One-step method for producing ethanol from methanol / dimethyl ether

Abstract

The invention discloses a method for producing ethanol from methanol / dimethyl ether by a one-step method, which comprises the following steps of: reacting carbon dioxide / carbon monoxide and hydrogen-rich gas with at least one reaction substrate selected from methanol, dimethyl ether and a mixture thereof in a reaction solvent containing a catalyst to generate a reaction product containing ethanol; performing gas-liquid separation on the reaction product through flash evaporation to obtain a volatile phase containing ethanol and the like and a non-volatile phase containing a catalyst and a reaction solvent; condensing the volatile phase to obtain a gas mixture and a liquid mixture containing ethanol and the like, and rectifying the obtained liquid mixture to obtain purified ethanol. The hydrogen-rich gas comprises coke-oven gas, synthesis gas, hydrogen and a mixture of the coke-oven gas, the synthesis gas and the hydrogen.

Description

Technical Field

[0001] The present invention belongs to the field of chemical engineering, and particularly relates to a method for producing ethanol from methanol / dimethyl ether in one step. Background Art

[0002] Ethanol is an important chemical raw material. Ethanol is widely used in the chemical industry for synthesizing other organic compounds. Ethanol can be used to manufacture various chemicals such as acetic acid, acetone, esters, etc., and has a wide range of applications in industries such as medicine, dyes, flavors, and coatings. In addition, ethanol is also an important energy alternative. Ethanol can be used as a fuel, especially in the application of automotive fuels. Compared with traditional gasoline, ethanol fuel has lower emissions and higher combustion efficiency. Ethanol-gasoline blended fuel has been widely used in some countries to reduce the dependence on traditional petroleum. Therefore, ethanol not only has a wide range of applications in the chemical field but also can be used as a fuel to replace petroleum, which is of great significance to environmental and energy sustainable development.

[0003] At present, there are mainly two technical routes for the industrial production of ethanol: saccharification fermentation method and petrochemical synthesis method: (1) Saccharification fermentation method: First, polysaccharide raw materials such as starch and cellulose are subjected to a saccharification reaction to convert polysaccharides into glucose. Then, the glucose solution is inoculated and mixed with fermentation microorganisms (usually yeast), and is converted into ethanol through a fermentation reaction. Finally, through separation and purification processes such as distillation and rectification, ethanol products are obtained; (2) Petrochemical synthesis method (ethylene hydration method): First, fossil energy such as petroleum or natural gas is cracked to obtain ethylene. Then, ethylene is catalytically reacted with water to generate ethanol. Finally, through separation and purification processes such as distillation and rectification, ethanol products are obtained. In both processes, the saccharification fermentation method is mainly used to produce ethanol using plant resources (such as corn, sugarcane, etc.), which has lower energy costs and environmental impacts, but has a smaller production scale and the problem of competing with humans for food, and its development potential has been affected; the petrochemical synthesis method is usually used for large-scale industrial production of ethanol, but consumes a large amount of the increasingly depleted petroleum resources. In order to address the challenges of competing with humans for food and the limited nature of petroleum resources, developing new technical routes for ethanol production is an important and urgent issue.

[0004] Methanol is an inexpensive bulk chemical and also a platform chemical. Dimethyl ether can be obtained by dehydrating methanol. Carbon dioxide is a greenhouse gas and the highest oxidation state of carbon. By converting it into valuable chemicals, its greenhouse effect can be reduced and the global warming problem can be alleviated. Hydrogen is a green and clean reducing agent and also an important basic chemical raw material. Hydrogen has a wide range of sources, especially it can be produced by electrolyzing water with renewable electric energy. Utilizing hydrogen to convert carbon dioxide into important chemicals is an effective way to fundamentally solve the carbon emission problem. Coke oven gas is a gas produced by coke oven gasification. Coal is the main raw material of coke oven gas. Through the coke oven coking process, the organic substances in coal undergo pyrolysis and oxidation reactions to produce coke and coke oven gas. Coke is used as a metallurgical raw material, while coke oven gas is used as an energy source or raw material in industrial production. The main component of coke oven gas is hydrogen, and high-purity hydrogen can be obtained by gas separation of coke oven gas. This is also the basis for carbon dioxide to react with coke oven gas to obtain ethanol. The average composition of the coke oven gas produced by the coking unit of a certain scale enterprise is as follows: 63.38% hydrogen; 20.39% methane; 0.53% ethane; 1.53% ethylene; 0.08% acetylene; 0.04% propane; 0.11% propylene; 8.38% carbon monoxide; 2.62% carbon dioxide; 0.15% oxygen; 2.79% nitrogen. By utilizing industrial waste gases such as coke oven gas and carbon dioxide, the resource utilization of waste gases is realized, not only reducing the emission of waste gases, but also converting the combustible components in the waste gases into useful products, which helps to reduce production costs. Syngas is a raw material gas mainly composed of carbon monoxide and hydrogen and is used in chemical production. It can be produced from coke oven gas as a raw material and is also a hydrogen-rich gas. Recycling and converting carbon dioxide into ethanol helps to reduce the emission of carbon dioxide and can also be used to replace traditional petrochemical fuels, reducing the dependence on limited petroleum resources. In summary, by reacting methanol, carbon dioxide / carbon monoxide and coke oven gas, syngas or hydrogen to produce ethanol, the efficient utilization of resources, environmental protection, energy substitution and economic benefits can be achieved, which has important significance. Summary of the Invention

[0005] The present invention aims to provide a method for producing ethanol from methanol and / or dimethyl ether and carbon dioxide / carbon monoxide and hydrogen-rich gas as raw materials. This method includes parts such as catalytic reaction, catalyst separation and reuse, crude product separation and purification, and reaction tail gas separation and reuse. The catalytic reaction is carried out in a kettle reactor or a tower reactor. The catalyst and the reaction solvent are separated from the crude product in a flash or distillation tank. The catalyst and the reaction solvent are pumped back to the reaction kettle from the bottom of the tank, and the reaction tail gas and the crude product are discharged from the top of the tank. During the reaction process, carbon dioxide will first be hydrogenated to produce carbon monoxide and then undergo subsequent hydroformylation reactions. Among them, hydrogen, carbon dioxide and carbon monoxide in the reaction tail gas are separated by pressure swing adsorption and pumped back to the reactor, and the crude product therein enters the rectification system for separation and purification to obtain the product.

[0006] The method for producing ethanol provided by the present invention includes the following steps: in a reaction solvent containing a catalyst, at least one of methanol, dimethyl ether, and their mixture reacts catalytically with carbon dioxide and / or carbon monoxide, and a hydrogen-rich gas to produce a reaction product containing ethanol.

[0007] Furthermore, the method further includes the following steps to achieve comprehensive utilization and recycling of resources:

[0008] (b) Vapor-liquid separation of the reaction product containing ethanol is carried out by flash distillation or distillation to obtain a volatile phase containing ethanol and a non-volatile phase containing the catalyst and the reaction solvent, respectively;

[0009] (c) The volatile phase containing ethanol is condensed to obtain a gas mixture and a liquid mixture containing ethanol, respectively. The obtained liquid mixture containing ethanol is subjected to distillation refining to obtain purified ethanol.

[0010] In the above method, the reaction solvent containing a catalyst includes a transition metal catalyst, an iodine-containing promoter, and a reaction solvent.

[0011] The transition metal catalyst is selected from compounds or their compositions containing one or two of the following metals: iridium, ruthenium, rhodium, cobalt, nickel, palladium, iron.

[0012] Furthermore, the transition metal catalyst includes, but is not limited to, RuCl3, RuI3, Ru3(CO) 12 , CoCl2, Co2(CO)8, Co4(CO) 12 .

[0013] According to one embodiment of the present invention, the transition metal catalyst is composed of RuCl3 and CoCl2;

[0014] According to another embodiment of the present invention, the transition metal catalyst is composed of Ru3(CO) 12 and Co2(CO)8;

[0015] According to still another embodiment of the present invention, the transition metal catalyst is composed of RuI3 and Co4(CO) 12 .

[0016] The iodine-containing promoter includes molecular iodine, inorganic iodides, organic iodides, and their mixtures; among them, the inorganic iodides are selected from at least one of the following: hydrogen iodide, lithium iodide, sodium iodide, and potassium iodide; the organic iodides are selected from at least one of the following: iodomethane, diiodomethane, and triiodomethane.

[0017] The reaction solvent is selected from at least one of the following: N-methylpyrrolidone, N-ethylpyrrolidone, 1,3-dimethyl-2-imidazolidinone.

[0018] Further, the mass content of the transition metal catalyst in the reaction solvent is 300-3000 ppm, and the mass content of the iodine-containing cocatalyst in the reaction solvent is 5-20%.

[0019] In the above method, the hydrogen-rich gas includes coke oven gas, synthesis gas, hydrogen and mixtures thereof.

[0020] In the above method, the catalytic reaction is carried out in a reactor, and the total pressure of carbon dioxide and hydrogen-rich gas in the reactor is 3-12 MPa, preferably 3-9 MPa, specifically such as 5.5 MPa, 6 MPa or 6.5 MPa, etc.

[0021] Further, the ratio of the sum of the pressures of carbon dioxide and / or carbon monoxide in the reactor to the hydrogen pressure is 1:1-1:6, preferably 1:2-1:4.

[0022] In the above method, the mass percentage content of the reaction substrate in the reaction solvent in the reactor is 6-50%.

[0023] In the above method, the reaction temperature of the catalytic reaction is: 130-250 °C, preferably 160-210 °C, specifically such as 190 °C, 200 °C, etc.

[0024] In the above method, before the catalytic reaction, it further includes a step of activating the catalyst. The specific method is as follows: Add the reaction solvent containing the catalyst to the reactor, and fill it with 1-3 MPa of synthesis gas (carbon monoxide: hydrogen = 1:5-3:5), heat the reactor to 150-200 °C to activate the catalyst, and the activation time is 3-5 hours.

[0025] In step (b) of the above method, the non-volatile phase containing the catalyst and the reaction solvent is returned to the reactor to recycle the catalyst.

[0026] In step (c) of the above method, the gas mixture includes carbon dioxide, hydrogen, carbon monoxide, methane, ethane, propane, etc. The gas mixture is separated, and carbon dioxide, hydrogen and carbon monoxide therein are returned to the reactor to continue to participate in the catalytic reaction. The separated methane can be used for the production of liquefied natural gas (LNG), etc.

[0027] In step (c) of the above method, the distillation and refining are carried out in a rectification separation system to separate various main liquid components. The unreacted methanol and / or dimethyl ether and a small amount of reaction solvent entrained during the separation process are returned to the reactor for recycling.

[0028] Compared with the prior art, the present invention has the following beneficial technical effects:

[0029] First of all, the process route for preparing ethanol provided by the present invention is short and efficient, including only a reaction process, a tail gas circulation and treatment process, and a rectification and purification process. The process flow is short, and the investment is much lower than that of the syngas-to-ethanol process. At the same time, the reaction conditions are relatively mild, the catalyst can be recycled, and it has the characteristics of long life and low cost. In addition, the ethanol product synthesized by this method has a high purity, few by-products, and less difficulty in subsequent separation and purification. This method is particularly suitable for enterprises with hydrogen and carbon dioxide resources such as coking and solar green hydrogen energy storage. Since it does not rely on CO from coal gasification, the production scale is more flexible, and it is economical from 10,000 tons to 300,000 tons. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic process flow diagram according to the method of the present invention.

[0031] Figure 1 Specific embodiments are exemplarily given and described in detail. Although the present invention can be modified and replaced in various ways, the present invention is not limited to the specific forms disclosed. The present invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the present invention as defined by the appended claims. DETAILED DESCRIPTION OF THE INVENTION

[0032] The present invention will be further described in detail below in conjunction with specific embodiments. The examples given are only for clarifying the present invention, rather than limiting the scope of the present invention. The following examples can be used as a guide for those of ordinary skill in the art to make further improvements, and do not limit the present invention in any way.

[0033] The experimental methods in the following examples are all conventional methods unless otherwise specified, and are carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. The materials, reagents, etc. used in the following examples can all be obtained from commercial sources.

[0034] Example 1

[0035] An appropriate amount of RuCl3 and CoCl2 catalysts and LiI cocatalyst were dissolved in an N-methylpyrrolidone solvent. The mass contents of Ru and Co in the solvent were controlled to be 500 ppm and 1500 ppm respectively, and the mass content of LiI in the solvent was 20%. After complete dissolution, they were added to a reactor, and syngas (carbon monoxide: hydrogen = 1:5) at 2 MPa was charged. The reactor was heated to 200 °C to activate the catalyst for 4 hours. After activation, the reaction gas was switched to a mixture of carbon dioxide and hydrogen (partial pressure ratio 1:3), the total pressure in the reactor was maintained at 9 MPa, methanol was pumped into the reactor and the mass percentage of methanol in the solvent in the reactor was controlled to be 50%, and the reactor temperature was maintained at 200 °C. After the reaction, the mother liquor entered a flash tank for separation of the catalyst and the crude product. The catalyst and the liquid mainly composed of the high-boiling reaction solvent (N-methylpyrrolidone) (catalyst mother liquor) were directly pumped back to the reactor from the bottom of the flash tank to realize the recycling of the catalyst. The volatile phase containing ethanol product was led out from the top of the flash tank and entered a gas-liquid separator. After preliminary condensation, gas-liquid separation was achieved. The gas was separated by pressure swing adsorption, and carbon dioxide, carbon monoxide and hydrogen were returned to the reactor together with the feed gas. The condensed liquid mixture containing ethanol entered a distillation separation system to realize the separation of various main liquid components. The unreacted methanol and a small amount of reaction solvent entrained during the separation were pumped back to the reactor for recycling. Ethanol was the main liquid product, and its yield based on methanol could reach 80%. There was a very small amount of propanol by-product in the reaction.

[0036] Example 2

[0037] An appropriate amount of Ru3(CO) 12,The Co2(CO)8 catalyst and CH3I cocatalyst are dissolved in the 1,3-dimethyl-2-imidazolidinone solvent. The mass contents of Ru and Co in the solvent are controlled to be 1500 ppm and 1000 ppm respectively, and the mass content of CH3I in the solvent is 10%. After sufficient dissolution, it is added to the reactor, and syngas (carbon monoxide: hydrogen = 2:5) at 2.5 MPa is charged. The reactor is heated to 190 °C to activate the catalyst for 3 hours. After activation is completed, the reaction gas is switched to a mixture of carbon dioxide and syngas. The ratio of the sum of the pressures of carbon dioxide and carbon monoxide to the hydrogen pressure is controlled to be 1:3, and the total pressure in the reactor is maintained at 3 MPa. Dimethyl ether is pumped into the reactor and the mass percentage of dimethyl ether in the solvent in the reactor is controlled to be 15%, and the reactor temperature is maintained at 190 °C. After the reaction, the mother liquor enters the distillation tank for the separation of the catalyst and the crude product. The catalyst and the liquid mainly composed of the high-boiling reaction solvent (1,3-dimethyl-2-imidazolidinone) (catalyst mother liquor) are directly returned to the reactor from the bottom of the distillation tank to realize the recycling of the catalyst. The volatile phase containing ethanol product is led out from the top of the distillation tank and enters the gas-liquid separator. After preliminary condensation, gas-liquid separation is achieved. The gas is separated by pressure swing adsorption, and carbon dioxide, carbon monoxide and hydrogen are returned to the reactor together with the raw material gas. The condensed liquid mixture containing ethanol enters the rectification separation system to realize the separation of various main liquid components. The unreacted dimethyl ether and a small amount of reaction solvent entrained during the separation are returned to the reactor for recycling. Ethanol is the main liquid product, and the yield based on dimethyl ether is 82%. There is a very small amount of propanol by-product in the reaction.

[0038] Example 3

[0039] An appropriate amount of RuI3,Co4(CO) 12The catalyst and KI cocatalyst are dissolved in N-ethylpyrrolidone. The mass contents of Ru and Co in the solvent are controlled to be 800 ppm and 1200 ppm respectively, and the mass content of KI in the solvent is 5%. After complete dissolution, they are added to the reactor, and syngas (carbon monoxide: hydrogen = 3:5) at 1.5 MPa is charged. The reactor is heated to 185 °C to activate the catalyst for 3 hours. After activation, the reaction gas is switched to a mixture of carbon dioxide and coke oven gas. The ratio of the sum of the pressures of carbon dioxide and carbon monoxide to the hydrogen pressure is controlled to be 1:4, and the total pressure in the reactor is maintained at 6.5 MPa. Methanol is pumped into the reactor, and the mass percentage of methanol in the solvent in the reactor is controlled to be 6%. The reactor temperature is maintained at 190 °C. After the reaction, the mother liquor enters the flash tank for separation of the catalyst and the crude product. The catalyst and the liquid mainly composed of the high-boiling reaction solvent (N-ethylpyrrolidone) (catalyst mother liquor) are directly returned to the reactor from the bottom of the flash tank to achieve the recycling of the catalyst. The volatile phase containing ethanol product is led out from the top of the flash tank and enters the gas-liquid separator. After preliminary condensation, gas-liquid separation is achieved. The gas is separated by pressure swing adsorption, and carbon dioxide, carbon monoxide, and hydrogen are returned to the reactor together with the raw material gas. The condensed liquid mixture containing ethanol enters the distillation separation system to achieve the separation of various main liquid components. The unreacted methanol and a small amount of reaction solvent entrained during the separation are returned to the reactor for recycling. Ethanol is the main liquid product, and the yield based on methanol is 85%. There is a very small amount of propanol by-product in the reaction.

[0040] Example 4

[0041] An appropriate amount of RuCl3 and CoCl2 catalysts and LiI cocatalyst are dissolved in an N-methylpyrrolidone solvent, controlling the mass contents of Ru and Co in the solvent to be 500 ppm and 1500 ppm respectively, and the mass content of LiI in the solvent to be 20%; after sufficient dissolution, they are added to a reactor, and syngas (carbon monoxide: hydrogen = 1:5) at 2 MPa is charged. The reactor is heated to 200 °C to activate the catalyst for 4 hours. After activation is completed, the reaction gas is switched to a mixture of carbon monoxide and hydrogen (partial pressure ratio 1:3), the total pressure in the reactor is maintained at 7 MPa, methanol is pumped into the reactor and the mass percentage of methanol in the solvent in the reactor is controlled to be 30%, and the reactor temperature is maintained at 190 °C. After the reaction, the mother liquor enters a flash tank for separation of the catalyst and the crude product. The catalyst and the liquid mainly composed of the high-boiling reaction solvent (N-methylpyrrolidone) (catalyst mother liquor) are directly returned to the reactor from the bottom of the flash tank to achieve recycling of the catalyst. The volatile phase containing ethanol product is led out from the top of the flash tank and enters a gas-liquid separator. After preliminary condensation, gas-liquid separation is achieved. The gas is separated by pressure swing adsorption, and carbon dioxide, carbon monoxide and hydrogen are returned to the reactor together with the feed gas; the condensed liquid mixture containing ethanol enters a distillation separation system to achieve separation of various main liquid components. Among them, the unreacted methanol and a small amount of reaction solvent entrained during the separation process are returned to the reactor for recycling. Ethanol is the main liquid product, and its yield based on methanol can reach 81%. There are very small amounts of by-products such as propanol and butanol in the reaction.

[0042] Comparative Example 1

[0043] An appropriate amount of RuCl3 and CoCl2 catalysts and LiI cocatalyst are dissolved in a pyridine solvent. The mass contents of Ru and Co in the solvent are controlled to be 500 ppm and 1500 ppm respectively, and the mass content of LiI in the solvent is 10%. After sufficient dissolution, it is added to the reactor, and syngas (carbon monoxide: hydrogen = 1:5) at 2 MPa is charged. The reactor is heated to 200 °C to activate the catalyst for 4 hours. After the activation is completed, the reaction gas is switched to a mixture of carbon dioxide and hydrogen (partial pressure ratio 1:3), the total pressure in the reactor is maintained at 6 MPa, methanol is pumped into the reactor and the mass percentage of methanol in the solvent in the reactor is controlled to be 10%, and the reactor temperature is maintained at 200 °C. After the reaction, the mother liquor enters the flash tank for separation of the catalyst and the crude product. The catalyst and the liquid mainly composed of the high-boiling reaction solvent (pyridine) (catalyst mother liquor) are directly returned to the reactor from the bottom of the flash tank to realize the recycling of the catalyst. The volatile phase is led out from the top of the flash tank and enters the gas-liquid separator. After preliminary condensation, gas-liquid separation is achieved. The gas is separated by pressure swing adsorption, and carbon dioxide, carbon monoxide and hydrogen are returned to the reactor together with the feed gas. The condensed liquid mixture enters the distillation separation system to realize the separation of various main liquid components. The unreacted methanol and a small amount of reaction solvent entrained during the separation are returned to the reactor for recycling. After three days of operation, it is found that no ethanol is produced, which may be due to the fact that pyridine as the reaction solvent cannot achieve the reaction to produce ethanol.

[0044] Comparative Example 2

[0045] An appropriate amount of Ru3(CO) 12,The Co2(CO)8 catalyst and CH3I cocatalyst are dissolved in 1,3-dimethyl-2-imidazolidinone solvent. The mass contents of Ru and Co in the solvent are controlled to be 1500 ppm and 1000 ppm respectively, and the mass content of CH3I in the solvent is 8%. After sufficient dissolution, they are added into the reactor, and syngas (carbon monoxide: hydrogen = 2:5) at 2.5 MPa is charged. The reactor is heated to 190 °C to activate the catalyst for 3 hours. After activation, the reaction gas is switched to a mixture of carbon dioxide and syngas. The ratio of the sum of the pressures of carbon dioxide and carbon monoxide to the hydrogen pressure is controlled to be 1:3, and the total pressure in the reactor is maintained at 5.5 MPa. Methanol is pumped into the reactor and the mass percentage of methanol in the solvent in the reactor is controlled to be 6 - 15%, and the reactor temperature is maintained at 130 °C. After the reaction, the mother liquor enters the flash tank for separation of the catalyst and the crude product. The catalyst and the liquid mainly composed of the high-boiling reaction solvent (1,3-dimethyl-2-imidazolidinone) (catalyst mother liquor) are directly returned to the reactor from the bottom of the flash tank to realize the recycling of the catalyst. The volatile phase is led out from the top of the flash tank and enters the gas-liquid separator. Gas-liquid separation is achieved after preliminary condensation. The gas is separated by pressure swing adsorption, and carbon dioxide, carbon monoxide and hydrogen are returned to the reactor together with the raw material gas. The condensed liquid mixture enters the distillation separation system to realize the separation of various main liquid components. The unreacted methanol and a small amount of reaction solvent entrained during the separation are returned to the reactor for recycling. Ethanol is the main liquid product. Due to the relatively low reaction temperature, the ethanol yield based on methanol is only 5%. There are very small amounts of propanol by-products in the reaction.

[0046] Comparative Example 3

[0047] An appropriate amount of RuI3, Co4(CO) 12The catalyst and LiI cocatalyst are dissolved in N-ethylpyrrolidone. The mass contents of Ru and Co in the solvent are controlled to be 800 ppm and 1200 ppm respectively, and the mass content of LiI in the solvent is 12%. After sufficient dissolution, they are added to the reactor, and syngas (carbon monoxide: hydrogen = 3:5) at 1.5 MPa is charged. The reactor is heated to 185 °C to activate the catalyst for 3 hours. After activation, the reaction gas is switched to a mixture of carbon dioxide and coke oven gas. The total pressure in the reactor is maintained at 2 MPa, and the ratio of the sum of the pressures of carbon dioxide and carbon monoxide to the hydrogen pressure is controlled to be 1:4. Methanol is pumped into the reactor, and the mass percentage of methanol in the solvent in the reactor is controlled to be 6%. The reactor temperature is maintained at 190 °C. After the reaction, the mother liquor enters the flash tank for separation of the catalyst and the crude product. The catalyst and the liquid mainly composed of the high-boiling reaction solvent (N-ethylpyrrolidone) (catalyst mother liquor) are directly returned to the reactor from the bottom of the flash tank to achieve the recycling of the catalyst. The volatile phase is led out from the top of the flash tank and enters the gas-liquid separator. Gas-liquid separation is achieved after preliminary condensation. The gas is separated by pressure swing adsorption, and carbon dioxide, carbon monoxide and hydrogen are returned to the reactor together with the raw material gas. The condensed liquid mixture enters the distillation separation system to separate various main liquid components. The unreacted methanol and a small amount of reaction solvent entrained during the separation are returned to the reactor for recycling. After three days of operation, it is found that the methanol conversion rate is very low and the ethanol production is very small, which may be due to the too low reaction pressure and the inability to efficiently achieve the reaction for producing ethanol.

[0048] Although the present invention has been described with reference to the preferred embodiments, obvious modifications and variations can be made by those skilled in the art. Therefore, the present invention is intended to fully cover all such modifications and variations within the scope defined by the claims or their equivalent features.

Claims

1. A method for synthesizing ethanol by a one-step process using methanol and / or dimethyl ether as raw materials, comprising the following steps: in a reaction solvent containing a catalyst, at least one of methanol, dimethyl ether and their mixtures is subjected to a catalytic reaction with carbon dioxide and / or carbon monoxide, and a hydrogen-rich gas to produce a reaction product containing ethanol.

2. The method according to claim 1, characterized in that: The catalyst-containing reaction solvent includes a transition metal catalyst, an iodine-containing cocatalyst, and a reaction solvent.

3. The method according to claim 2, characterized in that: The transition metal catalyst is selected from compounds or compositions containing one or two of the following metals: iridium, ruthenium, rhodium, cobalt, nickel, palladium, iron; Alternatively, the iodine-containing cocatalyst includes molecular iodine, inorganic iodides, organic iodides, and mixtures thereof; wherein, the inorganic iodides are selected from at least one of the following: hydrogen iodide, lithium iodide, sodium iodide, and potassium iodide; the organic iodides are selected from at least one of the following: iodomethane, diiodomethane, and triiodomethane; Alternatively, the reaction solvent is selected from at least one of the following: N-methylpyrrolidone, N-ethylpyrrolidone, 1,3-dimethyl-2-imidazolidinone.

4. The method according to claim 3, characterized in that: The mass content of the transition metal catalyst in the reaction solvent is 300 - 3000 ppm, and the mass content of the iodine-containing cocatalyst in the reaction solvent is 5 - 20%.

5. The method according to any one of claims 1-4, characterized in that: The hydrogen-rich gas includes coke oven gas, synthesis gas, hydrogen, and mixtures thereof.

6. The method according to any one of claims 1-5, characterized in that: The mass percentage of the reaction substrate in the reaction solvent in the reactor is 6 - 50%.

7. The method according to any one of claims 1-6, characterized in that: The catalytic reaction is carried out in a reactor, and the total pressure of carbon dioxide / carbon monoxide and hydrogen-rich gas in the reactor is 3 - 12 MPa, preferably 3 - 9 MPa; Alternatively, the ratio of the total pressure of carbon dioxide and / or carbon monoxide to the hydrogen pressure in the reactor is 1:1 - 1:6, preferably 1:2 - 1:

4.

8. The method according to any one of claims 1-7, characterized in that: The reaction temperature of the catalytic reaction is: 130 - 250 °C, preferably 160 - 210 °C.

9. The method according to any one of claims 1-8, characterized in that: Before the catalytic reaction, it further includes a step of activating the catalyst. The specific method is as follows: Add the catalyst-containing reaction solvent into the reactor, and fill in 1 - 3 MPa of synthesis gas. Heat the reactor to 150 - 200 °C to activate the catalyst, and the activation time is 3 - 5 hours; the volume ratio of carbon monoxide to hydrogen in the synthesis gas is 1:5 - 3:

5.

10. The method according to any one of claims 1-9, characterized in that: The method further includes the following steps: (b) Perform gas-liquid separation on the reaction product containing ethanol by flash distillation or distillation to obtain a volatile phase containing ethanol and a non-volatile phase containing the catalyst and the reaction solvent respectively; (c) Condense the volatile phase containing ethanol to obtain a gas mixture and a liquid mixture containing ethanol respectively. Distill and refine the obtained liquid mixture containing ethanol to obtain purified ethanol; Further, in the step (b), the non-volatile phase containing the catalyst and the reaction solvent is returned to the reactor to recycle the catalyst; Alternatively, further, in the step (c), the gas mixture includes carbon dioxide, hydrogen, carbon monoxide, methane, ethane, propane; Separate this gas mixture, and return the carbon dioxide, hydrogen, and carbon monoxide therein to the reactor.

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