阅读说明：本技术 Co2加氢制乙醇的铁基催化剂、制备方法与应用 (CO2Iron-based catalyst for preparing ethanol by hydrogenation, preparation method and application ) 是由 张燚 卢方旭 陈鑫 于 2020-05-22 设计创作，主要内容包括：本发明公开了一种CO<Sub>2</Sub>加氢制乙醇的铁基催化剂、制备方法与应用,所述CO<Sub>2</Sub>加氢制乙醇的铁基催化剂的活性位包括Fe<Sub>5</Sub>C<Sub>2</Sub>、Fe<Sub>2</Sub>C和Fe<Sub>3</Sub>C,且所述Fe<Sub>5</Sub>C<Sub>2</Sub>:Fe<Sub>2</Sub>C:Fe<Sub>3</Sub>C质量比为20-36:7-12:4-6。本发明还公开了该催化剂的制备方法和应用。本发明催化剂在CO<Sub>2</Sub>加氢制乙醇过程中,乙醇选择性≥20％,CO选择性≤10％；本发明CO<Sub>2</Sub>加氢制乙醇的铁基催化剂的制备方法制得的催化剂实现了助剂与活性金属铁氧化物的高效协同作用,助剂有效改变了活性金属铁氧化物的还原性能,高效的调控了催化剂的活性金属铁碳化合物的种类和比例,进而提高了催化剂的催化反应性。(The invention discloses CO 2 Iron-based catalyst for preparing ethanol by hydrogenation, preparation method and application thereof, and CO 2 The active site of the iron-based catalyst for preparing ethanol by hydrogenation comprises Fe 5 C 2 、Fe 2 C and Fe 3 C, and said Fe 5 C 2 :Fe 2 C:Fe 3 The mass ratio of C is 20-36:7-12: 4-6. The invention also discloses a preparation method and application of the catalyst. The catalyst of the invention is used in CO 2 In the process of preparing ethanol by hydrogenation, the selectivity of ethanol is more than or equal to 20 percent, and the selectivity of CO is less than or equal to 10 percent; CO of the invention 2 The catalyst prepared by the preparation method of the iron-based catalyst for preparing ethanol by hydrogenation realizes the efficient synergistic effect of the auxiliary agent and the active metal iron oxide, the auxiliary agent effectively changes the reduction performance of the active metal iron oxide, and efficiently regulates and controls the type and proportion of the active metal iron-carbon compound of the catalyst, thereby improving the catalytic reactivity of the catalyst.)

1. CO (carbon monoxide)₂The iron-based catalyst for preparing ethanol by hydrogenation is characterized in that: the active sites of the iron-based catalyst comprise Fe₅C₂、Fe₂C and Fe₃C, and said Fe₅C₂:Fe₂C:Fe₃The mass ratio of C is 20-36:7-12: 4-6.

2. The iron-based catalyst of claim 1, wherein: said Fe₅C₂:Fe₂C:Fe₃The mass ratio of C is 20-28:10-12: 4-6.

3. The iron-based catalyst of claim 1, wherein: said Fe₅C₂:Fe₂C:Fe₃The mass ratio of C is 21:12: 5.

4. CO according to any one of claims 1 to 3₂The preparation method of the iron-based catalyst for preparing ethanol by hydrogenation is characterized by comprising the following steps:

s1, selecting an auxiliary agent salt precursor containing an auxiliary agent component, and dissolving the auxiliary agent salt in a solvent to form an auxiliary agent salt solution;

s2, dipping the auxiliary agent salt solution into Fe₃O₄Stirring and drying on a catalyst to obtain Fe containing an auxiliary agent₃O₄A solid;

s3, adding Fe containing auxiliary agent₃O₄Tabletting the solid, granulating, sieving, introducing activating gas under heating, reducing and activating to regulate and control the active site ratio of iron base to obtain CO₂An iron-based catalyst for preparing ethanol by hydrogenation.

5. The method for preparing an iron-based catalyst according to claim 4, wherein: in step S1, the auxiliary salt is selected from one or more of the following: lithium citrate, trisodium citrate, tripotassium citrate, potassium nitrate, manganese nitrate, magnesium sulfate and manganese acetate; preferably, the adjuvant salt is selected from the group consisting of: sodium permanganate and copper sulfate, sodium sulfate and manganese sulfate; preferably, the adjuvant salt is selected from the following three substances in combination: lithium citrate, manganese acetate and zirconium nitrate; lithium citrate, manganese acetate and zinc nitrate; sodium citrate, manganese acetate and magnesium nitrate; sodium citrate, manganese acetate and zirconium nitrate; sodium citrate, manganese acetate and zinc nitrate;

preferably, in step S1, the solvent includes one or more of the following: water, ethanol, ethylene glycol, ethylenediamine, DMF, THF, methanol, glycerol, 1-2-ethanediol, acetonitrile, acetone; preferably, the solvent comprises one or more of: water, ethanol, methanol, ethylene glycol, acetone.

6. The method for preparing an iron-based catalyst according to claim 4, wherein: in step S2, the impregnation is excess impregnation or equal volume impregnation;

preferably, in step S2, the stirring time is 15-45 min;

preferably, in step S2, the drying temperature is 60-300 ℃; more preferably, the drying temperature is 120-.

7. The method for preparing an iron-based catalyst according to claim 4, wherein: in step S3, the granulation and sieving particle sizes are: 20-80 meshes; more preferably, the particle size is 20-40 mesh;

preferably, in step S3, the activated gas is: synthesis gas, H₂Or CO.

8. The method for preparing an iron-based catalyst according to claim 4, wherein: in step S3, when the auxiliary agent salt in step 1) is selected from one of lithium citrate, trisodium citrate, tripotassium citrate and manganese acetate, activating by using synthesis gas for 6-20 hours at the activation temperature of 280-400 ℃; preferably, the activation time is 10-15 hours, and the activation temperature is 300-350 ℃;

when the auxiliary agent salt in the step 1) is selected from one of potassium nitrate, manganese nitrate and magnesium sulfate, H is adopted₂Activating for 6-20 hours at 300-450 deg.C; preferably, the activation time is 10-15 hours, and the activation temperature is 350-400 ℃;

when the salt of the auxiliary agent in step 1) is selected from the following two substances in combination: sodium permanganate and copper sulfate or sodium sulfate and manganese sulfate are activated and regulated by CO for 8 to 20 hours at the activation temperature of 300 to 450 ℃; preferably, the activation time is 10-12 hours, and the activation temperature is 320-380 ℃;

when the adjuvant salt in step 1) is selected from the following three substances in combination: lithium citrate, manganese acetate and zirconium nitrate; lithium citrate, manganese acetate and zinc nitrate; sodium citrate, manganese acetate and magnesium nitrate; sodium citrate, manganese acetate and zirconium nitrate; sodium citrate, manganese acetate and zinc nitrate; activating and regulating by adopting synthesis gas, wherein the activation time is 6-20 hours, and the activation temperature is 280-400 ℃; preferably, the activation time is 10-15 hours and the activation temperature is 300-350 ℃.

9. A CO according to any one of claims 1 to 3₂The application of the iron-based catalyst for preparing ethanol by hydrogenation is characterized by comprising the following steps: in CO₂CO is introduced into iron-based catalyst for preparing ethanol by hydrogenation₂/H₂Atmospheric gas, carrying out CO₂Hydrogenation reaction for preparing ethanol; the CO is₂/H₂The atmosphere comprises one or more of: h₂/CO₂＝1、H₂/CO₂＝2、H₂/CO₂＝3、H₂/CO₂4; preferably, the CO is₂/H₂Atmosphere is H₂/CO₂＝3、H₂/CO₂＝4。

10. Use according to claim 9, characterized in that: the CO is₂In the reaction for preparing the ethanol by hydrogenation, the reaction pressure is 1MPa to 6MPa, and the reaction temperature is 280 ℃ to 400 ℃; preferably, the reaction pressure is 2MPa-5MPa, and the reaction temperature is 300-350 ℃.

Technical Field

The invention relates to a catalyst, a preparation method and application. More particularly, it relates to a CO₂Iron base for preparing ethanol by hydrogenationCatalyst, preparation method and application.

Background

The excessive use of fossil fuels leads to a drastic decrease in the content of fossil fuels and a drastic increase in the emission of carbon dioxide, which is however an abundant, non-toxic carbon source for industrial waste gases, catalytically converting CO due to significant global warming and other environmental problems₂Are highly attractive as various valuable fuels and chemical feedstocks (e.g., lower olefins, carbonates, formic acid, and alcohols). Among these base stocks, ethanol is a basic chemical product, an important solvent, an industrial building block, and a promising renewable fuel. Direct CO generation₂Hydrogenation to ethanol is a particularly attractive and promising route to ethanol production and hydrogen storage. However, there are still technical challenges, such as activating CO₂A higher energy barrier and a high CH are required₄And high selectivity to CO by-product. Therefore, high efficiency and reasonable CO₂Catalysts for catalytic conversion are the focus of research. Therefore, it is imperative to develop enhanced catalysts to further improve ethanol selectivity.

A number of Fe, Co, Ni and Pt-based catalysts have been developed for the conversion of CO₂Generation of C₂₊Product of which the majority is C₂₊Hydrocarbons, since most of these processes follow the Fischer-Tropsch mechanism. With respect to C₂₊Production of oxygenates, Pt/Co has been developed₃O₄Pd-Cu and Rh-Fe catalysts for the removal of CO from₂Hydrogenation to ethanol, wherein_xAnd two different C's of CO₁Coupling of intermediates to form C₂Oxygenates are important. Although reaction pathways have been identified on these Pt, Pd or Rh based catalysts, rare success has been achieved in exploring principles for the rational tuning of these intermediates. On the other hand, the use of non-noble metal-based catalysts is required, which will favor CO₂-scalable implementation of ethanol conversion. Based on these knowledge, further exploration for optimization C₁The relationship between intermediates and ethanol production is very important. At present, iron, cobalt, nickelThe base catalyst has good application prospect, not only because the conversion rate is relatively high, but also the active components are relatively cheap, the further amplification and industrialization of the catalyst can be realized in the future, but the reaction products are extremely complex through the traditional Fischer-Tropsch synthesis route, and the catalyst has the characteristics in the aspects of product selectivity on different metal active sites. Studies have shown that CO is present in the form of iron as the active metal₂The intermediate of the water gas reaction of (1) is a COOH species which is subjected to OH removal hydrogenation to form water and CO, and CH_xAnd CO, resulting in higher value-added organic oxygenates. Although CO has been discovered by researchers as an intermediate in the reaction, the route to ethanol production via the formate intermediate is also extensively studied to reduce CO by-products. Thus, the existing catalyst CO₂The iron-based catalyst for preparing ethanol by hydrogenation has the defects of high CO output as a byproduct and low ethanol selectivity.

Disclosure of Invention

The first technical problem to be solved by the invention is to provide CO₂An iron-based catalyst for preparing ethanol by hydrogenation. The catalyst is in CO₂In the process of preparing ethanol by hydrogenation, the selectivity of ethanol is more than or equal to 20 percent, and the selectivity of CO is less than or equal to 10 percent; i.e. the catalyst is capable of reacting CO₂High-efficiency catalytic conversion into ethanol with high added value, and effectively reduces the output of byproduct CO, thereby realizing CO₂The efficient utilization of the water is realized.

The second technical problem to be solved by the invention is to provide CO₂A preparation method of an iron-based catalyst for preparing ethanol by hydrogenation. The catalyst prepared by the preparation method realizes the efficient synergistic effect of the auxiliary agent and the active metal iron oxide, the auxiliary agent effectively changes the reduction performance of the active metal iron oxide, and efficiently regulates and controls the type and the proportion of the active metal iron-carbon compound of the catalyst, thereby improving the catalytic reactivity of the catalyst.

The third technical problem to be solved by the invention is to provide CO₂Application of iron-based catalyst for preparing ethanol by hydrogenation.

In order to solve the first technical problem, the invention adopts the following technical scheme:

CO (carbon monoxide)₂Iron-based catalyst for preparing ethanol by hydrogenation, wherein active sites of the iron-based catalyst comprise Fe₅C₂、Fe₂C and Fe₃C, and said Fe₅C₂:Fe₂C:Fe₃The mass ratio of C is 20-36:7-12: 4-6.

As a further improvement of the technical proposal, the Fe₅C₂:Fe₂C:Fe₃The mass ratio of C is 20-28:10-12: 4-6.

Preferably, the Fe₅C₂:Fe₂C:Fe₃The mass ratio of C is 21:12: 5.

In order to solve the second technical problem, the invention adopts the following technical scheme:

CO (carbon monoxide)₂The preparation method of the iron-based catalyst for preparing ethanol by hydrogenation comprises the following steps:

s1, selecting an auxiliary agent salt precursor containing an auxiliary agent component, and dissolving the auxiliary agent salt in a solvent to form an auxiliary agent salt solution;

s2, dipping the auxiliary agent salt solution into Fe₃O₄Stirring and drying on a catalyst to obtain Fe containing an auxiliary agent₃O₄A solid;

s3, adding Fe containing auxiliary agent₃O₄Tabletting the solid, granulating, sieving, introducing activating gas under heating, reducing and activating to regulate and control the active site ratio of iron base to obtain CO₂An iron-based catalyst for preparing ethanol by hydrogenation.

As a further improvement of the technical solution, in step S1, the auxiliary salt is selected from one or more of the following substances: lithium citrate, trisodium citrate, tripotassium citrate, potassium nitrate, manganese nitrate, magnesium sulfate and manganese acetate; preferably, the adjuvant salt is selected from the group consisting of: sodium permanganate and copper sulfate, sodium sulfate and manganese sulfate; preferably, the adjuvant salt is selected from the following three substances in combination: lithium citrate, manganese acetate and zirconium nitrate; lithium citrate, manganese acetate and zinc nitrate; sodium citrate, manganese acetate and magnesium nitrate; sodium citrate, manganese acetate and zirconium nitrate; sodium citrate, manganese acetate and zinc nitrate.

Preferably, in step S1, the solvent includes one or more of the following: water, ethanol, ethylene glycol, ethylenediamine, DMF, THF, methanol, glycerol, 1-2-ethanediol, acetonitrile, acetone; preferably, the solvent comprises one or more of: water, ethanol, methanol, ethylene glycol, acetone.

As a further improvement of the technical solution, in step S2, the impregnation is an excess impregnation or an equal volume impregnation.

Preferably, in step S2, the stirring time is 15-45 min.

Preferably, in step S2, the drying temperature is 60-300 ℃; more preferably, the drying temperature is 120-.

As a further improvement of the technical solution, in step S3, the size of the granulated and sieved particles is: 20-80 meshes; more preferably, the particle size is 20-40 mesh.

Preferably, in step S3, the activated gas is: synthesis gas, H₂Or CO.

Preferably, in step S3, when the auxiliary salt in step 1) is selected from one of lithium citrate, trisodium citrate, tripotassium citrate and manganese acetate, activating with syngas for 6-20 hours at 280-400 ℃; preferably, the activation time is 10-15 hours, and the activation temperature is 300-350 ℃;

when the auxiliary agent salt in the step 1) is selected from one of potassium nitrate, manganese nitrate and magnesium sulfate, H is adopted₂Activating for 6-20 hours at 300-450 deg.C; preferably, the activation time is 10-15 hours, and the activation temperature is 350-400 ℃;

when the salt of the auxiliary agent in step 1) is selected from the following two substances in combination: sodium permanganate and copper sulfate or sodium sulfate and manganese sulfate are activated and regulated by CO for 8 to 20 hours at the activation temperature of 300 to 450 ℃; preferably, the activation time is 10-12 hours, and the activation temperature is 320-380 ℃;

when the adjuvant salt in step 1) is selected from the following three substances in combination: lithium citrate, manganese acetate and zirconium nitrate; lithium citrate, manganese acetate and zinc nitrate; sodium citrate, manganese acetate and magnesium nitrate; sodium citrate, manganese acetate and zirconium nitrate; sodium citrate, manganese acetate and zinc nitrate; activating and regulating by adopting synthesis gas, wherein the activation time is 6-20 hours, and the activation temperature is 280-400 ℃; preferably, the activation time is 10-15 hours and the activation temperature is 300-350 ℃.

To solve the third technical problem, the invention provides a CO₂The application of the iron-based catalyst for preparing ethanol by hydrogenation comprises the following steps: in CO₂CO is introduced into iron-based catalyst for preparing ethanol by hydrogenation₂/H₂Atmospheric gas, carrying out CO₂Hydrogenation reaction for preparing ethanol; the CO is₂/H₂The atmosphere comprises one or more of: h₂/CO₂＝1、H₂/CO₂＝2、H₂/CO₂＝3、H₂/CO₂＝4。

Preferably, the CO is₂/H₂Atmosphere is H₂/CO₂＝3、H₂/CO₂＝4。

Preferably, in the reaction, the reaction pressure is 1MPa-6MPa, and the reaction temperature is 280-400 ℃; preferably, the reaction pressure is 2MPa-5MPa, and the reaction temperature is 300-350 ℃.

Any range recited herein is intended to include the endpoints and any number between the endpoints and any subrange subsumed therein or defined therein.

The starting materials of the present invention are commercially available, unless otherwise specified, and the equipment used in the present invention may be any equipment conventionally used in the art or may be any equipment known in the art.

Compared with the prior art, the invention has the following beneficial effects:

1) the present invention utilizes active iron-based oxides (Fe)₃O₄) The method for reducing the catalyst into the high-efficiency metal carbide and the metal simple substance by taking the catalyst as the raw material comprises the following steps: in the reduction process, hydrogen is used as a reduction gas, so that a large amount of metal simple substances are generated; by using carbon monoxideAs a reducing gas, a large amount of metal carbides will be produced; carbon monoxide and hydrogen are used as reducing gas, metal carbide and simple substance with relative content are generated, and Fe is accurately controlled by changing the reducing atmosphere of the catalyst₅C₂、Fe₂C and Fe₃The content and the proportion of C effectively regulate and control the distribution of products, thereby achieving the high-efficiency catalytic conversion of CO₂The purpose of (1).

2) According to the invention, a small amount of metal auxiliary is added to the surface of the metal oxide by using metal auxiliary salt through a simple common impregnation mode, and the content and variety of active components are more accurately regulated and controlled by changing the variety and content of the metal auxiliary salt in the reduction process, so that the purpose of efficiently converting CO is achieved₂And the selective output of the product is regulated and controlled, and the aim of relieving the environmental pressure can be fulfilled.

3) The present invention utilizes active iron-based oxides (Fe)₃O₄) The catalyst is used as a raw material, and the CO is successfully prepared by regulating and controlling the activation and reaction conditions of the catalyst₂Lower energy barrier is converted; compared with other materials which have high byproduct CO selectivity of more than 60 percent and reaction pressure of 5.0-6.0MPa, the iron-based oxide can be used for efficiently producing ethanol, the proportion of high-efficiency active sites is accurately regulated and controlled under relatively low pressure, the CO selectivity is effectively controlled within 10 percent, and CO is efficiently catalytically converted₂Producing ethanol.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.