and even more preferably 300°C or higher. There are no particular restrictions on the upper limit, but from the perspective of energy balance and equipment, it is preferably 500°C or lower, more preferably 400°C or lower.

The reaction pressure is not particularly limited, but a pressure above atmospheric pressure is preferred to facilitate subsequent gas-liquid separation. Industrially, a fixed-bed flow reaction is preferred, as it facilitates catalyst separation, but a liquid-phase suspension bed or fluidized bed may also be used.

In ethanol dehydration reactions, the reaction yield depends on the amount of water contained in the ethanol supplied as a raw material. Generally, when performing a dehydration reaction, it is preferable to avoid water, considering the efficiency of water removal. However, in the case of ethanol dehydration reactions using a solid catalyst, the absence of water tends to increase the amount of other olefins, particularly butene, produced. The lower limit of the allowable water content is 0.1% by mass or more, preferably 0.5% by mass or more. There are no particular upper limits, but from the standpoint of material balance and heat balance, it is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

By carrying out the ethanol dehydration reaction as described above, a mixture of ethylene, water, and a small amount of unreacted ethanol is obtained. However, because ethylene is in a gaseous state at room temperature and below approximately 5 MPa, water and ethanol can be removed from this mixture by gas-liquid separation to obtain ethylene. This method can be carried out by any known method. The ethylene obtained by gas-liquid separation is then further distilled. There are no particular restrictions on the distillation method, operating temperature, residence time, etc., except that the operating pressure must be above atmospheric pressure.

Ethanol derived from recyclable resources, such as that produced in the present invention using carbon monoxide- and hydrogen-containing gases as substrates, exhibits a unique peak in gas chromatographs measured by gas chromatography-mass spectrometry that is not seen in ethanol derived from fossil fuels. Therefore, it is believed that ethylene obtained from ethanol contains trace amounts of impurities. Depending on the intended use of ethylene, these trace amounts of impurities may be problematic, so they may be removed by purification. The purification method is not particularly limited, and conventionally known methods can be used. An example of a suitable purification procedure is adsorption purification. The adsorbent used is not particularly limited, and conventionally known adsorbents can be used. For example, caustic water treatment may be used in combination as a method for purifying impurities in ethylene. If caustic water treatment is performed, it is preferable to perform it before adsorption purification. In that case, a water removal treatment is required after caustic treatment and before adsorption purification.

The polymerization method for ethylene-containing monomers is not particularly limited and can be carried out by conventionally known methods. The polymerization temperature and polymerization pressure should be adjusted appropriately depending on the polymerization method and polymerization apparatus. The polymerization apparatus is also not particularly limited and conventionally known apparatus can be used. An example of a method for polymerizing ethylene-containing monomers is described below.

The polymerization method for polyolefins, particularly ethylene polymers and copolymers of ethylene and α-olefins, can be selected appropriately depending on the type of polyethylene desired, such as differences in density and branching, such as high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE). For example, it is preferable to use a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst as the polymerization catalyst, and to carry out the polymerization in one or more stages using one of the following methods: gas-phase polymerization, slurry polymerization, solution polymerization, or high-pressure ionic polymerization.

The single-site catalyst is a catalyst capable of forming a uniform active species, and is typically prepared by contacting a metallocene transition metal compound or a non-metallocene transition metal compound with an activating cocatalyst. Single-site catalysts are preferred because, compared to multi-site catalysts, they have a uniform active site structure and can polymerize polymers with high molecular weights and highly uniform structures. Metallocene catalysts are particularly preferred as single-site catalysts. Metallocene catalysts are catalysts that contain the following catalytic components: a transition metal compound of Group IV of the periodic table containing a ligand with a cyclopentadienyl skeleton, a cocatalyst, and, optionally, an organometallic compound and a carrier.

In transition metal compounds of Group IV of the periodic table that contain a ligand having a cyclopentadienyl skeleton, the cyclopentadienyl skeleton can be a cyclopentadienyl group, a substituted cyclopentadienyl group, or the like. Substituted cyclopentadienyl groups have a substituent such as a hydrocarbon group having 1 to 30 carbon atoms. Examples of transition metals include zirconium, titanium, and hafnium, with zirconium and hafnium being particularly preferred. The transition metal compound typically contains two ligands having a cyclopentadienyl skeleton, and it is preferred that the respective cyclopentadienyl ligands are bonded to each other via a bridging group. The above transition metal compounds can be used alone or as a mixture of two or more types as the catalyst component.

The co-catalyst refers to a substance that can effectively make the transition metal compounds described above function as polymerization catalysts or that can balance the ionic charge in a catalytically activated state. Examples of co-catalysts include benzene-soluble aluminoxanes of organoaluminum oxy compounds and benzene-insoluble organoaluminum oxy compounds, ion-exchangeable layered silicates, boron compounds, ionic compounds consisting of a cation with or without an active hydrogen group and a non-coordinating anion, lanthanoid salts such as lanthanum oxide, tin oxide, and phenoxy compounds containing a fluoro group.

The transition metal compounds may be used by being supported on an inorganic or organic carrier, preferably an inorganic or organic porous oxide, such as montmorillonite or other ion-exchange layered silicates, SiO ₂ , _{Al 2} O ₃ , MgO, ZrO 2 , TiO ₂ , B ₂ O ₃ , CaO, ZnO, BaO, ThO ₂ , or mixtures thereof.

Further examples of organometallic compounds that may be used if necessary include organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Of these, organoaluminum compounds are preferred.

Furthermore, as the polyolefin, ethylene polymers and copolymers of ethylene and α-olefins may be used alone or in combination of two or more types.

<Acetaldehyde>
Acetaldehyde is an important industrial chemical, useful as a raw material for, for example, acetic acid and ethyl acetate.

Acetaldehyde can be produced by oxidizing ethanol using conventional methods. For example, acetaldehyde can be produced by oxidizing ethanol with chlorine. Chlorine is typically reacted with ethanol in a gaseous state. Chlorine may be supplied at a concentration of approximately 100%, or it may be diluted with an inert gas (e.g., nitrogen, helium, neon, argon, etc.). In this case, the degree of dilution is 50% by weight or less, preferably 25% by weight or less, taking into account reaction efficiency. Ethanol and chlorine are preferably reacted at a supply rate of 25 to 100 sccm per 100 g of aqueous ethanol solution, for example.

Oxidation of ethanol with chlorine is preferably carried out using a chlorine-containing compound such as chlorine gas, hydrogen chloride, phosphorus pentachloride, phosphorus trichloride, phosphorus oxychloride, thionyl chloride, or a hypochlorous acid compound. This oxidation can be achieved, for example, by photoreaction, thermal reaction, catalytic reaction, or the like. Among these, photochlorination and thermal chlorination of ethanol with chlorine gas are preferred, with photochlorination with chlorine gas being more preferred. Photoreactions include irradiation with light of various wavelengths, such as ultraviolet light and visible light. Of these, irradiation with light from a light source having a wavelength of approximately 300 to 500 nm is preferred. The light source is not particularly limited, and examples include fluorescent lamps, mercury lamps, halogen lamps, xenon lamps, metal halide lamps, excimer lamps, and LED lamps. The reaction temperature is approximately 0 to 80°C, preferably approximately 0 to 50°C. The reaction time is approximately 1 to 5 hours.

As another example, acetaldehyde can be produced by oxidizing ethanol in the gas phase in the presence of oxygen molecules and a catalyst. For example, a base metal oxide with gold particles dispersed and fixed therein can be used as the catalyst. Examples of base metal oxides include _La2O3 , _MoO3 , _Bi2O3 , _SrO , _Y2O3 , MgO, BaO, _WO3 , _{CuO ,} and composite oxides containing one or more of these.

The oxidation reaction of ethanol is carried out by contacting a gas containing ethanol and molecular oxygen with the catalyst at, for example, 100 to 280°C. The molecular oxygen used in the reaction may be supplied as oxygen gas or air. The raw material gas may contain a dilution gas (carrier gas) as needed. The reaction apparatus used in this reaction may be any conventional apparatus typically used for gas-phase reactions. For example, a catalyst is filled into a reaction tube, the reaction tube is heated to a predetermined temperature, and a gas containing ethanol and oxygen gas or air is introduced into the reaction tube. The raw material gas is brought into contact with the catalyst, and the reaction gas is recovered. The reaction pressure can be atmospheric pressure, or, if necessary, increased to approximately 0.5 to 5 Pa (atmospheres). Examples of dilution gases include so-called inert gases such as nitrogen, argon, helium, and carbon dioxide. The amount of dilution gas used can be determined appropriately taking into account the composition, flow rate, and heat of reaction of the raw material gas, but is typically 1 to 100 times the volume of ethanol.

The ratio of ethanol to oxygen molecules (oxygen gas) supplied to the reaction tube is not particularly limited, but is usually 0.5 to 100% by volume of oxygen gas or oxygen gas in air relative to ethanol, preferably 1 to 10% by volume, and more preferably 2 to 5% by volume. The amount of catalyst used is also not particularly limited, but if the inner diameter of the reaction tube is 6 to 10 mm, it is generally sufficient to use about 0.1 to 1.0 g. Practically, in relation to the gas flow rate, it is preferable to use an amount such that the space velocity (SV) is within the range of about 10,000 to 40,000 hr ^-1 ml g _cat ^-1 .

Acetaldehyde can also be produced by dehydrogenating ethanol in the presence of a catalyst. Examples of such catalysts include solid catalysts containing copper as the active species. The copper as the active species may be in any form that is active in converting ethanol to acetaldehyde, such as metallic copper (elementary copper) or a copper compound (oxide, hydroxide, copper salt (inorganic acid salts such as copper sulfate, copper phosphate, copper nitrate, and copper carbonate; organic acid salts such as copper salts of carboxylic acids), etc.). The solid catalyst may contain at least one species selected from these elemental copper and copper compounds. The copper as the active species is preferably in the form of metallic copper. Copper may be used as metallic copper or a copper compound, either directly or supported on a carrier. The copper as the active species acts as the primary catalyst of the solid catalyst, and may be used in combination with a co-catalyst. The solid catalyst may also be in a form in which both the copper and the co-catalyst are supported on a carrier.

The above dehydrogenation reaction can be a liquid-phase reaction as long as it brings ethanol into contact with a solid catalyst. However, it is typically a gas-phase reaction in which gaseous ethanol is brought into contact with a solid catalyst in the gas phase. Considering the equilibrium between ethanol and acetaldehyde and catalyst life, the reaction temperature may be around 150 to 350°C, preferably 170 to 300°C, and more preferably 200 to 280°C. Note that the higher the reaction temperature, the more the equilibrium shifts toward acetaldehyde, thereby improving the conversion rate. The reaction may be carried out under pressure, but for convenience, it may also be carried out under atmospheric pressure. It can also be carried out under reduced pressure, which is advantageous for ethanol conversion.

<Acetic acid>
Acetic acid is an important industrial chemical, useful as a raw material for, for example, vinyl acetate monomer, acetic anhydride, and acetate esters.

Acetic acid can be produced by the oxidation of acetaldehyde using conventional methods. For example, acetic acid can be produced by air oxidation of acetaldehyde in the presence of a catalyst. Examples of catalysts include manganese acetate and cobalt acetate.

<Ethyl t-butyl ether>
Ethyl tert-butyl ether (ETBE) is an important chemical used as an industrial raw material. ETBE is useful, for example, as a substitute for gasoline, particularly as a premium fuel.

ETBE can be synthesized from ethanol and isobutene using conventional methods. For example, it can be produced by reacting ethanol and isobutene in the presence of a reaction catalyst. The molar ratio of isobutene to the raw material ethanol is preferably 0.1 to 10 moles, and more preferably 0.5 to 2 moles.

As the reaction catalyst, a cation exchange resin is preferably used, and a strongly acidic cation exchange resin is more preferably used. As such a strongly acidic cation exchange resin, a porous type (MR type) styrene-based resin into which strong acid groups such as sulfonic acid groups (—SO ₃ H) have been introduced as ion exchange groups is preferred. The particle size of the strongly acidic cation exchange resin is preferably 0.5 to 1.0 mm. The amount of reaction catalyst used is preferably 1 to 90 g, more preferably 1 to 90 g, and even more preferably 4 to 9 g per mole of ethanol.

The reaction catalyst may be used in any manner, including in a fixed bed, fluidized bed, or suspension bed. There are no particular restrictions on the manner in which isobutene and ethanol are reacted, but a pressurized gas-liquid mixed-phase reaction method, which maintains the ethanol in a liquid phase, is preferred. This method further improves the yield of ETBE.

<Ester>
A wide variety of esters can be synthesized by reacting ethanol with various carboxylic acids. For example, ethyl benzoate can be obtained from ethanol and benzoic acid, and diethylene glycol, a raw material for polyester, can also be obtained from ethanol via ethylene. By producing polyethylene using the ethanol of the present invention, it is possible to realize an ultimate resource-recycling society that is not dependent on petroleum resources.

The polyester is composed of diol units and dicarboxylic acid units, and is obtained by a polycondensation reaction using ethylene glycol as the diol units and terephthalic acid, isophthalic acid, or the like as the dicarboxylic acid units. The ethanol used in the present invention is used as a raw material for the ethylene glycol, and ethylene glycol can be obtained, for example, by converting ethanol to ethylene oxide using a conventional method.

Dicarboxylic acids can include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and their derivatives. Examples of aromatic dicarboxylic acids include terephthalic acid and isophthalic acid. Examples of aromatic dicarboxylic acid derivatives include lower alkyl esters of aromatic dicarboxylic acids, such as methyl esters, ethyl esters, propyl esters, and butyl esters. Among these, terephthalic acid is preferred, and dimethyl terephthalate is preferred as a derivative of an aromatic dicarboxylic acid. Examples of aliphatic dicarboxylic acids include linear or alicyclic dicarboxylic acids typically containing 2 to 40 carbon atoms, such as oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, and cyclohexanedicarboxylic acid. Examples of aliphatic dicarboxylic acid derivatives include lower alkyl esters of the above aliphatic dicarboxylic acids, such as methyl esters, ethyl esters, propyl esters, and butyl esters, as well as cyclic acid anhydrides of the above aliphatic dicarboxylic acids, such as succinic anhydride. Among these, adipic acid, succinic acid, dimer acid, or a mixture thereof is preferred, with those containing succinic acid as the main component being particularly preferred. As derivatives of aliphatic dicarboxylic acids, methyl esters of adipic acid and succinic acid, or a mixture thereof, are more preferred.

The polyester can be obtained by a conventionally known method of polycondensing the above-mentioned diol units and dicarboxylic acid units. Specifically, it can be produced by a common melt polymerization method in which an esterification reaction and/or transesterification reaction between the above-mentioned dicarboxylic acid component and diol component is carried out, followed by a polycondensation reaction under reduced pressure, or by a known solution heating dehydration condensation method using an organic solvent.

The polycondensation reaction is preferably carried out in the presence of a polymerization catalyst, such as a titanium compound, a zirconium compound, or a germanium compound.

The reaction temperature for the esterification reaction and/or transesterification reaction between the dicarboxylic acid component and the diol component is typically in the range of 150 to 260°C, and the reaction atmosphere is typically an inert gas atmosphere such as nitrogen or argon.

In the polycondensation reaction step, a chain extender (coupling agent) may be added to the reaction system. After polycondensation is complete, the chain extender is added to the reaction system in a homogeneous molten state without a solvent, and is reacted with the polyester obtained by polycondensation.

After solidification, the resulting polyester may be further subjected to solid-state polymerization, if necessary, to increase the degree of polymerization or to remove oligomers such as cyclic trimers.

During the polyester manufacturing process, various additives may be added as long as they do not impair the polyester's properties. Examples of additives that can be added include plasticizers, UV stabilizers, color inhibitors, matting agents, deodorizers, flame retardants, weather resistance agents, antistatic agents, friction reducers, release agents, antioxidants, ion exchange agents, and color pigments.

The ethanol produced by this invention can be used as a raw material for a variety of polymers, not just the polymers mentioned above. Because the resulting polymer molded products are carbon-neutral, it will be possible to realize the ultimate resource-circulating society that is not dependent on petroleum resources.

<Products containing ethanol>
The ethanol of the present invention can be used not only as a polymer raw material as described above, but also in a variety of other products. Examples of such products include cosmetics, perfumes, fuels, antifreeze, disinfectants, sanitizers, cleaning agents, mold removers, detergents, hair washes, soaps, antiperspirants, facial cleansing sheets, solvents, paints, adhesives, diluents, and food additives. By using it in these applications, it can exhibit effects appropriate for each application.

<Fuel>
The ethanol according to the present invention can also be used as a raw material for fuels (e.g., jet fuel, kerosene, diesel, gasoline), etc. Because ethanol has high bactericidal properties, it can also function as a disinfectant to prevent the proliferation of bacteria in fuel systems such as engines and piping.

The Japan Society of Automotive Engineers of Japan's (2006) standard stipulates that the ethanol concentration in fuel ethanol must be 99.5% by volume or higher. Other countries (such as India) also stipulate that the ethanol concentration in fuel ethanol must be 99.5% by volume or higher. Therefore, ethanol with a purity of 99.5 to 99.9% by volume is suitable for use in dedicated ethanol vehicles. Furthermore, because fuel ethanol can be used for purposes other than dedicated ethanol vehicles, ethanol with a purity of 99.5 to 99.9% by volume is particularly versatile.

The ethanol produced by this invention can also be mixed with gasoline to produce ethanol-blended gasoline. Using ethanol-blended gasoline reduces the environmental impact. The purity of the ethanol used in ethanol-blended gasoline is 92.0% by volume or higher, preferably 95.0% by volume or higher, and more preferably 99.5% by volume or higher.

The ethanol content in ethanol-blended gasoline is preferably 1% by volume or more and 15% by volume or less, more preferably 2% by volume or more and 12% by volume or less, and even more preferably 3% by volume or more and 10% by volume or less. If the ethanol content is 1% by volume or more, the benefit of improving the octane number by blending ethanol can be obtained, and if the ethanol content is 15% by volume or less, evaporation characteristics will not change significantly due to the azeotropic phenomenon with other gasoline base stocks, ensuring proper drivability for gasoline-powered vehicles.

The water content in ethanol-blended gasoline is preferably 0.01% by mass or more and 0.9% by mass or less, and more preferably 0.01% by mass or more and 0.7% by mass or less. The lower limit of the water content depends on the saturated water content of the gasoline base material and the water content of the ethanol, but is essentially around 0.01% by mass. An upper limit of 0.9% by mass or less can prevent phase separation, and even if phase separation occurs, the gasoline layer will ensure proper operation of the gasoline engine. The water content can be measured according to JIS K 2275, "Crude oil and petroleum products - Test method for water content," using, for example, Karl Fischer coulometric titration.

Any commonly used gasoline base stock can be used as the gasoline base stock, and there are no particular limitations. Examples of gasoline base stocks include light naphtha obtained by atmospheric distillation of crude oil, preferably desulfurized light naphtha obtained by desulfurizing it, catalytic reformate obtained by desulfurizing heavy naphtha and then catalytically reforming it, and benzene-free catalytic reformate obtained by removing benzene from heavy naphtha, benzene-free light catalytic reformate, benzene-free heavy catalytic reformate, and mixtures thereof; cracked gasoline obtained by catalytic cracking or hydrocracking, light cracked gasoline, heavy cracked gasoline, and mixtures thereof; and isomerized gasoline obtained by isomerizing light naphtha.

Furthermore, the ethanol-based ETBE of the present invention can be blended with gasoline to produce ETBE-blended gasoline. Using ETBE-blended gasoline reduces the environmental impact. The ETBE content of ETBE-blended gasoline is preferably 1% by volume or more and 15% by volume or less, more preferably 2% by volume or more and 12% by volume or less, and even more preferably 3% by volume or more and 10% by volume or less. An ETBE content of 1% by volume or more provides the benefit of improved octane rating due to blending with ETBE, while a content of 15% by volume or less prevents significant changes in evaporation characteristics due to the azeotropic phenomenon with other gasoline base stocks, ensuring proper drivability for gasoline-powered vehicles.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples as long as they do not depart from the gist of the present invention.

<Ethanol component evaluation method>
In the following Examples and Comparative Examples, the sodium content in ethanol was measured using an ELAN DRC II inductively coupled plasma mass spectrometry (ICP-MS) manufactured by PerkinElmer.

<Butadiene Quantitative Method>
Quantitative evaluation of butadiene was carried out by analysis using a gas chromatography device (GC-2014, manufactured by Shimadzu Corporation). The measurement conditions were as follows.
<GC/MS analysis conditions>
Column: Rt-Q-BOND (length 30 m, inner diameter 0.32 mm, film thickness 10 μm)
Oven temperature: 60°C, 11.5 minutes → 10°C/min → 100°C, 14.5 minutes → 10°C/min → 250°C
Sampling time: 5 minutes Carrier gas: He (30 cm / s)
Split ratio: 75

<Quantitative method for ethyl benzoate>
The quantitative evaluation of ethyl benzoate was carried out by analysis using a gas chromatography device under the following measurement conditions.
<GC/MS analysis conditions>
Column: DB-1 (length 30.0 m, inner diameter 0.254 mm, film thickness 0.25 m)
Temperature increase conditions: 30°C - 300°C 15°C/min
Carrier gas: He 100 kPa
Split ratio: 50

<Combustion efficiency quantification method>
The ethanol combustion efficiency was quantitatively evaluated by gross calorific value analysis using a cone calorimeter manufactured by FTT.

[Example 1]
<Preparation of ethanol>
Ethanol was produced as follows.
(Raw material gas generation process)
The gas discharged after incineration of municipal waste in a waste incineration facility was used. The raw material gas consisted of approximately 30% by volume of carbon monoxide, approximately 30% by volume of carbon dioxide, approximately 30% by volume of hydrogen, and approximately 10% by volume of nitrogen.

(Synthetic gas purification process)
The raw material gas produced as described above was heated to 80°C using a PSA apparatus, which is an impurity removal apparatus, and carbon dioxide contained in the synthesis gas was removed to 60 to 80% by volume of the original content (approximately 30% by volume) under conditions such that the gas temperature was increased. The gas was then heated in a double-pipe heat exchanger using steam at 150°C and re-cooled in a double-pipe heat exchanger using cooling water at 25°C to precipitate impurities, which were then removed using a filter, thereby producing a synthesis gas.

(Microbial fermentation process)
The synthesis gas obtained as described above was continuously supplied to a continuous fermentation apparatus (microbial fermenter) equipped with a main reactor, a synthesis gas inlet, and a discharge port, and filled with an inoculum of Clostridium autoethanogenum (a microorganism) and a liquid culture medium for bacterial culture (containing appropriate amounts of phosphorus compounds, nitrogen compounds, various minerals, etc.), and culture (microbial fermentation) was carried out continuously for 300 hours. After that, approximately 8,000 L of the ethanol-containing culture medium was withdrawn from the discharge port.

(separation process)
The culture solution obtained in the above fermentation step was subjected to a solid-liquid separation filter device under conditions of a culture solution introduction pressure of 200 kPa or more to obtain an ethanol-containing solution.

(Distillation process)
Subsequently, the ethanol-containing liquid was introduced into a distillation apparatus equipped with a heater using steam at 170 ° C. After the temperature of the bottom of the distillation column was raised to 101 ° C. within 8 to 15 minutes, the ethanol-containing liquid was introduced from the middle of the distillation column. During continuous operation, the column bottom was kept at 101 ° C., the middle at 99 ° C., and the top at 91 ° C., and the distillation was continued at 15 sec/L to obtain purified ethanol. The sodium content in the obtained ethanol was 190 mg/L.

(Method for producing butadiene)
Butadiene was produced using the ethanol obtained as described above. First, the obtained ethanol was vaporized through a single tube heated to 90°C to prepare a gas for reaction, and the vaporized ethanol gas was combined with nitrogen. The mass flow was controlled so that the ethanol gas flow rate was 360 L/hr/L and the nitrogen flow rate was 840 L/hr/L, resulting in a mixed gas of 30% by volume (gas equivalent) ethanol and 70% by volume (gas equivalent) nitrogen. Subsequently, the mixed gas was continuously supplied to a stainless steel cylindrical reaction tube with a diameter of 1/2 inch (1.27 cm) and a length of 15.7 inches (40 cm) filled with 0.85 g of a butadiene synthesis catalyst mainly composed of Hf, Zn, and Ce, while maintaining the temperature at 350°C and the pressure (reaction bed pressure) at 0.1 MPa, thereby producing a butadiene-containing gas. The butadiene content of the obtained butadiene-containing gas was quantified using a gas chromatography apparatus GC-2014 (manufactured by Shimadzu Corporation). The results are shown in Table 1.

[Comparative Example 1]
Butadiene was produced in the same manner as in Example 1 using 99% ethanol (manufactured by Amakasu Chemical Industry Co., Ltd.), which is fossil fuel-derived ethanol, and the butadiene content was quantified in the same manner as in Example 1. The results are shown in Table 1. The sodium content in the 99% ethanol, which is fossil fuel-derived ethanol, was 120 mg/L.

[Comparative Example 2]
Butadiene was produced in the same manner as in Example 1 using 99% ethanol (manufactured by Amakasu Chemical Industry Co., Ltd.) derived from the saccharification and fermentation of plants, and the butadiene content was quantified in the same manner as in Example 1. The results are shown in Table 1. The sodium content in the 99% ethanol derived from the saccharification and fermentation of plants was 140 mg/L.

As shown in Table 1, ethanol produced using the gas emitted after incineration of municipal waste in waste incineration plants has a higher conversion efficiency to butadiene than ethanol derived from conventional fossil fuels or ethanol derived from saccharification and fermentation of plants.

[Example 2]
(Production of ethyl benzoate)
Ethyl benzoate was produced using the same ethanol as used in Example 1 as follows. First, 36.8 g of benzoic acid and 200 ml of ethanol were mixed under an argon stream, and 9 ml of concentrated sulfuric acid was added. The mixture was stirred under reflux for 5 hours. The mixture was then allowed to cool to room temperature, and unreacted ethanol was removed under reduced pressure. Ethyl benzoate synthesized with 100 ml of diethyl ether was recovered. The recovered solution was washed with distilled water, dried over magnesium sulfide, and then filtered and concentrated.
The obtained filtrate was subjected to component analysis using a gas chromatograph to quantify the amount of ethyl benzoate synthesized. The analytical conditions are shown below. The analytical results are shown in Table 2.
Column: DB-1 (length 30.0 m, inner diameter 0.254 mm, film thickness 0.25 m)
Temperature increase conditions: 30-300°C, 15°C/min
Carrier gas: He 100 kPa
Split ratio: 50

[Comparative Example 3]
Ethyl benzoate was produced and quantified in the same manner as in Example 2, except that the petrochemical-derived ethanol used in Comparative Example 1 was used. The analytical results are shown in Table 2.

[Comparative Example 4]
Ethyl benzoate was produced and quantified in the same manner as in Example 2, except that the petrochemical-derived ethanol used in Comparative Example 2 was used. The analytical results are shown in Table 2.

As shown in Table 2, ethanol produced using the gas emitted after incineration of municipal waste in waste incineration plants was found to have a higher conversion efficiency to ethyl benzoate than conventional ethanol derived from fossil fuels or ethanol derived from saccharification and fermentation of plants.

[Example 3]
The combustion efficiency of ethanol was quantified using the same ethanol as used in Example 1. The fuel efficiency was quantified by placing 30 g of ethanol in a heat-resistant container measuring 60 mm long x 60 mm wide x 30 mm high under unheated conditions, igniting it, measuring the amount of oxygen lost until the ethanol was completely burned in a cone calorimeter (manufactured by FTT), and calculating the total calorific value based on the amount of oxygen lost. The quantitative results are shown in Table 3.

[Comparative Example 5]
The combustion efficiency of ethanol was quantified in the same manner as in Example 3, except that the ethanol used in Comparative Example 1 was used. The results of the quantification are shown in Table 3.

[Comparative Example 6]
The combustion efficiency of ethanol was quantified in the same manner as in Example 3, except that the ethanol used in Comparative Example 2 was used. The results of the quantification are shown in Table 3.

As shown in Table 3, ethanol produced using the gas emitted after incinerating municipal waste in waste incineration facilities has higher combustion efficiency than ethanol derived from conventional fossil fuels or ethanol derived from saccharification and fermentation of plants.

Claims (13)

a step of producing a raw material gas containing carbon monoxide and hydrogen by gasifying waste as a carbon source; a step of purifying the raw material gas using at least one type of separation device selected from pressure swing adsorption, temperature swing adsorption, and pressure temperature swing adsorption to obtain a synthesis gas containing carbon monoxide and hydrogen; a microbial fermentation step of supplying the synthesis gas to a fermenter containing Clostridium bacteria as microorganisms to obtain an ethanol-containing liquid by microbial fermentation; a separation step of separating the ethanol-containing liquid into microorganisms and/or proteins derived from the microorganisms, and ethanol; and a purification step of purifying the ethanol composition,
A waste-derived ethanol composition containing inorganic components and having a sodium content of 150 mg/L or more and 1000 mg/L or less. A waste-derived ethanol composition obtained by a method comprising: a step of producing a raw material gas containing carbon monoxide and hydrogen by gasifying waste as a carbon source; a step of purifying the raw material gas using at least one type of separation device selected from pressure swing adsorption, temperature swing adsorption, and pressure temperature swing adsorption to obtain a synthesis gas containing carbon monoxide and hydrogen; a microbial fermentation step of supplying the synthesis gas to a fermenter containing Clostridium bacteria as microorganisms to obtain an ethanol-containing liquid by microbial fermentation; and a purification step of purifying the ethanol-containing liquid after removing the microorganisms,
A waste-derived ethanol composition containing inorganic components and having a sodium content of 150 mg/L or more and 1000 mg/L or less. generating a raw material gas containing carbon monoxide and hydrogen by gasifying waste as a carbon source;
purifying the feed gas using at least one separation device of a pressure swing adsorption type, a temperature swing adsorption type, or a pressure temperature swing adsorption type to obtain a synthesis gas containing carbon monoxide and hydrogen;
a microbial fermentation step of supplying the synthesis gas to a fermenter containing Clostridium bacteria as microorganisms and obtaining an ethanol-containing liquid by microbial fermentation;
a separation step of separating the ethanol-containing liquid into microorganisms and/or proteins derived from microorganisms, and ethanol;
a purification step of purifying the ethanol composition;
Including,
A method for producing a waste-derived ethanol composition, wherein the purified ethanol composition has a sodium content of 150 mg/L or more and 1000 mg/L or less. generating a raw material gas containing carbon monoxide and hydrogen by gasifying waste as a carbon source;
purifying the feed gas using at least one separation device of a pressure swing adsorption type, a temperature swing adsorption type, or a pressure temperature swing adsorption type to obtain a synthesis gas containing carbon monoxide and hydrogen;
a microbial fermentation step of supplying the synthesis gas to a fermenter containing Clostridium bacteria as microorganisms and obtaining an ethanol-containing liquid by microbial fermentation;
a purification step of purifying the ethanol-containing liquid after removing the microorganisms;
Including,
A method for producing a waste-derived ethanol composition, wherein the purified ethanol composition has a sodium content of 150 mg/L or more and 1000 mg/L or less. The ethanol composition according to claim 1 or 2, which is for use in chemical products. The ethanol composition according to claim 1 or 2, which is for use as a fuel. The ethanol composition according to claim 1 or 2, which is used as a polymer raw material. A chemical product made from the ethanol composition described in claim 1 or 2. A fuel comprising the ethanol composition according to claim 1 or 2 and/or ethyl t-butyl ether derived from the ethanol composition according to claim 1 or 2. A polymer raw material made from the ethanol composition described in claim 1 or 2. The polymer raw material of claim 10, selected from the group consisting of ethylene, propylene, butadiene, ethyl acetate, isobutene, methyl (meth)acrylate, acrylic acid, aminohexanoic acid, and diethyl carbonate. A polymer made from the polymer raw material described in claim 10 or 11. A molded article made from the polymer described in claim 12.