CuFe-based catalyst for preparing C2 + alcohol through carbon dioxide hydrogenation as well as preparation method and application of CuFe-based catalyst

Abstract

The invention provides a CuFe-based catalyst for preparing C2 + alcohol through hydrogenation of carbon dioxide and a preparation method and application thereof.The CuFe-based catalyst is prepared through a parallel flow coprecipitation-impregnation method, a mixed solution of a Cu salt solution, a Zn salt solution and an Fe salt solution and a precipitant solution are dropwise added in a parallel flow mode, a filter cake obtained through reaction is impregnated with an isopyknic modification additive, and the catalyst is obtained. The preparation method of the catalyst is simple, the raw materials are low in price and easy to obtain, the CO2 conversion rate is high, the selectivity of byproducts is low, the catalyst suitable for preparing the high-carbon alcohol through hydrogenation of the carbon dioxide can be prepared from the raw materials which are low in price and easy to obtain by utilizing the preparation method provided by the invention, and the catalyst has relatively high environmental benefits and economic benefits and wide industrial application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and further to a method for preparing C 2+ A CuFe-based catalyst for alcohols and a preparation method and application thereof. Background Art

[0002] Excessive carbon dioxide emissions lead to global warming, ocean acidification, sea level rise and extreme weather, which seriously threaten the human living environment. Converting captured CO2 into high-value chemicals through chemical methods has attracted attention as an important way to utilize CO2 resources. CO2 is a fully oxidized, thermodynamically stable and chemically inert molecule, so the activation of CO2 and its hydrocarbonization and alcoholization are very challenging. How to achieve carbon chain growth and highly selective synthesis of C 2+ Alcohol has always been a key and difficult point in scientific research. Its activation reaction mechanism is still unclear. Therefore, it is necessary to study the catalytic mechanism of CO2 hydrogenation conversion in depth, break through the difficulty of precise control of reaction products, realize the directional conversion of CO2, and create efficient CO2 hydrogenation to C 2+ Alcohol high-value chemical catalysts enhance the added value of coal-based diversified products, and are of great significance for net zero carbon emissions from fossil energy and carbon-based resources, helping to achieve the "dual carbon" strategic goals, and promoting social sustainable development.

[0003] Currently, CO2 hydrogenation to C 2+ The catalytic reaction of alcohols is a complex process and currently faces many challenges, including the complexity of the reaction pathway, the difficulty in precisely controlling the product distribution, and the 2+ The selectivity and space-time yield of alcohols are not high. In response to these problems, researchers have developed a variety of catalysts to optimize the reaction performance. 2+ Alcohol catalysts can be roughly divided into: precious metal rhodium-based catalysts, molybdenum-based catalysts, modified methanol synthesis catalysts and modified Fischer-Tropsch synthesis catalysts. Rhodium-based catalysts have bifunctional catalytic activity and high selectivity for low-carbon alcohols, but the expensive price and limited reserves of precious metal rhodium limit its industrial application; molybdenum-based catalysts have excellent sulfur resistance and carbon deposition resistance, and the water-gas shift activity of molybdenum-based catalysts is very good, which reduces the cost of later dehydration, but the system requires high temperature and high pressure, and the active components are easy to lose, affecting product separation; modified methanol synthesis catalysts mainly include Cu-Zn and Zn-Cr based catalysts, but the reaction product is still mainly methanol; modified Fischer-Tropsch synthesis CuFe catalysts have attracted much attention due to their mild reaction conditions, low price and high selectivity for low-carbon alcohols.

[0004] Based on the above content, research and develop a method with low material cost, simple preparation method, high CO2 conversion rate and high yield to product C 2+CuFe catalysts with high alcohol selectivity have important application value and significance. Summary of the invention

[0005] For the existing CO2 hydrogenation to C 2+ The alcohol catalytic reaction is complex, the product distribution is difficult to control, and C 2+ The present invention aims to provide a method for preparing C 2+ The invention discloses a CuFe-based catalyst for alcohol, a preparation method and application thereof. The catalyst is prepared by a co-current co-precipitation-impregnation method, wherein a mixed solution of a Cu salt solution, a Zn salt solution and a Fe salt solution is co-precipitated with a precipitant solution in an alkaline environment, and the active component obtained by the reaction is impregnated with an equal volume of a modification auxiliary solution. The product is dried and calcined to obtain the CuFe-based catalyst. The catalyst has a simple preparation method, the raw materials are cheap and readily available, the CO2 conversion rate is high, the selectivity of by-products such as CO and CH4 is less than 15%, and the catalyst is suitable for industrial production.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing C by hydrogenation of carbon dioxide 2+ The invention discloses a method for preparing a CuFe-based catalyst for alcohol, comprising: subjecting a mixed solution of a Cu salt solution, a Zn salt solution and a Fe salt solution to a coprecipitation reaction with a precipitant solution under alkaline conditions, and subjecting the coprecipitation reaction product to aging, filtering, drying and roasting treatments in sequence to obtain an active component of the CuFe-based catalyst; and impregnating the active component obtained above in an equal volume of a modification auxiliary agent solution, and drying and roasting again after the impregnation is completed to obtain the CuFe-based catalyst.

[0008] In some embodiments, in the mixed solution of the Cu salt solution, the Zn salt solution and the Fe salt solution, the molar ratio of Cu, Zn and Fe is: (0.5-1): (0.5-1): (0-0.5); the concentration of the mixed solution is 0.5 mol / L-2 mol / L; the Cu salt solution, the Zn salt solution and the Fe salt solution are one of nitrate, sulfate, acetate and chloride.

[0009] In some embodiments, the modification aid is a carbonate or nitrate of one or more of Li, Na, Sr, K, Rb, Cs, Zr, Ce, La, Y, Mn, and Ga; the molar ratio of the metal ion of the modification aid to Cu is 0.05 to 0.5.

[0010] In some embodiments, the precipitant is carbonate, and the concentration of the precipitant solution is 0.5 mol / L to 2 mol / L.

[0011] In some embodiments, the coprecipitation reaction temperature is 60-90° C., the pH value is 7-10, and the reaction time is 1-3 hours.

[0012] In some embodiments, the drying temperature is 100-120° C., and the drying time is 12-16 h; and / or the calcining temperature is 350-400° C., and the drying time is 4-6 h.

[0013] The present invention also provides a method for preparing C by hydrogenating carbon dioxide. 2+ The CuFe-based catalyst for alcohol is prepared by the above-mentioned preparation method.

[0014] The present invention also provides a method for preparing C by hydrogenating carbon dioxide. 2+ Application of CuFe-based catalysts for the production of alcohols, using the above-mentioned CuFe-based catalysts, or the CuFe-based catalysts prepared by the above-mentioned preparation method in the production of C 2+ Alcohol reaction.

[0015] In some embodiments, the carbon dioxide is hydrogenated to produce C 2+ The reaction conditions of the alcohol reaction are: the molar ratio of CO2 to H2 is 1:2-1:4, the reaction temperature is 280-340°C, the reaction pressure is 3-7 MPa, and the space velocity is 1000-8000 h -1 .

[0016] In some embodiments, in the application of the carbon dioxide hydrogenation to C 2+ Before the alcohol reaction, the method further comprises: reducing the CuFe-based catalyst.

[0017] Compared with the prior art, the carbon dioxide hydrogenation method provided by the present invention is 2+ The CuFe-based catalyst for alcohol and its preparation method and application have the following beneficial effects:

[0018] 1. The preparation method of the CuFe-based catalyst provided by the present invention adopts a parallel flow co-precipitation-impregnation method. The parallel flow co-precipitation method can make the metal ions precipitate evenly on the carrier, and the interaction between the active component and the carrier is strong, which also helps to further fix the active component during the impregnation process and reduce the loss during the reaction process. The subsequent impregnation step can further improve the dispersibility of the active component, thereby improving the activity and stability of the catalyst.

[0019] 2. The preparation method of the CuFe-based catalyst provided by the present invention has simple and controllable process, cheap and readily available raw materials, low cost, and is easy to promote and apply;

[0020] 3. The CuFe-based catalyst provided by the present invention has excellent performance and can catalyze the hydrogenation of carbon dioxide to produce C under high temperature and high pressure (300°C, 6MPa) reaction conditions. 2+ Alcohol, total alcohol selectivity is about 25-30%, C 2+ The alcohol proportion is greater than 85%, which can realize the efficient preparation of high-value-added chemicals from carbon dioxide, has good industrial application prospects, and can also realize the resource utilization of carbon dioxide, with high environmental and economic benefits. DETAILED DESCRIPTION

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation of the present invention will be described below.

[0022] In this document, “a” or “an” not only means “only one” but also may mean “more than one”.

[0023] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0024] In this document, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In addition, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0026] Example 1

[0027] This embodiment provides a method for producing C 2+ A method for preparing a CuFe-based catalyst for alcohol, comprising the steps of:

[0028] S1. Prepare a mixed solution of Cu salt solution, Zn salt solution and Fe salt solution.

[0029] S2. Add the mixed solution and the precipitant solution in parallel under alkaline conditions to carry out a co-precipitation reaction. After a period of reaction, the obtained co-precipitation product is aged, filtered and washed with water.

[0030] S3, drying and calcining the washed coprecipitated product to obtain the active component of the CuFe-based catalyst, and then impregnating it with an equal volume of the modification auxiliary agent solution, and drying and calcining it again after the impregnation to obtain the CuFe-based catalyst.

[0031] The preparation of CuFe-based catalysts adopts the parallel co-precipitation-impregnation method. The parallel co-precipitation allows Cu and Fe to be uniformly precipitated on Zn, which enhances the interaction between the active components and the carrier. It also helps to more effectively fix these active components in the subsequent impregnation step, significantly reducing the risk of loss during the catalytic reaction. In addition to acting as a carrier, Zn also functions as an electronic additive, optimizing the overall electronic properties of the catalyst, thereby improving its catalytic efficiency. The impregnation process further optimizes the dispersibility of the active components, further improving the activity and stability of the catalyst.

[0032] In some embodiments, in step S1, the molar ratio of Cu, Zn and Fe in the mixed solution is: (0.5-1): (0.5-1): (0-0.5), and the concentration of the mixed solution is 0.5 mol / L-2 mol / L.

[0033] Furthermore, the Cu salt solution, the Zn salt solution and the Fe salt solution may be selected from one of nitrate, sulfate, acetate and chloride, but preferably nitrate, such as copper nitrate, zinc nitrate and iron nitrate.

[0034] In some embodiments, in step S2, the precipitant is a carbonate, preferably sodium carbonate, and the concentration of the precipitant solution is 0.5 mol / L to 2 mol / L.

[0035] In some embodiments, in step S2, the temperature for the co-precipitation reaction of the mixed solution and the precipitant solution is 60-90° C., the pH value is 7-10, and the reaction time is 1-3 hours.

[0036] In some embodiments, in step S3, the modification aid can be selected as nitrate or carbonate of one or more of Li, Na, Sr, K, Rb, Cs, Zr, Ce, La, Y, Mn, and Ga, and the molar ratio of metal ions to Cu in the modification aid is 0.05 to 0.5.

[0037] In some embodiments, in step S3, the temperature and time of the two dryings are the same, that is, the temperature for drying the filter cake and the temperature for drying again after immersion are both 100-120° C., and the time for the two dryings is both 12-16 hours.

[0038] In some embodiments, in step S3, the temperature and time of the two calcinations are the same, that is, the temperature of calcining the filter cake and the temperature of calcining again after impregnation are both 350-400° C., and the time of the two calcinations is both 4-6 hours.

[0039] Example 2

[0040] Based on Example 1, this example provides a method for preparing C by hydrogenation of carbon dioxide. 2+ The CuFe-based catalyst for alcohol is prepared by the preparation method provided in Example 1.

[0041] Example 3

[0042] Based on Examples 1 and 2, this example provides the above-mentioned method for preparing C by hydrogenation of carbon dioxide. 2+ Application of CuFe-based catalysts for alcohols,

[0043] The CuFe-based catalyst in Example 2 or the CuFe-based catalyst prepared by the preparation method provided in Example 1 is applied to the hydrogenation of carbon dioxide to produce C 2+ Alcohol reaction.

[0044] Carbon dioxide hydrogenation to C 2+ The reaction conditions for the alcohol reaction are:

[0045] The molar ratio of CO2 to H2 is 1:2-1:4, the reaction temperature is 280-340°C, the reaction pressure is 3-7 MPa, and the space velocity is 1000-8000 h -1 .

[0046] The above reaction process is carried out in a fixed bed reactor.

[0047] Furthermore, in the catalytic hydrogenation of carbon dioxide to produce C 2+ Before the alcohol reaction, the CuFe-based catalyst is reduced under the following conditions: the reducing gas is H2, the reducing pressure is 0.1-0.5 MPa, the reducing temperature is 300-500°C, and the reducing time is 3-12 hours.

[0048] The technical solution of the present invention is described below by specific examples:

[0049] Example 4

[0050] S1. Weigh 24.16 g of copper nitrate, 29.749 g of zinc nitrate and 20.2 g of ferric nitrate and dissolve them in 300 mL of water to prepare a mixed solution.

[0051] S2. Take another 940mL of 0.5mol / L sodium carbonate solution, add 200mL of deionized water into a three-necked flask under 70℃ water bath condition, add the above mixed solution and sodium carbonate solution into the three-necked flask in parallel, and co-precipitate to obtain a co-precipitation product. Control the pH value of the co-precipitation reaction at about 8. After the addition is complete, age at 80℃ for 1h. After the aging is completed, cool to room temperature, filter, and wash away excess sodium with deionized water.

[0052] S3. Dry at 120°C overnight, then place in a muffle furnace and roast at 350°C for 6 hours. Weigh 2.073 g of potassium carbonate and soak it in an equal volume overnight, dry at 120°C for 16 hours, then place in a muffle furnace and roast at 350°C for 6 hours to obtain a CuFe-based catalyst.

[0053] S4. Application: Take 5g CuFe-based catalyst (20-40 mesh) and 6g quartz sand and mix them evenly.

[0054] H2 reduction was carried out at a reduction pressure of 0.5 MPa and a reduction temperature of 400°C for 6 hours.

[0055] After the reduction was completed, the reaction pressure was 6.0 MPa, the reaction temperature was 300 °C, and the space velocity was 3000 h -1 Under the conditions, catalytic hydrogenation of carbon dioxide to C 2+ The reaction results of CuFe-based catalysts are shown in Table 1 below.

[0056] Example 5

[0057] The preparation method is the same as that of Example 4, except that in step S3, 3.579 g of zirconium nitrate is added to the metal solution to dissolve. The reaction results are shown in Table 1 below.

[0058] Example 6

[0059] The preparation method is the same as that of Example 4, except that in step S3, 4.3422 g of cerium nitrate is added to the metal solution to dissolve. The reaction results are shown in Table 1 below.

[0060] Example 7

[0061] The preparation method is the same as that of Example 4, except that: after impregnating potassium carbonate in step S3, 1.6246 g of lanthanum nitrate solution is weighed and impregnated overnight, dried at 120° C. for 16 h, and then placed in a muffle furnace and calcined at 350° C. for 6 h. The reaction results are shown in Table 1 below.

[0062] Example 8

[0063] S1. Weigh 24.16 g of copper nitrate, 20.2 g of iron nitrate and 3.579 g of manganese nitrate and dissolve them in 300 mL of water to prepare a mixed solution.

[0064] S2. Take another 0.5 mol / L sodium carbonate solution, add 200 mL of deionized water into a three-necked flask under a 70°C water bath condition, add the above mixed solution and sodium carbonate solution into the three-necked flask in parallel, and perform a co-precipitation reaction to obtain a co-precipitation product. Control the pH value of the co-precipitation reaction to be around 8. After the addition is complete, age at 80°C for 1 h. After the aging is completed, cool to room temperature, filter, and wash away excess sodium with deionized water.

[0065] S3. Dry at 120°C for 16 hours, then put into a muffle furnace and roast at 350°C for 6 hours, weigh 1.5899g of sodium carbonate and soak it overnight, dry at 120°C for 16 hours, then put into a muffle furnace and roast it at 350°C for 6 hours to obtain a CuFe-based catalyst.

[0066] S4. Application: The steps are the same as those in Example 4. The reaction results of the CuFe-based catalyst are shown in Table 1 below.

[0067] Example 9

[0068] S1. Weigh 24.16 g of copper nitrate, 29.749 g of zinc nitrate and 20.2 g of ferric nitrate and dissolve them in 300 mL of water to prepare a mixed solution.

[0069] S2. Take another 875 mL of 0.5 mol / L sodium carbonate solution, add 200 mL of deionized water into a three-necked flask under 70°C water bath conditions, add the above mixed solution and sodium carbonate solution into the three-necked flask in parallel, and perform co-precipitation reaction to obtain a co-precipitation product. Control the pH value of the co-precipitation reaction to be around 8. After the addition is complete, age at 80°C for 1 h. After the aging is completed, cool to room temperature, filter, and wash away excess sodium with deionized water.

[0070] S3. Dry at 120°C overnight, then place in a muffle furnace and roast at 350°C for 6 hours, weigh 1.5899g of sodium carbonate solution and soak overnight, dry at 120°C for 16 hours, then place in a muffle furnace and roast at 350°C for 6 hours, weigh 2.1163g of strontium nitrate solution and soak overnight, dry at 120°C for 16 hours, then place in a muffle furnace and roast at 350°C for 6 hours.

[0071] S4. Application: The steps are the same as those in Example 4. The reaction results of the CuFe-based catalyst are shown in Table 1 below.

[0072] Example 10

[0073] The preparation method is the same as that of Example 4, except that:

[0074] S1. Weigh 12.08 g of copper nitrate, 14.874 g of zinc nitrate, 10.1 g of iron nitrate and 3.8361 g of gallium nitrate and dissolve them in 150 mL of water to prepare a mixed solution.

[0075] S2. Take another 0.5 mol / L sodium carbonate solution, add 100 mL of deionized water into a three-necked flask under 70°C water bath conditions, add the above mixed solution and sodium carbonate solution into the three-necked flask in parallel, and co-precipitate to obtain a co-precipitation product. Control the pH value of the co-precipitation reaction to be around 8. After the addition is complete, age at 80°C for 1 h. After the aging is completed, cool to room temperature, filter, and wash away excess sodium with deionized water.

[0076] S3, drying at 120°C for 16 h, and then calcining in a muffle furnace at 350°C for 6 h.

[0077] S4. Application: The steps are the same as those in Example 4. The reaction results of the CuFe-based catalyst are shown in Table 1 below.

[0078] Embodiment 11

[0079] The preparation method is the same as that of Example 4, except that: in step S3, 2.1466 g of zirconium nitrate is added to the metal solution to dissolve, and an equal volume of 0.691 g of potassium carbonate solution is weighed and immersed overnight, dried at 120° C. for 16 h, and then placed in a muffle furnace and calcined at 400° C. for 6 h. The reaction results of the CuFe-based catalyst are shown in Table 1 below.

[0080] Example 12

[0081] The preparation method is the same as that of Example 4, except that: in step S3, 1.915 g of yttrium nitrate is added to the metal solution to dissolve, and an equal volume of 0.691 g of potassium carbonate solution is weighed and immersed overnight, dried at 120° C. for 16 h, and then placed in a muffle furnace and calcined at 400° C. for 6 h. The reaction results of the CuFe-based catalyst are shown in Table 1 below.

[0082] Comparative Example 1

[0083] S1. Weigh 24.16 g of copper nitrate, 29.749 g of zinc nitrate and 20.2 g of ferric nitrate and dissolve them in 300 mL of water to prepare a mixed solution.

[0084] S2. Take another 940mL of 0.5mol / L sodium carbonate solution, add 200mL of deionized water into a three-necked flask under 70℃ water bath condition, add the above mixed solution and sodium carbonate solution into the three-necked flask in parallel, and perform co-precipitation reaction to obtain a co-precipitation product. Control the pH value of the co-precipitation reaction at about 8. After the addition is complete, age at 80℃ for 1h. After the aging is completed, cool to room temperature, filter, and wash away excess sodium with deionized water.

[0085] S3, dried at 120°C overnight, and then calcined in a muffle furnace at 350°C for 6h to obtain a comparative catalyst. The reaction results are shown in Table 1 below.

[0086] Table 1 Reaction performance of the catalysts described in Examples 4 to 12 and Comparative Example 1

[0087]

[0088] The evaluation results of the catalytic hydrogenation performance in Examples 4 to 12 and Comparative Example 1 are shown in Table 1. The above results show that the present invention prepares the catalyst by adding different additives and exhibits better carbon dioxide hydrogenation to C by optimizing the reaction conditions. 2+ Alcohol catalytic performance, total alcohol selectivity in the product ≥ 25%, C 2+The proportion of alcohol in the alcohol is >85%, and the selectivity of by-products such as CO and CH4 is less than 15%.

[0089] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Carbon dioxide hydrogenation to produce C 2+ A method for preparing a CuFe-based catalyst for alcohol, characterized in that: include: A mixed solution of a Cu salt solution, a Zn salt solution and a Fe salt solution is subjected to a coprecipitation reaction with a precipitant solution under alkaline conditions, and the coprecipitation reaction product is subjected to aging, filtering, drying and calcining treatments in sequence to obtain an active component of a CuFe-based catalyst; The active components obtained above are impregnated in an equal volume of a modification aid solution, and after the impregnation is completed, the solution is dried and calcined again to obtain the CuFe-based catalyst.

2. The preparation method according to claim 1, characterized in that: In the mixed solution of the Cu salt solution, the Zn salt solution and the Fe salt solution: The molar ratio of Cu, Zn and Fe is: (0.5-1): (0.5-1): (0-0.5); The concentration of the mixed solution is 0.5 mol / L to 2 mol / L; The Cu salt solution, the Zn salt solution and the Fe salt solution are one of nitrate, sulfate, acetate and chloride.

3. The preparation method according to claim 1, characterized in that: The modification aid is a carbonate or nitrate of one or more of Li, Na, Sr, K, Rb, Cs, Zr, Ce, La, Y, Mn, and Ga; The molar ratio of the metal ion of the modification aid to Cu is 0.05 to 0.

5.

4. The preparation method according to claim 1, characterized in that: The precipitant is carbonate, and the concentration of the precipitant solution is 0.5 mol / L to 2 mol / L.

5. The preparation method according to claim 1, characterized in that: The coprecipitation reaction temperature is 60-90° C., the pH value is 7-10, and the reaction time is 1-3 hours.

6. The preparation method according to claim 1, characterized in that: The drying temperature is 100-120°C and the drying time is 12-16 hours; and / or, The calcination temperature is 350-400° C. and the calcination time is 4-6 hours.

7. A method for producing C by hydrogenation of carbon dioxide 2+ A CuFe-based catalyst for alcohols, characterized in that The CuFe-based catalyst is prepared by the preparation method according to any one of claims 1 to 6.

8. A method for producing C by hydrogenation of carbon dioxide 2+ Application of a CuFe-based catalyst to alcohols, characterized in that The CuFe-based catalyst according to claim 7 or the CuFe-based catalyst prepared by the preparation method according to any one of claims 1 to 6 is used in the hydrogenation of carbon dioxide to produce carbon dioxide. 2+ Alcohol reaction.

9. The use according to claim 8, characterized in that: The method of preparing C by hydrogenation of carbon dioxide 2+ The reaction conditions for the alcohol reaction are: The molar ratio of CO2 to H2 is 1:2-1:4, the reaction temperature is 280-340°C, the reaction pressure is 3-7 MPa, and the space velocity is 1000-8000 h -1 .

10. The use according to claim 8, characterized in that: In the application of carbon dioxide hydrogenation to C 2+ Before the alcohol reaction, the method further comprises: reducing the CuFe-based catalyst.

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