Method for producing oxygen compound

Abstract

This method for producing an oxygen compound comprises a step for obtaining a gas containing an oxygen compound from a raw material gas containing carbon oxide, hydrogen, and water, in the presence of a catalyst (A) containing rhodium, wherein the content of the water in the raw material gas is 0.03-2.0 vol%, and the content of the rhodium in the catalyst (A) is 0.6-2.9 mass%. Moreover, in this method for producing an oxygen compound, the raw material gas further contains at least one selected from among methanol, ethanol, and acetaldehyde, and the total content of the methanol, the ethanol, and the acetaldehyde in the raw material gas is 0.05-1.0 vol%.

Description

Method for producing oxygen compounds

[0001] This invention relates to a method for producing oxygen compounds.

[0002] Bioethanol, obtained primarily by fermenting plant-derived biomass, is attracting attention as a promising alternative fuel for reducing environmental impact and achieving energy sustainability. However, conventional fermentation processes have the drawback that the biomass raw materials are usually limited to grains rich in sugars, such as sugarcane, which could potentially compete with food supply.

[0003] To overcome this drawback, second-generation ethanol technology using non-edible cellulosic biomass as raw material has been developed. However, many technical challenges remain before its practical application, including yield and process stability.

[0004] To overcome these challenges, a process for synthesizing ethanol from synthesis gas, which is composed of carbon monoxide and hydrogen, through a catalytic chemical reaction is attracting attention. This process is expected to be superior to fermentation in terms of reaction rate and yield, and it is also considered important from the perspective of waste recycling because it can use not only biomass but also general waste, waste paper, waste clothing, and waste plastics as raw materials for synthesis gas.

[0005] Regarding the above process, previous research has proposed the use of metal catalysts such as copper, chromium, zinc, and rhodium. For example, Patent Document 1 discloses a technology for producing ethanol from a raw material gas containing carbon monoxide and hydrogen using a rhodium-containing catalyst.

[0006] Japanese Patent Publication No. 2012-1441

[0007] However, conventional methods for producing oxygen compounds such as ethanol do not always provide satisfactory catalyst lifespan, and there is a need for a method of producing oxygen compounds with superior catalytic activity stability.

[0008] In view of these problems, the object of the present invention is to provide a method for producing oxygen compounds that exhibits excellent retention of the carbon oxide conversion rate.

[0009] The method for producing an oxygen compound according to the present invention includes the step of obtaining a gas containing an oxygen compound from a raw material gas containing carbon oxide, hydrogen, and water in the presence of a catalyst (A) containing rhodium, wherein the water content in the raw material gas is 0.03% by volume or more and 2.0% by volume or less, and the rhodium content in the catalyst (A) is 0.6% by mass or more and 2.9% by mass or less.

[0010] The present invention provides a method for producing oxygen compounds that exhibits excellent retention of the carbon oxide conversion rate.

[0011] The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments.

[0012] The method for producing an oxygen compound according to this embodiment includes a step (also referred to as step (a)) of obtaining a gas containing an oxygen compound from a raw material gas in the presence of a catalyst (A) containing rhodium. Step (a) is preferably carried out by contacting the raw material gas with the catalyst (A).

[0013] In this specification, the "volume" used to calculate the gas content expressed in "volume %", the gas supply rate expressed in "mL / min", and the "raw material gas flow rate (L·h)" used to calculate the "space velocity" of the gas are defined as follows: －１ In the above, the "volume" represented by "L" is the value converted to the "volume at 0°C and 1 atmosphere".

[0014] (Raw material gas) The raw material gas includes carbon oxide, hydrogen, and water.

[0015] As the carbon oxide, for example, carbon monoxide, carbon dioxide, etc., can be used. The carbon oxide may be used alone or in combination of two or more types. The carbon oxide is preferably carbon monoxide. In addition to the carbon oxide obtained by the raw material gas production process described later, carbon oxide recovered from the air may also be used.

[0016] The raw material gas is not particularly limited as long as it contains carbon dioxide, hydrogen, and water. The raw material gas may be produced by decomposing biomass, or obtained by decomposing organic waste such as general waste, waste paper, and waste clothing. The raw material gas may be produced from fossil raw materials, or it may be a gas generated in the process of utilizing fossil resources as energy, or it may be a gas generated in the manufacturing process of steel or chemical products, or it may be a gas produced using waste plastics as a raw material. The raw material gas can be obtained by conventionally known methods, such as heating biomass with steam. If the raw material gas contains carbon dioxide, it may also contain carbon monoxide converted from carbon dioxide and hydrogen by a reverse water-gas shift reaction.

[0017] The raw material gas may contain impurities. Examples of such impurities include tar components, char components, sulfur, nitrogen, and chlorine. The method for producing the oxygen compound according to this embodiment may include a step of purifying the raw material gas before carrying out step (a) in order to remove the impurities from the raw material gas.

[0018] The total content of carbon oxide and hydrogen in the raw material gas is preferably 15% by volume or more, more preferably 30% by volume or more, and even more preferably 50% by volume or more. The higher the total content of carbon oxide and hydrogen in the raw material gas, the higher the efficiency of ethanol production can be. The total content of carbon oxide and hydrogen in the raw material gas is not particularly limited, but may be 100% by volume or less, 90% by volume or less, or 80% by volume or less.

[0019] H in the aforementioned raw material gas ２ The H / CO ratio ([volume % of hydrogen] / [volume % of carbon monoxide]) may be 0.3 or higher, 0.5 or higher, 0.7 or higher, 0.9 or higher, or 1.0 or higher. ２The CO ratio may be 4.0 or less, 3.5 or less, 3.0 or less, 2.5 or less, or 2.0 or less.

[0020] H in the aforementioned raw material gas ２ To adjust the CO ratio, hydrogen may be introduced into the raw material gas from an external source. The specific means of the hydrogen production process for introducing the hydrogen into the raw material gas are not particularly limited. That is, the hydrogen may be, for example, hydrogen derived from fossil fuels, hydrogen produced by the decomposition of ammonia or the electrolysis of water, etc., introduced into the raw material gas from an external source.

[0021] In the method for producing oxygen compounds according to this embodiment, after carrying out step (a) or step (b) described later, the gas obtained in step (a) or step (b) is separated into a gas mainly composed of oxygen compounds and a gas mainly composed of unreacted gas containing carbon oxide, hydrogen, and water, and at least a portion of the gas mainly composed of unreacted gas containing carbon oxide, hydrogen, and water (also called reaction recycled gas) is introduced into step (a) as part of the raw material gas.

[0022] The water in the raw material gas is not particularly limited and may be, for example, water generated in the manufacturing process of the raw material gas, or water contained in the reaction recycled gas. As the water, ionized water, ion-exchanged water, distilled water, tap water, industrial water, etc., may be introduced into the raw material gas from an external source.

[0023] The water content in the raw material gas is 0.03% by volume or more and 2.0% by volume or less. The water content in the raw material gas may be 0.04% by volume or more, 0.05% by volume or more, 0.07% by volume or more, or 0.1% by volume or more. The water content in the raw material gas may be 1.9% by volume or less, 1.8% by volume or less, 1.7% by volume or less, 1.6% by volume or less, 1.5% by volume or less, 1.3% by volume or less, or 1.0% by volume or less.

[0024] When the water content in the raw material gas is within the above numerical range, the maintenance rate of the conversion rate of carbon monoxide is improved.

[0025] The supply rate of the raw material gas is appropriately adjusted so that the space velocity of the raw material gas becomes a preferable value. The space velocity of the raw material gas may be 10 h －１ or more, may be 100 h －１ or more, may be 500 h －１ or more, may be 1000 h －１ or more, may be 2000 h －１ or more. The space velocity of the raw material gas may be 200000 h －１ or less, may be 100000 h －１ or less, may be 50000 h －１ or less, may be 10000 h －１ or less, may be 5000 h －１ or less. The space velocity is defined as the value obtained by dividing the volume of the gas passing through the catalyst per unit time by the volume of the catalyst ([raw material gas flow rate (L·h －１ )] / [volume of catalyst (L)]).

[0026] As one aspect, the raw material gas contains carbon monoxide, hydrogen, and water obtained by the thermochemical gasification reaction of plastic. The thermochemical gasification reaction refers to a reaction in which plastic is decomposed into gas components such as hydrogen, carbon monoxide, and water, and solid components such as slag by heating the plastic. The plastic may be plastic recovered from the market.

[0027] When the raw material gas contains carbon monoxide, hydrogen, and water obtained by the thermochemical gasification reaction of plastic, it becomes possible to recycle the plastic and contribute to reducing the environmental load.

[0028] In addition to the carbon monoxide, hydrogen, and water, the raw material gas may contain methane, ethane, ethylene, methanol, ethanol, acetaldehyde, nitrogen, helium, argon, etc. The raw material gas preferably further contains one or more selected from methanol, ethanol, and acetaldehyde.

[0029] When the raw material gas contains methane, the methane content in the raw material gas is preferably 50% by volume or less, more preferably 30% by volume or less, and even more preferably 10% by volume or less.

[0030] By ensuring that the methane content in the raw material gas meets the above upper limit, the concentrations of carbon oxide and hydrogen in the raw material gas can be kept above a certain level, thereby improving the efficiency of ethanol production.

[0031] If the raw material gas further contains one or more selected from methanol, ethanol, and acetaldehyde in addition to the carbon oxide, hydrogen, and water, the total content of methanol, ethanol, and acetaldehyde in the raw material gas is preferably 0.05% by volume or more and 1.0% by volume or less. The total content of methanol, ethanol, and acetaldehyde in the raw material gas may be 0.06% by volume or more, 0.07% by volume or more, 0.1% by volume or more, 0.2% by volume or more, 0.4% by volume or more, or 0.5% by volume or more. The total content of methanol, ethanol, and acetaldehyde in the raw material gas may be 0.9% by volume or less, 0.8% by volume or less, 0.7% by volume or less, or 0.6% by volume or less.

[0032] The ethanol is not particularly limited, but for example, ethanol obtained in step (a) or step (b) described later, biomass-derived ethanol, ethanol produced by the hydration reaction of ethylene, etc. may be used. In addition, commercially available reagents may be used as the ethanol. For example, reagent-grade ethanol manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. may be used as the ethanol. The ethanol is not limited to the manufacturer and grade of these reagents, and commercially available products from other manufacturers may be used, or the amount of commercially available products of other grades with different purities added may be adjusted so that the concentration of each component in the raw material gas reaches a specific value. These ethanols can be used individually or in combination of two or more types.

[0033] The methanol and the acetaldehyde are not particularly limited, but the methanol and acetaldehyde obtained in step (a) or step (b) described later can be used. Also, commercially available reagents may be used as the methanol and the acetaldehyde. For example, as the methanol, a special grade manufactured by Kanto Chemical Co., Inc. may be used, and as the acetaldehyde, a first grade reagent manufactured by Fujifilm Wako Pure Chemical Corporation may be used. The methanol and the acetaldehyde are not limited to the manufacturers and grades of these reagents, and commercially available products of other manufacturers may be used. Alternatively, the addition amounts of commercially available products of other grades with different purities may be adjusted so that the concentrations of the respective components in the raw material gas become specific values and then used.

[0034] The raw material gas preferably further contains at least one selected from methanol, ethanol, and acetaldehyde obtained in step (a), and more preferably further contains ethanol obtained in step (a). Also, the raw material gas preferably further contains at least one selected from methanol, ethanol, and acetaldehyde obtained in step (b) described later, and more preferably further contains ethanol obtained in step (b).

[0035] (Oxygen compound) Examples of the oxygen compound include methanol, ethanol, propanol, butanol, acetaldehyde, acetic acid, methyl acetate, ethyl acetate, and the like.

[0036] (Catalyst (A)) The catalyst (A) contains rhodium.

[0037] F The valence of the rhodium is not particularly limited, and may be zero valence indicating a reduced state or a positive valence indicating an oxidized state.

[0038] In the production of catalyst (A), a rhodium-containing compound can be used as a raw material compound. The rhodium-containing compound is not particularly limited, but examples include inorganic salts such as chlorides, bromides, iodides, cyanides, oxides, hydroxides, nitrates, sulfates, carbonates, and phosphates; organic salts such as carboxylates and ethylenediamine acetates; acetylacetonate complexes, ammine complexes, alkoxide compounds, chelate compounds, carbonyl compounds, and cyclopentadienyl compounds. As the chloride, for example, rhodium chloride and rhodium chloride trihydrate can be used.

[0039] The rhodium content in catalyst (A) is 0.6% by mass or more and 2.9% by mass or less. The rhodium content in catalyst (A) may be 0.8% by mass or more, or 1.0% by mass or more. The rhodium content in catalyst (A) may be 2.5% by mass or less, 2.0% by mass or less, or 1.6% by mass or less.

[0040] The rhodium content in catalyst (A) can be determined using the following formula (1), where rhodium mass and catalyst (A) mass are used. In formula (1), "rhodium mass" refers to the mass of the element rhodium.

[0041] Rhodium content (mass%) in catalyst (A) = [Mass of rhodium (g)] / [Mass of catalyst (A) (g) - Mass of rhodium (g)] × 100 ... (1)

[0042] By having the rhodium content in catalyst (A) within the above numerical range, the maintenance rate of carbon oxide conversion is improved, and the amount of rhodium used in catalyst (A) can be relatively reduced, contributing to a reduction in the amount of precious metals used.

[0043] The catalyst (A) preferably further comprises at least one of manganese and lithium, and more preferably further comprises manganese and lithium.

[0044] The conversion rate of carbon oxide is further improved by further including at least one of manganese and lithium in the catalyst (A).

[0045] The valency of the manganese is not particularly limited and may be zero, indicating a reduced state, or positive, indicating an oxidized state.

[0046] In the production of catalyst (A), a manganese-containing compound can be used as a raw material compound. The manganese-containing compound is not particularly limited, but examples include inorganic salts such as chlorides, bromides, iodides, cyanides, oxides, hydroxides, nitrates, sulfates, carbonates, and phosphates; organic salts such as carboxylates and ethylenediamine acetates; acetylacetonate complexes; ammine complexes; alkoxide compounds; chelate compounds; carbonyl compounds; and cyclopentadienyl compounds. Examples of the chlorides include manganese chloride, manganese chloride dihydrate, and manganese chloride tetrahydrate.

[0047] The manganese content in catalyst (A) may be 0.05% by mass or more, 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more. The manganese content in catalyst (A) may be 3.0% by mass or less, 2.5% by mass or less, 2.0% by mass or less, 1.5% by mass or less, or 1.0% by mass or less.

[0048] The valency of the lithium is not particularly limited and may be zero, indicating a reduced state, or positive, indicating an oxidized state.

[0049] In the production of catalyst (A), a lithium-containing compound can be used as a raw material compound. The lithium-containing compound is not particularly limited, but examples include inorganic salts such as chlorides, bromides, iodides, cyanides, oxides, hydroxides, nitrates, sulfates, carbonates, and phosphates; organic salts such as carboxylates and ethylenediamine acetates; acetylacetonate complexes; ammine complexes; alkoxide compounds; chelate compounds; carbonyl compounds; and cyclopentadienyl compounds. Examples of chlorides that can be used include lithium chloride and lithium chloride monohydrate.

[0050] The lithium content in catalyst (A) may be 0.01% by mass or more, 0.02% by mass or more, or 0.03% by mass or more. The lithium content in catalyst (A) may be 3.0% by mass or less, 2.5% by mass or less, 2.0% by mass or less, 1.5% by mass or less, or 1.0% by mass or less.

[0051] The manganese content and lithium content in catalyst (A) can be determined by replacing "rhodium" in formula (1) with "manganese" or "lithium." In this formula, "mass of manganese" or "mass of lithium" represents the mass of these elements.

[0052] The molar ratio of manganese to rhodium in catalyst (A) is preferably 0.03 to 9.0, more preferably 0.1 to 5.0, and even more preferably 0.5 to 1.0.

[0053] The molar ratio of lithium to rhodium in catalyst (A) is preferably 0.05 to 70, more preferably 0.1 to 10, and even more preferably 0.2 to 5.0.

[0054] The molar ratio of lithium to manganese in catalyst (A) is preferably 0.02 to 400, more preferably 0.1 to 100, and even more preferably 0.2 to 10.

[0055] The catalyst (A) can be used in either a homogeneous catalyst or a heterogeneous catalyst (also called a supported catalyst). Preferably, the catalyst (A) is a supported catalyst (A').

[0056] If catalyst (A) is a supported catalyst (A'), the rhodium content in the supported catalyst (A') may be 0.6% by mass or more, 0.8% by mass or more, or 1.0% by mass or more. If catalyst (A) is a supported catalyst (A'), the rhodium content in the supported catalyst (A') may be 2.9% by mass or less, 2.5% by mass or less, 2.0% by mass or less, or 1.6% by mass or less.

[0057] The rhodium content in the supported catalyst (A') can be determined by the following formula (1') using the mass of rhodium and the mass of the support described later. In formula (1') below, "mass of rhodium" refers to the mass of the element rhodium.

[0058] Rhodium content (mass%) in supported catalyst (A') = [Mass of rhodium (g)] / [Mass of support (g)] × 100 ... (1')

[0059] The stability of the catalytic activity is improved when the rhodium content in the supported catalyst (A') is within the above numerical range.

[0060] If the catalyst (A) is a supported catalyst (A'), the manganese content in the supported catalyst (A') may be 0.05% by mass or more, 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more. If the catalyst (A) is a supported catalyst (A'), the manganese content in the supported catalyst (A') may be 3.0% by mass or less, 2.5% by mass or less, 2.0% by mass or less, 1.5% by mass or less, or 1.0% by mass or less.

[0061] If the catalyst (A) is a supported catalyst (A'), the lithium content in the supported catalyst (A') may be 0.01% by mass or more, 0.02% by mass or more, or 0.03% by mass or more. If the catalyst (A) is a supported catalyst (A'), the lithium content in the supported catalyst (A') may be 3.0% by mass or less, 2.5% by mass or less, 2.0% by mass or less, 1.5% by mass or less, or 1.0% by mass or less.

[0062] The manganese content and lithium content in the supported catalyst (A') can be determined by a calculation formula obtained by replacing "rhodium" in formula (1') with "manganese" or "lithium." In this calculation formula, "mass of manganese" or "mass of lithium" represents the mass of these elements.

[0063] As the support for the supported catalyst (A'), for example, silica, alumina, titania, zirconia, ceria, magnesia, zeolite, activated carbon, etc., can be used. Preferably, the support for the supported catalyst (A') is silica.

[0064] By using silica or the like as the support for the supported catalyst (A'), a catalyst with uniform particle size can be prepared, and the rhodium can be highly dispersed and supported on the silica or the like, thereby further improving the carbon oxide conversion rate.

[0065] The particle size of the carrier is appropriately determined according to the type of reactor, the type of carrier, and the reaction conditions. The particle size of the carrier is preferably 1 to 5000 μm, more preferably 10 to 4000 μm, and even more preferably 50 to 3000 μm.

[0066] The content of the support in the supported catalyst (A') is preferably 80 to 99% by mass, and more preferably 90 to 99% by mass.

[0067] (Use of Catalyst) When filling the reactor with a catalyst such as catalyst (A), the catalyst may be mixed with a diluent that is inert to the raw material gas and reaction products such as oxygen compounds. Examples of diluents include alumina, zirconia, quartz, glass, and silicon carbide. Diluents may be molded into granular, spherical, cylindrical, or amorphous forms.

[0068] (Process Conditions) Process (a) can be carried out using a reactor. Examples of reactors that can be used include an external heat exchange type fixed bed reactor, an insulated fixed bed reactor, a fluidized bed reactor, a pseudo-moving bed reactor, a riser type fluidized bed reactor, a radial flow type fixed bed reactor, etc. One type of reactor may be used, or two or more types may be used in combination. In addition, multiple reactors of the same type may be used in combination.

[0069] The temperature in the step of obtaining the gas containing the oxygen compound is preferably 150°C to 400°C, and more preferably 200°C to 300°C.

[0070] The temperature of the gas containing the raw material gas may be the temperature in process (a). For example, if process (a) is carried out using a reactor equipped with a thermometer for measuring the temperature of the gas inside, the temperature in process (a) can be measured by the thermometer.

[0071] By having the above-mentioned lower limit temperature in the process of obtaining the gas containing the oxygen compound, the efficiency of ethanol production can be improved, and by having the above-mentioned upper limit temperature, the risk of runaway reaction can be reduced.

[0072] The pressure in the step of obtaining the gas containing the oxygen compound is preferably 0.5 MPaG or more and 10 MPaG or less, more preferably 2 MPaG or more and 8 MPaG or less, and even more preferably 3 MPaG or more and 5 MPaG or less.

[0073] The pressure of the gas containing the raw material gas may be the pressure in process (a). For example, if process (a) is carried out using a reactor equipped with a pressure gauge for measuring the internal gas pressure, the pressure in process (a) can be measured by the pressure gauge.

[0074] The conversion rate of carbon oxide is further improved when the pressure in step (a) is within the above numerical range.

[0075] In one embodiment, the method for producing an oxygen compound according to this embodiment further includes a step (also referred to as step (b)) of obtaining a gas containing ethanol from a gas containing the oxygen compound in the presence of a catalyst (B) containing at least one of copper and zinc. More preferably, step (b) is carried out by contacting the gas containing the oxygen compound with the catalyst (B).

[0076] By further including step (b) in the method for producing the oxygen compound, the yield of ethanol in the final product obtained by the method for producing the oxygen compound can be improved. The obtained ethanol can be converted to an olefin by conventionally known methods and used as a raw material for various chemical substances, or it can be purified and separated and used as is for various applications.

[0077] The ethanol-containing gas may also contain methanol, acetaldehyde, and the like in addition to ethanol. The ethanol, methanol, and acetaldehyde obtained in step (b) may be supplied to step (a). For example, the ethanol-containing gas may be separated into a vapor component containing at least one selected from ethanol, methanol, and acetaldehyde, and a liquid component containing a high-boiling point compound, and then the vapor component may be supplied to step (a).

[0078] (Catalyst B) The catalyst (B) preferably contains at least one of copper and zinc, and more preferably contains copper and zinc.

[0079] The catalyst (B) contains at least one of copper and zinc, which can further improve the yield of ethanol in step (b).

[0080] The valency of the copper is not particularly limited and may be zero, indicating a reduced state, or positive, indicating an oxidized state.

[0081] In the production of catalyst (B), copper-containing compounds can be used as raw material compounds. The copper-containing compounds are not particularly limited, but examples include inorganic salts such as chlorides, bromides, iodides, cyanides, oxides, hydroxides, nitrates, sulfates, carbonates, and phosphates; organic salts such as carboxylates and ethylenediamine acetates; acetylacetonate complexes, ammine complexes, alkoxide compounds, chelate compounds, carbonyl compounds, and cyclopentadienyl compounds.

[0082] The copper content in catalyst (B) may be 2% by mass or more, 4% by mass or more, 5% by mass or more, 6% by mass or more, or 7% by mass or more. The copper content in catalyst (B) may be 30% by mass or less, 25% by mass or less, 20% by mass or less, 18% by mass or less, or 15% by mass or less.

[0083] The valency of the zinc is not particularly limited and may be zero, indicating a reduced state, or positive, indicating an oxidized state.

[0084] In the production of catalyst (B), a zinc-containing compound can be used as a raw material compound. The zinc-containing compound is not particularly limited, but examples include inorganic salts such as chlorides, bromides, iodides, cyanides, oxides, hydroxides, nitrates, sulfates, carbonates, and phosphates; organic salts such as carboxylates and ethylenediamine acetates; acetylacetonate complexes, ammine complexes, alkoxide compounds, chelate compounds, carbonyl compounds, and cyclopentadienyl compounds.

[0085] The zinc content in catalyst (B) may be 2% by mass or more, 4% by mass or more, 5% by mass or more, 6% by mass or more, or 7% by mass or more. The zinc content in catalyst (B) may be 30% by mass or less, 25% by mass or less, 20% by mass or less, 18% by mass or less, or 15% by mass or less.

[0086] The copper and zinc content in catalyst (B) can be determined by replacing "rhodium" with "copper" or "zinc" in formula (1) and replacing "catalyst (A)" with "catalyst (B)" in formula (1). In this formula, "mass of copper" or "mass of zinc" represents the mass of these elements.

[0087] The catalyst (B) can be used in either a homogeneous catalyst or a supported catalyst form. Preferably, the catalyst (B) is a supported catalyst (B').

[0088] When catalyst (B) is the supported catalyst (B'), the copper content in the supported catalyst (B') may be 2% by mass or more, 4% by mass or more, 5% by mass or more, 6% by mass or more, or 7% by mass or more. When catalyst (B) is the supported catalyst (B'), the copper content in the supported catalyst (B') may be 30% by mass or less, 25% by mass or less, 20% by mass or less, 18% by mass or less, or 15% by mass or less.

[0089] When catalyst (B) is the supported catalyst (B'), the zinc content in the supported catalyst (B') may be 2% by mass or more, 4% by mass or more, 5% by mass or more, 6% by mass or more, or 7% by mass or more. When catalyst (B) is the supported catalyst (B'), the zinc content in the supported catalyst (B') may be 30% by mass or less, 25% by mass or less, 20% by mass or less, 18% by mass or less, or 15% by mass or less.

[0090] The copper content and zinc content in the supported catalyst (B') can be determined by a calculation formula obtained by replacing "rhodium" with "copper" or "zinc" in formula (1') and replacing "supported catalyst (A')" with "supported catalyst (B')" in formula (1'). In this calculation formula, "mass of copper" or "mass of zinc" represents the mass of these elements.

[0091] As the support for the supported catalyst (B'), for example, silica, alumina, titania, zirconia, ceria, magnesia, zeolite, activated carbon, etc., can be used. Preferably, the support for the supported catalyst (B') is silica.

[0092] The content of the support in the supported catalyst (B') is preferably 50 to 99% by mass, more preferably 60 to 99% by mass, and even more preferably 70 to 99% by mass.

[0093] (Process conditions) Process (b) can be carried out using the same reactor as in process (a).

[0094] The temperature in the step of obtaining the ethanol-containing gas is preferably 150°C to 400°C, and more preferably 200°C to 300°C.

[0095] The temperature in process (b) can be measured in the same manner as the temperature in process (a).

[0096] By keeping the temperature in step (b) within the above numerical range, the yield of ethanol in step (b) can be further improved.

[0097] The pressure in the step of obtaining the ethanol-containing gas is preferably 0.5 MPaG or more and 10 MPaG or less, more preferably 2 MPaG or more and 8 MPaG or less, and even more preferably 3 MPaG or more and 5 MPaG or less.

[0098] The pressure in process (b) can be measured in the same manner as the pressure in process (a).

[0099] By keeping the pressure in step (b) within the above numerical range, the yield of ethanol in step (b) can be further improved.

[0100] In one embodiment of the method for producing the oxygen compound according to this embodiment, the temperature in the step of obtaining the gas containing the oxygen compound is 150°C or more and 400°C or less, and the temperature in the step of obtaining the gas containing ethanol is 150°C or more and 400°C or less.

[0101] By keeping the temperatures in steps (a) and (b) within the above numerical range, the yield of ethanol can be further improved.

[0102] In one embodiment of the method for producing the oxygen compound according to this embodiment, the pressure in the step of obtaining the gas containing the oxygen compound is 0.5 MPaG or more and 10 MPaG or less, and the pressure in the step of obtaining the gas containing ethanol is 0.5 MPaG or more and 10 MPaG or less.

[0103] By keeping the pressures in process (a) and process (b) within the above numerical range, the yield of ethanol can be further improved.

[0104] [Method for preparing supported catalyst (A') and supported catalyst (B')] Supported catalyst (A') and supported catalyst (B') can be prepared by impregnation, immersion, ion exchange, coprecipitation, kneading, etc. For example, when preparing supported catalyst (A') by impregnation, the rhodium is dissolved in a solvent such as water, methanol, or ethanol to make a solution, the support is immersed in the solution, and then the solvent is evaporated to obtain a catalyst precursor. Subsequently, the catalyst precursor is calcined to obtain supported catalyst (A') in which rhodium is supported on a support. Similar methods can be used when obtaining supported catalyst (A') by supporting manganese and lithium on a support, and when obtaining supported catalyst (B') by supporting copper and zinc on a support.

[0105] In the method for producing oxygen compounds according to this embodiment, the supported catalyst (A') and supported catalyst (B') may be used as is, or they may be used after being reduced with a reducing gas (hydrogen, a mixture of hydrogen and nitrogen, a gas containing carbon monoxide, etc.). Preferably, the supported catalyst (A') and supported catalyst (B') are reduced with hydrogen or a mixture of hydrogen and nitrogen (also called hydrogen reduction treatment). The hydrogen reduction treatment is carried out by raising the temperature while bringing the supported catalyst (A') and supported catalyst (B') into contact with a gas containing hydrogen. The temperature in the hydrogen reduction treatment may be 200°C or more and 500°C or less, or 300°C or more and 400°C or less.

[0106] The method for producing the oxygen compound according to this embodiment, when carried out in the manner described above, exhibits excellent maintenance of the carbon oxide conversion rate.

[0107] The present invention includes the following embodiments: [1] A method for producing an oxygen compound, comprising the step of obtaining a gas containing an oxygen compound from a raw material gas containing carbon oxide, hydrogen, and water in the presence of a catalyst (A) containing rhodium, wherein the water content in the raw material gas is 0.03% by volume or more and 2.0% by volume or less, and the rhodium content in the catalyst (A) is 0.6% by mass or more and 2.9% by mass or less. [2] The method for producing an oxygen compound according to [1], wherein the raw material gas further comprises one or more selected from methanol, ethanol, and acetaldehyde, wherein the total content of methanol, ethanol, and acetaldehyde in the raw material gas is 0.05% by volume or more and 1.0% by volume or less. [3] The method for producing an oxygen compound according to [1] or [2], wherein the catalyst (A) further comprises at least one of manganese and lithium. [4] The method for producing an oxygen compound according to any one of [1] to [3], further comprising the step of obtaining a gas containing ethanol from a gas containing an oxygen compound in the presence of a catalyst (B) containing at least one of copper and zinc. [5] The method for producing an oxygen compound according to [4], wherein the temperature in the step of obtaining the gas containing the oxygen compound is 150°C or more and 400°C or less, and the temperature in the step of obtaining the gas containing ethanol is 150°C or more and 400°C or less. [6] The method for producing an oxygen compound according to [4] or [5], wherein the pressure in the step of obtaining the gas containing the oxygen compound is 0.5 MPaG or more and 10 MPaG or less, and the pressure in the step of obtaining the gas containing ethanol is 0.5 MPaG or more and 10 MPaG or less. [7] The method for producing an oxygen compound according to any one of [1] to [6], wherein the catalyst (A) is a supported catalyst (A'). [8] The method for producing an oxygen compound according to [7], wherein the support for the supported catalyst (A') is silica. [9] The method for producing an oxygen compound according to any one of [1] to [8], wherein the raw material gas contains carbon monoxide, hydrogen, and water obtained by a thermochemical gasification reaction of plastic.

[0108] Furthermore, the method for producing oxygen compounds according to the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the present invention. In addition, configurations, methods, etc., of embodiments other than those described above may be arbitrarily adopted and combined.

[0109] The present invention will be described more specifically below with reference to examples. The present invention is not limited to these examples.

[0110] The ethanol, methanol, and acetaldehyde used in each example and comparative example were all commercially available reagents. Specifically, ethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., reagent grade), methanol (manufactured by Kanto Chemical Co., Ltd., special grade), and acetaldehyde (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., reagent grade 1) were used.

[0111] (Example 1) [Preparation of supported catalyst (A')] Rhodium chloride trihydrate (RhCl ３ 3H ２ O) 0.192 g, manganese chloride tetrahydrate (MnCl ２ 4H ２ An aqueous solution was prepared by dissolving 0.189 g of (O) and 0.023 g of lithium chloride (LiCl) in 8.69 g of pure water. 10.0 g of silica (Carriact Q-10, manufactured by Fuji Silicia Co., Ltd., particle size: 75-150 μm) as a support in this aqueous solution, and then drying at room temperature for 24 hours to obtain a solid catalyst precursor. The catalyst precursor was calcined to obtain a supported catalyst (A'). The calcination was carried out in air by raising the temperature from room temperature to 350°C over 2 hours and holding at 350°C for 3 hours.

[0112] The rhodium content in the obtained supported catalyst (A') was determined by the following formula (1'). In formula (1'), "mass of rhodium" refers to the mass of the element rhodium.

[0113] Rhodium content (mass%) in supported catalyst (A') = [Mass of rhodium (g)] / [Mass of support (g)] × 100 ... (1')

[0114] The rhodium content in the obtained supported catalyst (A') was 0.75% by mass.

[0115] [Testing of Supported Catalyst (A')] 0.2 g of the obtained supported catalyst (A') was packed into a stainless steel reaction tube (inner diameter 2.5 mm, hereinafter referred to as "reaction tube"). Subsequently, the supported catalyst (A') was subjected to hydrogen reduction treatment under the following conditions. Specifically, hydrogen (H) was added to the reaction tube packed with the supported catalyst (A'). ２ (Fuel rate: 5.0 mL / min), and nitrogen (N ２ The gas was supplied at a rate of 10.0 mL / min under atmospheric pressure. Here, the supply rate represents the volume of gas supplied per unit time. In the description of the example, the "volume" used to calculate the supply rate expressed in "mL / min" was converted to the value of "volume at 0°C and 1 atmosphere". After that, the reaction tube was heated in an electric furnace. In this heating, the temperature of the reaction tube was raised from room temperature to 350°C at a heating rate of 3°C / min, and then held at 350°C for 1 hour.

[0116] After the hydrogen reduction treatment described above, the temperature of the reaction tube was lowered to 280°C and the reaction pressure was increased to 5.0 MPaG. Next, the raw material gas was supplied. Specifically, synthesis gas (H) was used as the raw material gas. ２ CO ratio ([volume % hydrogen] / [volume % carbon monoxide]) = 2.0, supply rate: 9.1 mL / min), nitrogen (N ２ The following materials were supplied: (at a supply rate of 6.3 mL / min), helium (He, supply rate of 1.0 mL / min), water (supply rate of 0.023 mL / min), and ethanol (supply rate of 0.016 mL / min). The water and ethanol content in the source gases was 0.14 vol% for water and 0.10 vol% for ethanol. In the description of the examples, the "volume" used to calculate the content expressed as "volume %" was converted to the value of "volume at 0°C and 1 atm".

[0117] (Example 2) Supported catalyst (A') was prepared and tested in the same manner as in Example 1, except that the rhodium content was 1.0% by mass.

[0118] (Example 3) Supported catalyst (A') was prepared and tested in the same manner as in Example 1, except that the rhodium content was 2.5% by mass.

[0119] (Comparative Example 1) A supported catalyst (A') was prepared and tested in the same manner as in Example 1, except that the rhodium content was 0.5% by mass.

[0120] (Comparative Example 2) Supported catalyst (A') was prepared in the same manner as in Example 1, except that the rhodium content was 0.5% by mass. Next, the supported catalyst (A') was tested in the same manner as in Example 1, except that the supply rate of nitrogen as the raw material gas was 6.1 mL / min and the supply rate of water was 0.17 mL / min, and ethanol was not used. The water content in the raw material gas was 1.00% by volume.

[0121] (Example 4) Supported catalyst (A') was prepared and tested in the same manner as in Comparative Example 2, except that the rhodium content was 1.0% by mass.

[0122] (Example 5) Supported catalyst (A') was prepared and tested in the same manner as in Comparative Example 2, except that the rhodium content was 1.5% by mass.

[0123] (Example 6) Supported catalyst (A') was prepared and tested in the same manner as in Comparative Example 2, except that the rhodium content was 2.0% by mass.

[0124] (Comparative Example 3) Supported catalyst (A') was prepared in the same manner as in Example 1, except that the rhodium content was 0.5% by mass. Next, the supported catalyst (A') was tested in the same manner as in Example 1, except that the supply rate of nitrogen as the raw material gas was 6.1 mL / min and the supply rate of water was 0.26 mL / min, and ethanol was not used. The water content in the raw material gas was 1.60% by volume.

[0125] (Example 7) A supported catalyst (A') was prepared and tested in the same manner as in Comparative Example 3, except that the rhodium content was 1.1% by mass.

[0126] (Example 8) Supported catalyst (A') was prepared and tested in the same manner as in Comparative Example 3, except that the rhodium content was 2.0% by mass.

[0127] (Comparative Example 4) Supported catalyst (A') was prepared in the same manner as in Example 1, except that the rhodium content was 0.5% by mass. Next, the supported catalyst (A') was tested in the same manner as in Example 1, except that the supply rate of nitrogen as the raw material gas was 6.0 mL / min and the supply rate of water was 0.32 mL / min, and ethanol was not used. The water content in the raw material gas was 2.00% by volume.

[0128] (Example 9) Supported catalyst (A') was prepared and tested in the same manner as in Comparative Example 4, except that the rhodium content was 1.5% by mass.

[0129] (Example 10) Supported catalyst (A') was prepared and tested in the same manner as in Comparative Example 4, except that the rhodium content was 2.0% by mass.

[0130] (Example 11) Supported catalyst (A') was prepared and tested in the same manner as in Comparative Example 4, except that the rhodium content was 2.5% by mass.

[0131] (Comparative Example 5) A supported catalyst (A') was prepared and tested in the same manner as in Comparative Example 4, except that the rhodium content was 3.0% by mass.

[0132] (Comparative Example 6) Supported catalyst (A') was prepared in the same manner as in Example 1, except that the rhodium content was 1.5% by mass. Next, the supported catalyst (A') was tested in the same manner as in Example 1, except that the nitrogen supply rate was 5.7 mL / min and the water supply rate was 0.65 mL / min as the raw material gas, and ethanol was not used. The water content in the raw material gas was 3.90% by volume.

[0133] (Comparative Example 7) Supported catalyst (A') was prepared and tested in the same manner as in Comparative Example 6, except that the rhodium content was 2.0% by mass.

[0134] (Example 12) Supported catalyst (A') was prepared in the same manner as in Example 1. Then, methanol was used instead of ethanol as the raw material gas, and the water supply rate was set to 0.022 mL / min and the methanol supply rate to 0.024 mL / min, except that the supported catalyst (A') was tested in the same manner as in Example 1. The water and methanol content in the raw material gas was 0.13 vol% for water and 0.15 vol% for methanol.

[0135] (Example 13) Supported catalyst (A') was prepared and tested in the same manner as in Example 12, except that the rhodium content was 1.0% by mass.

[0136] (Example 14) Supported catalyst (A') was prepared and tested in the same manner as in Example 12, except that the rhodium content was 1.5% by mass.

[0137] (Example 15) Supported catalyst (A') was prepared and tested in the same manner as in Example 12, except that the rhodium content was 2.0% by mass.

[0138] (Example 16) Supported catalyst (A') was prepared and tested in the same manner as in Example 12, except that the rhodium content was 2.5% by mass.

[0139] (Comparative Example 8) Supported catalyst (A') was prepared and tested in the same manner as in Example 12, except that the rhodium content was 0.5% by mass.

[0140] (Example 17) Supported catalyst (A') was prepared in the same manner as in Example 1, except that the rhodium content was 1.8% by mass. Then, methanol was used instead of ethanol as the raw material gas, and the water supply rate was set to 0.16 mL / min and the methanol supply rate to 0.091 mL / min, except that the supported catalyst (A') was tested in the same manner as in Example 1. The water and methanol content in the raw material gas was 1.00% by volume for water and 0.55% by volume for methanol.

[0141] (Example 18) Supported catalyst (A') was prepared and tested in the same manner as in Example 17, except that the rhodium content was 1.6% by mass.

[0142] (Example 19) Supported catalyst (A') was prepared and tested in the same manner as in Example 17, except that the rhodium content was 0.8% by mass.

[0143] (Example 20) Supported catalyst (A') was prepared and tested in the same manner as in Example 17, except that the rhodium content was 0.6% by mass.

[0144] (Example 21) Supported catalyst (A') was prepared and tested in the same manner as in Example 17, except that the rhodium content was 1.25% by mass.

[0145] (Comparative Example 9) Supported catalyst (A') was prepared and tested in the same manner as in Example 17, except that the rhodium content was 0.5% by mass.

[0146] (Example 22) Supported catalyst (A') was prepared in the same manner as in Example 1, except that the rhodium content was 1.8% by mass. Next, acetaldehyde was used as the raw material gas instead of ethanol, and the water supply rate was set to 0.27 mL / min and the acetaldehyde supply rate to 0.024 mL / min, except that the supported catalyst (A') was tested in the same manner as in Example 1. The water and acetaldehyde content in the raw material gas was 1.60% by volume for water and 0.14% by volume for acetaldehyde.

[0147] (Example 23) Supported catalyst (A') was prepared and tested in the same manner as in Example 22, except that the rhodium content was 1.0% by mass.

[0148] (Example 24) Supported catalyst (A') was prepared and tested in the same manner as in Example 22, except that the rhodium content was 1.5% by mass.

[0149] (Example 25) Supported catalyst (A') was prepared and tested in the same manner as in Example 22, except that the rhodium content was 2.5% by mass.

[0150] [Initial CO conversion rate and CO conversion rate maintenance rate] The reaction time was defined as 0 hours, with the time two hours after the start of raw material gas supply being considered 0 hours. The gas discharged from the outlet of the reaction tube at reaction time 0 hours and reaction time 48 hours was analyzed by gas chromatography. In the following explanation, "carbon monoxide" may be simply referred to as "CO".

[0151] The CO conversion rate maintenance rate was calculated using the following formula (2).

[0152] Maintenance rate of CO conversion (%) = [CO conversion rate after 48 reaction time (%)] / [Initial CO conversion rate (%)] × 100 ... (2)

[0153] In equation (2), the initial CO conversion rate was determined by subtracting the integral value of the CO peak in the chromatogram obtained when analyzing the gas discharged from the outlet of the reaction tube at reaction time 0 hours using gas chromatography from the integral value of the CO peak in the chromatogram obtained when analyzing the unreacted raw material gas using gas chromatography.

[0154] In equation (2), the CO conversion rate after a reaction time of 48 hours was determined by subtracting the integral value of the CO peak in the chromatogram obtained when analyzing the gas discharged from the outlet of the reaction tube after a reaction time of 48 hours using gas chromatography from the integral value of the CO peak in the chromatogram obtained when analyzing the unreacted raw material gas using gas chromatography.

[0155] Table 1 shows the initial CO conversion rate and the retention rate of the CO conversion rate for each example and comparative example.

[0156]

[0157] Table 1 shows that each example that satisfies all the constituent elements of the present invention exhibits a better retention rate of CO conversion than each comparative example. Furthermore, the results from Examples 1 to 3 confirm that the retention rate of CO conversion is good even when the raw material gas contains ethanol.

[0158] From the above, it can be seen that the present invention provides a method for producing oxygen compounds that exhibits excellent retention of the carbon oxide conversion rate.

Claims

1. A method for producing an oxygen compound, comprising the step of obtaining a gas containing an oxygen compound from a raw material gas containing carbon oxide, hydrogen, and water in the presence of a catalyst (A) containing rhodium, wherein the water content in the raw material gas is 0.03% by volume or more and 2.0% by volume or less, and the rhodium content in the catalyst (A) is 0.6% by mass or more and 2.9% by mass or less.

2. The method for producing an oxygen compound according to claim 1, wherein the raw material gas further comprises one or more selected from methanol, ethanol, and acetaldehyde, and the total content of methanol, ethanol, and acetaldehyde in the raw material gas is 0.05% by volume or more and 1.0% by volume or less.

3. The method for producing an oxygen compound according to claim 1 or 2, wherein the catalyst (A) further comprises at least one of manganese and lithium.

4. A method for producing an oxygen compound according to claim 1 or 2, further comprising the step of obtaining a gas containing ethanol from a gas containing the oxygen compound in the presence of a catalyst (B) containing at least one of copper and zinc.

5. The method for producing an oxygen compound according to claim 4, wherein the temperature in the step of obtaining the gas containing the oxygen compound is 150°C or more and 400°C or less, and the temperature in the step of obtaining the gas containing ethanol is 150°C or more and 400°C or less.

6. The method for producing an oxygen compound according to claim 4, wherein the pressure in the step of obtaining the gas containing the oxygen compound is 0.5 MPaG or more and 10 MPaG or less, and the pressure in the step of obtaining the gas containing ethanol is 0.5 MPaG or more and 10 MPaG or less.

7. The method for producing an oxygen compound according to claim 1 or 2, wherein the catalyst (A) is a supported catalyst (A').

8. The method for producing an oxygen compound according to claim 7, wherein the support for the supported catalyst (A') is silica.

9. The method for producing an oxygen compound according to claim 1 or 2, wherein the raw material gas comprises carbon monoxide, hydrogen, and water obtained by a thermochemical gasification reaction of plastic.

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