Preparation method of three-way catalyst for preparing CO through CO2 hydrogenation reduction

Abstract

The invention discloses a preparation method of a three-way catalyst for preparing CO by hydrogenation reduction of CO2, which comprises the following steps: (1) mixing In2O3 nano powder and ZrO2 nano particles, and fully grinding to obtain In2O3 / ZrO2; (2) adding the In2O3 / ZrO2 prepared in the step (1) and nickel salt into deionized water, and fully stirring to obtain a suspension; and carrying out vacuum drying on the suspension, and calcining the dried solid to obtain the three-way catalyst Ni / In2O3 / ZrO2. According to the method, the three-way catalyst Ni / In2O3 / ZrO2 in which In2O3 and NiO are uniformly dispersed on the zirconium oxide carrier respectively can be obtained, in the process of preparing CO through CO2 hydrogenation reduction by the three-way catalyst with the morphology, due to Ni doping and high hydrogen content, RWGS reaction and catalyst reconstruction reaction are synchronously carried out, the three-way catalyst is reconstructed in the reaction atmosphere, and the CO content is reduced. The hydrogenation catalytic activity of the catalyst is effectively improved by high-reaction-activity substances generated after reconstruction, meanwhile, the problem of activity loss caused by excessive reduction of In2O3 in a hydrogen atmosphere can be effectively avoided, and the catalytic stability of the catalyst is greatly improved.

Description

Technical Field

[0001] The present invention relates to a preparation method of a ternary catalyst for hydrogenation reduction of CO2 to CO. Background Art

[0002] As one of the main greenhouse gases, the excessive emission of CO2 is considered to be the main factor causing climate change. Therefore, people increasingly attach importance to reducing the emission of CO2 in the atmosphere. At the same time, CO2 is also a carbon source, so its effective utilization is an important means to control greenhouse gases. Due to the inherent thermodynamic stability and kinetic inertia of CO2 molecules, its activation has become a major challenge. The main methods for hydrogenation of CO2 to produce high-value products include CO2 methanation, hydrogenation of CO2 to methanol, and reverse water gas shift reaction. The RWGS reaction is used for CO production and can be combined with other processes such as Fischer-Tropsch synthesis to synthesize corresponding hydrocarbons and alcohols. Therefore, developing an RWGS catalyst with high activity and high stability has become a crucial task.

[0003] Indium oxide (In2O3) and In2O3-supported catalysts have become efficient catalysts for CO2 hydrogenation. In2O3 is easily loaded or modified to generate abundant O v sites, thereby enhancing the activation of more CO2 molecules and stabilizing the surface intermediates near O v However, when In2O3 is exposed to a H2 atmosphere, it is prone to over-reduction and sintering, resulting in the easy inactivation of the catalytic activity of the catalyst and the inability to maintain lasting catalytic stability. Summary of the Invention

[0004] Object of the Invention: The object of the present invention is to provide a preparation method of a ternary catalyst for hydrogenation reduction of CO2 to CO. When the catalyst prepared by this method is used for hydrogenation reduction of CO2 to CO, even in a H2 atmosphere with a high inlet gas volume, there will be no over-reduction problem. Instead, it can greatly improve the catalytic activity of the catalyst for CO2 hydrogenation, and there is no obvious carbon deposition on the catalyst surface during the reaction process.

[0005] Technical Solution: The preparation method of the ternary catalyst for hydrogenation reduction of CO2 to CO according to the present invention includes the following steps:

[0006] (1) Mix In2O3 nanopowder with ZrO2 nanoparticles, and obtain In2O3 / ZrO2 after sufficient grinding;

[0007] (2) Add the In2O3 / ZrO2 prepared in step (1) and nickel salt to deionized water, stir well to obtain a suspension; vacuum-dry the suspension, and calcine the dried solid to obtain the ternary catalyst Ni / In2O3 / ZrO2.

[0008] Among them, in step (1), the mass ratio of In2O3 to ZrO2 added is 0.01 - 0.031:1; the grinding time is not less than 20 min.

[0009] In step (2), the nickel salt is one of Ni(NO3)2·6H2O, NiSO4 or NiCl2; the mass ratio of the nickel salt to In2O3 / ZrO2 added is 0.05 - 0.152:1; the vacuum drying temperature is 60 - 70 °C, and drying is carried out overnight; the calcination temperature is 500 - 550 °C, and the roasting time is 4 - 4.5 h; the ternary catalyst Ni / In2O3 / ZrO2 prepared by the present invention uses zirconia as a carrier, and In2O3 and NiO are loaded on the zirconia carrier, and In2O3 and NiO are evenly dispersed on the zirconia carrier respectively.

[0010] Calculated by the mass of Ni, the loading amount of nickel element on the catalyst is 1 - 3 wt.% (relative to the total mass of the catalyst); the loading amount of In2O3 on the catalyst is 1 - 3 wt.%.

[0011] Application of the ternary catalyst prepared by the above preparation method in the hydrogenation reduction of CO2 to CO. The specific application process is as follows: After the Ni / In2O3 / ZrO2 ternary catalyst is heated to 400 - 600 °C in a nitrogen atmosphere, the nitrogen atmosphere is switched to a raw material gas for hydrogenation reduction of CO2 for the RWGS reaction; among them, in the raw material gas for hydrogenation reduction of CO2, the molar ratio of H2 to CO2 is not less than 4:1; the flow rate of the raw material gas for hydrogenation reduction of CO2 is not less than 60 mL / min.

[0012] The present invention uses a ternary catalyst as a catalyst for the hydrogenation reduction of CO2 to CO, and directly adopts an in-situ atmosphere induction method to induce the reconstruction of the catalyst using a raw material gas for hydrogenation reduction of CO2 (including a CO2 / H2 mixture). The reaction atmosphere induces In2O3 to be more evenly and widely dispersed on the carrier ZrO2 and tends to migrate towards the Ni species. After migration, NiO is reduced to Ni, and Ni enters the metal site lattice of In2O3 to form a complex NiInO x structure (Ni and In in the active site are still in the oxidized state. Ni enters the indium oxide lattice, and the oxidized Ni is the favorable part in the reaction. The reason represented by O x is the existence of an oxygen vacancy structure), and the NiInO x structure contains InO induced to form a metastable but highly reactive structure xlayer, and there is also a SMSI effect between In2O3 and Ni. Electron transfer occurs between In2O3 and Ni. On the one hand, it is beneficial to further increase the number of oxygen vacancies, thereby enhancing the adsorption of CO2 and improving the CO yield. On the other hand, the doping of Ni helps to improve the catalytic activity of In2O3 while avoiding its over-reduction, so that it maintains persistent catalytic activity and has good catalytic stability (doping Ni in the catalyst system can effectively avoid the over-reduction of In2O3 in a hydrogen atmosphere. Through characterization, it is found that In presents an oxidized state before and after the catalytic reaction, and there is no obvious In 0 existing, because In-O-In / Ni is formed during the dynamic migration process, thus avoiding the over-reduction of In).

[0013] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: The method of the present invention can obtain a ternary catalyst Ni / In2O3 / ZrO2 in which In2O3 and NiO are uniformly dispersed on a zirconia support. During the process of hydrogenation reduction of CO2 to CO by the ternary catalyst with the above morphology, due to the doping of Ni and the high hydrogen content, the RWGS reaction and the catalyst reconstruction reaction are carried out synchronously. Under the above reaction atmosphere, the ternary catalyst is reconstructed, and the highly reactive substances generated after reconstruction effectively improve the hydrogenation catalytic activity of the catalyst, and at the same time can effectively avoid the problem of the loss of activity caused by the over-reduction of In2O3 in a hydrogen atmosphere, and greatly improve the catalytic stability of the catalyst. Description of the Drawings

[0014] Figure 1 shows the CO yields of the ternary catalyst 2Ni / 2In2O3 / ZrO2 and the binary catalyst 2In2O3 / ZrO2 prepared in Example 1 and Comparative Example 1; reaction conditions: 400 °C, WHSV = 24000 mL g -1 h -1 , H2 / CO2 = 4, P = 0.1 Mpa;

[0015] Figure 2 shows the CO2 conversion rates and CO selectivities of the ternary catalyst 2Ni / 2In2O3 / ZrO2 and the binary catalyst 2In2O3 / ZrO2 prepared in Example 1 and Comparative Example 1; reaction conditions: 400 °C, WHSV = 24000 mL g -1 h -1 , H2 / CO2 = 4, P = 0.1 Mpa;

[0016] Figure 3CO2 conversion rates and CO selectivities of the ternary catalyst 2Ni / 2In2O3 / ZrO2 and the binary catalyst 2In2O3 / ZrO2 prepared in Example 1 and Comparative Example 1 under different reaction atmosphere induction conditions; reaction conditions: 400 °C, 30 h, WHSV = 24000 mL g -1 h -1 , P = 0.1 Mpa;

[0017] Figure 4 CO yields of the ternary catalyst 2Ni / 2In2O3 / ZrO2 prepared in Example 1 at different temperatures; reaction conditions: WHSV = 24000 mLg -1 h -1 , H2 / CO2 = 4, P = 0.1 MPa;

[0018] Figure 5 CO yields corresponding to the ternary catalysts prepared in Examples 1 - 3 during the hydrogenation reduction of CO2 to CO; reaction conditions: 500 °C, 30 h, WHSV = 24000 mL g -1 h -1 , H2 / CO2 = 4, P = 0.1 Mpa;

[0019] Figure 6 XRD patterns of the ternary catalyst 2Ni / 2In2O3 / ZrO2 and the binary catalyst 2In2O3 / ZrO2 prepared in Example 1 and Comparative Example 1 before and after the catalytic reaction; reaction conditions: 400 °C, WHSV = 24000 mL g -1 h -1 , H2 / CO2 = 4, P = 0.1 Mpa;

[0020] Figure 7 High - angle annular dark - field scanning transmission electron microscopy (HAADF - STEM), energy - dispersive X - ray (EDX) spectroscopic mapping images, and high - resolution transmission electron microscopy (HRTEM) images of the ternary catalyst 2Ni / 2In2O3 / ZrO2 prepared in Example 1 before and after the catalytic reaction; reaction conditions: 400 °C, 50 h, WHSV = 24000 mL g -1 h -1 , H2 / CO2 = 4, P = 0.1 MPa;

[0021] Figure 8 XPS spectra of the catalysts in Examples 1 - 3 and Comparative Example 2 after the catalytic reaction; a is In 3d, b is InMN1, c is Ni2p, and d is O1s; reaction conditions during the catalytic reaction: 500 °C, 30 h, WHSV = 24000 mL g -1 h -1 , H2 / CO2 = 4, P = 0.1 Mpa;

[0022] Figure 9 Thermogravimetric analysis (TGA) of 3In2O3 / ZrO2, 3Ni / 1In2O3 / ZrO2, 2Ni / 2In2O3 / ZrO2, and 1Ni / 3In2O3 / ZrO2 catalysts after the catalytic reaction; reaction conditions: 500 °C, 30 h, WHSV = 24,000 mL g -1 h -1 , H2 / CO2 = 4, P = 0.1 MPa. Detailed implementation manners

[0023] Example 1

[0024] The preparation method of the ternary catalyst of the present invention comprises the following steps:

[0025] (1) Synthesize In2O3 nanoparticles by the solvothermal method: Weigh 4 mmol of In(NO3)3·xH2O and 4 g of CO(NH2)2 and place them in a beaker. Then add 70 mL of diethylene glycol (C4H 10 O3) and 4 mL of deionized water, and stir well at room temperature for 0.5 h to ensure uniform dispersion; then transfer the mixture to a stainless-steel hydrothermal autoclave lined with polytetrafluoroethylene and react at 200 °C for 24 h; after the reaction, collect the product by centrifugation and wash it with anhydrous ethanol and deionized water multiple times; then dry the product in vacuo at 60 °C for 4 h. Finally, heat the dried sample in air at a heating rate of 2 °C / min to 400 °C and calcine it at this temperature for 2 h to obtain a pale yellow In2O3 product;

[0026] (2) Prepare the In2O3 / ZrO2 binary catalyst: Mix 0.0408 g of the In2O3 nanopowder prepared in step (1) and 2 g of ZrO2 nanoparticles in a mortar and grind for 20 min to obtain the In2O3 / ZrO2 catalyst;

[0027] (3) Add 0.0152 g of Ni(NO3)2·6H2O and 0.15 g of In2O3 / ZrO2 to 5 mL of deionized water and stir well for 5 h to obtain a suspension; dry the suspension in vacuo at 60 °C overnight; calcine the dried powder obtained after vacuum drying in air at a heating rate of 2 °C / min at 500 °C for 4 h to obtain a ternary catalyst, named 2Ni / 2In2O3 / ZrO2; wherein, in the ternary catalyst, calculated by the mass of Ni, the loading amount of Ni element is 2% of the catalyst mass; the loading amount of In2O3 is 2% of the catalyst mass.

[0028] Comparative Example 1

[0029] A preparation method of a binary catalyst, comprising the following steps:

[0030] (1) Synthesize In2O3 nanoparticles by solvothermal method: Weigh 4 mmol of In(NO3)3·xH2O and 4 g of CO(NH2)2 and place them in a beaker. Then add 70 mL of diethylene glycol (C4H 10 O3) and 4 mL of deionized water, and stir well at room temperature for 0.5 h to ensure uniform dispersion. Then, transfer the mixture to a stainless-steel autoclave lined with polytetrafluoroethylene, and react at 200 °C for 24 h. After the reaction, collect the product by centrifugation and wash it with anhydrous ethanol and deionized water multiple times. Then dry the product in vacuum at 60 °C for 4 h. Finally, heat the dried sample in air at a heating rate of 2 °C / min to 400 °C and calcine it at this temperature for 2 h to obtain a pale yellow In2O3 product;

[0031] (2) Prepare the In2O3 / ZrO2 binary catalyst: Mix 0.0408 g of the In2O3 nanopowder prepared in step (1) and 2 g of ZrO2 nanoparticles in a mortar and grind for 20 min to obtain a binary catalyst; name it 2In2O3 / ZrO2. Among them, in the catalyst, the loading amount of In2O3 is 2% of the catalyst mass.

[0032] Apply the ternary catalyst 2Ni / 2In2O3 / ZrO2 and the binary catalyst 2In2O3 / ZrO2 prepared in Example 1 and Comparative Example 1 respectively to the hydrogenation reduction of CO2 to produce CO. Specifically:

[0033] Heat 0.15 g of the ternary catalyst 2Ni / 2In2O3 / ZrO2 to 400 °C under a nitrogen atmosphere with a flow rate of 50 mL / min, and then switch the nitrogen atmosphere to a CO2 hydrogenation reduction raw material gas to synchronously carry out catalyst reconstruction and RWGS reaction for 50 h; the flow rate of the CO2 hydrogenation reduction raw material gas is 60 mL / min, and the molar ratio of gas CO2:H2 is 1:4.

[0034] Heat 0.15 g of the binary catalyst 2In2O3 / ZrO2 to 400 °C under a nitrogen atmosphere with a flow rate of 50 mL / min, and then switch the nitrogen atmosphere to a CO2 hydrogenation reduction raw material gas to carry out RWGS reaction for 30 h; the flow rate of the CO2 hydrogenation reduction raw material gas is 60 mL / min, and the molar ratio of gas CO2:H2 is 1:4.

[0035] Within 30 h of the reaction, for the 2Ni / 2In2O3 / ZrO2 ternary catalyst, the CO yield can reach 2.43 (10 -2 mol h -1 g cat -1) The CO2 conversion rate can reach 23.9%, and the CO selectivity is 93.7%. The CO yield of the 2In2O3 / ZrO2 binary catalyst can reach 1.94(10 - 2 mol h -1 g cat -1 ), the CO2 conversion rate can reach 19.4%, and the CO selectivity is 95.2%.

[0036] For the catalyst in Example 1, the CO yield still shows an upward trend after 30 h of reaction. Within 50 h, the highest CO yield can reach 2.69(10 -2 mol h -1 g cat -1 ), the CO selectivity is 92.7%, and the CO2 conversion rate can reach 27.5%. However, for the catalyst in Comparative Example 1, the CO yield does not show an upward trend after 30 h of reaction but instead shows a certain degree of decline.

[0037] As shown by Figure 1 and Figure 2 , compared with 2In2O3 / ZrO2, the catalytic performance of 2Ni / 2In2O3 / ZrO2 is significantly improved, reaching a higher rate at the initial stage of the RWGS reaction. The highest CO generation rate within 30 h reaches 2.43(10 -2 mol h -1 g cat -1 ), indicating that the ternary catalyst of the present invention has high activity and long-term stability after being induced by the reaction atmosphere. Electron transfer occurs between In2O3 and Ni. On the one hand, it is beneficial to further increase the number of oxygen vacancies, thereby enhancing the adsorption of CO2 and improving the CO yield. On the other hand, the doping of Ni can help improve the catalytic activity of In2O3 while avoiding its over-reduction because In-O-In / Ni is formed during the dynamic migration process, which can avoid the generation of 0 In, so that it maintains persistent catalytic activity and has good catalytic stability.

[0038] As shown by Figure 3 , as the hydrogen content in the reaction gas increases, the CO2 conversion rate of the catalyst increases, confirming that the induced reduction of H2 is the main reason for the dynamic dispersion of In2O3 on the carrier ZrO2.

[0039] Figure 6The diffraction peaks in the middle are highly consistent with those of m-ZrO2. This support belongs to the monoclinic structure (Literature number: PDF#37-1484), and no obvious change was observed in the diffraction peaks of the catalyst after the reaction. It is inferred that In is not doped into the ZrO2 lattice and this property is maintained during the RWGS reaction. No diffraction peaks of In2O3, metallic Ni, and their compounds were observed for the catalyst before and after the reaction, indicating that In2O3 and Ni are highly dispersed on ZrO2.

[0040] Figure 7 In the 2Ni / 2In2O3 / ZrO2 catalyst, the dispersion sites of In2O3 and Ni species are not the same, which is because the Ni / In2O3 / ZrO2 ternary catalyst is prepared by a two-step method. After the RWGS reaction (400 °C, 50 h), In species mainly migrate and distribute on the surface of the ZrO2 support nanoparticles, and a partially reduced indium oxide (InO x ) layer is observed to form on the surface of the ZrO2 support. The distributions of In species and Ni species in the 2Ni / 2In2O3 / ZrO2 catalyst after the reaction highly overlap, which means that there may be a strong interaction between the two, forming a complex structure. The 2Ni / 2In2O3 / ZrO2 catalyst after the reaction was measured by HAADF-STEM and attempts were made to further analyze it by local magnification. The high-resolution transmission electron microscope (HRTEM) was used to further study the changes in the structure of the 2Ni / 2In2O3 / ZrO2 catalyst caused by the dynamic evolution during the RWGS reaction. It can be observed that the interplanar spacing of the crystal plane of the ZrO2 support is 0.271 nm, corresponding to the (220) plane of ZrO2, and a complex structure formed by the interaction of In2O3 and Ni is distributed on the surface of the ZrO2 support. In addition, it cannot be excluded that there is some exposed Ni on the surface of the complex structure NiInO x . At the same time, an InO x layer can be observed on the surfaces of the ZrO2 support and the complex structure NiInO x .

[0041] Example 2

[0042] The preparation method of the ternary catalyst of the present invention includes the following steps:

[0043] (1) Synthesize In2O3 nanoparticles by the solvothermal method: Weigh 4 mmol of In(NO3)3·xH2O and 4 g of CO(NH2)2 and place them in a beaker, and then add 70 mL of diethylene glycol (C4H 10O3), and 4 mL of deionized water were added to a beaker, and the mixture was stirred thoroughly at room temperature for 0.5 h to ensure uniform dispersion. Subsequently, the mixture was transferred to a stainless-steel hydrothermal autoclave lined with polytetrafluoroethylene and reacted at 200 °C for 24 h. After the reaction, the product was collected by centrifugation and washed repeatedly with absolute ethanol and deionized water. Then the product was dried in vacuo at 60 °C for 4 h. Finally, the dried sample was heated to 400 °C in air at a heating rate of 2 °C / min and calcined at this temperature for 2 h to obtain a pale yellow In2O3 product;

[0044] (2) Preparation of In2O3 / ZrO2 binary catalyst: 0.0619 g of the In2O3 nanopowder prepared in step (1) and 2 g of ZrO2 nanoparticles were mixed in a mortar and ground for 20 min to obtain the In2O3 / ZrO2 catalyst;

[0045] (3) 0.0075 g of Ni(NO3)2·6H2O and 0.15 g of In2O3 / ZrO2 were added to 5 mL of deionized water and stirred thoroughly for 5 h to obtain a suspension. The suspension was dried in vacuo at 60 °C overnight. The dried powder obtained after vacuum drying was calcined in air at a heating rate of 2 °C / min at 500 °C for 4 h to obtain a ternary catalyst named 1Ni / 3In2O3 / ZrO2. Among them, in the ternary catalyst, based on the mass of Ni, the loading amount of Ni element is 1% of the mass of the catalyst; the loading amount of In2O3 is 3% of the mass of the catalyst.

[0046] Comparative Example 2

[0047] A method for preparing a binary catalyst, comprising the following steps:

[0048] (1) Synthesis of In2O3 nanoparticles by solvothermal method: Weigh 4 mmol of In(NO3)3·xH2O and 4 g of CO(NH2)2 and place them in a beaker. Subsequently, add 70 mL of diethylene glycol (C4H 10 O3) and 4 mL of deionized water, and stir thoroughly at room temperature for 0.5 h to ensure uniform dispersion. Subsequently, the mixture was transferred to a stainless-steel hydrothermal autoclave lined with polytetrafluoroethylene and reacted at 200 °C for 24 h. After the reaction, the product was collected by centrifugation and washed repeatedly with absolute ethanol and deionized water. Then the product was dried in vacuo at 60 °C for 4 h. Finally, the dried sample was heated to 400 °C in air at a heating rate of 2 °C / min and calcined at this temperature for 2 h to obtain a pale yellow In2O3 product;

[0049] (2) Preparation of In2O3 / ZrO2 binary catalyst: Mix 0.0619 g of the In2O3 nanopowder prepared in step (1) and 2 g of ZrO2 nanoparticles in a mortar and grind for 20 min to obtain a binary catalyst named 3In2O3 / ZrO2. Among them, in the binary catalyst, the loading amount of In2O3 is 3% of the catalyst mass.

[0050] Apply the ternary catalyst 3In2O3 / ZrO2 prepared in Comparative Example 2 to the hydrogenation reduction of CO2 to CO, specifically as follows:

[0051] Heat 0.15 g of the binary catalyst 3In2O3 / ZrO2 to 500 °C under a nitrogen atmosphere with a flow rate of 50 mL / min, and then switch the nitrogen atmosphere to the raw material gas for hydrogenation reduction of CO2 to simultaneously perform catalyst reconstruction and RWGS reaction for 30 h; the flow rate of the raw material gas for hydrogenation reduction of CO2 is 60 mL / min, and the molar ratio of gas CO2:H2 is 1:4.

[0052] Example 3

[0053] The preparation method of the ternary catalyst of the present invention includes the following steps:

[0054] (1) Synthesize In2O3 nanoparticles by solvothermal method: Weigh 4 mmol of In(NO3)3·xH2O and 4 g of CO(NH2)2 and place them in a beaker, then add 70 mL of diethylene glycol (C4H 10 O3) and 4 mL of deionized water, and stir well at room temperature for 0.5 h to ensure uniform dispersion; then transfer the mixture to a stainless steel autoclave lined with polytetrafluoroethylene, and react at 200 °C for 24 h; after the reaction, collect the product by centrifugation and wash it with anhydrous ethanol and deionized water for multiple times; then dry the product in vacuo at 60 °C for 4 h, and finally heat the dried sample in air at a heating rate of 2 °C / min to 400 °C and calcine at this temperature for 2 h to obtain a pale yellow In2O3 product;

[0055] (2) Preparation of In2O3 / ZrO2 binary catalyst: Mix 0.0202 g of the In2O3 nanopowder prepared in step (1) and 2 g of ZrO2 nanoparticles in a mortar and grind for 20 min to obtain an In2O3 / ZrO2 catalyst;

[0056] (3) 0.0226 g of Ni(NO3)2·6H2O and 0.15 g of In2O3 / ZrO2 were added to 5 mL of deionized water and stirred thoroughly for 5 h to obtain a suspension; the suspension was dried under vacuum at 60 °C overnight; the dried powder obtained after vacuum drying was calcined in air at a heating rate of 2 °C / min at 500 °C for 4 h to obtain a ternary catalyst named 3Ni / 1In2O3 / ZrO2; among them, in the ternary catalyst, based on the mass of Ni, the loading of Ni element was 3% of the catalyst mass; the loading of In2O3 was 1% of the catalyst mass.

[0057] The ternary catalysts 2Ni / 2In2O3 / ZrO2, 1Ni / 3In2O3 / ZrO2, and 3Ni / 1In2O3 / ZrO2 prepared in Examples 1 to 3 were respectively applied to the hydrogenation reduction of CO2 to CO. Specifically:

[0058] After heating 0.15 g of the ternary catalyst 2Ni / 2In2O3 / ZrO2 to 500 °C under a nitrogen atmosphere with a flow rate of 50 mL / min, the nitrogen atmosphere was switched to the raw material gas for hydrogenation reduction of CO2 to simultaneously carry out catalyst reconstruction and RWGS reaction for 30 h; the flow rate of the raw material gas for hydrogenation reduction of CO2 was 60 mL / min, and the molar ratio of gas CO2:H2 was 1:4.

[0059] After heating 0.15 g of the ternary catalyst 1Ni / 3In2O3 / ZrO2 to 500 °C under a nitrogen atmosphere with a flow rate of 50 mL / min, the nitrogen atmosphere was switched to the raw material gas for hydrogenation reduction of CO2 to simultaneously carry out catalyst reconstruction and RWGS reaction for 30 h; the flow rate of the raw material gas for hydrogenation reduction of CO2 was 60 mL / min, and the molar ratio of gas CO2:H2 was 1:4.

[0060] After heating 0.15 g of the ternary catalyst 3Ni / 1In2O3 / ZrO2 to 500 °C under a nitrogen atmosphere with a flow rate of 50 mL / min, the nitrogen atmosphere was switched to the raw material gas for hydrogenation reduction of CO2 to simultaneously carry out catalyst reconstruction and RWGS reaction for 30 h; the flow rate of the raw material gas for hydrogenation reduction of CO2 was 60 mL / min, and the molar ratio of gas CO2:H2 was 1:4.

[0061] The CO yield is as Figure 5 shown, and as Figure 5 shown, in the RWGS reaction at a temperature of 500 °C, a pressure of 0.1 MPa, an H2 / CO2 ratio of 4, and a WHSV of 24000 mL g -1 h -1 , the 1Ni / 3In2O3 / ZrO2 catalyst had stable activity within 30 h, the CO2 conversion rate could reach 52%, and the CO yield could reach 4.94 (10-2 mol h -1 g cat -1 )。The 2Ni / 2In2O3 / ZrO2 catalyst has stable activity within 30 h, the CO2 conversion rate can reach 41%, and the CO production rate can reach 3.98(10 -2 mol h -1 g cat -1 )。For the 3Ni / 1In2O3 / ZrO2 catalyst, the CO production rate starts to decline after 9.5 h. The highest CO2 conversion rate can reach 42%, and the highest CO production rate can reach 3.98(10 -2 mol h -1 g cat -1 )。

[0062] The CO2 hydrogenation capabilities of the 2Ni / 2In2O3 / ZrO2 and 3Ni / 1In2O3 / ZrO2 catalysts are similar, with a CO2 conversion rate of 41%. For the 1Ni / 3In2O3 / ZrO2 catalyst, the RWGS rate is significantly increased, and the CO2 conversion rate can reach 52%. This may be because the main reaction sites are located on In2O3, and Ni acts as a promoter.

[0063] As Figure 4 shown, the ternary catalyst 2Ni / 2In2O3 / ZrO2 exhibits better catalytic performance at higher temperatures. This is mainly because the RWGS reaction is an endothermic process (Δ r ]>H(298K) = +41.2 kJ mol -1 ), and higher temperatures are more favorable for the progress of this reaction. At the same time, it is observed that the induction time of the catalyst shortens with increasing temperature. At the initial stage of the reaction at 400 °C, the CO generation rate of 2Ni / 2In2O3 / ZrO2 shows a downward trend, and the catalytic activity gradually recovers and shows an upward trend after 3 h. When the temperature reaches 500 °C and above, the phenomenon of the initial reaction activity decline disappears, the CO production rate continuously increases, and reaches a stable state. It is speculated that some Ni in the catalyst can be rapidly reduced to form metallic Ni NPs in an atmosphere with a high H2 content. At 400 °C, the migration and dispersion rate of In2O3 is slow and cannot quickly migrate to the Ni sites, and the exposed metallic Ni may be unfavorable for the reaction.

[0064] Figure 8 In, In2O3 exhibits two characteristic peaks at ~452 and ~444.3 eV. At the same time, no obvious evidence of In 3+ →In 0 reduction is detected in the In MN1 spectrum. The results show that In species exist in the form of In n+ . With the increase in Ni content, In3+ The binding energy slightly increases, revealing the electron transfer between In and Ni. Meanwhile, this phenomenon implies a strong interaction between Ni and In2O3. This results in the formation of a negatively charged layer on Ni and a positively charged layer on In2O3. The formation of the space electric field promotes the migration of In n+ . In the figure, for the typical peaks on the Ni 2p orbital, the high-energy peak located at 855.7 eV corresponds to the Ni 2p 3 / 2 orbital, attributed to Ni 3+ , and the peak centered at 853.1 eV corresponds to Ni 0 . The strong Ni 3+ signal may be due to Ni 2+ replacing In 3+ . Part of Ni is very likely to exist in the form of Ni 3+ ions in or on the surface of indium oxide. In the figure, the XPS measurement results of the O1s binding energy, after fitting, are asymmetric characteristic peaks, confirming the existence of various types of O on the reacted catalyst. The main peak at 529.5 - 531.0 eV corresponds to lattice oxygen (O L ), the main peak at 531.0 - 532.0 eV corresponds to O v , and the main peak at 532.5 - 533.0 eV corresponds to chemisorbed oxygen (O C ). The oxygen vacancy content of the 3In2O3 / ZrO2 catalyst after the reaction is only 13.26%. With the increase of Ni content, the oxygen vacancy rate in the 1Ni / 3In2O3 / ZrO2 catalyst increases significantly, reaching 21.17%. The increase in oxygen vacancies can enhance the adsorption of carbon dioxide and improve the activity of the sites.

[0065] Figure 9 Shows the thermogravimetric analysis (TGA) results of the 3In2O3 / ZrO2, 3Ni / 1In2O3 / ZrO2, 2Ni / 2In2O3 / ZrO2, 1Ni / 3In2O3 / ZrO2 catalysts after the catalytic reaction. It shows that the catalysts prepared by the present invention do not cause obvious carbon deposition in the RWGS reaction and have good anti-carbon deposition performance. The increase in the total weight may be due to the oxidation of metallic Ni and partially reduced InO x in the catalyst, which is consistent with the XPS analysis. The results show that the total weights of the 3In2O3 / ZrO2 and 1Ni / 3In2O3 / ZrO2 catalysts increase by 1.09% and 0.78% respectively. Compared with the binary system, the observed increase in the total weight in the ternary system is smaller, indicating that a limited number of Ni species do not cause a significant reduction in indium oxide species, thus effectively preventing the loss of active sites.

Claims

1. A preparation method of a ternary catalyst for the hydrogenation reduction of CO2 to CO, characterized in that, The steps include: (1) In2O3 nanopowder and ZrO2 nanoparticles are mixed and ground thoroughly to obtain In2O3 / ZrO2; (2) adding the In2O3 / ZrO2 and nickel salt obtained in step (1) into deionized water and stirring thoroughly to obtain a suspension; vacuum drying the suspension, and calcining the dried solid to obtain a ternary catalyst Ni / In2O3 / ZrO2.

2. The preparation method according to claim 1, characterized in that: In step (1), the added mass ratio of In2O3 to ZrO2 is 0.01-0.031:

1.

3. The preparation method according to claim 1, wherein: In step (1), the grinding time is not less than 20 min.

4. The preparation method according to claim 1, characterized in that: In step (2), the nickel salt is one of Ni(NO3)2·6H2O, NiSO4 or NiCl2.

5. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of nickel salt to In2O3 / ZrO2 added is 0.05 to 0.152:

1.

6. The preparation method according to claim 1, characterized in that: In step (2), the vacuum drying temperature is 60-70° C. and the drying is carried out overnight; the calcination temperature is 500-550° C. and the calcination time is 4-4.5 hours.

7. The preparation method according to claim 1, characterized in that: In step (2), the ternary catalyst Ni / In2O3 / ZrO2 uses zirconia as a carrier, and In2O3 and NiO are loaded on the zirconia carrier, and In2O3 and NiO are respectively and evenly dispersed on the zirconia carrier.

8. The preparation method according to claim 7, characterized in that: Calculated by Ni mass, the loading amount of nickel element on the catalyst is 1-3% of the catalyst mass; the loading amount of In2O3 on the catalyst is 1-3% of the catalyst mass.

9. Use of the ternary catalyst prepared by the preparation method according to claim 1 in the hydrogenation reduction of CO2 to CO, characterized in that, The specific application process is as follows: after the Ni / In2O3 / ZrO2 ternary catalyst is heated to 400-600°C under a nitrogen atmosphere, the nitrogen atmosphere is switched to CO2 hydrogenation reduction raw gas for RWGS reaction; wherein, the molar ratio of H2 to CO2 in the CO2 hydrogenation reduction raw gas is not less than 4:

1.

10. The application according to claim 9, wherein: The flow rate of CO2 hydrogenation reduction raw gas is not less than 60mL / min.

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