Preparation method and application of Pt / LaCoO3 catalyst for efficient photothermal catalytic reverse water gas shift reaction to synthesize carbon monoxide

Abstract

The present invention discloses a preparation method and application of a Pt / LaCoO3 catalyst for synthesizing carbon monoxide by a highly efficient photothermal catalytic reverse water vapor shift reaction. The catalyst is prepared by sequentially preparing a lanthanum cobaltate perovskite support by a sol-gel method, loading platinum oxide on the lanthanum cobaltate perovskite support, and reducing a catalyst precursor. The strong interaction between platinum nanoparticles and the lanthanum cobaltate perovskite support enhances the adsorption and dissociation of carbon dioxide, lowers the initial reaction temperature, increases the yield of carbon monoxide, and ultimately reduces the activation energy (Ea) of the entire reaction. In addition, light energy and heat energy are effectively combined to form photothermal catalysis, and light-induced heat provides sufficient heat energy to activate the adsorbed hydrogen and carbon dioxide, thereby achieving a highly efficient photothermal reverse water vapor shift reaction rate.

Description

Technical Field

[0001] The present invention belongs to the field of synthesizing carbon monoxide by reverse water vapor shift reaction, and specifically relates to a preparation method and application of a Pt / LaCoO3 catalyst for synthesizing carbon monoxide by a high-efficiency photothermal catalytic reverse water vapor shift reaction. Background Art

[0002] The continued consumption of fossil fuels has led to massive carbon dioxide emissions, exacerbating the greenhouse effect and causing global climate change. In recent years, the concept of carbon neutrality has been adopted globally to limit greenhouse gas-induced temperature rise and the greenhouse effect. Therefore, converting carbon dioxide into fuels and chemicals can not only effectively reduce atmospheric carbon dioxide concentrations but also artificially enhance the carbon cycle and generate substantial economic benefits. In this context, the reverse water gas shift reaction is considered a promising approach because it can successfully consume carbon dioxide, a major greenhouse gas, and convert it into carbon monoxide (CO). CO is an important platform molecule in Fischer-Tropsch synthesis, a key reaction for converting C1 into higher-carbon compounds. However, the traditional thermally driven reverse water gas shift reaction requires high temperatures and energy input to achieve high CO conversion and CO yields. These high reaction temperatures can easily lead to catalyst sintering and deactivation. Conventional photocatalysts, such as TiO2, have a large band gap and can only absorb the shorter-wavelength ultraviolet light in sunlight, resulting in low solar energy utilization and slow photocatalytic reaction rates. Therefore, there is an urgent need to develop high-performance catalysts and reaction processes that can reduce reaction energy consumption and improve CO conversion and CO yield.

[0003] In recent years, the reaction of synthesizing carbon monoxide by reverse water gas shift under mild conditions has attracted more and more research. The specific reaction is as follows:

[0004] CO2+H2=CO+H2O ΔH=+42.1kJ / mol

[0005] During the reverse water gas shift reaction, metal nanoparticles are responsible for the activation and dissociation of hydrogen molecules, while oxides generally serve as supports, providing active sites for the adsorption and activation of carbon dioxide. However, traditional thermal or photocatalytic reverse water gas shift reactions suffer from certain drawbacks, such as high thermal energy consumption, low selectivity, and slow photocatalytic reaction rates. Effectively combining light and heat energy to form photothermal catalysis not only successfully and efficiently converts carbon dioxide into the desired product, but also reduces reaction energy consumption and increases reaction rate. In the photothermal catalytic reverse water gas shift reaction to synthesize carbon monoxide, light-induced heat provides sufficient thermal energy to activate adsorbed hydrogen and carbon dioxide. Furthermore, light excites the semiconductor to generate photogenerated electrons and holes, which participate in the activation of carbon dioxide and hydrogen, respectively. Hydrogen dissociates on the metal particles to form hydrogen radicals, which act as reducing species. These hydrogen radicals further overflow and adsorb onto adjacent oxygen vacancies, activating carbon dioxide and forming carboxyl intermediates. After further activation of the carbon monoxide bond of the carboxyl group, carbon monoxide ultimately dissociates from the surface, leaving behind oxygen vacancies that continuously adsorb and activate carbon dioxide, forming a stable catalytic cycle. Therefore, the continuous search for the synthesis of new catalysts to lower the initial reaction temperature and increase the yield of carbon monoxide, thereby reducing the overall reaction Ea, has become one of the research directions of many researchers. Summary of the Invention

[0006] In response to the above technical problems, the present invention aims to provide a preparation method and application of a Pt / LaCoO3 catalyst for synthesizing carbon monoxide by an efficient photothermal catalytic reverse water vapor shift reaction. The catalyst is prepared by sequentially preparing a lanthanum cobaltate perovskite support by a sol-gel method, loading platinum oxide on the lanthanum cobaltate perovskite support, and reducing a catalyst precursor. The lanthanum cobaltate perovskite support increases the surface oxygen vacancies of the catalyst. The abundant oxygen vacancies on the support are conducive to the adsorption and activation of carbon dioxide. In addition, the support can be photoexcited by the semiconductor to generate photogenerated electrons and holes, which participate in the activation process of carbon dioxide and hydrogen, respectively. In addition, the platinum metal with good dispersion further reduces the recombination of photogenerated electrons and holes. The strong interaction between platinum nanoparticles and the lanthanum cobaltate perovskite support enhances the adsorption and dissociation of carbon dioxide, reduces the initial reaction temperature, increases the yield of carbon monoxide, and ultimately reduces the overall reaction Ea. In addition, light energy and thermal energy are effectively combined to form photothermal catalysis, and light-induced heat provides sufficient thermal energy to activate the adsorbed hydrogen and carbon dioxide to obtain an efficient photothermal reverse water vapor shift reaction rate.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preparing a Pt / LaCoO3 catalyst for synthesizing carbon monoxide via a high-efficiency photothermal catalytic reverse water gas shift reaction is provided, wherein the catalyst is prepared in the following steps:

[0009] (S1) Preparation of lanthanum cobaltate perovskite support by sol-gel method

[0010] Lanthanum nitrate hexahydrate and cobalt nitrate hexahydrate are added to deionized water and stirred at room temperature. Citric acid and ethylene glycol are then added and stirred for 2 to 24 hours until uniform. The mixed solution is transferred to a heater and heated at 80 to 130° C. for 2 to 8 hours. The aqueous solution is evaporated to obtain a gel.

[0011] The obtained gel is transferred to an oven for drying at a temperature of 80 to 130° C. for a drying time of 8 to 24 hours to obtain a solid substance, which is ground into a solid powder using a mortar. The solid powder is then calcined in a muffle furnace and cooled to obtain a lanthanum cobaltate perovskite support.

[0012] (S2) Lanthanum cobaltate perovskite support loaded with platinum oxide

[0013] A chloroplatinic acid solution is prepared, and the chloroplatinic acid solution is added dropwise onto a lanthanum cobaltate perovskite support in a mass ratio of chloroplatinic acid to the lanthanum cobaltate perovskite support of (2-8): (147-149), and the support is impregnated for 4-24 hours, and then dried in an oven. The dried material is calcined in a muffle furnace to obtain platinum oxide supported on the lanthanum cobaltate perovskite;

[0014] (S3) Catalyst Precursor Reduction

[0015] Platinum oxide is loaded on lanthanum cobaltate perovskite, pressed and sieved into catalyst particles of 20 to 40 mesh, which are then loaded into a reactor and reduced under a hydrogen atmosphere to obtain a Pt / LaCoO3 catalyst.

[0016] As a limitation of the present invention, in step (S1), the molar ratio of the lanthanum nitrate hexahydrate, the cobalt nitrate hexahydrate and the citric acid is 1:1:2.

[0017] As a second limitation of the present invention, in step (S1), the calcination temperature is 500-900° C., and the calcination time is 2-6 hours.

[0018] As a third limitation of the present invention, in step (S2), the calcination temperature is 400-800°C and the calcination time is 2-8h;

[0019] In the present invention, the roasting process can convert metal ions into oxides and remove impurities, moisture or some harmful substances, further making the material harder, more resistant to high temperatures or having specific electrical conductivity, magnetic properties and other characteristics. An oxidation reaction occurs in this process, which will lay the foundation for the subsequent reduction to nano-sized platinum metal in a hydrogen atmosphere.

[0020] As a fourth limitation of the present invention, in step (S3), the reduction temperature is 300-800° C., the reduction time is 0.5-2 h, and the flow rate of hydrogen is 10-60 mL / min.

[0021] The present invention is also limited in that the particle size of platinum metal in the Pt / LaCoO3 catalyst is very small and difficult to observe, and the platinum loading is 0.5 to 2 wt% based on the total mass of the catalyst.

[0022] The present invention also provides the use of the Pt / LaCoO3 catalyst for synthesizing carbon monoxide by the high-efficiency photothermal catalytic reverse water vapor shift reaction, wherein the catalyst is used for catalytic synthesis of carbon monoxide by the photothermal reverse water vapor shift reaction.

[0023] In the present invention, the strong interaction between the metal nanoparticles and the perovskite support can enhance the adsorption and dissociation of carbon dioxide, reduce the initial reaction temperature, and increase the yield of carbon monoxide, thereby reducing the overall reaction Ea. Lanthanum cobalt oxide perovskite is rich in oxygen vacancies and has a narrow band gap to enhance the adsorption of carbon dioxide molecules and promote the generation of photogenerated carriers. At the same time, due to the effect of surface tension, the liquid penetrates into the interior of the capillaries, the active components diffuse in the pores and adsorb on the surface of the support. Under the action of the support, the platinum nanoparticles generated by reduction after impregnation have high dispersibility. The platinum nanoparticles help reduce the recombination of photogenerated carriers and are used for the activation and dissociation of hydrogen molecules. During the catalytic process, the strong synergistic interaction between the lanthanum cobalt oxide perovskite support and the platinum nanoparticles helps the catalyst absorb and utilize light, adsorb carbon dioxide, and activate and dissociate hydrogen molecules. In addition, light-induced heat provides sufficient thermal energy to activate the adsorbed hydrogen and carbon dioxide, thereby achieving an efficient photothermal reverse water vapor shift reaction rate for synthesizing carbon monoxide.

[0024] The above technical solution of the present invention is taken as a whole, and the various steps are closely related and influence each other, which jointly determine the morphological characteristics and performance of the product.

[0025] The above technical solution has the following advantages or beneficial effects:

[0026] The present invention uses irregularly shaped crystalline lanthanum cobaltate perovskite composed of lanthanum and cobalt as a carrier. This material has abundant oxygen vacancies, which can enhance the adsorption and activation of carbon dioxide molecules. Its narrow band gap promotes light absorption and generates more photogenerated carriers. Simultaneously, the strong interaction between the evenly dispersed platinum nanoparticles and the lanthanum cobaltate perovskite carrier enhances the adsorption and dissociation of carbon dioxide, lowering the initial reaction temperature and increasing the carbon monoxide yield, thereby reducing the overall reaction Ea. Furthermore, light-induced heat provides sufficient thermal energy for the adsorption of hydrogen and carbon dioxide, thereby achieving a highly efficient photothermal reverse water vapor shift reaction rate. The preparation process of the present invention is easy to control, the method is simple, and it is easy to promote and apply industrially.

[0027] The invention is suitable for preparing a catalyst for synthesizing carbon monoxide by reverse water-gas shift reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 XRD patterns of the reduced LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 catalysts prepared in Comparative Example 3 and Examples 1-3, respectively;

[0029] Figure 2 The SEM images of the catalysts after reduction of LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3 and 2.0Pt / LaCoO3 prepared in Comparative Example 3 and Examples 1-3 respectively;

[0030] Figure 3 Comparative Examples 1-3 and Examples 1-3 are Pt / La2O3, Pt / CoO x , N2 adsorption-desorption isotherms and pore size distribution diagrams of LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 catalysts.

[0031] Figure 4 Comparative Examples 1-3 and Examples 1-3 are Pt / La2O3, Pt / CoO x , LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 catalysts.

[0032] Figure 5 Comparative Examples 1-3 and Examples 1-3 are Pt / La2O3, Pt / CoO x , LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 catalysts’ photothermal conversion capabilities.

[0033] Figure 6 The SEM images of the catalysts after reduction of Pt / LaCuO3, Pt / LaNiO3, Pt / LaMnO3 and Pt / Al2O3 prepared in Comparative Examples 4-7 are shown;

[0034] Figure 7 Comparative Examples 1-3 and Examples 1-3 are Pt / La2O3, Pt / CoO x , the carbon dioxide conversion rate of carbon monoxide synthesized by reverse water gas shift reaction under pure thermal conditions of LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 varies with temperature;

[0035] Figure 8 Comparative Examples 1-3 and Examples 1-3 are Pt / La2O3, Pt / CoO x , LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, 2.0Pt / LaCoO3 under pure thermal conditions of reverse water gas shift reaction to synthesize carbon monoxide as a function of temperature;

[0036] Figure 9 Graph showing the carbon dioxide conversion rate at 350°C for the reverse water gas shift reaction of carbon monoxide synthesized under photothermal conditions using LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 prepared in Comparative Example 3 and Examples 1-3, respectively;

[0037] Figure 10 The graph of the generation rates of carbon monoxide and methane at 350°C for the reverse water gas shift reaction of carbon monoxide synthesized by LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 prepared in Comparative Example 3 and Examples 1-3, respectively;

[0038] Figure 11 This is a test diagram of the cyclic catalytic stability of 1.0Pt / LaCoO3 prepared in Example 2 under photothermal conditions;

[0039] Figure 12 The carbon dioxide conversion rate and carbon monoxide selectivity of Pt / LaCuO3, Pt / LaNiO3, and Pt / LaMnO3 prepared in Comparative Examples 4-6 are plotted at 350°C for the reverse water gas shift reaction to synthesize carbon monoxide under photothermal conditions;

[0040] Figure 13 This is a graph showing the changes in carbon dioxide conversion rate and carbon monoxide selectivity with temperature for the reverse water gas shift reaction to synthesize carbon monoxide under photothermal conditions for Pt / Al2O3 prepared in Comparative Example 7. DETAILED DESCRIPTION

[0041] The following embodiments are merely some of the embodiments of the present invention, rather than all of them. Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by those skilled in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0042] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0043] (1) Catalyst preparation

[0044] Example 1: Preparation of 0.5Pt / LaCoO3 Catalyst

[0045] This embodiment prepares a Pt / LaCoO3 catalyst for the photothermal catalytic reverse water gas shift reaction to synthesize carbon monoxide, which is prepared in the following steps:

[0046] (S1) Preparation of lanthanum cobaltate perovskite support by sol-gel method

[0047] 4.33 g of lanthanum nitrate hexahydrate and 2.91 g of cobalt nitrate hexahydrate were added to 100 mL of deionized water and stirred at room temperature. Subsequently, 4.20 g of citric acid and 5.0 mL of ethylene glycol were added and stirred for 2 h until uniform. The mixed solution was transferred to a heater and heated at 80°C for 8 h. The aqueous solution was evaporated to obtain a gel.

[0048] The obtained gel was transferred to an oven for drying at a drying temperature of 130°C for 8 hours to obtain a solid substance, which was ground into a solid powder using a mortar. The solid powder was then calcined in a muffle furnace at a calcination temperature of 500°C for 6 hours, and then cooled to obtain a lanthanum cobaltate perovskite support.

[0049] (S2) Lanthanum cobaltate perovskite support loaded with platinum oxide

[0050] A 0.077 mol / L chloroplatinic acid solution was prepared, and 500 μL of the chloroplatinic acid solution was added dropwise to the lanthanum cobaltate perovskite support. The mass ratio of chloroplatinic acid to the lanthanum cobaltate perovskite support was 2:149. The solution was immersed for 4 hours and then dried in an oven at 80°C. The dried material was placed in a muffle furnace and calcined at 400°C for 8 hours to obtain platinum oxide supported on the lanthanum cobaltate perovskite.

[0051] (S3) Catalyst Precursor Reduction

[0052] The lanthanum cobaltate perovskite is loaded with platinum oxide, which is pressed and sieved into catalyst particles of 20 to 40 mesh. The particles are loaded into a reactor and reduced in a hydrogen atmosphere at 500°C for 2 hours to obtain a 0.5Pt / LaCoO3 catalyst.

[0053] The Pt / LaCoO 3 catalyst prepared in this example has a platinum loading of 0.5 wt % based on the total mass of the catalyst.

[0054] Example 2: Preparation of 1.0Pt / LaCoO3 Catalyst

[0055] This embodiment prepares a Pt / LaCoO3 catalyst for the photothermal catalytic reverse water gas shift reaction to synthesize carbon monoxide, which is prepared in the following steps:

[0056] (S1) Preparation of lanthanum cobaltate perovskite support by sol-gel method

[0057] 4.33 g of lanthanum nitrate hexahydrate and 2.91 g of cobalt nitrate hexahydrate were added to 100 mL of deionized water and stirred at room temperature. 4.20 g of citric acid and 5.0 mL of ethylene glycol were then added and stirred for 10 h until uniform. The mixed solution was transferred to a heater and heated at 120° C. for 5 h. The aqueous solution was evaporated to obtain a gel.

[0058] The obtained gel was transferred to an oven for drying at a drying temperature of 120°C for 12 hours to obtain a solid substance, which was ground into a solid powder using a mortar. The solid powder was then calcined in a muffle furnace at a calcination temperature of 800°C for 3 hours, and then cooled to obtain a lanthanum cobaltate perovskite support.

[0059] (S2) Lanthanum cobaltate perovskite support loaded with platinum oxide

[0060] A 0.077 mol / L chloroplatinic acid solution was prepared, and 1000 μL of the chloroplatinic acid solution was added dropwise to the lanthanum cobaltate perovskite support. The mass ratio of chloroplatinic acid to the lanthanum cobaltate perovskite support was 4:149. The solution was immersed for 10 hours and then dried in an oven at 80°C. The dried material was placed in a muffle furnace and calcined at 500°C for 4 hours to obtain platinum oxide supported on the lanthanum cobaltate perovskite.

[0061] (S3) Catalyst Precursor Reduction

[0062] The lanthanum cobaltate perovskite was loaded with platinum oxide, which was pressed and sieved into catalyst particles of 20 to 40 mesh. The particles were loaded into a reactor and reduced in a hydrogen atmosphere at 300°C for 1 hour to obtain a 1.0Pt / LaCoO3 catalyst.

[0063] The Pt / LaCoO 3 catalyst prepared in this example has a platinum loading of 1.0 wt % based on the total mass of the catalyst.

[0064] Example 3: Preparation of 2.0Pt / LaCoO3 Catalyst

[0065] This embodiment prepares a Pt / LaCoO3 catalyst for the photothermal catalytic reverse water gas shift reaction to synthesize carbon monoxide, which is prepared in the following steps:

[0066] (S1) Preparation of lanthanum cobaltate perovskite support by sol-gel method

[0067] 4.33 g of lanthanum nitrate hexahydrate and 2.91 g of cobalt nitrate hexahydrate were added to 100 mL of deionized water and stirred at room temperature. 4.20 g of citric acid and 5.0 mL of ethylene glycol were then added and stirred for 24 h until uniform. The mixed solution was transferred to a heater and heated at 130° C. for 2 h. The aqueous solution was evaporated to obtain a gel.

[0068] The obtained gel was transferred to an oven for drying at 80°C for 24 hours to obtain a solid substance, which was ground into a solid powder using a mortar. The solid powder was then calcined in a muffle furnace at 900°C for 2 hours, and then cooled to obtain a lanthanum cobaltate perovskite support.

[0069] (S2) Lanthanum cobaltate perovskite support loaded with platinum oxide

[0070] A 0.077 mol / L chloroplatinic acid solution was prepared, and 2000 μL of the chloroplatinic acid solution was added dropwise to the lanthanum cobaltate perovskite support. The mass ratio of chloroplatinic acid to the lanthanum cobaltate perovskite support was 8:147. The solution was immersed for 24 hours and then dried in an oven at 80°C. The dried material was placed in a muffle furnace and calcined at 800°C for 2 hours to obtain platinum oxide loaded on the lanthanum cobaltate perovskite.

[0071] (S3) Catalyst Precursor Reduction

[0072] The lanthanum cobaltate perovskite is loaded with platinum oxide, which is pressed and sieved into catalyst particles of 20 to 40 mesh. The particles are loaded into a reactor and reduced in a hydrogen atmosphere at 800°C for 0.5h to obtain a 2.0Pt / LaCoO3 catalyst.

[0073] The Pt / LaCoO 3 catalyst prepared in this example has a platinum loading of 2.0 wt % based on the total mass of the catalyst.

[0074] Comparative Example 1: Preparation of Pt / La2O3 Catalyst

[0075] The catalyst preparation process of this comparative example was carried out as follows:

[0076] (1) 4.33 g of lanthanum nitrate hexahydrate was added to 100 mL of deionized water and stirred at room temperature, followed by the addition of 4.20 g of citric acid and 5.0 ml of ethylene glycol, and the mixture was stirred evenly. The mixture was then transferred to a heater and heated at 120°C to evaporate the water until a gel was formed, followed by drying in an oven at 120°C for 12 h to form a solid. The obtained solid was ground and calcined in a muffle furnace at 800°C for 3 h, and then cooled to obtain a lanthanum oxide carrier.

[0077] (2) 1.5 g of lanthanum oxide carrier was added to a mixture of 10 mL of deionized water and 10 mL of ethanol and stirred evenly. 1 mL of chloroplatinic acid solution was then added dropwise to the carrier solution. After stirring evenly, the mixture was heated at 80°C to remove water and then dried in an 80°C oven. The dried material was calcined in a muffle furnace at 500°C for 4 h to prepare lanthanum oxide carrier-supported platinum oxide.

[0078] (3) The lanthanum oxide-supported platinum oxide catalyst prepared in step (2) was pressed into tablets, sieved into 20-40 meshes, loaded into a fixed bed reactor, and reduced in a hydrogen atmosphere at 300° C. for 1 h to obtain a Pt / La2O3 catalyst.

[0079] Comparative Example 2: Pt / CoO x Catalyst preparation

[0080] The preparation process of Comparative Example 2 is similar to that of Comparative Example 1, except that in step (1), 2.91 g of cobalt nitrate hexahydrate is used instead of lanthanum nitrate hexahydrate.

[0081] Comparative Example 3: Preparation of LaCoO3 catalyst

[0082] The preparation process of Comparative Example 3 is similar to that of Comparative Example 1, except that in step (1), 4.33 g of lanthanum nitrate hexahydrate and 2.91 g of cobalt nitrate hexahydrate are added, and step (2) is not performed, and the obtained support is directly reduced in step (3).

[0083] Comparative Example 4: Preparation of Pt / LaCuO3 Catalyst

[0084] The preparation process of Comparative Example 4 is similar to that of Comparative Example 1, except that 4.33 g of lanthanum nitrate hexahydrate and 1.70 g of copper chloride dihydrate are added in step (1).

[0085] Comparative Example 5: Preparation of Pt / LaNiO3 Catalyst

[0086] The preparation process of Comparative Example 5 is similar to that of Comparative Example 1, except that 4.33 g of lanthanum nitrate hexahydrate and 2.91 g of nickel nitrate hexahydrate are added in step (1).

[0087] Comparative Example 6: Preparation of Pt / LaMnO3 Catalyst

[0088] The preparation process of Comparative Example 6 is similar to that of Comparative Example 1, except that 4.33 g of lanthanum nitrate hexahydrate and 1.98 g of manganese chloride tetrahydrate are added in step (1).

[0089] Comparative Example 7: Preparation of Pt / Al2O3 Catalyst

[0090] The preparation process of Comparative Example 7 is similar to that of Comparative Example 1, except that the carrier prepared in step (1) is replaced by commercial alumina calcined in a muffle furnace at 600°C for 5 hours, and then steps (2) and (3) are performed.

[0091] (2) Catalyst characterization

[0092] Figure 1 For comparative example 3, the XRD patterns of the catalysts prepared in Examples 1-3 are LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 after reduction. Figure 1 It can be seen that Figure X The peaks on the RD are all attributed to LaCoO3. No platinum peaks are observed in any of the samples. This may be due to too little platinum loading or too high a dispersion. It also means that the LaCoO3 crystal structure did not undergo significant changes during the loading process.

[0093] Figure 2 Comparative Example 3, Examples 1-3 are the SEM images of the catalysts after reduction of LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 respectively. Figure 2 It can be seen that LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 are irregularly shaped particles, all of which maintain a structure similar to that of 1.0Pt / LaCoO3, indicating that the Pt loading does not affect the structure of the catalyst.

[0094] Figure 3 For comparative examples 1-3, examples 1-3 are prepared Pt / La2O3, Pt / CoO x The N2 adsorption-desorption isotherms and pore size distributions of LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 catalysts are shown in Figure 2. The N2 adsorption-desorption curves show that all samples conform to the type IV isotherm, and the average pore size of the Pt / LaCoO3 catalyst ranges from 3.0nm to 4.5nm.

[0095] Figure 4 For comparative examples 1-3, examples 1-3 are prepared Pt / La2O3, Pt / CoO x, electrochemical impedance spectroscopy (EIS) of LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 catalysts was used to determine the interfacial charge transfer in the photocatalytic reaction. It can be seen from the figure that the minimum semicircle of 1.0Pt / LaCoO3 indicates that it has superior charge carrier transport.

[0096] Figure 5 For comparative examples 1-3, examples 1-3 are prepared Pt / La2O3, Pt / CoO x , LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, 2.0Pt / LaCoO3 catalyst photothermal conversion capacity diagram. It can be seen from the figure that under the full spectrum of irradiation, Pt / LaCoO3 catalyst has good photothermal conversion capacity.

[0097] Figure 6 The SEM images of the catalysts after reduction of Pt / LaCuO3, Pt / LaNiO3, Pt / LaMnO3 and Pt / Al2O3 prepared in Comparative Examples 4-7 are shown in FIG. Figure 6 It can be seen that the particles in Comparative Examples 4-6 are all irregularly shaped.

[0098] (3) Catalyst evaluation

[0099] The catalyst prepared above was tableted and sieved to obtain catalyst particles of 20-40 mesh. The particles were loaded into a fixed bed tubular reactor with an inner diameter of Φ6 mm and a length of 40 cm.

[0100] First, the catalyst prepared above was heated to 300°C under a nitrogen atmosphere and kept for 5 minutes. After the treatment, hydrogen was introduced for reduction. The reduction temperature was 300°C, the pressure was normal pressure, the catalyst mass was 0.16g, and the mixture of carbon dioxide, nitrogen and hydrogen (volume ratio CO2:H2:N2=1:4:2) was 64mL / min.

[0101] The reaction data looks like this:

[0102] Figure 7 For comparative examples 1-3, examples 1-3 are prepared Pt / La2O3, Pt / CoO x The carbon dioxide conversion rate of the reverse water gas shift reaction to carbon monoxide in LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 under pure thermal conditions varies with temperature, and the gas phase space velocity is 24000ml·g cat -1 ·h -1 .from Figure 7It was found that the carbon dioxide conversion rates of Comparative Example 1, Comparative Example 3 and Examples 1-3 all increased with increasing temperature, among which the carbon dioxide conversion rates of Comparative Examples 1 and 3 were relatively low.

[0103] Figure 8 For comparative examples 1-3, examples 1-3 are prepared Pt / La2O3, Pt / CoO x The selectivity of carbon monoxide synthesis in the reverse water-gas shift reaction of LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 under purely thermal conditions varies with temperature at a gas phase space velocity of 24000 ml·g cat -1 ·h -1 .from Figure 8 It was found that the carbon monoxide selectivity of Comparative Example 1 and Examples 1-3 was higher and decreased slightly with increasing temperature, while the carbon monoxide selectivity of Comparative Example 2 and Comparative Example 3 was lower.

[0104] Figure 9 Comparative Example 3: Examples 1-3 are the carbon dioxide conversion rates of LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 prepared under photothermal conditions at 350°C in reverse water gas shift reaction. The gas phase space velocity is 24000ml·g cat -1 ·h -1 , temperature is 350℃, light intensity is 1.2W·cm -2 .from Figure 9 It was found that the carbon dioxide conversion rate increased with the increase of platinum loading, among which the carbon dioxide conversion rate of Comparative Example 3 at 350°C was extremely low.

[0105] Figure 10 Comparative Example 3: Examples 1-3 are LaCoO3, 0.5Pt / LaCoO3, 1.0Pt / LaCoO3, and 2.0Pt / LaCoO3 prepared respectively. The generation rates of carbon monoxide and methane at 350°C and gas phase space velocity of 24000ml·g cat -1 ·h -1 , temperature is 350℃, light intensity is 1.2W·cm -2 .from Figure 10 It was found that the carbon monoxide generation rate increased with the increase of platinum loading, and the carbon monoxide generation rate of Example 2 under light irradiation was as high as 58.61 mmol·g cat -1 ·h -1 .

[0106] Figure 11 The cyclic catalytic stability test of 1.0Pt / LaCoO3 prepared in Example 2 under photothermal conditions was conducted with a gas phase space velocity of 36000ml·g cat -1 ·h -1 , temperature is 350℃, light intensity is 1.2W·cm -2 After two cycles, the carbon dioxide conversion rate was over 11% and the carbon monoxide selectivity was over 97% under pure heat; the carbon dioxide conversion rate was over 17% and the carbon monoxide selectivity was over 96% under photothermal heat, indicating that the catalyst 1.0Pt / LaCoO3 has good stability.

[0107] Figure 12 Comparative Examples 4-6 are the carbon dioxide conversion rate and carbon monoxide selectivity of Pt / LaCuO3, Pt / LaNiO3, and Pt / LaMnO3 prepared under photothermal conditions at 350°C by reverse water gas shift reaction. The gas phase space velocity is 24000 ml·g cat -1 ·h -1 , temperature is 350℃, light intensity is 1.2W·cm -2 .from Figure 12 It was found that the carbon dioxide conversion rate of Comparative Example 5 at 350° C. was high, but its carbon monoxide selectivity was extremely low. The carbon dioxide conversion rates of Comparative Examples 4 and 6 were both low.

[0108] Figure 13 Comparative Example 7 shows the carbon dioxide conversion rate and carbon monoxide selectivity of the Pt / Al2O3 prepared under photothermal conditions under reverse water gas shift reaction as a function of temperature. The gas phase space velocity is 24000 ml·g cat -1 ·h -1 , light intensity is 1.2W·cm -2 .from Figure 13 It was found that the carbon dioxide conversion rate of Comparative Example 7 increased with increasing temperature, and the carbon monoxide selectivity was high and remained almost unchanged with increasing temperature.

[0109] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. An application of a Pt / LaCoO3 catalyst, characterized in that: The catalyst is used for synthesizing carbon monoxide by photothermal catalytic reverse water gas shift reaction; the catalyst is prepared in the following steps: (S1) Preparation of lanthanum cobalt oxide perovskite support by sol-gel method Lanthanum nitrate hexahydrate and cobalt nitrate hexahydrate are added to deionized water and stirred at room temperature. Citric acid and ethylene glycol are then added and stirred for 2 to 24 hours until the mixture is uniform. The mixed solution is transferred to a heater and heated at 80 to 130°C for 2 to 8 hours. The aqueous solution is evaporated to obtain a gel. The obtained gel is transferred to an oven for drying at a temperature of 80 to 130°C for a time of 8 to 24 hours to obtain a solid material. The solid material is ground into a solid powder using a mortar. The solid powder is then calcined in a muffle furnace and cooled to obtain a lanthanum cobaltate perovskite support. (S2) Lanthanum cobaltate perovskite support loaded with platinum oxide A chloroplatinic acid solution is prepared and added dropwise onto a lanthanum cobaltate perovskite support in a mass ratio of chloroplatinic acid to lanthanum cobaltate perovskite support of (2-8):(147-149). The solution is impregnated for 4-24 hours and then dried in an oven. The dried material is calcined in a muffle furnace to obtain platinum oxide supported on the lanthanum cobaltate perovskite. (S3) Catalyst precursor reduction The lanthanum cobaltate perovskite is loaded with platinum oxide and pressed into tablets, sieved into catalyst particles of 20 to 40 mesh, loaded into a reactor, and reduced under a hydrogen atmosphere to obtain a Pt / LaCoO3 catalyst.

2. The use according to claim 1, characterized in that In step (S1), the molar ratio of the lanthanum nitrate hexahydrate, the cobalt nitrate hexahydrate and the citric acid is 1:1:

2.

3. The use according to claim 1, characterized in that In step (S1), the calcination temperature is 500-900°C, and the calcination time is 2-6 hours.

4. The use according to claim 1, characterized in that In step (S2), the calcination temperature is 400-800°C, and the calcination time is 2-8 hours.

5. The use according to claim 1, characterized in that In step (S3), the reduction temperature is 300-800°C, and the reduction time is 0.5-2 h.

6. The use according to claim 1, characterized in that In the Pt / LaCoO3 catalyst, the platinum loading is 0.5 ~ 2 wt% based on the total mass of the catalyst.

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