JPS6136730B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in the selective production of dioxygenated hydrocarbons, namely acetic acid, ethanol and/or acetaldehyde, from synthesis gas. More particularly, the present invention relates to the reaction of synthesis gas in the presence of a rhodium-sodium catalyst under heterogeneous reaction conditions correlated to the production of the two carbon atom products described above. The production of hydrocarbons and oxygenated hydrocarbons from synthesis gas (substantially a mixture of carbon monoxide and hydrogen) has been extensively studied and industrially employed. Reaction conditions generally include temperatures on the order of 150 to 450°C, with pressures from atmospheric to about 700 Kg/cm ² gauge (about 10,000 psig), and hydrogen to carbon monoxide ratios ranging from 4:1 to about 1:4. , hydrogenation catalysts such as iron group or noble metals. One of the significant inabilities of most syngas processes for the production of oxygenated hydrocarbons having two or more carbon atoms has been the non-selectivity or non-specificity of the product distribution. Catalysts with acceptable activity generally tend to yield a wide range of products, such as hydrocarbons and oxygenated hydrocarbons having a wide distribution of carbon atom contents. This not only complicates the recovery of the desired product, but also consumes the reactants for by-products of no industrial interest. GB 1501892 is directed to a process for the selective production of a mixture of two carbon atom oxygenated compounds, namely acetic acid, ethanol and acetaldehyde, using a rhodium catalyst. UK patent no.
No. 1,501,891 describes a process that favors the production of ethanol compared to acetic acid and acetaldehyde by incorporating iron into the rhodium-based catalyst. U.S. Pat. No. 4,096,164 and co-pending U.S. Patent Application Ser. ) relating to enhancing the productivity and/or changing the distribution of said two carbon atom oxygenated compounds by adding respective elements such as uranium. Among other materials, rhodium catalysts supported on sodium-containing supports have been used for the production of oxygenated hydrocarbons from synthesis gas. The table of GB 1501892 describes various rhodium catalysts used in the experiments therein, some of which were prepared on Davison 59 silica gel. Shown as being supported. The chemical composition of the above grade 59 silica gel is listed in Grace Technical Bulletin IC-773-15.
and therein 0.10 wt% _Na2O
(equivalent to 0.074 wt% Na) is present in the gel. Lower sodium values for this type of gel are disclosed in Grace Technical Bulletin 202 (1958), page 2,
A sodium level of 0.02% by weight is shown therein as a typical value for Davison silica gel. The Journal of Catharsis
Journal of Catalysis, Vol. 54, pp. 120-128 (1978), Bhasin et al. disclose a syngas reaction with a rhodium catalyst supported on Davison Grace 59 silica gel. In Table 1 on page 121 of this publication, the sodium content of this silica gel carrier is
It is reported to be 0.085% by weight. Thus, the sodium content of silica gel supports of the type used in connection with the rhodium catalysts described in the above-mentioned British patent specification and the disclosure of Bassin et al. ranges from as low as 0.02% by weight in the technical literature.
As high as 0.085% by weight have been reported. An undesirable feature of the synthesis gas process disclosed in the above patents and the publication The Journal of Catalysis is the production of methane along with the desired two carbon atom oxygenated hydrocarbons. Generally, the greater the reaction efficiency to methane, the lower the production of the desired oxygenated hydrocarbon. Methane production is economically undesirable because methane is a significantly less valuable industrial chemical than either ethanol, acetic acid or acetaldehyde. Moreover, since the reactants of these processes, carbon monoxide and hydrogen, are generally produced industrially by steam reforming of methane, the production of methane from synthesis gas is necessarily reversed. Impairs overall process efficiency. The present invention discloses a catalyst for producing two carbon atom oxygenated hydrocarbons from the reaction of carbon monoxide and hydrogen. The catalyst of the present invention suppresses the production of methane while maintaining selectivity to the two-carbon atom compound in the overall reaction, while controlling the distribution of the two-carbon atom oxygenated hydrocarbons produced by the reaction. It acts to move it to the acetic acid side. The process of the invention involves contacting a catalyst consisting of rhodium in combination with sodium with synthesis gas under suitable reaction conditions to produce acetic acid,
selectively producing ethanol and/or acetaldehyde, wherein the concentration of sodium in the catalyst is at least 0.1% by weight.
It is something that is. The catalyst can optionally be combined with an alkali metal such as lithium, potassium, cesium or rubidium to suppress the production of methane as a co-product in the desired oxygenated compounds. In a preferred embodiment of the invention, the catalyst further contains manganese to improve the reaction rate for the production of two carbon atom products. The reaction is such that collectively at least about 50%, preferably at least about 75%, of acetic acid, ethanol and/or acetaldehyde are produced by weight of the compound having two or more carbon atoms obtained by the reaction. The reaction is carried out under reaction conditions of temperature, pressure, gas composition, and space velocity that are correlated to .
Desirably, the reaction is conducted under these correlated conditions to achieve a carbon efficiency of 10% or more, often 50% or more, based on carbon consumption for a particular product. Under optimal reaction conditions, especially at relatively low conversions, there is little conversion to three-carbon atom hydrocarbons, higher hydrocarbons, and oxygenated hydrocarbons, and minimal conversion to methane and methanol. be able to. The reaction efficiency or selectivity for two carbon atom compounds is at least about 10%, usually about 25% or more, and under favorable conditions exceeds 50% and reaches 90% or more under optimal conditions. be able to. Selectivity is defined herein as the percentage of carbon atoms converted from carbon monoxide to a specific compound or a compound other than CO ₂ . In this way, the independent reaction variables are correlated so that substantial proportionate amounts of the desired two-carbon atom oxygenated hydrocarbons (acetic acid, ethanol and acetaldehyde) are produced. This ratio, expressed as carbon conversion efficiency, is usually greater than 25% and often exceeds 50%. In one aspect of the present invention, this correlation is important for maintaining mild reaction conditions, thereby limiting the conversion of CO to no more than about 1/4, and preferably no more than about 1/8. This is a combination of conditions. The fractional conversion rate shown above is calculated using a single pass (single pass).
pass). As explained in detail below, this correlation is accomplished primarily in combination with high space velocities. However, other factors (eg H ₂ /CO ratio, catalyst activity, pressure, bed geometry, etc.) also influence conversion. It is noted that at high conversions, hydrocarbons and higher carbon number oxygenated hydrocarbons are produced in excess, with a loss of efficiency to two carbon atom compounds. The reaction conditions with respect to temperature, pressure and gas composition are generally substantially within the conventional ranges for the conversion of synthesis gas, and in particular within the ranges employed for the production of methanol. The reaction can therefore be carried out using current technology and, in some cases, current equipment. The reaction is highly exothermic and both the thermodynamic balance and the kinetic reaction rate are governed by the reaction temperature. The average catalyst bed temperature is usually about 150 ~
450℃, but for optimum conversion the bed temperature should be approx.
Keep within the range of 200-400°C, typically about 250-350°C. Reaction temperature is an important process variable, affecting not only the overall productivity but also the selectivity to one or more of the desired two-carbon atom products.
Over a relatively narrow temperature range, such as 10°C or 20°C, increasing temperature slightly increases overall syngas conversion, increases the efficiency of ethanol production, and increases the efficiency of acetic acid and acetaldehyde production. There may be a tendency for efficiency to decrease. At the same time, however, high temperatures favor methane production, and at high temperatures the production of methane clearly increases more rapidly than the conversion to the desired two-carbon atom product takes place. Therefore, for a given catalyst, and holding all other variables constant, the optimum temperature depends more on product and process economics than on thermodynamic or kinetic considerations; Although the production of oxygenated products increases, the co-product methane tends to increase unduly. The temperatures given in the above discussion represent average values of reaction bed temperatures. Because of the high temperature exothermic nature of the reaction, it is desirable to control the temperature so that runaway methanation does not occur. In runaway methanation, the production of methane increases as the temperature rises, and the resulting heat generation causes the temperature to rise further.
This temperature control can be accomplished, for example, by using a fluidized bed reaction zone, by using a multistage fixed bed adiabatic reactor with interstage cooling, or by using a multitubular reactor with a cooling liquid surrounding the catalyst-filled tubes. Conventional temperature control techniques are utilized, such as the use of relatively small catalyst particles (see U.S. Pat. No. 4,125,553, issued Nov. 14, 1978). The pressure in the reaction zone is approximately 1.05Kg/cm ² gauge pressure (approx.
15psig) to approx. 700Kg/cm ² gauge pressure (approx.
10,000 psig), preferably within the range of approximately 21 to 350 Kg/
A range of ^cm2 gauge pressure (approximately 300-5000 psig) is economical. A higher pressure in the reaction zone increases the total weight of product obtained per unit time and likewise improves the selectivity to two carbon atom compounds. The ratio of hydrogen to carbon monoxide in the synthesis gas can vary over a wide range. Usually the molar ratio of hydrogen to carbon monoxide is within the range of 20:1 to 1:20, preferably within the range of about 5:1 to about 1:5. However, in some cases it may be advantageous to operate at a lower molar ratio of hydrogen to carbon monoxide, such as about 1:200. In most of the experimental work reported herein, the molar ratio of hydrogen to carbon monoxide is approximately 1:1. An increase in this ratio tends to increase the overall reaction rate, in some cases quite significantly, and yet has a small but beneficial effect on the rate of formation of the two carbon atom product. But at the same time the selectivity to methane increases. An increase in the hydrogen to carbon monoxide ratio also favors the production of more highly reduced products, ie, favors the production of ethanol rather than acetaldehyde or acetic acid. Carbon dioxide, which can typically be present in the synthesis gas in amounts up to about 10 mole percent, has virtually no effect. One feature of the present invention is that a low conversion, e.g. preferably 20% or less of CO per pass, is achieved by using a substantial proportion (generally 10% or more) of acetic acid;
It is recognized that it is advantageous for the production or manufacture of ethanol and/or acetaldehyde. This conversion is dependent on other reaction variables (e.g. temperature,
This is advantageously achieved by employing high space velocities as a function of pressure, gas composition and catalyst). Typically a gas space velocity of about 10 ³ per hour (per volume of catalyst per hour,
Reaction gas volume at 0°C and 760 mm mercury pressure,
Although space velocities of GHSV or higher are generally employed, space velocities within the range of about 10 ⁴ to about 10 ⁶ per hour are preferred. Too high space velocities lead to uneconomically low conversions, while too low space velocities lead to the production of a more diverse range of reaction products, including high boiling hydrocarbons and oxygenated hydrocarbons. The rhodium-sodium catalyst of the invention consists of rhodium provided on a support material in combination with sodium. This catalysis is typically carried out by depositing rhodium and sodium on a particulate support and then placing the supported combination in a reaction zone. To accomplish the purpose of the present invention, lithium,
Other elements can be conveniently included, such as alkali metals selected from potassium, cesium and rubidium; iron, manganese and molybdenum/tungsten. Along with rhodium
Regarding the use of these elements, June 1979
Co-pending U.S. Patent Application Serial No. 052841 filed on May 28th
No. 676129, also filed on April 12, 1976
No. 4,014,913 and US Pat. No. 4,096,164, respectively. Based on experience to date, the amount of catalyst on the support is approximately
It should range from 0.01% to about 25% by weight. Preferably the amount of catalyst is from about 0.1 to about
It is within the range of 10% by weight. The molar ratio of sodium to rhodium in the catalyst should generally be varied from about 0.01 to about 10, preferably from about 0.1 to about 5, to reduce methane-carbon efficiency in accordance with the present invention. Most preferably the sodium/rhodium molar ratio should be within the range of about 0.2 to 1. Particulate carriers with a relatively high surface area, e.g.
It is preferable to have a surface area of 10 m ² /g or more (BET low-temperature nitrogen adsorption isothermal method), preferably about 10 m ² /g or more. However, surface area is not the only determining variable. Based on the research to date, silica gel is preferred as the base material or carrier for the catalyst, and graphite,
Graphitized carbon, alpha-alumina, manganese oxide, magnesia, eta-alumina, gamma-alumina and activated carbon are less preferred. For purposes of this invention, rhodium deposited on either sodium oxide particles or a sodium-containing support is considered to be substantially the same as rhodium and sodium co-deposited on any of the above support materials. . The rhodium and sodium can be deposited on the catalyst substrate or support by any technique commonly employed in catalyst preparation, such as impregnation from organic or inorganic solutions, precipitation, coprecipitation, or cation exchange. Conveniently, a solution of thermally decomposable inorganic or organic rhodium and sodium compounds is contacted as support material, and the support is then dried and heated, said heating being carried out under reducing conditions, to ensure a clean dispersion. form a sodium-containing rhodium catalyst. At the same time, both of these materials
or can be deposited subsequently. Initially, the inorganic or organic compounds of rhodium and sodium are suitably brought into contact with a carrier material, then the carrier is dried and heated, the heating being under reducing conditions, to form a neatly dispersed rhodium and sodium. Suffice it to say that it forms. The deposited rhodium is in metallic form, preferably in fine, discrete particles. In its metallic form, sodium forms an alloy with rhodium. The reactor used in these studies was a J-type reactor with a catalyst cage installed in the center and a product outlet pipe. M. Designed by JMBerty
The autoclave was a 316 stainless steel, bottom-stirred, "magnetically driven" autoclave. This reactor was built in 1969
The American Institute of Chemical Engineers (AIChE) Symposium on Advances in High Pressure Technology Part was held from March 16 to 20, 2019 in New Orleans, Louisiana, USA.
Reactor for Vapor Force Catalytic Studies, submitted as Proceedings 42E to the 64th Conference of Pressure Technology-Part), available from AIChE, 345 East 47th Street, New York 10017, New York.
It is of the form illustrated in Figure 1 of the paper by Berty, Hambrick, Malone, and Ullock entitled ``For Vapor-Phase Catalytic Studies''. A variable speed magnetically driven blower continuously circulated the reaction mixture over the catalyst bed. It was found that the following improvements made the operation easier and moreover suppressed the runaway methanation reaction. 1 Hydrogen feed gas was introduced continuously into the bottom of the autoclave through the hole for the shaft of the magnetically driven stirrer. 2 Carbon monoxide feed gas was introduced continuously through a separate port in the bottom of the autoclave to avoid hydrogen-rich zones of the autoclave. Effluent gas was removed through a port in the side of the reactor. The condensable liquid product was removed from the outlet stream in a brine cooled condenser at about 5-10°C and collected in a storage tank under pressure. The noncondensable components in the outlet stream were measured for their total volume through a wet test meter at atmospheric pressure.
A rubber septum in the atmospheric pressure conduit allowed for syringe sampling of non-condensable gases. No external recirculation was employed. The bulk volume of the weighed catalyst sample was determined and the sample was placed in a catalyst cage. The catalyst charge is approximately 10c.c.
It varied from about 100 c.c. The catalyst charge was selected to obtain an estimated reaction gas conversion of less than 10%. Thin layers of gold-plated wire mesh and glass wool were placed above and below the catalyst bed to prevent circulation of solid particulates. The catalyst cage was loaded into the reactor and the reactor was then sealed. The sealed reactor and process conduits were pressure tested at ambient temperature to pressures of about 35 to about 70 Kg/cm ² gauge (about 500 to about 1000 psig) above the maximum expected working pressure. Nitrogen, hydrogen or a mixture of the two were used in this test. When the reactor was found to be free of leaks, pure hydrogen was passed through the reactor and the temperature was raised to approximately 240°C.
Next, the flow of hydrogen and carbon monoxide was adjusted to a molar ratio of 1:1.
Adjust the purge speed to approximately 500STP (temperature 0
℃, pressure 1 atm (standard temperature and pressure)/hour. This corresponds to a space velocity of about 5,000 to about 50,000 STP gas volumes per hour of catalyst volume, depending on the charged catalyst volume in each example.
The hydrogen to carbon monoxide ratio was determined by gas chromatographic analysis of an aliquot of the effluent gas. When the appropriate gas composition was obtained, the reactor temperature was increased to the desired value. It took about 0.5 to about 1 hour for the reactor to reach steady state at the new temperature. The liquid product trap was then drained and the wet test scale was read and the time recorded as the experiment began. One or more effluent gas samples were analyzed for hydrogen, carbon monoxide, acetaldehyde, methane, and other volatile hydrocarbons during the course of the experiment. The liquid product was collected at the end of the experiment and the volume of effluent gas was recorded. The liquid product was analyzed by gas chromatography. Subsequent experiments were carried out using the same catalyst either under the same conditions or under new conditions for temperature and feed gas flow. If any conditions change, approximately 1
Allow the reactor to reach a new stable state over time. All of the catalysts shown in the examples below were prepared by a sequential process essentially as follows. Depending on the desired catalyst composition, the desired amounts of rhodium trichloride or rhodium nitrate (), manganese nitrate (), and sodium nitrate were dissolved in distilled water at ambient temperature. The volume of distilled water used to prepare this solution was chosen to just fill the void volume (pores) of the carrier sample to be impregnated. Davison® Grade 59 Silica Gel (US Sieve Size 8)
~20 mesh) was placed in a vacuum flask. The top of the flask was sealed with a rubber septum and the flask was then evacuated through a side tube. The solution was then injected onto the evacuated carrier using a syringe needle.
When the addition was complete, the impregnated support was left at 1 atmosphere for about 30 minutes. The support is then carefully subjected to a series of operations as described below in a nitrogen atmosphere.
i.e. 80℃ (1 hour), 110℃ (2 hours), 150℃
(2 hours) and at about 250°C (2 hours).
This impregnated and dried carrier is placed in a quartz tube,
Hydrogen was continuously passed through the quartz tube. The temperature was increased from 100° to 500°C over 5 to 6 hours and then held at 500°C for 1 hour. The reduced, alloyed catalyst was cooled to ambient temperature in a nitrogen or hydrogen flow atmosphere. The Davison™ Grade 59 silica support was first washed with oxalic acid prior to use as a catalyst support to remove significant amounts of impurities that were present in the support material as received from the manufacturer. The above process involves adding a mixture of oxalic acid, glycerin and water in a 1:1.5:2.5 weight ratio, respectively, to a bed of carrier material (with a length to diameter ratio of approximately 20:1) contained in a glass tube.
25) and draining through a stop at the base of the glass tube. The contents of the glass tube were maintained at a temperature of approximately 90° C. by a resistance heating wire wrapped around the outside of the glass tube. Approximately 2.5
One volume of 8-20 mesh silica gel was washed using 1 volume of oxalic acid solution for 3 hours. The carrier material is then washed with about 6 ml of distilled water at a temperature of 90°C for about 4 hours and then at 350°C.
It was dried for about 4 hours at a temperature of . Following the above treatment, the silica gel was chemically analyzed for iron, aluminum, sodium and calcium impurities and the following values were obtained. Iron ( _{as Fe2O3} ) 0.01±0.004% by weight Aluminum (as _Al2O3 ) 0.01±0.004% by weight Sodium (as _Na2O ) 0.01±0.004% by weight Calcium (as _CaO ) 0.02±0.01% by weight Below: The table summarizes data for a series of manganese and sodium containing rhodium catalysts supported on silica gel. The catalyst was tested according to the test procedure described above in the test reactor at a temperature of 300° C., a total pressure of about 70 Kg/cm ² gauge (1000 psig) and a molar ratio of hydrogen to carbon monoxide of about 1. In determining production rates and selectivities used in the data presented in this case, the ethyl ester and acetate produced were included as ethanol and acetic acid. That is, when calculating the values of ethanol and acetic acid, the amounts obtained by hydrolysis of the esters whose presence has been confirmed are included in the above values. The examples in the table illustrate the effect of sodium addition on rhodium catalysts: a significant decrease in carbon efficiency to methane and an increase in acetic acid selectivity among 2 carbon atom oxygenated hydrocarbon products. 【table】

Claims (1)

[Claims] 1. A method for reacting synthesis gas containing carbon monoxide and hydrogen in the presence of a hydrogenation catalyst, comprising:
The synthesis gas is treated with a heterogeneous catalyst made of metal rhodium alloyed with metal sodium, and which achieves a product efficiency of 10% or more based on carbon consumption, and generates 2 carbon by the reaction. At least about 50% by weight of the compound of atoms or more carbon atoms
of ethanol, acetic acid and acetaldehyde, and the concentration of sodium in the catalyst is at least 0.1% by weight, thereby reducing the production of methane such that the carbon efficiency for methane is lower than that in the absence of sodium in the heterogeneous catalyst. If the reaction conditions are reduced to be lower than the equivalent carbon efficiency in the case, the reaction conditions are at a temperature within the range of about 150-450 °C, about
A pressure in the range of 1.05 to 700 Kg/cm ² gauge pressure (about 15 to 10,000 psig), a molar ratio of hydrogen to carbon monoxide of about 20:1 to about 1:200, and a gas hourly space velocity of about
Selective production of two carbon atom oxygenated hydrocarbon products while minimizing production of methane, characterized by continuous contacting under conditions comprising a gas feed rate of 10 ⁴ to 10 ⁶ An improved method of the above method. 2. A method for reacting synthesis gas containing carbon monoxide and hydrogen in the presence of a hydrogenation catalyst,
The synthesis gas is reacted with a heterogeneous catalyst consisting of metal rhodium alloyed with metal sodium and metal manganese, achieving a product efficiency of 10% or more based on carbon consumption, and producing the product by the reaction. at least about 50% by weight of compounds with two or more carbon atoms
amounts of ethanol, acetic acid, and acetaldehyde, and the sodium concentration in the catalyst is at least 0.1% by weight, thereby controlling the production of methane such that the carbon efficiency for methane is reduced by the amount of sodium and manganese in the heterogeneous catalyst. The carbon efficiency is reduced to be lower than the equivalent carbon efficiency in the case where the reaction conditions are at a temperature in the range of about 150-450 °C, about
A pressure in the range of 1.05 to 700 Kg/cm ² gauge pressure (about 15 to 10,000 psig) and a hydrogen to carbon monoxide molar ratio of about 20:1 to about 1:200 and a gas hourly space velocity of about
Selective production of two carbon atom oxygenated hydrocarbon products while minimizing production of methane, characterized by continuous contacting under conditions including gas feed rates of 10 ⁴ to ^{10 6} An improved method of the above method. 3 The reaction conditions are at a temperature within the range of approximately 250 to 350°C, approximately
Claims encompassing a pressure within the range of 21 to 350 Kg/ ^cm2 gauge pressure (about 300 to 5000 psig) and a molar ratio of hydrogen to carbon monoxide within the range of about 5:1 to about 1:5. The method described in Section 1. 4. The method according to claim 1, wherein the conversion rate of CO in the synthesis gas is about 1/4 or less based on one pass.