An iron-cobalt-zirconium catalyst suitable for carbon dioxide hydrogenation, its preparation method and application

Abstract

This invention discloses an iron-cobalt-zirconium catalyst suitable for carbon dioxide hydrogenation, its preparation method, and its application in the co-production of low-carbon olefins from carbon dioxide hydrogenation to liquid hydrocarbons. The catalyst is prepared from iron nitrate, cobalt nitrate, and zirconium nitrate as raw materials through co-precipitation, hydrothermal synthesis, drying, and calcination. This invention provides a carbon dioxide hydrogenation catalyst using the above technology and specifies its preparation method. The preparation method is simple, and the obtained catalyst exhibits high activity, high selectivity for liquid hydrocarbons and low-carbon olefins at 280℃, good stability, and is relatively economical, showing good prospects for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to an iron-cobalt-zirconium catalyst suitable for catalytic hydrogenation of carbon dioxide to liquid hydrocarbons and co-production of low-carbon olefins, as well as its preparation method and application. Background Technology

[0002] Against the backdrop of global climate change and energy transition, the conversion and utilization of carbon dioxide has become a hot topic of concern for the scientific and industrial communities. As a major greenhouse gas, the massive emissions of carbon dioxide have had a significant impact on the global climate system. Therefore, exploring efficient conversion pathways for carbon dioxide, especially its transformation into high-value-added chemicals such as low-carbon olefins (ethylene, propylene, butene) and liquid hydrocarbons (gasoline, diesel, etc.), is of great significance for achieving the recycling of carbon resources, alleviating the energy crisis, and addressing climate change.

[0003] Significant progress has been made in the research of producing low-carbon olefins and liquid hydrocarbons from carbon dioxide. Through chemical conversion methods such as catalytic hydrogenation, carbon dioxide can be converted into low-carbon olefins and liquid hydrocarbons under certain conditions. This process not only realizes the resource utilization of carbon dioxide but also promotes the development of green chemistry and sustainable energy. However, current technologies still face challenges in areas such as catalyst activity, selectivity, stability, and cost, requiring further research and optimization.

[0004] Chinese patent CN 117282463 A discloses a method for preparing a composite catalyst for the hydrogenation of carbon dioxide to produce high-value-added liquid fuels. This method improves the directed synthesis of products by introducing one or more molecular sieves to adjust the shell catalyst composition of the capsule catalyst. This type of catalyst exhibits high selectivity for liquid hydrocarbons at 300°C, but its carbon dioxide conversion rate is relatively low. Furthermore, the preparation process of the physically coated coupled catalyst is inconvenient, hindering large-scale industrial production. Chinese patent CN108421547 B discloses a carbon dioxide hydrogenation catalyst for oil production with high selectivity for low-carbon olefins and liquid hydrocarbons at low temperatures (250°C), but its carbon dioxide conversion rate is low, and the additive is Pd, resulting in high cost. Chinese patent CN 112570031A proposes a high-carbon hydrocarbon catalyst prepared by using Fe-based metal-organic frameworks as precursors and impregnating them with additives (Zn, K, Na, Mn, etc.). The catalyst achieves a carbon dioxide conversion rate of 37.87% and a liquid hydrocarbon selectivity of 83.78% at 340℃. However, the metal additive components impregnated in this catalyst are prone to agglomeration, which is not conducive to the uniform dispersion of metal components and results in poor catalyst stability.

[0005] To achieve large-scale industrial application of carbon dioxide catalytic hydrogenation, it is necessary to develop catalysts that are simple and practical to prepare, easy to industrialize, have good reproducibility, and are highly efficient, so as to improve the conversion rate of carbon dioxide while increasing the yield of high-value-added products—low-carbon olefins and liquid hydrocarbons. Summary of the Invention

[0006] To address the aforementioned technical problems in the existing technology, the present invention aims to provide an iron-cobalt-zirconium catalyst suitable for carbon dioxide hydrogenation, its preparation method, and its application. The prepared iron-cobalt-zirconium catalyst can be used in reactions such as carbon dioxide hydrogenation to produce liquid hydrocarbons and low-carbon olefins. This catalyst has advantages such as good carbon dioxide hydrogenation activity, high product selectivity, and good stability.

[0007] This invention provides a method for preparing an iron-cobalt-zirconium catalyst suitable for carbon dioxide hydrogenation, the specific steps of which are as follows: Step S1: Dissolve ferric nitrate nonahydrate, cobalt nitrate hexahydrate and zirconium nitrate pentahydrate in deionized water and stir at room temperature to obtain a homogeneous solution; Step S2: Add an alkaline solution dropwise to the above-mentioned homogeneous solution, heat in a water bath and stir continuously; in this step, the nitrate solution reacts with the alkaline solution to form a hydroxide precipitate; Step S3: The above-mentioned stirred suspension is transferred to a reaction vessel and placed in an oven for heating and reaction. In this step, a hydrothermal reaction occurs, and the solute in the solution in the reaction vessel gradually reaches a supersaturated state, and crystals begin to grow on suitable crystal nuclei.

[0008] Step S4 involves cooling, centrifuging, washing, and drying the suspension after the above reaction to obtain the catalyst precursor. In this step, cooling, centrifugation, and washing are performed to remove excess sodium ions, while drying is mainly for removing water.

[0009] Step S5 involves calcining the catalyst precursor to obtain the iron-cobalt-zirconium catalyst. The purpose of calcination in this step is to stabilize the crystal structure and phase of the catalyst, preventing sintering due to heat at the reaction temperature.

[0010] As an improvement, in step S1, the molar ratio of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, and zirconium nitrate pentahydrate is 100:20~70:0.5~20; preferably 100:45~55:1~10.

[0011] As an improvement, in step S2, the alkaline solution is a sodium hydroxide solution, a potassium hydroxide solution, or a mixture of sodium hydroxide and potassium hydroxide, preferably a sodium hydroxide solution. The molar ratio of the alkaline solution to ferric nitrate nonahydrate is 4~8:1, preferably 4.5~5.5:1.

[0012] As an improvement, in step S2, the water bath heating temperature is 40~90℃ and the time is 0.3~2 h, preferably 55~65℃ water bath for 0.5~1.5 h.

[0013] As an improvement, in step S3, the temperature of the oven is 120~200℃, the reaction time is 10~24 h, preferably 175~185℃, and the heating time is preferably 12~15 h.

[0014] As an improvement, in step S4, the washing is performed at least twice, preferably three times. The drying temperature is 60~100℃, and the drying time is 12~24 h, preferably 75~85℃ for 13~15 h.

[0015] As an improvement, in step S5, the calcination involves placing the precursor in a muffle furnace and calcining it at 350-500°C for 3-6 hours in an air atmosphere, with a heating rate of 2-10°C / min. Preferably, the calcination is carried out at 400-450°C for 3.5-4.5 hours, with a heating rate of 2.5-5°C / min.

[0016] In the catalyst prepared by this invention, iron is the main active species in the carbon dioxide hydrogenation reaction, meaning that iron can convert carbon dioxide into carbon monoxide. Highly dispersed cobalt can effectively convert carbon monoxide attached to the iron surface into hydrocarbons via Fischer-Tropsch synthesis, and iron exhibits strong chain growth ability in Fischer-Tropsch synthesis, generating long-chain hydrocarbons. As an additive, the addition of zirconium can enhance the structural stability and electronic properties of the catalyst, preventing sintering and agglomeration during the reaction, thereby improving the catalyst's activity and stability.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The iron-cobalt-zirconium catalyst disclosed in this invention has a very significant effect on improving the activity of carbon dioxide hydrogenation even when the zirconium content is very low. (2) The iron-cobalt-zirconium catalyst disclosed in this invention has good stability. At 280°C, the single-pass conversion rate of carbon dioxide can reach more than 40%, the total selectivity of low-carbon olefins and liquid hydrocarbons in the product reaches more than 70%, and the yield of low-carbon olefins and liquid hydrocarbons reaches 30%.

[0018] This invention relates to a catalyst prepared from iron nitrate, cobalt nitrate, and zirconium nitrate through co-precipitation, hydrothermal synthesis, drying, and calcination. The catalyst prepared by this invention significantly improves carbon dioxide conversion, suppresses side reactions, and enhances selectivity for low-carbon olefins and liquid hydrocarbons at 280°C. The preparation method of this catalyst is simple and practical, maintains excellent performance under various reaction conditions, is not easily deactivated, and exhibits high stability. This catalyst does not contain precious metal elements, uses common reagents, and is relatively economical. Attached Figure Description

[0019] Figure 1 The images show the XRD patterns of the catalysts in Examples 1, 2, 3, 4, 5 and Comparative Example 1 of this invention.

[0020] Figure 2 The graphs show the carbon dioxide hydrogenation performance of the catalysts in Examples 1, 2, 3, 4, 5, 6, 7, 8 and Comparative Example 1 of this invention.

[0021] Figure 3 The graphs show the carbon dioxide hydrogenation performance of the catalysts in Example 3 and Comparative Examples 2, 3, 4, 5, and 6 of this invention. Detailed Implementation

[0022] The invention will now be described in conjunction with specific embodiments. It should be noted that the embodiments only describe the preparation process of the catalyst within a certain scope. Other researchers can make multiple modifications to the invention without departing from the technical premise of the invention, and these modifications should also be considered within the scope of protection of the invention. Example 1

[0023] (1) Dissolve 0.04 mol ferric nitrate nonahydrate, 0.02 mol cobalt nitrate hexahydrate and 0.0004 mol zirconium nitrate pentahydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 180°C for 14 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 80°C for 14 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 400°C for 4 h in an air atmosphere at normal pressure. The heating rate was 2.5°C / min. Black powder was obtained. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which was denoted as catalyst 1. Example 2

[0024] (1) Dissolve 0.04 mol ferric nitrate nonahydrate, 0.02 mol cobalt nitrate hexahydrate and 0.002 mol zirconium nitrate pentahydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 180°C for 14 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 80°C for 14 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 400°C for 4 h in an air atmosphere at normal pressure. The heating rate was 2.5°C / min. Black powder was obtained. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which was designated as catalyst 2. Example 3

[0025] (1) Dissolve 0.04 mol ferric nitrate nonahydrate, 0.02 mol cobalt nitrate hexahydrate and 0.004 mol zirconium nitrate pentahydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 180°C for 14 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 80°C for 14 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 400°C for 4 h in an air atmosphere at normal pressure. The heating rate was 2.5°C / min. Black powder was obtained. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which was designated as catalyst 3. Example 4

[0026] (1) Dissolve 0.04 mol ferric nitrate nonahydrate, 0.02 mol cobalt nitrate hexahydrate and 0.006 mol zirconium nitrate pentahydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 180°C for 14 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 80°C for 14 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 400°C for 4 h in an air atmosphere at normal pressure. The heating rate was 2.5°C / min. Black powder was obtained. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which was designated as catalyst 4. Example 5

[0027] (1) Dissolve 0.04 mol ferric nitrate nonahydrate, 0.02 mol cobalt nitrate hexahydrate and 0.008 mol zirconium nitrate pentahydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 180°C for 14 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 80°C for 14 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 400°C for 4 h in an atmospheric air atmosphere at normal pressure. The heating rate was 2.5°C / min to obtain black powder. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which is denoted as catalyst 5. Example 6

[0028] (1) Dissolve 0.04 mol ferric nitrate nonahydrate, 0.02 mol cobalt nitrate hexahydrate and 0.004 mol zirconium nitrate pentahydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 185°C for 15 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 80°C for 14 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 400°C for 4 h in an air atmosphere at normal pressure. The heating rate was 2.5°C / min. Black powder was obtained. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which was designated as catalyst 6. Example 7

[0029] (1) Dissolve 0.04 mol ferric nitrate nonahydrate, 0.02 mol cobalt nitrate hexahydrate and 0.004 mol zirconium nitrate pentahydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 180°C for 14 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 75°C for 15 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 400°C for 4 h in an air atmosphere at normal pressure. The heating rate was 2.5°C / min. Black powder was obtained. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which was designated as catalyst 7. Example 8

[0030] (1) Dissolve 0.04 mol ferric nitrate nonahydrate, 0.02 mol cobalt nitrate hexahydrate and 0.004 mol zirconium nitrate pentahydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 180°C for 14 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 80°C for 14 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 500°C for 4 h in an air atmosphere at normal pressure. The heating rate was 2.5°C / min. Black powder was obtained. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which was designated as catalyst 8. Comparative Example 1

[0031] (1) Dissolve 0.04 mol ferric nitrate nonahydrate and 0.02 mol cobalt nitrate hexahydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 180°C for 14 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 80°C for 14 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 400°C for 4 h in an air atmosphere at normal pressure. The heating rate was 2.5°C / min to obtain black powder. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which is referred to as reference catalyst 1. Comparative Example 2

[0032] (1) Dissolve 0.04 mol ferric nitrate nonahydrate, 0.02 mol cobalt nitrate hexahydrate and 0.004 mol calcium nitrate tetrahydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 180°C for 14 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 80°C for 14 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 400°C for 4 h in an air atmosphere at normal pressure. The heating rate was 2.5°C / min. Black powder was obtained. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which was designated as reference catalyst 2. Comparative Example 3

[0033] (1) Dissolve 0.04 mol ferric nitrate nonahydrate, 0.02 mol cobalt nitrate hexahydrate and 0.004 mol zinc nitrate hexahydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 180°C for 14 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 80°C for 14 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 400°C for 4 h in an atmospheric air atmosphere at normal pressure. The heating rate was 2.5°C / min to obtain black powder. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which was designated as reference catalyst 3. Comparative Example 4

[0034] (1) Dissolve 0.04 mol ferric nitrate nonahydrate, 0.02 mol cobalt nitrate hexahydrate and 0.004 mol copper nitrate trihydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 180°C for 14 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 80°C for 14 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 400°C for 4 h in an air atmosphere at normal pressure. The heating rate was 2.5°C / min to obtain black powder. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which is referred to as reference catalyst 4. Comparative Example 5

[0035] (1) Dissolve 0.04 mol ferric nitrate nonahydrate, 0.016 mol cobalt nitrate hexahydrate and 0.004 mol zirconium nitrate hexahydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 180°C for 14 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 80°C for 14 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 400°C for 4 h in an air atmosphere at normal pressure. The heating rate was 2.5°C / min. Black powder was obtained. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which was designated as reference catalyst 5. Comparative Example 6

[0036] (1) Dissolve 0.04 mol ferric nitrate nonahydrate, 0.024 mol cobalt nitrate hexahydrate and 0.004 mol zirconium nitrate hexahydrate in 50 mL of deionized water and stir at room temperature to obtain a homogeneous solution; (2) Add 50 mL of 4 mol / L sodium hydroxide solution dropwise to the above uniformly mixed solution and stir continuously for 1 h in a water bath at 60°C; (3) Transfer the above-stirred suspension to a stainless steel reactor lined with polytetrafluoroethylene and heat it in an oven at 180°C for 14 h. (4) After the reaction is complete, the reactor is cooled to room temperature, the product is obtained by centrifugation, and then washed three times with 300 mL of deionized water. The precipitate obtained by washing is transferred to a beaker and dried in an oven at 80°C for 14 h to obtain the catalyst precursor; (5) The catalyst precursor was placed in a muffle furnace and calcined at 400°C for 4 h in an air atmosphere at normal pressure. The heating rate was 2.5°C / min to obtain black powder. The powder was pressed into tablets, crushed and sieved to obtain the desired particulate catalyst, which is referred to as reference catalyst 6.

[0037] The catalysts were tested for their performance in the carbon dioxide hydrogenation reaction under the same conditions. Specifically, 0.5 g of catalyst was mixed with 1.5 g of quartz sand and loaded into a fixed-bed reactor. The mixture was reduced in pure H2 gas at 350 °C and atmospheric pressure for 5 h, and then reacted for 24 h in a CO2:N2:H2 mixture at 280 °C, 2.0 MPa, and 50 mL / min (volume ratio of 23:8:69). The products were analyzed using a gas chromatograph equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID). The results of the catalyst's reaction performance tests are shown in Table 1.

[0038] Table 1. Performance of carbon dioxide hydrogenation on different catalysts Example 1 38.42 26.84 50.05 29.54 Example 2 41.05 24.35 48.27 29.81 Example 3 43.89 22.09 48.18 30.84 Example 4 44.83 20.96 40.15 27.40 Example 5 45.28 13.45 39.29 23.88 Example 6 43.96 22.01 48.06 30.80 Example 7 43.64 22.23 47.36 30.37 Example 8 44.53 21.34 47.12 30.49 Comparative Example 1 32.89 23.15 48.92 23.70 Comparative Example 2 54.44 0.26 16.62 9.19 Comparative Example 3 33.77 22.17 52.14 25.09 Comparative Example 4 21.51 11.73 55.96 12.04 Comparative Example 5 43.14 23.16 43.01 28.55 Comparative Example 6 44.21 20.81 45.58 29.35 Figure 1 The XRD patterns of the catalysts in Examples 1, 2, 3, 4, 5 and Comparative Example 1 of this invention are shown. As can be seen from the figures, the main phase of the samples is cobalt ferrite, and the zirconium dioxide phase is only detected when the zirconium content is high, possibly due to the high dispersion of low-content zirconium within the cobalt ferrite.

[0039] Figure 2The figures show the carbon dioxide hydrogenation performance of the catalysts in Examples 1, 2, 3, 4, 5, 6, 7, 8, and Comparative Example 1. As can be seen from the figures and Table 1, with the increase of zirconium content, the carbon dioxide conversion rate continuously increases, while the selectivity for low-carbon olefins and liquid hydrocarbons continuously decreases. The yields of low-carbon olefins and liquid hydrocarbons show a trend of first increasing and then decreasing. This indicates that the addition of zirconium has a very significant effect on improving the activity of the cobalt ferrite catalyst in carbon dioxide hydrogenation, but with the increase of zirconium content, the selectivity of the target product is somewhat inhibited. When the Fe / Co / Zr molar ratio is 100 / 50 / 10, the target product yield is the highest, with a carbon dioxide conversion rate of 43.89% and a total selectivity of 70.27% for low-carbon olefins and liquid hydrocarbons. The difference between Comparative Example 1 and the catalysts in Examples 1, 2, 3, 4, and 5 is that Comparative Example 1 did not add zirconium. Its carbon dioxide conversion rate is lower than any of the catalysts with added zirconium, indicating that zirconium can improve the activity of the catalyst even at very low contents. The difference between Examples 6, 7, and 8 and Example 3 lies in the use of the same raw materials, but the conditions during the preparation process are slightly different. Example 6 was prepared under hydrothermal conditions of 185°C for 15 h, Example 7 underwent drying at 75°C for 15 h, and Example 8 underwent calcination at 500°C for 4 h. These slight changes in preparation conditions had little effect on the catalyst; the activity and yield remained almost unchanged.

[0040] Figure 3 The figures show the carbon dioxide hydrogenation performance of the catalysts in Example 3 and Comparative Examples 2, 3, 4, 5, and 6 of this invention. The difference between Comparative Examples 2, 3, and 4 and Example 3 lies in the substitution of zirconium with other elements in the same amount. Comparative Example 2 added calcium, which significantly improved the carbon dioxide conversion rate, but the target product selectivity was very low, resulting in a low yield. Comparative Example 3 added zinc, which resulted in a higher target product selectivity, but the carbon dioxide conversion rate was low, leading to a low yield. Comparative Example 4 added copper, which also resulted in low target product selectivity and a low carbon dioxide conversion rate, leading to a very low yield. The difference between Comparative Examples 5 and 6 and Example 3 lies in the cobalt content in the catalysts. In Comparative Example 5, the molar ratio of iron, cobalt, and zirconium was 100:40:10; in Comparative Example 6, it was 100:60:10; and in Example 3, it was 100:50:10. It can be observed that the target product selectivity of Comparative Examples 5 and 6 is lower than that of Example 3, and the yield of the target product is also lower than that of Example 3.

[0041] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing an iron-cobalt-zirconium catalyst suitable for carbon dioxide hydrogenation, characterized in that, The process includes the following steps: S1: Dissolve ferric nitrate nonahydrate, cobalt nitrate hexahydrate and zirconium nitrate pentahydrate in deionized water and stir at room temperature to obtain a homogeneous solution; S2: Add alkaline solution dropwise to the above uniformly mixed solution, heat in a water bath and stir continuously; S3: Transfer the above-stirred suspension to a reaction vessel and place it in an oven for heating and reaction; S4: The suspension after the above reaction is cooled, centrifuged, washed and dried to obtain the catalyst precursor; S5: Calcining the above catalyst precursor yields an iron-cobalt-zirconium catalyst; In step S2, the alkaline solution is a sodium hydroxide solution, a potassium hydroxide solution, or a mixed solution of sodium hydroxide and potassium hydroxide; in step S5, calcination involves placing the precursor in a muffle furnace and calcining it at 350~500℃ for 3~6 h in an air atmosphere, with a heating rate of 2~10℃ / min. In step S1, the molar ratio of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, and zirconium nitrate pentahydrate is 100:20~70:0.5~20; In step S2, the molar ratio of alkaline solution to ferric nitrate nonahydrate is 4~8:1; In step S2, the water bath heating temperature is 40~90℃ and the time is 0.3~2 h.

2. The method for preparing an iron-cobalt-zirconium catalyst suitable for carbon dioxide hydrogenation according to claim 1, characterized in that, In step S3, the oven temperature is 120~200℃ and the reaction time is 10~24 h.

3. The method for preparing an iron-cobalt-zirconium catalyst suitable for carbon dioxide hydrogenation according to claim 1, characterized in that, In step S4, the washing is performed more than twice; the drying temperature is 60~100℃, and the drying time is 12~24 h.

4. An iron-cobalt-zirconium catalyst suitable for carbon dioxide hydrogenation, characterized in that, It is prepared by the preparation method described in any one of claims 1-3.

5. The application of the iron-cobalt-zirconium catalyst as described in claim 4 in the catalytic hydrogenation of carbon dioxide to liquid hydrocarbons and the co-production of low-carbon olefins.

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