Catalyst for selective catalytic reduction of CO2 into CO and application thereof

Abstract

The invention provides a catalyst for selective catalytic reduction of CO2 into CO, tetrabutyl titanate, concentrated sulfuric acid and deionized water are jointly dissolved in absolute ethyl alcohol and uniformly mixed to obtain a mixed solution, the mixed solution is reacted for 2-6 h at 160-200 DEG C, after natural cooling, the obtained product is post-treated to obtain TiO2, and the TiO2 is added into the mixed solution to obtain the catalyst for selective catalytic reduction of CO2 into CO. Mixing TiO2, SrCl2. 6H2O, NaOH and deionized water to obtain a second mixed solution, reacting at 160-200 DEG C for 4-10 hours, naturally cooling, cleaning and drying the obtained product, and roasting at 400-500 DEG C for 3-6 hours to obtain nano spherical SrTiO3; the preparation method comprises the following steps: uniformly mixing a La (NO3) 3 aqueous solution and nano spherical SrTiO3, drying at 80-120 DEG C, uniformly grinding, and roasting at 300-500 DEG C to obtain the catalyst for selectively catalytically reducing CO2 into CO, the method is applied to photo-thermal catalytic reduction of CO2 into CO, is efficient and high in selectivity, is more green and efficient, and has relatively high industrialization potential.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive utilization of CO2, specifically relating to a catalyst for selective catalytic reduction of CO2 to CO and its preparation method, as well as its application in the field of selective photothermal catalytic reduction of CO2 to CO. Technical Background

[0002] The continued burning of large quantities of fossil fuels has led to a surge in the production of the greenhouse gas carbon dioxide (C60). Emissions have risen sharply. Excessive carbon dioxide (C₂) Emissions have become a trigger for a series of severe environmental problems. The trend of global warming is becoming increasingly evident, posing a serious threat to human survival and sustainable development. Under the urgent need for global energy transition and carbon emission reduction, the emission of carbon dioxide (CO2) is becoming increasingly critical. Transforming C into high-value-added chemicals or energy carriers has become a research hotspot. As a carbon source, C can utilize the energy provided by renewable energy sources. It is converted into carbon-based chemicals.

[0003] Among them, C Selective reduction of carbon monoxide (CO) to form carbon monoxide (reverse water-gas shift reaction) has significant strategic value. As a core component of syngas, CO is a fundamental feedstock in chemical processes such as Fischer-Tropsch synthesis and methanol production, with downstream products spanning fuels, plastics, and pharmaceutical intermediates. Furthermore, a carbon cycle system using CO as a feedstock can effectively connect renewable energy with traditional chemical industries, driving the industrial system towards a low-carbon transformation. Therefore, developing efficient CO production... CO2 reduction technology is not only about efficient resource utilization, but also a key step in achieving carbon neutrality.

[0004] Currently, C The main pathways for CO reduction include electrocatalysis, thermocatalysis, photocatalysis, and biocatalysis. Electrocatalytic reduction offers mild reaction conditions and precise product selectivity control through potential regulation, but suffers from high energy consumption and poor catalyst stability. Thermocatalysis is a mature technology with fast reaction rates, but it relies on high temperature and pressure conditions and is prone to side reactions. Biocatalysis is environmentally friendly, but its slow reaction rate makes it difficult to meet the needs of large-scale industrial production. Due to the limitations of these traditional technologies in terms of efficiency, energy consumption, and selectivity, there is a need to continuously explore more efficient and sustainable new catalytic systems.

[0005] Photothermal catalytic reduction of C The technology of generating CO provides an innovative solution to the above-mentioned problems by integrating the advantages of photocatalysis and thermal catalysis. This technology uses solar energy as the driving energy, not only effectively reducing the dependence on fossil fuels, but also breaking through the thermodynamic limit through the synergistic effect of light and heat to achieve the efficient activation and conversion of C under mild conditions. On the one hand, the carriers generated by light excitation can accelerate the adsorption and dissociation of C molecules, increasing the reaction activity; on the other hand, the introduction of thermal energy promotes the conversion of intermediate products, significantly improving the selectivity of CO. In addition, the photo-thermal catalyst can be designed and controlled in structure to achieve efficient absorption of the full spectrum of sunlight, further enhancing the catalytic performance. Compared with other reduction paths, the photo-thermal catalysis technology has the advantages of green environmental protection, high energy utilization efficiency, adjustable product selectivity, etc., showing great potential for industrial application from the laboratory, and is expected to become one of the core technologies for the resource utilization of C in the future.

[0006] However, it cannot be ignored that the current photo-thermal catalytic reduction of C technology still faces many challenges in practical application. Most photo-thermal catalysts have obvious deficiencies in the absorption of full-spectrum solar energy, resulting in low photo-thermal conversion efficiency, which makes it difficult to achieve ideal catalytic activity and selectivity. For example, TiO2, which is the most widely used in photocatalysis, can only absorb ultraviolet light, limiting the conversion rate of CO2. While SrTiO3, obtained by modification, has good hydrogenation performance, but the selectivity is reduced, and part of CH4 is easily generated. At the same time, the active sites of the catalyst are not fully exposed, and the carrier mobility and conductivity are not good enough, which seriously restricts the improvement of reaction rate and product selectivity. In addition, the current researchers' understanding of the photo-thermal catalytic reaction mechanism is not comprehensive enough, and there is a lack of systematic and perfect theoretical guidance, which undoubtedly sets an obstacle for the design and development of high-performance photo-thermal catalysts.

[0007] Therefore, the present application is based on the design features of photo-thermal catalysts, and aims to provide a catalyst with high conversion rate and high selectivity to significantly improve the possibility of CO2 conversion to CO. SUMMARY

[0008] The purpose of the present application is to provide a semiconductor catalyst for selective photo-thermal catalytic reduction of CO2 to CO in response to the needs in the background art. The method provided by the present application is simple, environmentally friendly and low in cost, providing an efficient solution for the resource utilization of CO2.

[0009] The photo-thermal catalysis described in the present application is a light-thermal reaction environment created by concentrating light or using high-power light source technology to create high light intensity and high temperature, which can effectively activate the C The process of reducing CO2 to CO by photo-thermal catalysis under the catalysis of the catalyst in the atmosphere.

[0010] The catalyst comprises La, Sr, Ti and O elements, and the main structure has the characteristics of La2O3 / SrTiO3, that is, a heterojunction structure composed of La2O3 and SrTiO3.

[0011] The application provides a catalyst for selectively catalytically reducing CO2 to CO, and a preparation method of the catalyst. (1) mixing TiO2, SrCl2·6H2O, NaOH and deionized water A to obtain a second mixed solution, reacting the second mixed solution at 160-200°C (preferably 180°C) for 4-10h (preferably 6h), naturally cooling, and then sequentially washing the obtained product with ethanol and deionized water B (4 times), drying (overnight drying at 80°C), grinding uniformly, and calcining at 400-500°C (preferably, the temperature is increased to 500°C at a rate of 5°C per minute) for 3-6h (preferably 5h) to obtain nanometer spherical SrTiO3; the mass ratio of TiO2, SrCl2·6H2O and NaOH is 1:0.5-4:2-18 (preferably 1:1:8.33). (2) uniformly mixing a La(NO3)3 aqueous solution and the nanometer spherical SrTiO3 in step (1), drying at 80-120°C (preferably 120°C), grinding uniformly, and calcining at 300-500°C (preferably 400°C) for 1-3h (preferably 2h) to obtain the catalyst for selectively catalytically reducing CO2 to CO, denoted as La2O3 / SrTiO3; the mass ratio of La(NO3)3 in the La(NO3)3 aqueous solution to the nanometer spherical SrTiO3 is 0.01-0.30:1 (preferably 0.05:1).

[0012] Further, TiO2 is prepared as follows: uniformly mixing tetrabutyl titanate, concentrated sulfuric acid and deionized water in anhydrous ethanol to obtain a mixed solution, reacting the mixed solution at 160-200°C for 2-6h (preferably 180°C for 4h), naturally cooling, and then post-treating the obtained product to obtain TiO2; the mass ratio of tetrabutyl titanate, sulfuric acid contained in concentrated sulfuric acid and deionized water is 1:0.2-0.6:0.5-3 (preferably 1:0.427:1.13), the volume of anhydrous ethanol is 5-20ml / g (preferably 75ml / 5.1g) based on the mass of tetrabutyl titanate, and the post-treatment is sequentially washing the obtained product with ethanol and deionized water B, and drying (at 80°C) to obtain TiO2.

[0013] Further, the roasting in step (1) is performed at a temperature of 20-60°C (preferably 25°C) and a temperature rising rate of 2-10°C / min (preferably 5°C / min) to a temperature of 500°C.

[0014] Further, the mass ratio of TiO2, SrCl2·6H2O and NaOH in step (1) is 1:1:8.33.

[0015] Further, the volume of deionized water A in step (1) is 2.8-8.4 L / mol based on the amount of substance of SrCl2·6H2O.

[0016] Further, the molar concentration of La(NO3)3 in the aqueous La(NO3)3 solution in step (2) is 0.01-0.15 mol.

[0017] The application also provides a use of a catalyst for selectively catalyzing reduction of CO2 to CO in a photo-thermal catalytic reduction of CO2 to CO.

[0018] Further, the use is: using a xenon lamp as a light source (using a lens to concentrate the light generated by the xenon lamp in a sealed reactor), so that the irradiance in the reactor is 10 4 ~1.4×10 6 W / m 2 , using CO2 as a reactant, under mixed gas conditions, and under the catalysis of the catalyst for selectively catalyzing reduction of CO2 to CO, to generate CO.

[0019] Preferably, the mixed gas is a mixed gas of CO2 and H2.

[0020] Further, the mixed gas in the reactor is a mixed gas of CO2 and H2, and the volume ratio of CO2 to H2 in the mixed gas is 1:1-4, and the pressure of the mixed gas is 0.1-1 MPa.

[0021] Further, the xenon lamp is used as a light source to irradiate the reactor, so that the temperature in the reactor is 100-500 o C.

[0022] The deionized water, deionized water A and deionized water B mentioned in the application all refer to deionized water, and the A and B labels only indicate that the deionized water appears in different steps.

[0023] The photo-thermal catalytic process described in the application is to press the catalyst particles into a tablet and put it into a reactor, and then fix the reactor to a device such as the attached Figure 1 (not limited to the attached Figure 1) as shown, the inert gas is introduced to purge the impurity gas such as air for 10 minutes, and the pressure in the reactor is increased to the required pressure. Then the light is focused into the reactor to provide the light intensity and the required reaction temperature, the product is guided out by the pipeline and detected by chromatography.

[0024] Compared with the prior art, the beneficial effects of the present application are: A semiconductor catalyst for selectively photocatalytic reduction of CO2 to CO is provided. The catalyst can efficiently and selectively convert CO2 to CO under photocatalytic conditions, with a single-pass conversion rate of CO2 of more than 78% and a CO selectivity of 100%. Compared with traditional thermal catalytic technology, it is more green and efficient; compared with existing photocatalytic technology, it has higher conversion efficiency and higher selectivity, and has higher industrialization potential. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The photocatalytic reactor is for the photocatalytic reaction.

[0026] Figure 2 The test result graph (Example 7) of a typical gas chromatograph (GC, 8860, Agilent) equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID). DETAILED DESCRIPTION

[0027] The preparation and application of the catalyst material in the present application will be further described below by specific examples, which are only for the purpose of better understanding the content of the present application and not for limiting the protection scope of the present application.

[0028] Example 1: Take 25.5g of tetrabutyl titanate (0.075mol), add 375ml of anhydrous ethanol, under stirring, add 1.65ml of concentrated sulfuric acid (0.03mol), 1.5mL of deionized water (0.105mol), mix and stir for 0.5h to make it evenly dispersed, transfer the mixed solution to a 500mL polytetrafluoroethylene hydrothermal kettle, seal it and put it in a 180℃ oven for 4h, naturally cool it, then wash it with ethanol and deionized water in turn, repeat 4 times, dry at 80℃, grind uniformly to get TiO2 (about 6.2g).

[0029] a. Take 0.2g of the prepared TiO2, pour it into a tablet press mold to press into a 3cm diameter tablet for standby.

[0030] b. Put the pressed tablet into the reactor (volume is 50ml, device structure is shown in Figure 1A sealed reactor was constructed, and a CO2:H2 mixture of 1:4 (50 mL / min) was introduced and leak checked. The pressure of the reaction system was controlled at 0.70 MPa using a back pressure valve. After everything was completed, the lamp was turned on, and the spot diameter was adjusted to 3 cm. The reaction was initiated using a 1000W xenon lamp. Under the action of a lens, the light was focused as much as possible into the reactor. A K-type thermocouple was used to monitor the temperature of the catalyst surface during the photothermal carbon dioxide conversion. The temperature was stabilized at 305℃, and gas chromatography was used for continuous monitoring for half an hour.

[0031] c. After the reaction was completed for 5 hours, the product was calculated based on the gas chromatography results. The final CO yield was determined to be 4.22 mmol / g / h, the selectivity was 99.99%, and the CO2 conversion rate was 3.51%.

[0032] Example 2: Weigh 20.4 g of tetrabutyl titanate (0.06 mol), add 360 ml of anhydrous ethanol, and add 0.88 ml of concentrated sulfuric acid (0.016 mol) and 0.6 ml of deionized water (0.032 mol) while stirring. Mix and stir for 0.5 h to disperse it evenly. Transfer the mixed solution to a 500 mL polytetrafluoroethylene hydrothermal reactor, seal it, and place it in an oven at 180 degrees Celsius for 4 h. After natural cooling, wash it with ethanol and deionized water in sequence, repeating 4 times. Dry it at 80 degrees Celsius and grind it evenly to obtain about 4.9 g of TiO2.

[0033] a. Weigh 0.2g of the prepared TiO2, pour it into a tableting mold and press it into tablets with a diameter of 3cm for later use.

[0034] b. Load the compressed tablets into the reactor (volume 50ml, see device structure). Figure 1 A sealed reactor was constructed, and a CO2:H2 mixture of 1:4 (50 mL / min) was introduced and leak checked. The pressure of the reaction system was controlled at 0.70 MPa using a back pressure valve. After everything was completed, the lamp was turned on, and the spot diameter was adjusted to 3 cm. The reaction was initiated using a 1000W xenon lamp. Under the action of a lens, the light was focused as much as possible into the reactor. A K-type thermocouple was used to monitor the temperature of the catalyst surface during the photothermal carbon dioxide conversion. The temperature was stabilized at 298℃, and gas chromatography was used for continuous monitoring for half an hour.

[0035] c. After the reaction was completed for 5 hours, the product was calculated based on the gas chromatography results. The final CO yield was determined to be 3.26 mmol / g / h, the selectivity was 99.99%, and the CO2 conversion rate was 3.48%.

[0036] Example 3: Take 25.5 g of tetrabutyl titanate (0.075 mol), add 300 ml of anhydrous ethanol, under stirring add 2.2 ml of concentrated sulfuric acid (0.04 mol), 3.0 ml of deionized water (0.17 mol), mix and stir for 0.5 h to make it evenly dispersed, transfer the mixed solution into a 500 mL polytetrafluoroethylene hydrothermal kettle, seal and put into an oven at 180 degrees Celsius for 4 h, naturally cool, wash with ethanol and deionized water in turn, repeat 3 times, dry at 80 degrees Celsius, grind evenly to obtain TiO2 (about 6.2 g).

[0037] a. Take 0.2 g of prepared TiO2, pour into a tablet mold and press into a 3 cm diameter tablet for standby.

[0038] b. Put the pressed tablet into the reactor (volume is 50 ml, device structure see Figure 1 ), seal the device, introduce CO2:H2=1:4 mixed gas (50 mL / min) and check for leaks, control the pressure of the reaction system at 0.70 Mpa through a back pressure valve. After everything is done, turn on the light, adjust the light spot diameter to 3 cm, start the reaction, the light source used in the reaction is a 1000 W xenon lamp, under the action of the lens, the light is as much as possible to be converged in the reactor, the temperature of the catalyst surface in the process of photo-thermal carbon dioxide conversion is monitored by a K-type thermocouple. The temperature is stabilized at 302°C, and the gas chromatography is continuously monitored for half an hour.

[0039] c. After 5 h of reaction, the product is calculated according to the gas chromatography result, the final CO yield is 2.89 mmol / g / h, the selectivity is 99.99%, and the CO2 conversion rate is 2.39%.

[0040] Example 4: Take 3.0 g (0.036 mol) of TiO2, take 10.0 g of SrCl2·6H2O (0.036 mol), add 300 ml of deionized water (16.67 mol), under stirring add 12 g of NaOH (0.3 mol), stir for another 0.5 h, then transfer the mixed solution into a 500 mL polytetrafluoroethylene hydrothermal kettle, seal and put into an oven at 180 degrees Celsius for 6 h. After natural cooling, wash with ethanol and deionized water in turn, repeat 4 times, dry at 80 degrees Celsius overnight, grind evenly, put into a muffle furnace, heat to 500°C at a rate of 5°C per minute, and calcine for 5 h to obtain 6.6 g of nanometer spherical SrTiO3.

[0041] a. Take 0.2 g of prepared SrTiO3, pour into a tablet mold and press into a 3 cm diameter tablet for standby.

[0042] b. Put the pressed tablet into the reactor (volume is 50 ml, device structure see Figure 1b. The pressed piece was loaded into the reactor (volume 50 ml, device structure see

[0043] c. After 5h of reaction, the products were calculated according to the gas chromatography results, and finally the CO yield was 17.59 mmol / g / h, the selectivity was 99.99%, and the CO2 conversion rate was 14.49%.

[0044] Example 5: 1.5 g (0.018 mol) of TiO2 was weighed, 10 g of SrCl2-6H2O (0.036 mol) was taken, 150 ml of deionized water (8.67 mol) was added, 3.0 g of NaOH (0.075 mol) was added under stirring, and then the mixture was stirred for another 0.5 h. Then the mixed solution was transferred into a 500 mL polytetrafluoroethylene hydrothermal kettle, and after sealing, it was placed in an oven at 180 degrees Celsius for 6 h. After natural cooling, it was washed with ethanol and deionized water in turn, repeated 4 times, dried at 80 degrees Celsius overnight, and then ground uniformly and placed in a muffle furnace, heated to 500 degrees Celsius at a heating rate of 5 degrees Celsius per minute, and calcined for 5 h to obtain 3.3 g of SrTiO3.

[0045] a. 0.2 g of the prepared SrTiO3 was weighed and poured into a tablet mold to press into a piece with a diameter of 3 cm for standby.

[0046] b. The pressed piece was loaded into the reactor (volume 50 ml, device structure see Figure 1 ), and the device was sealed, CO2:H2=1:4 mixed gas (50 mL / min) was introduced and leak tested, and the pressure of the reaction system was controlled at 0.70 Mpa through a back pressure valve. After everything was completed, the light was turned on, the light spot diameter was adjusted to 3 cm, and the reaction was started. The light source for the reaction was a 1000 W xenon lamp, and under the action of the lens, the light was as much as possible to be concentrated in the reactor. A K-type thermocouple was used to monitor the temperature of the catalyst surface during the photo-thermal carbon dioxide conversion process. The temperature was stabilized at 320 degrees Celsius, and the gas chromatography was continuously monitored for half an hour.

[0047] c. After 5h of reaction, the products were calculated according to the gas chromatography results, and finally the CO yield was 17.59 mmol / g / h, the selectivity was 99.99%, and the CO2 conversion rate was 14.49%.

[0048] Example 5: Take 1.5 g (0.018 mol) of TiO2, take 15 g of SrCl2·6H2O (0.054 mol), take 150 mL of deionized water (8.67 mol), add 12 g of NaOH (0.3 mol) under stirring, and then stir for another 0.5 h. Then, the mixed solution is transferred into a 500 mL polytetrafluoroethylene hydrothermal kettle, which is sealed and placed in an oven at 180 degrees Celsius for 6 h. After natural cooling, the product is washed with ethanol and deionized water in sequence, repeated for 4 times, dried overnight at 80 degrees Celsius, and then ground uniformly. The product is placed in a muffle furnace, heated to 500 degrees Celsius at a rate of 5 degrees Celsius per minute, and then calcined for 5 h to obtain 3.3 g of SrTiO3.

[0049] a. Take 0.2 g of the prepared SrTiO3, pour it into a tablet mold, and press it into a tablet with a diameter of 3 cm for standby use.

[0050] b. The pressed tablet is loaded into a reactor (with a volume of 50 mL, see the device structure in Figure 1 ), the device is sealed, CO2:H2=1:4 mixed gas (50 mL / min) is introduced, and leakage is detected. The pressure of the reaction system is controlled at 0.70 Mpa through a back pressure valve. After everything is completed, the light is turned on, the light spot diameter is adjusted to 3 cm, the reaction is started, and the light source used in the reaction is a 1000 W xenon lamp. The light is as much as possible concentrated in the reactor under the action of the lens. The temperature of the catalyst surface in the process of photo-thermal carbon dioxide conversion is monitored by a K-type thermocouple. The temperature is stabilized at 316 degrees Celsius, and the gas chromatography is continuously monitored for half an hour.

[0051] c. After 5 h of reaction, the products are calculated according to the gas chromatography results, and finally the CO yield is 16.90 mmol / g / h, the selectivity is 99.99%, and the CO2 conversion rate is 13.92%.

[0052] Example 7: La2O3 / SrTiO3 is prepared by the impregnation method, and the specific experimental details are as follows: 12 mL of deionized water (0.67 mol) is added, 0.1863 g of La(NO3)2 (0.00042 mol) is weighed to prepare a La(NO3)2 aqueous solution, and then 1.5 g (0.0072 mol) of SrTiO3 prepared in Example 4 above is added to a shaker and shaken at 180 rpm for 2 h to make the dispersion uniform. Then, it is dried in an oven at 120 degrees Celsius, and then ground uniformly. After drying, it is calcined in a muffle furnace at 400 degrees Celsius for 2 h to obtain a catalyst for selectively catalyzing the reduction of CO2 to CO, which is 1.52 g, and is recorded as La2O3 / SrTiO3.

[0053] a. Take 0.2 g of the prepared La2O3 / SrTiO3, pour it into a tablet mold, and press it into a tablet with a diameter of 3 cm for standby use.

[0054] b. The pressed tablet was loaded into the reactor (volume 50 ml, see the device configuration in Figure 1 ), the device was closed, and CO : 2:H2=1:4 mixed gas (50 mL / min) was introduced, and the system was checked for leaks. The pressure of the reaction system was controlled at 0.70 MPa by a back pressure valve. After everything was completed, the light was turned on, the light spot diameter was adjusted to 3 cm, and the reaction was started. The light source used in the reaction was a 1000 W xenon lamp, and the light was as much as possible converged in the reactor under the action of the lens. The temperature of the catalyst surface in the process of photo-thermal carbon dioxide conversion was monitored by a K-type thermocouple. The temperature was 354℃, and the gas chromatography was continuously monitored for half an hour.

[0055] c. After 5h of reaction, the products were calculated according to the gas chromatography results, and the final CO yield was 95.31 mmol / g / h, the selectivity was 99.99%, and the C conversion rate was 78.52%

[0056] Example 8: La2O3 / SrTiO3 was prepared by the impregnation method, and the specific experimental details are as follows: 12 mL of deionized water (0.67 mol) was added, 0.3736 g of La(NO3)2 (0.00029 mol) was weighed to prepare a La(NO3)2 aqueous solution, and then 1.5 g (0.0081 mol) of the nanometer spherical SrTiO3 prepared in Example 4 above was added and uniformly dispersed on a shaker at 180 rpm for 2 h. Then, it was dried in an oven at 120℃, and after being uniformly ground, it was calcined in a muffle furnace at 400℃ for 2 h to obtain a catalyst for selectively catalyzing the reduction of CO2 to CO, 1.80 g, denoted as La2O3 / SrTiO3.

[0057] a. 0.2 g of prepared SrTiO3 was weighed and poured into a tablet press mold to press into a tablet with a diameter of 3 cm for standby use.

[0058] b. The pressed tablet was loaded into the reactor (volume 50 ml, see the device configuration in Figure 1 ), the device was closed, and CO2:H2=1:4 mixed gas (50 mL / min) was introduced and checked for leaks. The pressure of the reaction system was controlled at 0.70 MPa by a back pressure valve. After everything was completed, the light was turned on, the light spot diameter was adjusted to 3 cm, and the reaction was started. The light source used in the reaction was a 1000 W xenon lamp, and the light was as much as possible converged in the reactor under the action of the lens. The temperature of the catalyst surface in the process of photo-thermal carbon dioxide conversion was monitored by a K-type thermocouple. The temperature was 348℃, and the gas chromatography was continuously monitored for half an hour.

[0059] c. After 5h of reaction, the product was accounted according to the gas chromatography results, and the CO yield was finally determined to be 78.14 mmol / g / h, the selectivity was 99.99%, and the CO2 conversion rate was 64.40%.

[0060] Example 9 La2O3 / SrTiO3 was prepared by the impregnation method, and the specific experimental details are as follows: 12 mL of deionized water (0.67 mol) was added, 0.7552 g of La(NO3)2 (0.00171 mol) was weighed to prepare a La(NO3)2 aqueous solution, and then 1.5 g (0.0081 mol) of the nanospherical SrTiO3 prepared in Example 4 above was added to a shaker and shaken at 180 rpm for 2 h to make the dispersion uniform, and then dried in an oven at 120 ℃, and after grinding uniformly, calcined at 400 ℃ for 3 h in a muffle furnace to obtain a catalyst for selective catalytic reduction of CO2 to CO, 0.68 g, denoted as La2O3 / SrTiO3.

[0061] a. 0.2 g of prepared SrTiO3 was weighed and poured into a tablet mold to press into a tablet with a diameter of 3 cm for standby.

[0062] b. The pressed tablet was loaded into the reactor (volume 50 ml, device structure see Figure 1 ), the device was sealed, CO2:H2=1:4 mixed gas (50 mL / min) was introduced and leak detection was performed, and the pressure of the reaction system was controlled at 0.70 Mpa through a back pressure valve. After everything was completed, the light was turned on, the light spot diameter was adjusted to 3 cm, the reaction was started, and the light source used for the reaction was a 1000 W xenon lamp, which was as much as possible to be converged in the reactor under the action of the lens. A K-type thermocouple was used to monitor the temperature of the catalyst surface in the process of photo-thermal carbon dioxide conversion, and the temperature was stabilized at 335 ℃, and gas chromatography was used for continuous monitoring for half an hour.

[0063] c. After 5h of reaction, the product was accounted according to the gas chromatography results, and the CO yield was finally determined to be 78.14 mmol / g / h, the selectivity was 99.99%, and the CO2 conversion rate was 64.40%. 32.72%.

[0064] Example 10 La2O3 / SrTiO3 was prepared by impregnation method. The specific experimental details are as follows: 4 mL of deionized water (0.222 mol) was added, and 0.0305 g of La(NO3)2 (0.00007 mol) was weighed to prepare an aqueous solution of La(NO3)2. Then, 0.5 g (0.0027 mol) of the nanosphere SrTiO3 prepared in Example 4 above was added and shaken on a shaker at 180 rpm for 2 h to disperse it evenly. Then, it was dried in an oven at 120 ℃. After drying and grinding evenly, it was calcined in a muffle furnace at 500 ℃ for 1 h to obtain 0.52 g of catalyst for selective catalytic reduction of CO2 to CO, which is denoted as La2O3 / SrTiO3.

[0065] a. Weigh 0.2g of the prepared SrTiO3, pour it into a tableting mold and press it into tablets with a diameter of 3cm for later use.

[0066] b. Load the compressed tablets into the reactor (volume 50ml, see device structure). Figure 1 A sealed reactor was used, with a CO2:H2 mixture of 1:4 (50 mL / min) introduced and leak checked. The pressure of the reaction system was controlled at 0.70 MPa using a back pressure valve. After everything was completed, the lamp was turned on, and the spot diameter was adjusted to 3 cm. The reaction was started using a 1000W xenon lamp. Under the action of the lens, the light was focused as much as possible into the reactor. A K-type thermocouple was used to monitor the temperature of the catalyst surface during the photothermal carbon dioxide conversion. The temperature stabilized at 344℃, and gas chromatography was used for continuous monitoring for half an hour.

[0067] c. After the reaction was completed for 5 hours, the product yield was calculated based on the gas chromatography results. The final CO yield was determined to be 74.60 mmol / g / h, with a selectivity of 99.99%. Conversion rate: 61.47%.

[0068] Example 11: a. Weigh 0.2g of La2O3 / SrTiO3 prepared in Example 7, pour it into a tableting mold and press it into tablets with a diameter of 3cm for later use.

[0069] b. Load the compressed tablets into the reactor (volume 50ml, see device structure). Figure 1 A sealed reactor was constructed, and a CO2:H2 mixture (1:2) was introduced at a rate of 50 mL / min, with leak checks performed. The pressure of the reaction system was controlled at 0.70 MPa using a back pressure valve. After all preparations were complete, the lamp was turned on, and the spot diameter was adjusted to 3 cm. The reaction was initiated using a 1000W xenon lamp. The light was focused into the reactor as much as possible using a lens. A K-type thermocouple was used to monitor the catalyst surface temperature during the photothermal carbon dioxide conversion. The temperature was stabilized at 368℃, and continuous monitoring was performed by gas chromatography for half an hour.

[0070] c. After the reaction was completed for 5 hours, the product yield was calculated based on the gas chromatography results. The final CO yield was determined to be 70.25 mmol / g / h, with a selectivity of 99.99%. Conversion rate: 57.87%.

[0071] Example 12: a. Weigh 0.2g of the La2O3 / SrTiO3 prepared in Example 7 and press it into a sheet with a diameter of 3cm for later use.

[0072] b. Load the compressed tablets into the reactor (volume 50ml, see device structure). Figure 1 ), sealed device, C is introduced : A 1:1 gas-to-liquid mixture (30 mL / min) was prepared and leak checked. The pressure of the reaction system was controlled at 0.70 MPa using a back pressure valve. After everything was completed, the lamp was turned on, and the spot diameter was adjusted to 3 cm. The reaction was started using a 1000W xenon lamp. Under the action of the lens, the light was focused into the reactor as much as possible. The temperature of the catalyst surface during the photothermal carbon dioxide conversion was monitored by K-type thermocouples, and gas chromatography was continuously monitored for half an hour.

[0073] c. After the reaction was completed for 5 hours, the product yield was calculated based on the gas chromatography results. The final determined CO yield was 27.12 mmol / g / h, with a selectivity of 99.99%. Conversion rate: 22.34%

[0074] Example 13: a. Weigh 0.2g of La2O3 / SrTiO3 prepared in Example 7 and press it into a sheet with a diameter of 3cm for later use.

[0075] b. Load the compressed tablets into the reactor (volume 50ml, see device structure). Figure 1 ), sealed device, C is introduced : A 1:4 gas-to-liquid mixture (50 mL / min) was prepared and leak checked. The pressure of the reaction system was controlled at 0.70 MPa using a back pressure valve. After everything was completed, the lamp was turned on, and the spot diameter was adjusted to 4 cm. The reaction was started using a 1000W xenon lamp. Under the action of the lens, the light was focused into the reactor as much as possible. The temperature of the catalyst surface during the photothermal carbon dioxide conversion was monitored by K-type thermocouples, and gas chromatography was continuously monitored for half an hour.

[0076] c. After the reaction was completed for 5 hours, the product yield was calculated based on the gas chromatography results. The final CO yield was determined to be 87.56 mmol / g / h, with a selectivity of 99.99%. Conversion rate: 72.12%

[0077] Example 14: a. 0.2 g of La2O3 / SrTiO3 prepared in Example 7 was weighed and pressed into a 3 cm diameter tablet for use.

[0078] b. The pressed tablet was loaded into a reactor (volume 50 ml, device structure see Figure 1 ), the device was sealed, and C : 1:4 mixed gas (50 mL / min) was introduced and leak tested, and the pressure of the reaction system was controlled at 0.70 Mpa by a back pressure valve. After everything was completed, the light was turned on, the light spot diameter was adjusted to 5 cm, the reaction was started, and the light source used in the reaction was a 1000 W xenon lamp. The light was as much as possible concentrated in the reactor under the action of a lens. A K-type thermocouple was used to monitor the temperature of the catalyst surface during the photo-thermal carbon dioxide conversion process, and gas chromatography was continuously monitored for half an hour. c. After 5 h of reaction, the products were calculated according to the gas chromatography results, and finally the CO yield was determined to be 59.02 mmol / g / h, the selectivity was 99.99%, and the C

[0079] conversion rate was 48.02%

[0080] Comparative Example 1: a. 0.2 g of La2O3 / SrTiO3 prepared in Example 7 was weighed and pressed into a 3 cm diameter tablet for use.

[0081] b. The pressed tablet was loaded into a reactor (volume 50 ml, device structure see Figure 1 ), the device was sealed, and C : 1:4 mixed gas (50 mL / min) was introduced and leak tested, and the pressure of the reaction system was controlled at 0.1 Mpa by a back pressure valve. After everything was completed, the light was turned on, and the reaction was started. The light source used in the reaction was a 1000 W xenon lamp, and no lens was used to concentrate the light. A K-type thermocouple was used to monitor the temperature of the catalyst surface during the photo-thermal carbon dioxide conversion process, and gas chromatography was continuously monitored for half an hour. c. After 5 h of reaction, the products were calculated according to the gas chromatography results, and finally the CO yield was determined to be 0.00 mmol / g / h, the selectivity was 0.00%, and the C

[0082] conversion rate was 0.00%

[0083] Comparative Example 2: a. 0.2 g of La2O3 / SrTiO3 prepared in Example 7 was weighed and prepared for subsequent use.

[0084] b. The catalyst was loaded into a thermal catalytic reactor (volume 50 ml, device structure see ​ ), the device was sealed, and C​​ =1:4 mixed gas (50 mL / min). After everything is done, start to increase the temperature, start the reaction, the temperature of the reaction is 280℃, 320℃, 350℃, gas chromatography half an hour continuous monitoring.

[0085] c. After the reaction is completed, according to the gas chromatography results, the product is calculated, and finally it is determined that the CO yield is 0.00 mmol / g / h, the selectivity is 0.00%, the CO2 conversion is 2.06%, the CO yield is 0.00 mmol / g / h, the selectivity is 0.00%, the CO2 conversion is 2.06% at 350℃. conversion 1.37%, CO yield 0.00 mmol / g / h, selectivity 0.00%, CO2 conversion 2.06% at 320℃, CO yield 0.00 mmol / g / h, selectivity 0.00%, CO2 conversion 2.06% at 350℃. conversion 2.71%.

[0086] The results of the above examples are summarized in Tables 1, 2 and 3.

[0087] Table 1 Summary of results of photocatalytic reduction of CO2 to CO by different catalysts

[0088] Table 2 Summary of results of photocatalytic reduction of CO2 to CO by La2O3 / SrTiO3 under different conditions (Examples 7-14)

[0089] Table 3 Summary of results of thermal catalytic reduction of CO2 to CO by La2O3 / SrTiO3 (Comparative Example 2)

[0090] The above embodiments are only illustrative of the principles and effects of the present application, and are not intended to limit the present application. The present application has many aspects that can be improved without departing from the general idea, and those skilled in the art can modify or change the above examples without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical idea disclosed by the present application should be covered by the claims of the present application.​

Claims

1. A catalyst for the selective catalytic reduction of CO2 to CO, characterized in that, The catalyst preparation method includes the following steps: (1) TiO2, SrCl2·6H2O, NaOH, and deionized water A are mixed to obtain a second mixed solution. The second mixed solution is reacted at 160-200℃ for 4-10h. After natural cooling, the product is washed with ethanol and deionized water B in sequence, dried and ground evenly. It is then calcined at 400-500℃ for 3-6h to obtain nano-spherical SrTiO3. The molar ratio of TiO2, SrCl2·6H2O, and NaOH is 1:0.5-4:2-18. (2) The La(NO3)3 aqueous solution and the nano-spherical SrTiO3 described in step (1) are mixed evenly, dried at 80-120℃, ground evenly, and then calcined at 300-500℃ for 1-3h to obtain the catalyst for selective catalytic reduction of CO2 to CO, denoted as La2O3 / SrTiO3; the molar ratio of La(NO3)3 to the nano-spherical SrTiO3 in the La(NO3)3 aqueous solution is 0.01-0.30:

1.

2. The catalyst for the selective catalytic reduction of CO2 to CO as described in claim 1, characterized in that, The TiO2 preparation steps in step (1) are as follows: Tetrabutyl titanate, concentrated sulfuric acid, and deionized water are dissolved together in anhydrous ethanol and mixed evenly to obtain a mixed solution. The mixed solution is reacted at 160-200℃ for 2-6 h. After natural cooling, the obtained product is post-treated to obtain TiO2. The molar ratio of tetrabutyl titanate, concentrated sulfuric acid, and deionized water is 1:0.2-0.6:0.5-3. The volume of anhydrous ethanol is 5-20 ml / g based on the mass of tetrabutyl titanate.

3. The catalyst for the selective catalytic reduction of CO2 to CO as described in claim 1, characterized in that, The calcination described in step (1) is carried out at 20-60℃ with a heating rate of 2-10℃ / min, and then heated to 500℃.

4. The catalyst for the selective catalytic reduction of CO2 to CO as described in claim 2, characterized in that, The post-treatment involves washing the obtained product sequentially with ethanol and deionized water B, and then drying it to obtain TiO2.

5. The catalyst for the selective catalytic reduction of CO2 to CO as described in claim 1, characterized in that, The molar concentration of La(NO3)3 in the La(NO3)3 aqueous solution in step (2) is 0.01-0.15 mol / L.

6. The catalyst for the selective catalytic reduction of CO2 to CO as described in claim 1, characterized in that, The volume of deionized water A in step (2) is 2.8-8.4 L / mol based on the amount of SrCl2·6H2O.

7. The application of the catalyst for selective catalytic reduction of CO2 to CO as described in claim 1 in photothermal catalytic reduction of CO2 to CO.

8. The application as described in claim 7, characterized in that, The application involves using a xenon lamp as the light source to achieve an irradiance of 10 ppm inside the reactor. 4 ~1.4×10 6 W / m 2 CO2 is used as a reactant, and under mixed gas conditions, it reacts to generate CO under the catalytic action of the catalyst that selectively catalytically reduces CO2 to CO. The mixed gas is a mixture of CO2 and H2.

9. The application as described in claim 8, characterized in that, The volume ratio of CO2 to H2 in the mixed gas is 1:1 to 4, and the pressure of the mixed gas is 0.1-1 MPa.

10. The application as described in claim 8, characterized in that, The xenon lamp is used as a light source to maintain the temperature inside the reactor at 100-500°C. o C.

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