A CO2 hydrogenation catalyst for olefin production and its preparation method and application

Abstract

The present invention relates to the field of catalyst technology, and discloses a CO2 hydrogenation to olefins catalyst, a preparation method thereof and an application thereof. The active components of the CO2 hydrogenation to olefins catalyst include iron, manganese, sodium and rhenium; in the CO2 hydrogenation to olefins catalyst, the molar amount of manganese is not less than 10% of the molar amount of iron, the proportion of rhenium is 5-8wt‰, and the proportion of sodium is not less than 1wt%. The CO2 hydrogenation to olefins catalyst of the present invention has good catalytic activity, selectivity and anti-carbon deposition ability, can achieve a high olefin space-time yield, and maintain good catalytic stability.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a CO2 hydrogenation to olefins catalyst, a preparation method and an application thereof. Background Art

[0002] Converting CO2 as a carbon source into high value-added chemicals or clean fuels is an effective way to convert and utilize CO2. Currently, the research on catalytic CO2 hydrogenation to olefins has attracted widespread attention. The products of CO2 hydrogenation to olefins have high value, including low-carbon olefins with 2 to 4 carbon atoms (C2 = ~C4 = ) and long-chain α-olefins with 5 or more carbon atoms (C 5+ = ) are the basic raw materials and important intermediates of the modern chemical industry. Ethylene, propylene and butene are one of the basic raw materials for the three major synthetic materials (synthetic fiber, synthetic rubber, plastic). α-olefins are widely used as raw materials for detergents, lubricants and plasticizers, which are closely related to production and life.

[0003] Iron-based catalysts are one of the commonly used catalysts in the CO2 hydrogenation reaction to produce olefins (for example, patent CN116116426A), but the existing iron-based catalysts have poor catalytic activity, resulting in a low olefin space-time yield. In addition, there is the problem of easy carbon deposition on the catalyst surface, which results in a short catalyst life and a significant decrease in catalytic activity after long-term use. Summary of the invention

[0004] In order to solve the technical problems of low olefin space-time yield and poor catalytic stability of existing CO2 hydrogenation to olefin catalysts, the present invention provides a CO2 hydrogenation to olefin catalyst and its preparation method and application. The CO2 hydrogenation to olefin catalyst of the present invention has good catalytic activity, selectivity and anti-carbon deposition ability, can achieve a high olefin space-time yield, and maintain good catalytic stability.

[0005] The specific technical scheme of the present invention is:

[0006] In the first aspect, the present invention provides a CO2 hydrogenation to olefins catalyst, the active components of the CO2 hydrogenation to olefins catalyst include iron, manganese, sodium and rhenium; in the CO2 hydrogenation to olefins catalyst, the molar amount of manganese is not less than 10% of the molar amount of iron, the proportion of rhenium is 5~8wt‰, and the proportion of sodium is not less than 1wt%.

[0007] In the present invention, by using iron (Fe), manganese (Mn), sodium (Na) and rhenium (Re) as active components, utilizing the mutual coordination between these four components, and controlling their ratios and proportions, the catalyst of the present invention can have good catalytic activity, selectivity and anti-carbon deposition ability when catalyzing the reaction of CO2 hydrogenation to olefins, thereby achieving a higher olefin space-time yield and maintaining good catalytic stability. Specifically:

[0008] (1) In the process of catalytic CO2 hydrogenation to olefins, Mn promotes the dispersion of Fe and enhances the x The formation of the phase can improve the activity of Fe-catalyzed CO2 hydrogenation to olefins reaction. Based on the interaction between Mn and Fe, the molar amount of manganese is controlled to be no less than 10% of the molar amount of iron, so that Mn can effectively play the above role, thereby improving the olefin space-time yield.

[0009] (2) In the process of catalytic CO2 hydrogenation to olefins, a certain amount of Na (accounting for no less than 2 wt% of the four active components) can promote the formation of iron carbide species and improve the carbon chain growth ability, thereby accelerating the reaction rate and increasing the olefin space-time yield. When the proportion of Na in the four active components is too low, it is difficult to effectively promote the formation of iron carbide species and carbon chain growth, resulting in a low olefin space-time yield.

[0010] (3) Mn and Na can regulate the synergistic reaction of reverse water gas shift (RWGS) and Fischer-Tropsch synthesis (FTS). In addition, Na can also promote the dissociation and activation of CO on Fe to form C and O species, which also helps to improve the space-time yield of olefins.

[0011] (4) Re is a metal with weak hydrogenation ability. The addition of an appropriate amount of Re can improve the hydrogen dissociation ability of the catalyst and inhibit the excessive hydrogenation of olefin products. Therefore, while promoting CO2 conversion, it can maintain good olefin selectivity, which is beneficial to improving the olefin space-time yield. On the other hand, the improvement of hydrogen dissociation ability eliminates carbon deposition on the catalyst surface to a certain extent, improves the catalyst's ability to resist carbon deposition, and thus improves the stability of the catalyst. However, when the proportion of Re is too large, the generated olefin products will be over-hydrogenated to alkanes, which will cause the olefin space-time yield to decrease, and the olefin content in the product will be relatively low. The present invention controls the proportion of Re in the four active components to 5~8wt‰, which can achieve a higher olefin space-time yield, olefin-alkane ratio and catalytic stability.

[0012] Preferably, the molar ratio of the iron element to the manganese element is 1:0.1~1.0.

[0013] Furthermore, the molar ratio of the iron element to the manganese element is 1:0.1-0.25.

[0014] Preferably, in the CO2 hydrogenation to olefins catalyst, the proportion of sodium element is 1~10wt%.

[0015] Furthermore, in the CO2 hydrogenation to olefins catalyst, the proportion of sodium element is 1~2wt%.

[0016] Sodium can promote the dissociation and activation of CO on Fe to form C and O species, but too much sodium will cause excessive deposition of C on Fe, resulting in reduced catalyst activity. When the proportion of Na in the catalyst is 1-10wt%, a higher olefin space-time yield can be achieved; on this basis, by controlling the proportion of Na to 1-2wt%, the olefin space-time yield can be further improved.

[0017] Preferably, the CO2 hydrogenation to olefins catalyst comprises a composite containing iron and manganese elements formed by conversion after co-precipitation, and also comprises sodium and rhenium elements supported on the composite.

[0018] The above-mentioned "conversion after coprecipitation" means that the soluble iron salt and manganese salt are coprecipitated under the action of a precipitant, and then roasted and reduced to form a complex composed of iron and manganese.

[0019] The introduction of Mn into the iron-based catalyst by coprecipitation rather than by impregnation can produce the following effects: during the coprecipitation and subsequent calcination to form metal oxides, the presence of Mn can promote the dispersion of Fe and enhance the FeO x The formation of the phase can improve the catalytic activity of Fe and enable the CO2 hydrogenation to olefins reaction to achieve a higher olefin space-time yield.

[0020] In a second aspect, the present invention provides a method for preparing the CO2 hydrogenation to olefins catalyst, characterized in that it comprises the following steps:

[0021] S1: A complex composed of an insoluble iron salt and an insoluble manganese salt is prepared by a coprecipitation method;

[0022] S2: loading sodium and rhenium into the composite obtained in step S1 to obtain a precursor;

[0023] S3: calcining the precursor to obtain an inactivated catalyst;

[0024] S4: reducing the inactivated catalyst with hydrogen to obtain an activated CO2 hydrogenation to olefins catalyst.

[0025] In the above process, step S4 is a process of activating the catalyst, which can be performed before the catalyst is used (for catalyzing the CO2 hydrogenation to olefins reaction).

[0026] Preferably, step S1 specifically comprises: dropping a mixed solution of iron salt and manganese salt together with a carbonate solution into water, performing a precipitation reaction, separating a precipitate, and obtaining a complex composed of an insoluble iron salt and an insoluble manganese salt.

[0027] Furthermore, in step S1, in the mixed solution of the iron salt and the manganese salt, the total concentration of iron ions and manganese ions is 0.05~1 mol / L; the concentration of the carbonate solution is 0.05~5 mol / L; and the specific process of the precipitation reaction includes: maintaining the pH at 8~10, stirring the reaction for 0.5~2h, and standing for aging for 1~10h.

[0028] Preferably, step S2 specifically comprises: mixing the composite obtained in step S1 with a solution containing sodium and rhenium elements, and drying to obtain a precursor.

[0029] Furthermore, in step S2, the volume ratio between the complex obtained in step S1 and the solution containing sodium element and rhenium element is 1:0.8-1.2.

[0030] Further, in step S2, the solution containing sodium and rhenium is a solution containing Na + and ReO4 - of solution.

[0031] Preferably, in step S3, the calcination temperature is 500-800° C. and the calcination time is 4-8 hours.

[0032] Preferably, step S4 specifically comprises: placing an unactivated catalyst in a reaction container, introducing hydrogen at a rate of 20-50 mL / min, and reacting at 350-450° C. for 4-10 hours.

[0033] In a third aspect, the present invention provides an application of the CO2 hydrogenation to olefins catalyst in catalyzing the CO2 hydrogenation to olefins reaction.

[0034] Preferably, the reactants of the CO2 hydrogenation to olefins reaction are H2 and CO2 in a molar ratio of 1 to 4:1, the reaction temperature is 250 to 450°C, and the pressure is 0.1 to 4 MPa.

[0035] Preferably, during the CO2 hydrogenation to olefins reaction, the reaction space velocity is 3600-300000 mL·h -1 ·g -1 .

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] (1) In the CO2 hydrogenation to olefins catalyst of the present invention, the coordination between the four components of Fe, Mn, Na and Re is utilized, and the ratio of iron to manganese and the proportion of rhenium to sodium are controlled, so that the catalyst can have better catalytic activity, selectivity and anti-carbon deposition ability, thereby achieving a higher olefin space-time yield and maintaining better catalytic stability;

[0038] (2) In the CO2 hydrogenation to olefins catalyst of the present invention, Mn is introduced into the iron-based catalyst by coprecipitation. During the coprecipitation and subsequent calcination to form metal oxides, the presence of Mn can promote the dispersion of Fe and enhance the FeO x The formation of the phase can improve the space-time yield of olefins when the catalyst is used to catalyze the CO2 hydrogenation reaction. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the embodiments.

[0040] A CO2 hydrogenation to olefins catalyst, wherein the active components of the CO2 hydrogenation to olefins catalyst include iron, manganese, sodium and rhenium; in the CO2 hydrogenation to olefins catalyst, the molar amount of manganese is not less than 10% of the molar amount of iron, the proportion of rhenium is 5-8wt‰, and the proportion of sodium is not less than 1wt%.

[0041] As a specific implementation, in the CO2 hydrogenation to olefins catalyst, the molar ratio of iron element to manganese element is 1:0.1~1.0, and the proportion of sodium element is 1~10wt%.

[0042] As a specific embodiment, the CO2 hydrogenation to olefins catalyst includes a composite containing iron and manganese elements formed by co-precipitation and conversion, and also includes sodium and rhenium elements supported on the composite.

[0043] A method for preparing the CO2 hydrogenation to olefins catalyst comprises the following steps:

[0044] S1: A complex composed of an insoluble iron salt and an insoluble manganese salt is prepared by a coprecipitation method;

[0045] S2: loading sodium and rhenium into the composite obtained in step S1 to obtain a precursor;

[0046] S3: calcining the precursor to obtain an inactivated catalyst;

[0047] S4: reducing the inactivated catalyst with hydrogen to obtain an activated CO2 hydrogenation to olefins catalyst.

[0048] As a specific implementation, step S1 specifically includes: adding a mixed solution of iron salt and manganese salt and a carbonate solution dropwise into water, performing a precipitation reaction, separating a precipitate, and obtaining a complex composed of an insoluble iron salt and an insoluble manganese salt. In the mixed solution of iron salt and manganese salt, the total concentration of iron ions and manganese ions is 0.05-1 mol / L; the concentration of the carbonate solution is 0.05-5 mol / L; the specific process of the precipitation reaction includes: maintaining the pH at 8-10, stirring the reaction for 0.5-2 hours, and standing for aging for 1-10 hours.

[0049] As a specific implementation, step S2 specifically includes: mixing the composite obtained in step S1 with a solution containing sodium and rhenium elements, and drying to obtain a precursor; the volume ratio between the composite obtained in step S1 and the solution containing sodium and rhenium elements is 1:0.8~1.2.

[0050] As a specific implementation, in step S3, the calcination temperature is 500-800°C and the time is 4-8h.

[0051] As a specific implementation, step S4 specifically includes: placing an unactivated catalyst in a reaction container, introducing hydrogen at a rate of 20-50 mL / min, and reacting at 350-450° C. for 4-10 hours.

[0052] The CO2 hydrogenation to olefins catalyst is used in catalyzing the CO2 hydrogenation to olefins reaction.

[0053] As a specific embodiment, in the process of the CO2 hydrogenation to olefins reaction, the reactants are H2 and CO2 in a molar ratio of 1 to 4:1, the reaction temperature is 250 to 450°C, the pressure is 0.1 to 4 MPa, and the reaction space velocity is 3600 to 300000 mL·h -1 ·g -1 .

[0054] The present invention is described below by specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be thought of by those skilled in the art are included in the present invention, and the attached claims and any equivalents thereof are the protection scope of the present invention.

[0055] Example 1~Example 2 and Comparative Example 1~Comparative Example 3: Effect of Re and its proportion

[0056] The CO2 hydrogenation to olefins catalyst is prepared by the following steps and used to catalyze the CO2 hydrogenation to olefins reaction:

[0057] (1) Preparation of a complex composed of insoluble iron salt and insoluble manganese salt by coprecipitation method:

[0058] 8.08g of ferric nitrate and 1.79g of manganese nitrate were prepared into a metal salt solution with a total concentration of 1 mol / L of iron ions and manganese ions, and 24.0g of sodium carbonate was prepared into a sodium carbonate solution with a concentration of 2 mol / L. The metal salt solution and sodium carbonate solution were uniformly dripped into a beaker containing 100mL of deionized water under stirring at room temperature, and the pH of the solution was controlled at 8-10. After the addition was completed, stirring was continued for 30 minutes, and then stirring was stopped and aged for 1 hour. After the reaction was completed, the precipitate obtained by filtration was fully washed with deionized water and dried.

[0059] (2) Impregnation method to load rhenium and sodium elements:

[0060] According to the Re ratio (i.e., the ratio of Re element in the final catalyst) and 2wt% Na ratio (i.e., the ratio of Na element in the final catalyst) in Table 1, ammonium perrhenate and sodium nitrate were dissolved in deionized water to prepare a loading liquid. Then, the product obtained in step (1) and the loading liquid were mixed in equal volumes, stirred and dried at 140°C for 1h, and then calcined at 550°C for 4h.

[0061] (3) Activation and catalysis of CO2 hydrogenation to olefins:

[0062] The product obtained in step (2) was made into particles of 20-60 mesh size using a sieve, mixed with quartz sand of 3 times its mass for dilution, and filled into the middle of a stainless steel tube. Before being used to catalyze the CO2 hydrogenation to olefins reaction, 20 mL / min of pure hydrogen was introduced for in-situ reduction at 400°C for 6 h to obtain an activated CO2 hydrogenation to olefins catalyst. The temperature was maintained at 340°C, and a mixed gas of H2 / CO2 / Ar / CO (wherein the molar ratio between the raw gas H2 and CO2 was 3:1, the volume content of Ar was 3%, and the volume content of CO was 4%) was introduced at a reaction space velocity of 7200 mL·h -1 ·g -1 The reactor pressure was increased to 2.0 MPa to carry out CO2 hydrogenation to olefins reaction, and the effects of Re and its proportion on the catalyst performance were investigated. The data are listed in Table 1. After 300 hours of reaction, the stability of the catalytic performance of the catalysts in Example 1 and Comparative Example 1 was investigated. The data are listed in Table 2.

[0063] Table 1 Effect of Re and its proportion on catalyst performance

[0064]

[0065] It can be seen from Table 1 that the olefin space-time yield can be improved by introducing a certain amount of Re into the catalyst; when the Re ratio is 5~8wt‰, the olefin-alkane ratio and olefin space-time yield are high; when the Re ratio is lower than 5wt‰, the olefin space-time yield is low; when the Re ratio is higher than 8wt‰, the olefin-alkane ratio and olefin space-time yield are low. This is because: Re is a metal with weak hydrogenation ability. The addition of an appropriate amount of Re can improve the dissociation ability of hydrogen on the catalyst and inhibit the excessive hydrogenation of olefin products. Therefore, while promoting CO2 conversion, it can maintain good olefin selectivity, which is beneficial to improve the olefin space-time yield. However, when the Re ratio is too large, the generated olefin product will be over-hydrogenated to alkane, which will cause the olefin space-time yield to decrease, and the olefin in the product is relatively low.

[0066] Table 2 Effect of Re introduction on catalyst stability

[0067]

[0068] Comparing Table 1 and Table 2, it can be seen that the introduction of Re into the catalyst can improve its stability, so that the catalyst can still maintain a high olefin space-time yield after long-term use. This is because the addition of an appropriate amount of Re can improve the dissociation ability of hydrogen on the catalyst, eliminate carbon deposits on the catalyst surface to a certain extent, and improve the catalyst's ability to resist carbon deposits, thereby improving the stability of the catalyst.

[0069] Example 3 to Example 5 and Comparative Example 4: Effect of Na and its proportion

[0070] The CO2 hydrogenation to olefins catalyst is prepared by the following steps and used to catalyze the CO2 hydrogenation to olefins reaction:

[0071] (1) Preparation of a complex composed of insoluble iron salt and insoluble manganese salt by coprecipitation method:

[0072] 8.08g of ferric nitrate and 1.79g of manganese nitrate were prepared into a metal salt solution with a total concentration of 1 mol / L of iron ions and manganese ions, and 24.0g of sodium carbonate was prepared into a sodium carbonate solution with a concentration of 2 mol / L. The metal salt solution and sodium carbonate solution were uniformly dripped into a beaker containing 100mL of deionized water under stirring at room temperature, and the pH of the solution was controlled at 8-10. After the addition was completed, stirring was continued for 30 minutes, and then stirring was stopped and aged for 1 hour. After the reaction was completed, the precipitate obtained by filtration was fully washed with deionized water and dried.

[0073] (2) Impregnation method to load rhenium and sodium elements:

[0074] According to the Na ratio in Table 3 (i.e., the ratio of Na element in the final catalyst) and the Re ratio of 5wt‰ (i.e., the ratio of Re element in the final catalyst), sodium nitrate and ammonium perrhenate were dissolved in deionized water to prepare an impregnation solution. Then, the product obtained in step (1) and the impregnation solution were stirred and mixed in equal volumes for impregnation, and then calcined at 550°C for 4h.

[0075] (3) Activation and catalysis of CO2 hydrogenation to olefins:

[0076] The product obtained in step (2) was made into particles of a certain size using a sieve, mixed with an appropriate amount of quartz sand for dilution, and filled into the middle of a stainless steel tube. Before being used to catalyze the CO2 hydrogenation to olefins reaction, 20 mL / min of pure hydrogen was introduced for in-situ reduction at 400°C for 6 h to obtain an activated CO2 hydrogenation to olefins catalyst. The temperature was maintained at 340°C, and a mixed gas of H2 / CO2 / Ar / CO (wherein the molar ratio between the raw gas H2 and CO2 was 3:1, the volume content of Ar was 3%, and the volume content of CO was 4%) was introduced at a reaction space velocity of 7200 mL·h -1 ·g -1 The reactor pressure was increased to 2.0 MPa for CO2 hydrogenation to olefins reaction, and the influence of Na and its proportion on the catalyst performance was investigated. The data are listed in Table 3.

[0077] Table 3 Effect of Na and its proportion on catalyst performance

[0078]

[0079] It can be seen from Table 3 that the olefin space-time yield can be increased by introducing a certain amount of Na into the catalyst, and as the Na content in the catalyst increases, the olefin space-time yield first increases and then decreases. This is because: in the process of catalytic CO2 hydrogenation to olefins, a certain amount of Na can promote the formation of iron carbide species and improve the carbon chain growth ability, thereby accelerating the reaction rate, but too much sodium will cause excessive deposition of C on Fe, resulting in reduced catalyst activity.

[0080] Example 6-Example 7: Effect of the molar ratio between Fe and Mn

[0081] The CO2 hydrogenation to olefins catalyst is prepared by the following steps and used to catalyze the CO2 hydrogenation to olefins reaction:

[0082] (1) Preparation of a complex composed of insoluble iron salt and insoluble manganese salt by coprecipitation method:

[0083] According to the Fe:Mn (molar ratio) in Table 4 and the total molar amount of ferric nitrate and manganese nitrate, the same as in Example 1, ferric nitrate and manganese nitrate are prepared into a metal salt solution with a total concentration of 1 mol / L of iron ions and manganese ions, and 24.0g of sodium carbonate is prepared into a sodium carbonate solution with a concentration of 2 mol / L. The metal salt solution and the sodium carbonate solution are uniformly dropped into a beaker containing 100mL of deionized water under stirring at room temperature, and the pH of the solution is controlled at 8-10, and stirring is continued for 30min after the addition is completed, and then the stirring is stopped and aged for 1h. After the reaction is completed, the precipitate obtained by filtration is fully washed with deionized water and dried.

[0084] (2) Impregnation method to load rhenium and sodium elements:

[0085] According to the Re ratio of 5wt‰ (i.e., the ratio of Re element in the final catalyst) and the Na ratio of 2wt% (i.e., the ratio of Na element in the final catalyst), ammonium perrhenate and sodium nitrate are dissolved in deionized water to prepare an impregnation solution. Then, the product obtained in step (1) and the impregnation solution are stirred and mixed in equal volumes for impregnation, and then calcined at 550°C for 4h.

[0086] (3) Activation and catalysis of CO2 hydrogenation to olefins:

[0087] The product obtained in step (2) was made into particles of a certain size using a sieve, mixed with an appropriate amount of quartz sand for dilution, and filled into the middle of a stainless steel tube. Before being used to catalyze the CO2 hydrogenation to olefins reaction, 20 mL / min of pure hydrogen was introduced for in-situ reduction at 400°C for 6 h to obtain an activated CO2 hydrogenation to olefins catalyst. The temperature was maintained at 340°C, and a mixed gas of H2 / CO2 / Ar / CO (wherein the molar ratio between the raw gas H2 and CO2 was 3:1, the volume content of Ar was 3%, and the volume content of CO was 4%) was introduced at a reaction space velocity of 7200 mL·h -1 ·g -1 The reactor pressure was increased to 2.0 MPa for CO2 hydrogenation to olefins reaction, and the effect of the molar ratio of Fe to Mn on the catalyst performance was investigated. The data are listed in Table 4.

[0088] Table 4 Effect of molar ratio of Fe to Mn on catalyst performance

[0089]

[0090] It can be seen from Table 4 that as the molar ratio of Fe to Mn increases, the olefin space-time yield increases first and then decreases. This is because Mn can promote the dispersion of Fe and enhance the FeO xThe formation of the Fe phase can improve the activity of Fe-catalyzed CO2 hydrogenation to olefins reaction. However, when the molar ratio between Fe and Mn is too large (too little Fe and too much Mn), the Fe contained in the catalyst is too little, which will cause the catalytic activity to decrease.

[0091] Example 8: Effect of the method of introducing manganese

[0092] The CO2 hydrogenation to olefins catalyst is prepared by the following steps and used to catalyze the CO2 hydrogenation to olefins reaction:

[0093] (1) Preparation of insoluble iron salts by precipitation method:

[0094] 10.5g of ferric nitrate (the molar amount is the same as the total molar amount of ferric nitrate and manganese nitrate in Example 1) is prepared into a 1mol / L ferric nitrate solution, and 24.0g of sodium carbonate is prepared into a 2mol / L sodium carbonate solution. The ferric nitrate solution and the sodium carbonate solution are uniformly dropped into a beaker containing 100mL of deionized water under stirring at room temperature, and the pH of the solution is controlled at 8-10. After the addition is completed, stirring is continued for 30min, and then stirring is stopped and aged for 1h. After the reaction is completed, the precipitate obtained by filtration is fully washed with deionized water and dried.

[0095] (2) Impregnation method to load rhenium, sodium and manganese elements:

[0096] According to the Re ratio of 5wt‰ (i.e., the ratio of Re in Fe, Mn, Na and Re in the final catalyst), the Na ratio of 2wt% (i.e., the ratio of Na in Fe, Mn, Na and Re in the final catalyst) and the Mn ratio of 18.3wt% (i.e., the ratio of Mn in Fe, Mn, Na and Re in the final catalyst, and the same as in Example 1), ammonium perrhenate, sodium nitrate and manganese nitrate are dissolved in deionized water to prepare an impregnation solution. Then, the product obtained in step (1) and the impregnation solution are stirred and mixed in equal volumes, impregnated, and then calcined at 550°C for 4h.

[0097] (3) Activation and catalysis of CO2 hydrogenation to olefins:

[0098] The product obtained in step (2) was made into particles of a certain size using a sieve, mixed with an appropriate amount of quartz sand for dilution, and filled into the middle of a stainless steel tube. Before being used to catalyze the CO2 hydrogenation to olefins reaction, 20 mL / min of pure hydrogen was introduced for in-situ reduction at 400°C for 6 h to obtain an activated CO2 hydrogenation to olefins catalyst. The temperature was maintained at 340°C, and a mixed gas of H2 / CO2 / Ar / CO (wherein the molar ratio between the raw gas H2 and CO2 was 3:1, the volume content of Ar was 3%, and the volume content of CO was 4%) was introduced at a reaction space velocity of 7200 mL·h -1 ·g -1The reactor pressure was increased to 2.0 MPa to carry out CO2 hydrogenation to olefins reaction, and the effect of the method of introducing manganese on the catalyst performance was investigated. The data are listed in Table 5.

[0099] Table 5 Effect of the method of introducing manganese on catalyst performance

[0100]

[0101] It can be seen from Table 5 that compared with the introduction of Mn by impregnation, the co-precipitation of Mn and Fe can improve the olefin space-time yield. This is because: in the process of co-precipitation and subsequent calcination to form metal oxides, the presence of Mn can promote the dispersion of Fe elements and enhance the formation of FeOx phase, thereby improving the catalytic activity of Fe. If Mn is introduced by impregnation, it will not be able to play the above role well.

[0102] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meanings as those commonly understood by ordinary technicians in the field to which the present disclosure belongs. Unless otherwise specified, the raw materials and equipment used in the present invention are conventional raw materials and equipment in the field and can be obtained from conventional commercial channels; unless otherwise specified, the methods used in the present invention are conventional methods in the field.

[0103] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A CO2 hydrogenation to olefins catalyst, characterized in that: The active components of the CO2 hydrogenation to olefins catalyst include iron, manganese, sodium and rhenium; in the CO2 hydrogenation to olefins catalyst, the molar ratio of iron to manganese is 1:0.1~1.0, the proportion of rhenium is 5~8wt‰, and the proportion of sodium is 1~10wt%; the CO2 hydrogenation to olefins catalyst includes a composite containing iron and manganese elements formed by conversion after coprecipitation, and also includes sodium and rhenium elements supported on the composite.

2. A method for preparing the CO2 hydrogenation to olefins catalyst according to claim 1, characterized in that: The following steps are involved: S1: A complex composed of an insoluble iron salt and an insoluble manganese salt is prepared by a coprecipitation method; S2: loading sodium and rhenium into the composite obtained in step S1 to obtain a precursor; S3: calcining the precursor to obtain an inactivated catalyst; S4: reducing the inactivated catalyst with hydrogen to obtain an activated CO2 hydrogenation to olefins catalyst.

3. The preparation method according to claim 2, characterized in that: Step S1 specifically includes: adding a mixed solution of iron salt and manganese salt together with a carbonate solution dropwise into water, performing a precipitation reaction, separating a precipitate, and obtaining a complex composed of an insoluble iron salt and an insoluble manganese salt.

4. The preparation method according to claim 3, characterized in that: In step S1, in the mixed solution of the iron salt and the manganese salt, the total concentration of iron ions and manganese ions is 0.05-1 mol / L.

5. The preparation method according to claim 3, characterized in that: In step S1, the concentration of the carbonate solution is 0.05-5 mol / L.

6. The preparation method according to claim 3, characterized in that: In step S1, the specific process of the precipitation reaction includes: maintaining the pH at 8-10, stirring the reaction for 0.5-2 hours, and standing for aging for 1-10 hours.

7. The preparation method according to claim 2, characterized in that: Step S2 specifically includes: mixing the composite obtained in step S1 with a solution containing sodium and rhenium elements, and drying to obtain a precursor.

8. The preparation method according to claim 2, characterized in that: In step S3, the calcination temperature is 500-800°C and the calcination time is 4-8 hours.

9. Use of the CO2 hydrogenation to olefins catalyst according to claim 1 in catalyzing the CO2 hydrogenation to olefins reaction.

Images