JP7575540B2 - ethanol - Google Patents

Description

The present invention relates to ethanol, and more specifically, to ethanol with an adjusted content of specific trace components. Furthermore, the present invention relates to a new resource-recycling type of ethanol that uses 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, their mass production and mass consumption have caused various environmental problems, which has become a major issue on a global scale. For example, polyethylene and polyvinyl chloride, which are representative petrochemical industry products, are consumed in large quantities and thrown away, and these waste products are a major cause of environmental pollution. In addition, concerns about the depletion of fossil fuel resources and the increase in carbon dioxide in the atmosphere are also being discussed as global environmental problems in the mass production of petrochemical industry products.

In response to growing global awareness of such environmental issues, methods for producing various organic substances from raw materials other than naphtha, which is the raw material for petrochemical industrial products, have been investigated in recent years. For example, a method for producing bioethanol from edible raw materials such as corn by sugar fermentation has attracted attention. However, such sugar fermentation methods using edible raw materials have been criticized for causing problems such as rising food prices, as they use limited agricultural land area for production other than food.

To solve this problem, the use of non-edible raw materials that would have been discarded in the past has also been 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 alcohol by fermentation, and methods have been proposed in which the above-mentioned biomass raw materials are gasified and the synthetic gas is used to produce alcohol using a catalyst, but these methods have not yet been put to practical use. Furthermore, even if various petrochemical products can be produced from these non-petroleum raw materials, they will ultimately become waste plastics that do not decompose naturally, so they are not effective as a fundamental solution to environmental problems.

Incidentally, the amount of combustible waste currently disposed of in Japan is approximately 60 million tons per year. The amount of energy is equivalent to approximately 200 trillion kilocalories, which is far more than the amount of energy contained in naphtha, a raw material for plastics in Japan, and these wastes can be said to be important resources. If these waste resources can be converted into petrochemical products, it will be possible to realize an ultimate resource recycling society that does not depend on petroleum resources. From the above perspective, Patent Documents 1 and 2, etc. disclose a technology for producing synthetic gas (a gas mainly composed of CO and _H2 ) from waste and producing ethanol from the synthetic gas by a fermentation method.

However, as pointed out in Patent Document 3, synthetic gas produced from waste contains a wide variety of impurities that have not been elucidated, some of which are toxic to microorganisms, and therefore productivity has been a major challenge in producing alcohol from synthetic gas by microbial fermentation. Furthermore, alcohol obtained by microbial fermentation of synthetic gas also contains various components resulting from the impurities in the synthetic gas, and these components cannot be completely removed even by purification processes such as distillation. For this reason, the development of derivatives from the alcohol obtained by microbial fermentation of synthetic gas has been a major technical challenge.

JP 2016-059296 A International Publication No. 2015-037710 JP 2018-058042 A

According to the study by the present inventors, for example, conventional C2 raw materials such as ethanol are known to be starting materials for various chemical products, but as described above, it has been found that alcohol produced from resources (recyclable resources) that are not based on petroleum resources or biomass resources contains various trace amounts of unknown substances, unlike chemical raw materials derived from naphtha. However, in the conventional technology, the properties of the substances are unknown, and there has been no sufficient consideration in the past 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, the current situation is that there is still room for technological improvement before the alcohol can be put to practical use.

On the other hand, although the above-mentioned documents disclose general fermentation and distillation methods and the optimal composition of synthetic gas, they do not describe the details of the process, nor do they specify the alcoholic substance obtained.

The present invention has been made in consideration of this background technology, and its objective is to provide a practical new alcohol and its derivatives that are more industrially valuable than existing petrochemical raw materials.

The inventors conducted intensive research to solve the above problems, and as a result, they identified the wide variety of trace substances contained in alcohol produced from recycled resources, and further found that it is possible to control the content within a specific range using a new production method, and further found that various derivatives thereof exhibit superior effects compared to existing petroleum-derived alcohol. For example, they discovered that in the process of synthesizing butadiene from ethanol, 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 higher than that of petroleum-derived alcohol can be obtained, leading to the present invention.

More specifically, they discovered that when ethanol is produced from a gas substrate containing carbon monoxide and hydrogen using waste as the carbon source, the conversion rate of ethanol improves when butadiene is synthesized from the ethanol. After a detailed investigation into the reason for this, they found that ethanol derived from recycled resources using a gas substrate containing carbon monoxide and hydrogen has an extremely low content of certain metal elements. The present invention is based on this finding.

That is, the present invention includes the following.
[1] Ethanol having a chromium content of 0.6 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 [2], wherein the gas containing carbon monoxide and hydrogen is derived from waste.
[5] A process for 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,
The method for producing ethanol, wherein the purified ethanol has a chromium content of 0.6 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 a waste material.
[8] 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] for use as a polymer raw material.
[11] A chemical product using the ethanol according to any one of [1] to [4] as a raw material.
[12] A fuel comprising the ethanol according to any one of [1] to [4] and/or ethyl t-butyl ether derived 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 obtained by using the polymer raw material according to [13] or [14] as a raw material.
[16] A molded article made of the polymer according to [15].

According to the present invention, by producing ethanol with an extremely low content of a specific metal element, various unique effects can be obtained compared to commercially available industrial ethanol. For example, according to the present invention, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and to improve the combustion efficiency when using ethanol as fuel. In addition, it is expected that the same effects can be obtained even with existing alcohols by adjusting the content of a specific metal element to an extremely low content.

The ethanol according to 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), etc. The ethanol according to the present invention can be used for various applications of chemical products such as cosmetics, perfumes, fuels, antifreeze, bactericides, disinfectants, cleaning agents, mold removers, detergents, hair washes, soaps, antiperspirants, face wash sheets, solvents, paints, adhesives, diluents, and food additives.

The following describes an example of a 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.

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

<Ethanol>
The Cr (chromium) content in the ethanol according to the present invention is 0.6 mg/L or less, preferably 0.5 mg/L or less. The Cr content is the amount of Cr compound converted to Cr element. By having the Cr content in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and to improve the combustion efficiency when using ethanol as a fuel.

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

The ethanol according to 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 it is easy to adjust the chromium content to the above-mentioned concentration in the production process of these ethanols. In addition, although commercially available industrial ethanol derived from fossil fuels usually contains chromium in excess of the above-mentioned concentration, the chromium content may be adjusted to the above-mentioned concentration by further refining.

Without being bound by theory, it is believed that in the present invention, by reducing the content of specific metals in ethanol to an extremely low value, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing carboxylic acid esters by adding ethanol to carboxylic acids, and to improve the combustion efficiency when using ethanol as fuel.

The ethanol according to the present invention may contain inorganic components other than Cr. For example, it may contain inorganic components such as Si, K, and Na. 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 compound converted into elemental Si. By having the Si content within the above range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and improve the combustion efficiency when using ethanol as a 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 compound converted into K element. By having the K content in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and improve the combustion efficiency when using ethanol as a fuel.

When Na is contained in ethanol, the Na content is preferably 150 mg/L or more, more preferably 170 mg/L or more, even more preferably 190 mg/L or more, and also preferably 1000 mg/L or less, more preferably 500 mg/L or less, even more preferably 400 mg/L or less, and more preferably 300 mg/L or less, relative to the ethanol. The Na content is the amount of Na in the Na compound converted into Na element. By having the Na content in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and improve the 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 into Fe elements. By having the Fe content within the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and improve the combustion efficiency when using ethanol as a 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, and may contain other components in addition to the unavoidable substances mentioned above. For example, it may contain trace amounts of aromatic compounds. Examples of aromatic compounds include toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene, and only one of these may be contained, or two or more of these may be contained. It is preferable that the aromatic compound contains ethylbenzene.

The content (total) 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 also 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. The content of aromatic compounds 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 the combustion efficiency when using ethanol as fuel.

When ethylbenzene is contained in ethanol, the content of ethylbenzene 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, based on the total ethanol. By having the content of ethylbenzene in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and to improve the combustion efficiency when using ethanol as a fuel.

When toluene is contained in ethanol, the toluene content 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, based on the total ethanol. By having the toluene content in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and improve the combustion efficiency when using ethanol as a fuel.

When o-xylene is contained in ethanol, the content of o-xylene 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, based on the total ethanol. By having the content of o-xylene in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and to improve the combustion efficiency when using ethanol as a fuel.

When m-xylene and/or p-xylene are contained in ethanol, the content (total) 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. By having the content of m-xylene and/or p-xylene within the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and to improve the combustion efficiency when using ethanol as a fuel.

The ethanol according to 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, hexadecane, etc., and only one of these may be contained, or two or more of these may be contained. It is preferable that the aliphatic hydrocarbons include one or more of n-hexane, n-decane, and n-dodecane.

The content (total) of aliphatic hydrocarbons contained 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, even more preferably 3 mg/L or less, based on the total ethanol. By having the content of aliphatic hydrocarbons in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and to improve the combustion efficiency when using ethanol as a fuel.

When n-hexane is contained in ethanol, the content of n-hexane 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, based on the total ethanol. By having the content of n-hexane in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and to improve the combustion efficiency when using ethanol as a fuel.

When n-heptane is contained in ethanol, the content of n-heptane 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, based on the total ethanol. By having the content of n-heptane in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and to improve the combustion efficiency when using ethanol as a fuel.

When n-octane is contained in ethanol, the content of n-octane 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, based on the total ethanol. By having the n-octane content within the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and improve the combustion efficiency when using ethanol as a fuel.

When n-decane is contained in ethanol, the content of n-decane 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, based on the total ethanol. By having the content of n-decane in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and to improve the combustion efficiency when using ethanol as a fuel.

When n-dodecane is contained in ethanol, the content of n-dodecane 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, based on the total ethanol. By having the content of n-dodecane in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and to improve the combustion efficiency when using ethanol as a fuel.

When n-tetradecane is contained in ethanol, the content of n-tetradecane 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, based on the total ethanol. By having the content of n-tetradecane in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and to improve the combustion efficiency when using ethanol as a fuel.

When hexadecane is contained in ethanol, the content of hexadecane 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, based on the total ethanol. By having the content of hexadecane in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and to improve the combustion efficiency when using ethanol as a fuel.

The ethanol according to the present invention may further contain a trace amount of 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 of them may be contained. As the dialkyl ether, it is preferable that dibutyl ether is contained.

The content (total) of dialkyl ether contained 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 is 100 mg/L or less, preferably 80 mg/L or less, more preferably 50 mg/L or less, even more preferably 30 mg/L or less, based on the total ethanol. The 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 a carboxylic acid ester by adding ethanol to a carboxylic acid, and improve the combustion efficiency when using ethanol as a fuel.

When dibutyl ether is contained in ethanol, the content of dibutyl ether 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. By having the dibutyl ether content in the above numerical range, it is possible to improve the ethanol conversion rate when synthesizing butadiene using ethanol as a raw material, to improve the reaction rate when synthesizing a carboxylic acid ester by adding ethanol to a carboxylic acid, and to improve the combustion efficiency when using ethanol as a 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. The concentration of ethanol, which is the main component in the ethanol (pure ethanol as a compound), 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 is 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 may be set according to the intended use. For example, 90% by volume or more is preferably used for cosmetics, and 75% by volume or more is preferably used for disinfectant ethanol. The upper limit can also be conveniently set according to the use. In terms of transportation costs, etc., the higher the ethanol concentration, the better for the product.

<Ethanol production method>
As a method for producing ethanol having a unique gas chromatographic peak as described above, for example, ethanol can be produced by microbial fermentation of a synthetic gas containing carbon monoxide derived from waste or exhaust gas. In such a method, the content of aromatic compounds and the like in the raw 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. Hereinafter, as an example, a method for producing ethanol by microbial fermentation of a synthetic gas containing carbon monoxide derived from waste or exhaust gas will be described.

The method for producing ethanol includes the steps of converting a carbon source into a synthetic gas containing carbon monoxide and hydrogen, a microbial fermentation step of supplying the synthetic gas containing carbon monoxide and hydrogen to a microbial fermenter to obtain 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. However, the method may also include a raw material gas generation step, a synthetic gas preparation step, a wastewater treatment step, etc., as necessary. Each step will be described below.

<Material gas generation process>
The raw gas generation process is a process of generating raw gas by gasifying a carbon source in a gasification section. A gasification furnace may be used in the raw gas generation process. The gasification furnace is a furnace that burns (incompletely combusts) a carbon source, and examples of such furnaces include shaft furnaces, kiln furnaces, fluidized bed furnaces, and gasification reforming furnaces. The gasification furnace is preferably a fluidized bed furnace type, since partial combustion of waste allows for high hearth load and excellent operability. By gasifying the waste in a fluidized bed furnace at low temperature (about 450 to 600°C) and in a low-oxygen atmosphere, the waste is decomposed into gas (carbon monoxide, carbon dioxide, hydrogen, methane, etc.) and char containing a large amount of carbon. Furthermore, since the non-combustible materials contained in the waste are separated from the bottom of the furnace in a hygienic and low-oxidization state, it is possible to selectively recover valuable materials such as iron and aluminum from the non-combustible materials. Therefore, such gasification of waste allows for efficient resource recycling.

The gasification temperature in the raw gas production process is not particularly limited, but is usually 100 to 2500°C, and preferably 200 to 2100°C.

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

The carbon source used in the raw gas generation process is not particularly limited, and various carbon-containing materials can be suitably used for the purpose of recycling, 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-produced by various industries.

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

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

In the above-mentioned raw gas generation process, the raw 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, as a gas containing carbon monoxide, although there is no particular limit, 0.1 vol. % or more, preferably 10 vol. % or more, and more preferably 20 vol. % or more.

<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 the raw gas. When the raw gas is derived from waste, the raw gas usually contains carbon monoxide at 0.1 vol.% to 80 vol.%, carbon dioxide at 0.1 vol.% to 70 vol.%, hydrogen at 0.1 vol.% to 80 vol.%, and tends to further 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. In addition, other environmental pollutants, dust particles, impurities, and other substances may be contained. Therefore, when supplying synthesis gas to a microbial fermenter, it is preferable to reduce or remove substances and compounds that are undesirable for stable cultivation of microorganisms from the raw gas, and to make the content of each component contained in the raw gas within a range suitable for stable cultivation of microorganisms.

In particular, in the synthesis gas purification process, a pressure swing adsorption apparatus filled with the above-mentioned regenerated adsorbent is used to adsorb the 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 conventionally known treatment processes to remove impurities and adjust the gas composition. As other treatment processes, for example, one or more of a gas chiller (moisture separator), a low-temperature separation type (cryogenic type) separator, a particulate (soot) separator such as a cyclone or a bag filter, a scrubber (water-soluble impurity separator), a desulfurization device (sulfide separator), a membrane separation type separator, a deoxygenation device, a pressure swing adsorption type separator (PSA), a temperature swing adsorption type separator (TSA), a pressure temperature swing adsorption type separator (PTSA), a separator using activated carbon, and a deoxygenation catalyst, specifically, a separator using a copper catalyst or a palladium catalyst, etc. may be used for treatment.

In the present invention, the concentrations of iron and chromium derived from the raw gas can be controlled by adjusting the conditions of the above-mentioned treatment process. For example, by adjusting the conditions of the scrubber residence time and membrane separation, these concentrations can be reduced to below the detection limit. By reducing the concentrations of iron and chromium in the raw gas in this way, the content of iron and chromium in the final ethanol can be reduced to below the detection limit.

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 a gas obtained by generating a raw material gas by gasifying a carbon source (raw material gas generation process), and then adjusting the concentrations of the components carbon monoxide, carbon dioxide, hydrogen, and nitrogen 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 usually 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 usually 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 usually 0.1 vol.% or more and 40 vol.% or less, preferably 0.3 vol.% or more and 30 vol.% or less, more preferably 0.5 vol.% or more and 10 vol.% or less, and particularly preferably 1 vol.% or more and 6 vol.% 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 usually 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 set within a specified range by changing the elemental composition of the hydrocarbons (carbon and hydrogen) and nitrogen in the carbon source in the raw gas generation process, or by appropriately changing the 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 to a carbon source 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 high oxygen concentration in the raw gas generation process.

In addition to the above-mentioned components, the synthetic gas used in the present invention may contain, without particular 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 is 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. By setting the content of sulfur compounds, phosphorus compounds, nitrogen compounds, etc. to the lower limit value or more, there is an advantage that microorganisms can be cultured suitably, and by setting the content to the upper limit value or less, there is an advantage that the medium is not contaminated by various nutrient sources that are not consumed by the microorganisms.

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

The synthetic gas may 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, even more preferably 0.1 mg/L or more, and preferably 70 mg/L or less, more preferably 50 mg/L or less, even more preferably 30 mg/L or less. By setting the content at or above the lower limit, microorganisms tend to be cultured favorably, and by setting the content at or below the upper limit, the medium tends to be less susceptible to contamination 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. In general, any shape of microbial fermenter can be used, including stirring type, airlift type, bubble column type, loop type, open bond type, and photobio type. In the present invention, the microbial fermenter can be suitably a known loop reactor having a main tank section and a reflux section. 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 fermentation tank satisfies the above-mentioned compositional conditions of the synthesis gas, the gas obtained through the raw gas generation process may be used as the synthesis gas as is, or another specified gas may be added to the gas obtained by reducing or removing impurities from the raw gas, and then the synthesis gas may be used. 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.

The microbial fermenter may be continuously supplied with synthetic gas and microbial culture liquid, but it is not necessary to supply synthetic gas and microbial culture liquid simultaneously, and synthetic gas may be supplied to a microbial fermenter to which microbial culture liquid has already been supplied. It is known that certain anaerobic microorganisms produce ethanol and the like from substrate gases such as synthetic gas through fermentation, and this type of gas-utilizing microorganism is cultured in a liquid medium. For example, a liquid medium and gas-utilizing bacteria may be supplied and contained, and synthetic gas may be supplied into the microbial fermenter while stirring the liquid medium in this state. In this way, gas-utilizing bacteria can be cultured in the liquid medium, and ethanol can be produced from synthetic gas through the fermentation action of the bacteria.

In the microbial fermenter, the temperature of the medium (culture temperature) may be any temperature, but is preferably about 30 to 45°C, more preferably about 33 to 42°C, and even more preferably about 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 upper limit, but from the viewpoint of regular maintenance of the equipment, it is preferably 720 days or less, and more preferably 365 days or less. The culture time means the time from adding the seed bacteria to the culture tank to discharging the entire amount of the culture liquid in the culture tank.

The microorganisms (species) contained in the microbial culture solution are not particularly limited as long as they can produce ethanol by microbial fermentation of synthetic gas using carbon monoxide as the main raw material. For example, the microorganisms (species) are preferably ones that produce ethanol from synthetic gas through the fermentation action of gas-utilizing bacteria, and are particularly preferably 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 thereto. Further examples are given below.

Gas-utilizing 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 Ralsotonia.

On the other hand, examples of archaea include Methanobacterium, Methanobrevibacter, Methanocalculus, Methanococcus, Methanosarcina, Methanosphaera, Methanothermobacter, Methanothrix, Methanoculleus, Methanofollis, and Methanogenium. Bacteria include 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, because of their excellent ability to assimilate carbon monoxide and carbon dioxide, archaea are preferably bacteria of the genus Methanosarcina, Methanothermobactor, or Methanococcus, 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 a high ability to produce the target ethanol are selected and used. For example, gas-utilizing bacteria with a high ability to produce ethanol include Clostridium autoethanogenum, Clostridium ljungdahlii, Clostridium aceticum, Clostridium carboxidivorans, Moorella thermoacetica, and Acetobacterium woodii, and among these, Clostridium autoethanogenum is particularly preferred.

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

The ethanol-containing liquid obtained by the microbial fermentation process can be obtained as a suspension containing microorganisms and their carcasses, proteins derived from the microorganisms, etc. The protein concentration in the suspension varies depending on the type of microorganism, but is usually 30 to 1000 mg/L. The protein concentration in the ethanol-containing liquid can be measured by the Kjeldahl method.

<Separation step>
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 into a liquid or solid component containing microorganisms and a gas component containing ethanol. In the conventional method, the ethanol-containing liquid obtained by the microbial fermentation process is distilled to separate and purify the desired ethanol, but since the ethanol-containing liquid contains microorganisms and proteins derived from microorganisms, if the ethanol-containing liquid is distilled as it is, foaming may occur in the distillation apparatus, hindering continuous operation. In addition, it is known to use a membrane evaporator as a method for purifying a foamable liquid, but the membrane evaporator has low concentration efficiency and is not suitable for purifying a liquid containing a solid component. In the present invention, before separating and purifying the desired ethanol from the ethanol-containing liquid obtained by the microbial fermentation process by a distillation operation or the like, the ethanol-containing liquid is heated to separate into a liquid or solid component containing microorganisms and a gas component containing ethanol, and the desired ethanol is separated and purified only from the separated gas 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. Also, since the ethanol concentration in the gaseous component containing ethanol becomes higher than the ethanol concentration in the ethanol-containing liquid, the separation and purification of ethanol can be efficiently carried out in the purification step described later.

In the present invention, from the viewpoint of efficiently separating the liquid or solid component containing microorganisms, their carcasses, proteins derived from microorganisms, etc., 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 under normal pressure, at a temperature of preferably 50 to 200°C, more preferably at a temperature of 80°C to 180°C, and even more preferably at a temperature of 100 to 150°C.

There are no particular limitations on the heating time in the separation step, so long as it is a time that allows gas components to be obtained, but from the standpoint of efficiency or economy, it is usually 5 seconds to 2 hours, preferably 5 seconds to 1 hour, and more preferably 5 seconds to 30 minutes.

In the above-mentioned separation process, any device can be used without particular restrictions as long as it can efficiently separate the ethanol-containing liquid into liquid or solid components (microorganisms or 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 viewpoint of efficiency in separating an ethanol-containing liquid with a particularly low concentration of solid components 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 device used in the liquefaction step is not particularly limited, but it is preferable to use a heat exchanger, particularly a condenser. Examples of the condenser include a water-cooled type, an air-cooled type, and an evaporative type, and among them, a water-cooled type is preferable. The condenser may be a single-stage condenser or a multi-stage condenser.

It is preferable that the liquefied product obtained by the liquefaction process does not contain components contained in the ethanol-containing liquid, such as microorganisms or their remains, or proteins derived from microorganisms, but 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. When components such as microorganisms have already been removed from the ethanol-containing liquid obtained in the microbial fermentation step, the ethanol-containing liquid can be supplied to the purification step without going through the above-mentioned separation step. The purification step is a step of separating the ethanol-containing liquid obtained in the liquefaction step 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 the apparatus 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. Heat distillation or membrane separation may be suitably used as a unit operation.

In the heat distillation, a distillation apparatus is used to obtain the desired ethanol as a distillate with high purity. The temperature inside the distillation apparatus during the distillation of ethanol is not particularly limited, but is preferably 100°C or less, and more preferably about 70 to 95°C. By setting the temperature inside the distillation apparatus within the above range, separation of ethanol from other components, i.e., distillation of ethanol, can be performed more reliably. 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 more, and the temperature of the bottom of the distillation column is raised to 90°C or more within 30 minutes, and then the ethanol-containing liquid is introduced from the middle of the distillation column, and the distillation process is performed with the temperature difference between the bottom, middle, and top of the column being within ±15°C, thereby obtaining high-purity ethanol. The distillation temperature difference is preferably ±13°C, and more preferably ±11°C. With the above distillation temperature difference, separation from other components, i.e., distillation of ethanol, can be performed more reliably.

The pressure inside the distillation apparatus during the distillation of ethanol may be normal pressure, but is preferably less than atmospheric pressure, and more preferably about 60 to 95 kPa (absolute pressure). By setting the pressure inside the distillation apparatus within the above range, it is possible to improve the efficiency of ethanol separation, and thus the ethanol yield. The ethanol yield (the concentration of ethanol contained in the distillate after distillation) is preferably 90% by volume or more, and more preferably 95% by volume or more.

For membrane separation, a known separation membrane can be used as appropriate, for example, a zeolite membrane can be preferably used.

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 step are substantially free of nitrogen compounds. In the present invention, "substantially free" does not mean that the concentration of nitrogen compounds is 0 mg/L, but means that the bottoms obtained in the purification step have a nitrogen compound concentration at a level that does not require a wastewater treatment step. In the separation step, the desired ethanol is not purified from the ethanol-containing liquid obtained in the microbial fermentation step, but the ethanol-containing liquid is separated into a liquid or solid component containing microorganisms and a gaseous component containing ethanol as described above. At that time, the nitrogen compounds remain in the liquid or solid component containing microorganisms, so that the gaseous component containing ethanol contains almost no nitrogen compounds. Therefore, it is considered that the bottoms obtained when ethanol is purified from a liquefied product obtained by liquefying the gaseous component does not substantially contain nitrogen compounds. Even if the bottoms contain nitrogen compounds, the concentration of the 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.

For the same reason as above, the bottoms separated in the purification process are substantially free of phosphorus compounds. Note that "substantially free" does not mean that the concentration of phosphorus compounds is 0 mg/L, but 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 concentration of phosphorus compounds 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, so that the wastewater treatment process that was previously required can be simplified.

<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 can 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 directly supplying the bottoms 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. In addition, 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 according to the present invention can be used as a raw material for producing various organic compounds. For example, the ethanol according to 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), etc. Below, a method for synthesizing butadiene using the ethanol according to 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 according to the present invention can also be used as a raw material for other chemical products and polymers.

<Method of synthesizing butadiene>
Butadiene is produced by refining the C4 fraction that is a by-product when ethylene is synthesized 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 a technology that converts ethanol (ethanol derived from microbial fermentation) that is not derived from fossil fuels into 1,3-butadiene instead of chemical industrial raw materials obtained from petroleum. As a method for synthesizing butadiene using such ethanol derived from microbial fermentation as a raw material, a method using MgO as a catalyst, a method using a mixture of Al ₂ O ₃ and ZnO, a catalyst having a magnesium silicate structure, and the like are known. In addition to the above, vanadium, manganese, iron, cobalt, nickel, copper, zinc, gallium, niobium, silver, indium, cerium, and the like are used as catalysts.

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

The heating temperature for promoting the conversion reaction is, for example, about 300 to 450°C, preferably about 350 to 400°C, in the reaction system. If the temperature in the reaction system falls below the above range, the catalytic activity is insufficient, and the reaction rate and production efficiency tend to decrease. On the other hand, if the temperature in the reaction system exceeds the above range, the catalyst may be easily deteriorated.

The reaction can be carried out by conventional methods such as batch, semi-batch, or continuous. When a batch or semi-batch system is used, the conversion rate of ethanol can be increased, but when the ethanol of the present invention is used, ethanol can be converted more efficiently than before, even when a continuous system is used. The reason for this is unclear, but it is thought to be due to the presence of a unique peak in the gas chromatograph measured by gas chromatography mass spectrometry in the ethanol derived from a recyclable resource such as that of the present invention, which uses a gas containing carbon monoxide and hydrogen as a substrate, that is not seen in ethanol derived from fossil fuels.

Methods for contacting the raw material with the catalyst include, for example, a suspension bed method, a fluidized bed method, a fixed bed method, and the like. Either a gas phase method or a liquid phase method may be used. In terms of ease of catalyst recovery and regeneration treatment, it is preferable to use a fixed bed type gas phase continuous flow reactor in which the catalyst is packed into a reaction tube to form a catalyst layer and the raw material is circulated as a gas to react in the gas phase. When the reaction is carried out 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 gas and supplied to the reactor.

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

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

First, ethylene, which is a raw material for polyethylene, is synthesized using the ethanol according to the present invention as a raw material. The method for producing ethylene is not particularly limited, and it can be obtained by a conventionally known method. As an example, ethylene can be obtained by a dehydration reaction of ethanol. A catalyst is usually used when obtaining ethylene by a dehydration reaction of ethanol, but this catalyst is not particularly limited, and a conventionally known catalyst can be used. A fixed bed flow reaction, which allows easy separation of the catalyst and the product, is advantageous from the viewpoint of the process, and for example, γ-alumina is preferable.

Since the dehydration reaction is an endothermic reaction, it is usually carried out under heating conditions. There are no limitations on the heating temperature as long as the reaction proceeds at a commercially useful reaction rate, but a temperature of 100°C or higher is preferable, more preferably 250°C or higher, and even more preferably 300°C or higher is appropriate. There is no particular upper limit, but from the viewpoint 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 equal to or higher than atmospheric pressure is preferred to facilitate the subsequent gas-liquid separation. From an industrial perspective, a fixed-bed flow reaction is preferred because it is easy to separate the catalyst, but a liquid-phase suspension bed, fluidized bed, etc. may also be used.

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

By carrying out the dehydration reaction of ethanol as described above, a mixture of ethylene, water, and a small amount of unreacted ethanol is obtained. At room temperature and below about 5 MPa, ethylene is in a gaseous state, so 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 at this time must be above normal pressure.

In the present invention, ethanol derived from a recyclable resource using a gas containing carbon monoxide and hydrogen as a substrate has a unique peak in a gas chromatograph 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 a very small amount of impurities. Depending on the use of ethylene, these very small amounts of impurities may be problematic, so they may be removed by purification. The purification method is not particularly limited, and can be performed by a conventionally known method. For example, an adsorption purification method can be mentioned as a suitable purification operation. The adsorbent used is not particularly limited, and a conventionally known adsorbent 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, it is necessary to perform a moisture removal treatment after caustic treatment and before adsorption purification.

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

The polymerization method for polyolefins, particularly ethylene polymers and copolymers of ethylene and α-olefins, can be appropriately selected depending on the type of polyethylene desired, for example, 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 carry out the polymerization in one stage or in multiple stages of two or more stages by any of the methods of gas phase polymerization, slurry polymerization, solution polymerization, and high pressure ionic polymerization.

The single-site catalyst is a catalyst capable of forming a uniform active species, and is usually prepared by contacting a metallocene transition metal compound or a nonmetallocene transition metal compound with an activating cocatalyst. Compared to multi-site catalysts, single-site catalysts have a uniform active site structure, and are therefore preferred because they can polymerize polymers with high molecular weights and highly uniform structures. As a single-site catalyst, it is particularly preferred to use a metallocene catalyst. A metallocene catalyst is a catalyst that contains each of the catalytic components of a transition metal compound of Group IV of the periodic table that contains a ligand having a cyclopentadienyl skeleton, a cocatalyst, and if necessary, an organometallic compound and a carrier.

In the transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, the cyclopentadienyl skeleton is a cyclopentadienyl group, a substituted cyclopentadienyl group, etc. The substituted cyclopentadienyl group has a substituent such as a hydrocarbon group having 1 to 30 carbon atoms. Examples of the transition metal include zirconium, titanium, hafnium, etc., and zirconium and hafnium are particularly preferred. The transition metal compound usually has two ligands having a cyclopentadienyl skeleton, and it is preferable that the ligands having each cyclopentadienyl skeleton are bonded to each other by a bridging group. The above transition metal compounds can be used as a catalyst component, either alone or in a mixture of two or more kinds.

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

The above-mentioned transition metal compounds may be used by being supported on an inorganic or organic carrier. The carrier is preferably an inorganic or organic porous oxide, specifically, ion _{-exchange layered silicate such as montmorillonite, SiO2, Al2O3, MgO, ZrO2, TiO2, B2O3 , CaO , ZnO ,} BaO, _{ThO2 ,} etc., or a mixture thereof.

Other examples of organometallic compounds that may be used as needed include organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Of these, organoaluminum compounds are preferably used.

As the polyolefin, a polymer of ethylene or a copolymer of ethylene and an α-olefin may be used alone or in combination of two or more kinds.

<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 a conventional method. For example, acetaldehyde can be produced by oxidizing ethanol with chlorine. Chlorine is usually reacted with ethanol in a gaseous state. Chlorine may be supplied at a concentration of approximately 100%, or 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 the reaction efficiency. It is preferable to react ethanol and chlorine at a supply rate of 25 to 100 sccm per 100 g of ethanol aqueous solution.

The 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 of ethanol with chlorine gas or thermal chlorination is preferred, and photochlorination with chlorine gas is more preferred. Photoreactions include methods of irradiating light of various wavelengths such as ultraviolet light and visible light, and among these, it is preferred to cause the reaction by irradiating light from a light source having a wavelength of about 300 to 500 nm. The light source is not particularly limited, and fluorescent lamps, mercury lamps, halogen lamps, xenon lamps, metal halide lamps, excimer lamps, LED lamps, and the like can be used. The reaction temperature is preferably about 0 to 80°C, and preferably about 0 to 50°C. The reaction time is preferably about 1 to 5 hours.

As another example, ethanol can be oxidized in the gas phase in the presence of oxygen molecules and a catalyst to produce acetaldehyde. For example, a base metal oxide having gold particles dispersed and fixed therein can be used as the catalyst. Examples of the base metal oxide 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 oxygen molecules with the catalyst at, for example, 100 to 280°C. The oxygen molecules used in the reaction may be supplied as oxygen gas, or air may be used. The raw gas, which is the gas, may contain a dilution gas (carrier gas) as necessary. The apparatus used in the reaction may be a general apparatus normally used for performing gas-phase reactions. For example, the catalyst is filled in a reaction tube, and the reaction tube is heated to a predetermined temperature. A gas containing ethanol and oxygen gas or air is sent into the reaction tube, and the raw gas is brought into contact with the catalyst and the reaction gas is recovered. The reaction pressure may be normal pressure, and may be increased to about 0.5 to 5 Pa (atmospheres) if necessary. The dilution gas may be, for example, a so-called inert gas such as nitrogen, argon, helium, or carbon dioxide. The amount of dilution gas used may be appropriately determined taking into consideration the composition, flow rate, and reaction heat of the raw gas, but it is usually preferable that the amount of dilution gas used is 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 about 0.1 to 1.0 g. Practically, it is preferable to use an amount that provides a space velocity (SV) in the range of about 10,000 to 40,000 hr ^-1 ml g _cat ^-1 in relation to the gas flow rate.

Furthermore, acetaldehyde can also be produced by dehydrogenating ethanol in the presence of a catalyst. For example, a solid catalyst containing copper as an active species can be used as such a catalyst. The copper as an active species may be in any form that has the activity of converting ethanol to acetaldehyde, and may be in any form of metallic copper (simple substance) or a copper compound (oxide, hydroxide, copper salt (inorganic acid salt such as copper sulfate, copper phosphate, copper nitrate, copper carbonate, etc.; organic acid salt such as copper salt of carboxylic acid, etc.). The solid catalyst may contain at least one selected from such simple copper and copper compounds. The copper as an active species is preferably in the form of metallic copper. Copper may be used as it is in the form of metallic copper or a copper compound, or may be used in the form supported on a carrier. Note that the copper as an active species may act as the main catalyst of the solid catalyst, and may be used in combination with a co-catalyst, etc. The solid catalyst may be in a form in which both copper and the co-catalyst are supported on a carrier.

The above dehydrogenation reaction may be a liquid phase reaction as long as ethanol is brought into contact with a solid catalyst, but is usually a gas phase reaction in which gaseous ethanol is brought into contact with a solid catalyst in the gas phase. In view of the equilibrium relationship between ethanol and acetaldehyde, catalyst life, etc., the reaction temperature may be about 150 to 350°C, preferably 170 to 300°C, and more preferably about 200 to 280°C. The higher the reaction temperature, the more the equilibrium shifts to the acetaldehyde side, and the higher the conversion rate can be. The reaction may be carried out under pressure, but may be carried out under normal pressure for convenience. It may also be carried out under reduced pressure, which is advantageous for the ethanol conversion rate.

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

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

ETBE can be synthesized from ethanol and isobutene by a conventional method. 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, it is preferable to use a cation exchange resin, and it is more preferable to use a strongly acidic cation exchange resin. As such a strongly acidic cation exchange resin, a porous type (MR type) styrene-based resin in which a strong acid group such as a sulfonic acid group (-SO ₃ H) is introduced as an ion exchange group is preferable. The particle size of the strongly acidic cation exchange resin is preferably 0.5 to 1.0 mm. The amount of the 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 method of using the reaction catalyst is not particularly limited, and it can be used in the reaction in a fixed bed, fluidized bed, or suspension bed state. The method of reacting isobutene with ethanol is not particularly limited, but it is preferable to carry out the reaction in a pressurized gas-liquid mixed phase reaction method in which ethanol can be maintained in a liquid phase. In this case, the yield of ETBE obtained is further improved.

<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 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. Ethylene glycol is obtained from the ethanol of the present invention as a raw material, and can be obtained, for example, by a method of producing ethylene glycol from ethanol via ethylene oxide using a conventionally known method.

As the dicarboxylic acid, aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and derivatives thereof can be used without limitation. Examples of aromatic dicarboxylic acids include terephthalic acid and isophthalic acid, and examples of derivatives of aromatic dicarboxylic acids include lower alkyl esters of aromatic dicarboxylic acids, specifically methyl esters, ethyl esters, propyl esters, and butyl esters. Among these, terephthalic acid is preferred, and examples of derivatives of aromatic dicarboxylic acids include dimethyl terephthalate. Examples of aliphatic dicarboxylic acids include chain or alicyclic dicarboxylic acids having a carbon number of 2 to 40, such as oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, and cyclohexanedicarboxylic acid. Examples of derivatives of aliphatic dicarboxylic acids include lower alkyl esters such as methyl esters, ethyl esters, propyl esters, and butyl esters of the above aliphatic dicarboxylic acids, and 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, and those containing succinic acid as the main component are 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 conventional method of polycondensing the above-mentioned diol unit and dicarboxylic acid unit. Specifically, the polyester can be produced by a general melt polymerization method in which an esterification reaction and/or an ester exchange 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, and examples of the polymerization catalyst include titanium compounds, zirconium compounds, and germanium compounds.

The reaction temperature for the esterification reaction and/or transesterification reaction between the dicarboxylic acid component and the diol component is usually in the range of 150 to 260°C, and the reaction atmosphere is usually 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 the polycondensation is completed, 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 subjected to solid-phase polymerization as necessary to further increase the degree of polymerization or to remove oligomers such as cyclic trimers.

In the polyester manufacturing process, various additives may be added as long as the properties of the polyester are not impaired. For example, plasticizers, UV stabilizers, color inhibitors, matting agents, deodorants, flame retardants, weather resistance agents, antistatic agents, friction reducers, release agents, antioxidants, ion exchange agents, color pigments, etc. may be added.

The ethanol produced by the present invention can be used as a raw material for a variety of other polymers, not just the polymers mentioned above, and the molded products made from the resulting polymers are carbon-neutral materials, making it possible to realize an ultimate resource-recycling society that is not dependent on petroleum resources.

<Products containing ethanol>
The ethanol according to the present invention can be used not only as a polymer raw material as described above, but also in various products. Examples of such products include chemical products such as cosmetics, perfumes, fuels, antifreeze, bactericides, disinfectants, cleaning agents, mold removers, detergents, hair washes, soaps, antiperspirants, face wash sheets, solvents, paints, adhesives, diluents, and food additives. By using it for these purposes, it can exert an appropriate effect according to the purpose.

<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. Since ethanol has high bactericidal properties, it can also function as a bactericide to prevent the proliferation of bacteria in fuel systems such as engines and piping.

The Japan Automotive Engineers Association standard (2006) stipulates that the ethanol concentration in ethanol fuel must be 99.5% by volume or more. Other countries (e.g. India) also stipulate that the ethanol concentration in ethanol fuel must be 99.5% by volume or more. Therefore, ethanol with a purity of 99.5 to 99.9% by volume is suitable for use in ethanol-only vehicles. Furthermore, since ethanol fuel can be used for purposes other than ethanol-only vehicles, ethanol with a purity of 99.5 to 99.9% by volume is particularly versatile.

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

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 advantage of improving the octane number by blending ethanol can be obtained, and if it is 15% by volume or less, the evaporation characteristics do not change significantly due to the azeotropic phenomenon with other gasoline base materials, and proper drivability of gasoline-powered automobiles can be ensured.

The water content in the ethanol-mixed 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 in the ethanol, but is essentially about 0.01% by mass. If the upper limit is 0.9% by mass or less, phase separation can be prevented, and even if phase separation occurs, the gasoline layer will enable proper operation of the gasoline engine. The water content can be measured according to "Crude oil and petroleum products - Water content test method" described in JIS K 2275, and for example, Karl Fischer coulometric titration method can be used.

As the gasoline base stock, any commonly used gasoline base stock may be used, and there is no particular limitation. Examples of gasoline base stocks include light naphtha obtained by atmospheric distillation of crude oil, preferably desulfurized light naphtha obtained by desulfurizing it, catalytic reformed gasoline obtained by catalytically reforming heavy naphtha after desulfurization, and benzene-free catalytic reformed gasoline obtained by debenzene-treating it, benzene-free light catalytic reformed gasoline, benzene-free heavy catalytic reformed gasoline, 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 ETBE made from ethanol according to the invention can be mixed with gasoline to produce ETBE-mixed gasoline. Using ETBE-mixed gasoline can reduce the environmental impact. The ETBE content of ETBE-mixed 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 ETBE content is 1% by volume or more, the advantage of improving the octane number by blending ETBE can be obtained, and if it is 15% by volume or less, the evaporation characteristics do not change significantly due to the azeotropic phenomenon with other gasoline base materials, and proper drivability of gasoline-powered automobiles can be ensured.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as they do not depart from the gist of the present invention.

<Method for evaluating ethanol content>
In the following Examples and Comparative Examples, the chromium content in ethanol was measured using an ELAN DRCII inductively coupled plasma mass spectrometry (ICP-MS) manufactured by PerkinElmer.

<Butadiene Quantitative Method>
The 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 min → 10° C./min → 100° C., 14.5 min → 10° C./min → 250° C.
Sampling time: 5 min 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 rise conditions: 30°C-300°C 15°C/min
Carrier gas: He 100 kPa
Split ratio: 50

<Method for quantifying combustion efficiency>
The ethanol combustion efficiency was quantitatively evaluated by total 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 general waste in a waste incineration facility was used. The raw gas contained 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 refining 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 of the gas temperature being raised. The gas was then heated in a double-pipe heat exchanger using steam at 150°C and re-cooled using 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 fermentation tank) equipped with a main reactor, a synthesis gas supply hole, and a discharge hole, and filled with a seed culture of Clostridium autoethanogenum (a microorganism) and a liquid medium for bacterial culture (containing appropriate amounts of phosphorus compounds, nitrogen compounds, various minerals, etc.), and culture (microbial fermentation) was performed continuously for 300 hours. After that, about 8000 L of the culture liquid containing ethanol was extracted from the discharge hole.

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

(Distillation process)
The ethanol-containing liquid was then 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, and during continuous operation, the column was continuously operated at 101°C at the bottom, 99°C at the middle, and 91°C at the top at 15 sec/L to obtain purified ethanol. The chromium content in the obtained ethanol was less than 0.5 mg/L.

(Method of 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 to be used in the reaction, and the vaporized ethanol gas was merged with nitrogen. The flow rate of the ethanol gas was controlled by mass flow so that the SV of the ethanol gas was 360 L/hr/L and the SV of the nitrogen was 840 L/hr/L, thereby obtaining a mixed gas of 30% by volume (gas equivalent) of ethanol and 70% by volume (gas equivalent) of nitrogen. Next, a cylindrical reaction tube made of stainless steel 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 was kept at a temperature of 350° C. and a pressure (pressure of the reaction bed) of 0.1 MPa, and the mixed gas was continuously supplied to the reaction tube to obtain 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 by the same method as in Example 1 using 99% ethanol (manufactured by Amakasu Chemical Industry Co., Ltd.), which is ethanol derived from fossil fuel, and the butadiene content was quantified in the same manner as in Example 1. The results are shown in Table 1. The chromium content in the 99% ethanol, which is ethanol derived from fossil fuel, was 0.7 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 chromium content in the 99% ethanol derived from the saccharification and fermentation of plants was 0.7 mg/L.

As shown in Table 1, ethanol produced from the gas emitted after incinerating general waste in a waste incineration facility 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 as follows using the same ethanol as used in Example 1. 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 and stirred for 5 hours under reflux. After that, the mixture was allowed to cool to room temperature, and unreacted ethanol was removed under reduced pressure, and ethyl benzoate synthesized with 100 ml of diethyl ether was recovered. The recovered liquid was washed with distilled water, dried using magnesium sulfide, and then filtered and concentrated.
The obtained filtrate was subjected to component analysis using a gas chromatograph to quantitatively determine the amount of ethyl benzoate synthesized. The analysis conditions are shown below. The analysis results are shown in Table 2.
Column: DB-1 (length 30.0 m, inner diameter 0.254 mm, film thickness 0.25 m)
Temperature rise 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 petrochemically 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 petrochemically 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 incinerating general waste in a waste incineration facility was found to have a higher conversion efficiency to ethyl benzoate than ethanol derived from conventional 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 adding 30 g of ethanol to a heat-resistant container of 60 mm length x 60 mm width x 30 mm height under non-heating conditions, igniting it, measuring the amount of oxygen reduction until complete combustion in a cone calorimeter (manufactured by FTT), and calculating the total calorific value based on the amount of oxygen reduction. 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 quantitative results 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 quantitative results are shown in Table 3.

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

Claims (18)

A waste-derived ethanol composition obtained by a method including the steps of: generating a raw gas containing carbon monoxide and hydrogen by gasifying waste as a carbon source; purifying the raw gas using a pressure swing adsorption type separation device to obtain a synthesis gas containing carbon monoxide and hydrogen; supplying the synthesis gas to a fermenter containing Clostridium genus as a microorganism to obtain an ethanol-containing liquid by microbial fermentation; and purifying the ethanol-containing liquid after removing the microorganism ,
A waste-derived ethanol composition having a chromium content of 0.6 mg/L or less. generating a feed gas comprising carbon monoxide and hydrogen by gasifying waste as a carbon source ;
purifying the feed gas using a pressure swing adsorption separation device to obtain a synthesis gas containing carbon monoxide and hydrogen;
a microbial fermentation step of supplying the synthesis gas to a fermenter containing the genus Clostridium as a microorganism and obtaining an ethanol-containing liquid by microbial fermentation;
a purification step of purifying the ethanol-containing liquid after removing the microorganisms ;
Including,
The method for producing an ethanol composition derived from waste, wherein the purified ethanol composition has a chromium content of 0.6 mg/L or less. The method according to claim 2 , wherein the purification step comprises a thermal distillation . The ethanol composition according to claim 1, wherein the ethanol concentration is 75% by volume or more. The ethanol composition according to claim 1, wherein the ethanol concentration is 90% by volume or more. The ethanol composition according to claim 1, wherein the ethanol concentration is 95% by volume or more. The method according to claim 2 or 3, wherein the concentration of ethanol is 75% by volume or more. The method according to claim 2 or 3, wherein the concentration of ethanol is 90% by volume or more. The method according to claim 2 or 3, wherein the concentration of ethanol is 95% by volume or more. The ethanol composition according to any one of claims 1 to 6, which is for use in chemical products. The ethanol composition according to any one of claims 1 to 6, which is for use as a fuel. The ethanol composition according to any one of claims 1 to 6, which is used as a polymer raw material. A chemical product made from the ethanol composition according to any one of claims 1 and 4 to 6 . A fuel comprising the ethanol composition according to any one of claims 1 and 4 to 6 and/or ethyl t-butyl ether produced from the ethanol composition according to any one of claims 1 and 4 to 6 . A polymer raw material obtained by using the ethanol composition according to any one of claims 1 and 4 to 6 as a raw material. 16. The polymeric feedstock of claim 15 , selected from the group consisting of ethylene, propylene, butadiene, ethyl acetate, isobutene, methyl (meth)acrylate, acrylic acid, aminohexanoic acid, and diethyl carbonate. A polymer obtained from the polymer raw material according to claim 15 or 16 . A molded article comprising the polymer of claim 17 .