Application of atomic-scale dispersion double-active-site Pt-Cu / TiO2 catalyst in propane oxidation catalysis

Abstract

The invention discloses application of an atomic-scale dispersion dual-active-site Pt-Cu / TiO2 catalyst in propane oxidation catalysis, and belongs to the field of environment-friendly catalytic materials and air pollution control. According to the catalyst, TiO2 serves as a carrier, Pt and Cu serve as dual-load catalytic active components, the loading amount of the active component Cu is 0.1-1 wt% of the mass of the TiO2 carrier, the loading amount of Pt is 0.02-0.06 wt% of the sum of the mass of Cu and TiO2, and Pt-O-Cu dual active sites are formed on the surface of the catalyst. The catalyst disclosed by the invention shows excellent propane catalytic oxidation performance and sulfur resistance.

Description

Technical Field

[0001] The present invention relates to the application of an atomically dispersed dual-active-site Pt-Cu / TiO2 catalyst with high activity and strong sulfur resistance in propane oxidation catalysis, belonging to the fields of environmental protection catalytic materials and air pollution control. Background Art

[0002] Propane (C3H8), as a common fuel, is the main component of liquefied petroleum gas (LPG). Propane is generally produced by catalytic cracking and thermal cracking of crude oil in refineries. Propane in the atmosphere mainly comes from petrochemical industries such as refineries and oil fields as stationary sources and vehicle exhaust emissions as mobile sources. Propane is a short-chain alkane volatile organic compound, and due to its stable molecular structure, it is considered to be one of the most difficult components to eliminate in VOCs.

[0003] Catalytic purification is one of the most effective technical means for the source control of current gaseous pollutants. Among them, the catalyst is the core to achieve efficient catalytic purification. However, under actual working conditions, the exhaust gas temperature changes greatly and the components are complex, such as containing impurities such as SO2 and H2O. This puts harsh requirements on the active temperature window, thermal stability and sulfur resistance of the catalyst. Therefore, designing and developing new stable and efficient environmental remediation catalysts is a key issue faced by scientists. Summary of the Invention

[0004] The purpose of the present invention is to provide the application of an atomically dispersed dual-active-site Pt-Cu / TiO2 catalyst with high activity and strong sulfur resistance in propane oxidation catalysis in view of the deficiencies of the prior art.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: The application of an atomically dispersed dual-active-site Pt-Cu / TiO2 catalyst in propane oxidation catalysis, wherein the catalyst uses TiO2 as the carrier and Pt and Cu as the dual-loaded catalytic active components. The loading amount of the active component Cu is 0.1-1 wt% of the mass of the TiO2 carrier, and the loading amount of Pt is 0.02-0.06 wt% of the sum of the masses of Cu and TiO2. Pt-O-Cu dual-active sites are formed on the surface of the catalyst.

[0006] Further, the catalyst is obtained according to the following preparation method: Using tetrabutyl titanate as the titanium precursor and poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) as the template agent, the catalyst carrier TiO2 is prepared by the sol-gel method; Using copper nitrate as the precursor of Cu, Cu was loaded onto the catalyst support TiO2 by the impregnation method to obtain a single-atom Cu / TiO2 precursor; NaBH4 was used to construct oxygen vacancies on the surface of the single-atom Cu / TiO2 precursor to obtain a single-atom Cu / TiO2 catalyst rich in oxygen vacancies; Using chloroplatinic acid as the precursor of Pt, Pt was loaded onto the single-atom Cu / TiO2 catalyst rich in oxygen vacancies by the impregnation method to obtain a dual-atom Pt-Cu / TiO2 catalyst.

[0007] Further, the catalyst support TiO2 was prepared by the sol-gel method, including: Stir poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol), tetrahydrofuran, acetic acid and concentrated hydrochloric acid to form a transparent solution, quickly add tetrabutyl titanate, and continue stirring until a golden solution is formed; Keep the golden solution warm and dry to obtain a hydrogel, dry the hydrogel to obtain a white precipitate, and calcine the white precipitate in air to obtain the TiO2 support.

[0008] Among them, the addition ratio of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol), tetrahydrofuran, acetic acid, concentrated hydrochloric acid and tetrabutyl titanate is 1.6g - 4.8g: 30 - 90mL: 2.4 - 7.2mL: 1.5 - 4.5mL: 0.01 - 0.03mol.

[0009] Among them, the temperature for keeping the golden solution warm and dry is 45°C - 65°C, and the drying time is 24 - 72h; The temperature for drying the hydrogel is 80 - 100°C, and the drying time is 15 - 25h; The temperature for calcining the white precipitate in air is 400 - 500°C, the calcining time is 3 - 5h, and the heating rate is 1 - 5°C / min.

[0010] Further, in the step of preparing the single-atom Cu / TiO2 precursor, the addition amount of copper nitrate is such that the copper loading is 0.1 - 1 wt% of the mass of the TiO2 support.

[0011] Further, in the step of using NaBH4 to construct oxygen vacancies on the surface of the single-atom Cu / TiO2 precursor, the mass ratio of NaBH4 to the single-atom Cu / TiO2 precursor is 0.18915 - 0.56745:1.

[0012] Further, the preparation steps of the single-atom Cu / TiO2 catalyst rich in oxygen vacancies specifically include: Disperse TiO2 evenly in deionized water to obtain a TiO2 suspension; Dissolve copper nitrate in deionized water, add it to the TiO2 suspension, and stir evenly to obtain a single-atom Cu / TiO2 precursor; Immerse the single-atom Cu / TiO2 precursor in a NaBH4 solution, stir well to obtain a single-atom Cu / TiO2 catalyst rich in oxygen vacancies.

[0013] More specifically, add an aqueous solution of copper nitrate to the TiO2 suspension and stir for 1 - 3 h; place it in an oven and dry at 70 - 90 °C for 8 - 24 h to obtain a single-atom Cu / TiO2 precursor; Immerse the single-atom Cu / TiO2 precursor in a NaBH4 solution, stir well for 15 - 35 min, wash it 3 - 5 times with deionized water and absolute ethanol, and place it in an oven at 70 - 90 °C to dry for 8 - 24 h to obtain a single-atom Cu / TiO2 catalyst rich in oxygen vacancies.

[0014] Furthermore, in the step of preparing the dual-atom Pt-Cu / TiO2 catalyst by the impregnation method, the addition amount of chloroplatinic acid is such that the loading amount of Pt is 0.02 - 0.06 wt% of the mass of the single-atom Cu / TiO2 catalyst rich in oxygen vacancies.

[0015] Furthermore, the preparation steps of the dual-atom Pt-Cu / TiO2 catalyst specifically include: Disperse the single-atom Cu / TiO2 catalyst rich in oxygen vacancies in deionized water to obtain solution A; Dissolve chloroplatinic acid in deionized water to obtain solution B; Drop solution B into solution A, adjust the pH of the solution to 8 - 10 using ammonia water, and after magnetic stirring, dry and calcine to obtain the dual-atom Pt-Cu / TiO2 catalyst.

[0016] Among them, after adjusting the pH of the solution to 8 - 10 using ammonia water, magnetic stir for 1 - 3 h; After stirring, place it in an oven at 70 - 90 °C and dry for 8 - 24 h; After drying, place it in a muffle furnace and calcine at 400 - 500 °C for 3 - 5 h to obtain the Pt-Cu / TiO2 catalyst.

[0017] Furthermore, the Pt-Cu / TiO2 catalyst has sulfur poisoning resistance in propane oxidation catalysis.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The catalyst prepared by the present invention can efficiently catalyze the oxidation of gaseous pollutants such as propane. Compared with the prior art, this catalyst system first synthesizes TiO2 by the sol-gel method, and further loads Cu on TiO2 to make the Cu species evenly dispersed and occupy the Ti vacancies on the surface of the TiO2 crystal; before loading atomically dispersed Pt, through NaBH4 reduction, surface oxygen vacancies are constructed on the surface of the Cu / TiO2 sample. The Cu occupying the Ti vacancy causes distortion of the TiO2 crystal, and the Cu-O bond between Cu and the adjacent surface lattice oxygen is unstable. After reduction by NaBH4, the Cu-O bond breaks to form oxygen vacancies. The oxygen vacancies constructed at the adjacent sites of Cu can serve as the anchoring sites for Pt, and the electron donor enhancement strategy induced by oxygen vacancies improves the stability of atomically dispersed Pt; By adjusting the pH value of the solution with ammonia water, the electronegativity of the Cu / TiO2 surface is regulated, thereby anchoring the atomically dispersed Cu-Pt dual active sites. The hybridization structure and charge transfer effect between the single-atom Cu occupying the Ti vacancy on the Cu / TiO2 surface and the TiO2 support endow the single-atom Cu site with a strong •OH affinity. The bonding of a large number of negatively charged •OH in the solution to the Cu site maximizes the ionic state of Pt n+ to be adjacent and connected to Cu, promoting the formation of the Pt-O-Cu dual sites and improving its catalytic oxidation activity and anti-sulfur performance for propane. In addition, the catalyst components are environmentally friendly, the preparation process is simple, the cost is low, the cost performance is high, and at the same time it has high mechanical strength, which can effectively reduce the operating cost of air pollution treatment. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of the catalyst prepared in Example 1 of the present invention; Figure 2 It is a comparison diagram of the catalytic oxidation activity of Pt-Cu / TiO2 prepared in Example 1 of the present invention for propane oxidation varying with temperature; Figure 3 It is a catalytic stability test diagram of Pt-Cu / TiO2 prepared in Example 1 of the present invention; Figure 4 It is an anti-sulfur performance test diagram of Pt-Cu / TiO2 prepared in Example 1 of the present invention; Figure 5 It is a comparison diagram of the catalytic oxidation activity of Pt-Cu / TiO2 for propane oxidation varying with temperature in Example 2 of the present invention; Figure 6 It is a catalytic stability test diagram of Pt-Cu / TiO2 prepared in Example 2 of the present invention; Figure 7 It is an anti-sulfur performance test diagram of Pt-Cu / TiO2 prepared in Example 2 of the present invention; Figure 8This is the comparison chart of the catalytic activity of Pt-Cu / TiO2 prepared in Example 3 of the present invention for propane oxidation varying with temperature; Figure 9 This is the test chart of the catalytic stability of Pt-Cu / TiO2 prepared in Example 3 of the present invention; Figure 10 This is the test chart of the sulfur resistance of Pt-Cu / TiO2 prepared in Example 3 of the present invention; Figure 11 This is the comparison chart of the catalytic activity of Pt-Cu / TiO2 in Comparative Example 1 of the present invention for propane oxidation varying with temperature; Figure 12 This is the test chart of the sulfur resistance of Pt-Cu / TiO2 in Comparative Example 1 of the present invention; Figure 13 This is the comparison chart of the catalytic activity of Pt-Cu / TiO2 in Comparative Example 2 of the present invention for propane oxidation varying with temperature; Figure 14 This is the test chart of the sulfur resistance of Pt-Cu / TiO2 in Comparative Example 2 of the present invention; Figure 15 This is the comparison chart of the catalytic activity of Cu / TiO2 in Comparative Example 3 of the present invention for propane oxidation varying with temperature; Figure 16 This is the test chart of the sulfur resistance of Cu / TiO2 in Comparative Example 3 of the present invention; Figure 17 This is the comparison chart of the catalytic activity of Pt / TiO2 in Comparative Example 4 of the present invention for propane oxidation varying with temperature; Figure 18 This is the test chart of the sulfur resistance of Pt / TiO2 in Comparative Example 4 of the present invention. Detailed implementation manners

[0020] The present invention will be further described below in conjunction with specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0021] It should be noted that unless otherwise specified, the technical terms or scientific terms used in this application should have the ordinary meanings understood by those skilled in the art to which the present invention belongs.

[0022] Example 1

[0023] (1) Preparation of the catalyst support TiO2 Preparation of TiO₂ by sol - gel method: Add 1.6 g of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) (P123) and 30 mL of tetrahydrofuran into a beaker, then dropwise add 2.4 mL of acetic acid and 1.5 mL of concentrated hydrochloric acid. After stirring the mixture to form a transparent solution, quickly add 3.4 g of tetrabutyl titanate (0.01 mol), and continue stirring until a golden - yellow solution is formed.

[0024] Place the beaker in a forced - air oven at 45 °C for 24 h to obtain a slightly yellowish - white TiO₂ hydrogel. Dry the hydrogel at 80 °C for 15 h to obtain a white TiO₂ precipitate. Then, calcine the obtained white TiO₂ precipitate in air at 400 °C for 3 h (heating rate: 1 °C / min) to obtain TiO₂.

[0025] (2) Preparation of single - atom Cu / TiO₂: Prepare a single - atom Cu / TiO₂ catalyst with a Cu loading of 0.1 wt% (mass ratio of copper to TiO₂ is 0.1:100) by impregnation method: Take 1 g of TiO₂ prepared in step (1) and disperse it evenly in 30 mL of deionized water to prepare a TiO₂ suspension. Weigh 0.003775 g of copper(II) nitrate trihydrate and dissolve it in 10 mL of deionized water. Add the copper(II) nitrate aqueous solution to the TiO₂ suspension and stir for 1 h. Place it in an oven at 70 °C and dry for 8 h.

[0026] Weigh 1 g of the obtained product and 0.18915 g of NaBH₄ and dissolve them in 50 mL of deionized water, stir well for 15 min. Take it out and wash it 3 times with deionized water and absolute ethanol, and finally place it in an oven at 70 °C and dry for 8 h to obtain a single - atom Cu / TiO₂ catalyst rich in oxygen vacancies.

[0027] (3) Preparation of dual - atom Pt - Cu / TiO₂ catalyst Disperse 1 g of Cu / TiO₂ catalyst in 30 mL of deionized water, denoted as solution A; weigh 0.000531 g of chloroplatinic acid (mass ratio of Pt to Cu / TiO₂ is 0.02:100) and dissolve it in 10 mL of deionized water, denoted as solution B; Drop solution B into solution A, adjust the pH of the solution to 8 with ammonia water, stir magnetically for 1 h; place it in an oven at 70 °C and dry for 8 h. Then calcine it in a muffle furnace at 400 °C for 3 h to obtain the Pt - Cu / TiO₂ catalyst.

[0028] The structure of the catalyst prepared in Example 1 is as Figure 1 shown.

[0029] (4) Catalytic activity test The propane catalytic oxidation reaction (converted to carbon dioxide and water) is carried out in a fixed-bed reactor operating at atmospheric pressure. The catalyst (100 mg; 60 mesh) is inserted into the center of a 500 mm long quartz tube with an inner diameter of 10 mm, and quartz wool is inserted at both ends of the catalyst. The propane content in the feed gas is 500 ppm, and the balanced gas mixture is 40 vol% O2, 10 vol% C3H8, and N2, (weight hourly space velocity (WHSV = 60000 mL⋅h -1 ⋅g −1 ). A gas chromatograph equipped with a flame ionization detector (FID) is used for on-line analysis of the propane and reaction product concentrations.

[0030] Figure 2 This is a comparison graph of the catalytic activity of Pt-Cu / TiO2 for propane oxidation with temperature in Example 1 of the present invention. It can be seen that at 270 °C, the propane removal efficiency reaches 100%.

[0031] Figure 3 This is a test graph of the catalytic stability of Pt-Cu / TiO2 prepared in Example 1 of the present invention. It can be seen that the stability of the catalyst is maintained at about 90% after 48 hours of use. 90 stability is maintained at about 90%.

[0032] (5) Sulfur resistance test The sulfur resistance test is carried out in a fixed-bed reactor operating at atmospheric pressure. The catalyst (100 mg; 60 mesh) is inserted into the center of a 500 mm long quartz tube with an inner diameter of 10 mm, and quartz wool is inserted at both ends of the catalyst. The propane content in the feed gas is 500 ppm, 500 ppm SO2; the balanced gas mixture is 30 vol% O2, 10 vol% SO2, 10 vol% C3H8, and N2 (weight hourly space velocity (WHSV = 60000 mL⋅h -1 ⋅g −1 ). A gas chromatograph equipped with a flame ionization detector (FID) is used for on-line analysis of the propane and reaction product concentrations.

[0033] Figure 4 This is a sulfur resistance test graph of Pt-Cu / TiO2 prepared in Example 1 of the present invention. During the test of propane catalytic oxidation, SO2 is introduced, and the propane conversion rate does not change significantly.

[0034] Example 2

[0035] (1) Preparation of the catalyst support TiO2 Preparation of TiO₂ by sol - gel method: Add 3 g of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) and 60 mL of tetrahydrofuran into a beaker, then dropwise add 4.8 mL of acetic acid and 3 mL of concentrated hydrochloric acid. After stirring the mixture to form a transparent solution, quickly add 6.8 g of tetrabutyl titanate (0.02 mol), and continue stirring until a golden-yellow solution is formed.

[0036] Place the beaker in a blast drying oven at 55 °C for 48 h to obtain a slightly yellowish-white TiO₂ hydrogel. Dry the hydrogel at 90 °C for 20 h to obtain a white TiO₂ precipitate. Then, calcine the obtained white TiO₂ precipitate in air at 450 °C for 3 h (heating rate: 3 °C / min) to obtain TiO₂.

[0037] (2) Preparation of single-atom Cu / TiO₂: Prepare a single-atom Cu / TiO₂ catalyst with a Cu loading of 0.5 wt% (mass ratio of copper to TiO₂ is 0.5:100) by impregnation method: Take 1 g of TiO₂ prepared in step 1 and disperse it evenly in 30 mL of deionized water to prepare a TiO₂ suspension. Weigh 0.018875 g of copper(II) nitrate trihydrate and dissolve it in 10 mL of deionized water, then add the copper(II) nitrate aqueous solution to the TiO₂ suspension and stir for 2 h. Place it in an oven at 80 °C and dry for 16 h.

[0038] Take 1 g of the product obtained above and 0.3873 g of NaBH₄ and dissolve them in 50 mL of deionized water, stir for 25 min. After taking it out, wash it 4 times with deionized water and absolute ethanol, and finally place it in an oven at 80 °C and dry for 16 h to obtain a single-atom Cu / TiO₂ catalyst rich in oxygen vacancies.

[0039] (3) Preparation of dual-atom Pt - Cu / TiO₂ catalyst Take 1 g of Cu / TiO₂ catalyst and disperse it in 30 mL of deionized water, denoted as solution A; weigh 0.00106 g of chloroplatinic acid (mass ratio of Pt to Cu / TiO₂ is 0.04:100) and dissolve it in 10 mL of deionized water, denoted as solution B; Drop solution B into solution A, adjust the pH of the solution to 9 using ammonia water, stir magnetically for 2 h; place it in an oven at 80 °C and dry for 15 h. Then place it in a muffle furnace and calcine at 450 °C for 4 h to obtain the Pt - Cu / TiO₂ catalyst.

[0040] (4) Catalytic activity test The propane oxidation catalytic reaction is carried out in a fixed-bed reactor operating at atmospheric pressure. The catalyst (100 mg; 70 mesh) is inserted into the center of a 500 mm long quartz tube with an inner diameter of 10 mm, and quartz wool is inserted at both ends of the catalyst. The propane content in the feed gas is 500 ppm, and the balanced gas mixture is 40 vol% O2, 10 vol% C3H8 and N2, (weight hourly space velocity (WHSV = 60000 mL⋅h -1 ⋅g −1 ). A gas chromatograph equipped with a flame ionization detector (FID) is used for on-line analysis of the propane and reaction product concentrations.

[0041] Figure 5 This is a comparative graph of the catalytic activity of Pt-Cu / TiO2 for propane oxidation varying with temperature in Example 2 of the present invention. It can be seen that at 270 °C, the propane removal efficiency reaches 100%.

[0042] Figure 6 This is a test graph of the catalytic stability of Pt-Cu / TiO2 prepared in Example 2 of the present invention. It can be seen that the stability of the catalyst remains at 90% after 48 hours of use. 90 stability still remains at 90%.

[0043] (5) Sulfur resistance test The sulfur resistance test is carried out in a fixed-bed reactor operating at atmospheric pressure. The catalyst (100 mg; 70 mesh) is inserted into the center of a 500 mm long quartz tube with an inner diameter of 10 mm, and quartz wool is inserted at both ends of the catalyst. The propane content in the feed gas is 500 ppm, 500 ppm SO2; the balanced gas mixture is 30 vol% O2, 10 vol% SO2, 10 vol% C3H8 and N2 (weight hourly space velocity (WHSV = 60000 mL⋅h -1 ⋅g −1 ). A gas chromatograph equipped with a flame ionization detector (FID) is used for on-line analysis of the propane and reaction product concentrations.

[0044] Figure 7 This is a sulfur resistance test graph of Pt-Cu / TiO2 prepared in Example 2 of the present invention. When SO2 is introduced during the test of propane catalytic oxidation, the propane conversion rate does not change significantly.

[0045] Example 3

[0046] (1) Preparation of the catalyst support TiO2 Preparation of TiO2 by sol-gel method: Add 4.8 g of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) and 90 mL of tetrahydrofuran into a beaker, and then dropwise add 7.2 mL of acetic acid and 4.5 mL of concentrated hydrochloric acid. After stirring the mixture to form a transparent solution, quickly add 10.2 g of tetrabutyl titanate (0.03 mol), and continue stirring until a golden-yellow solution is formed.

[0047] Place the beaker in a forced-air oven at 65 °C for 72 h to obtain a slightly yellowish TiO2 hydrogel. Dry the hydrogel at 100 °C for 25 h to obtain a white TiO2 precipitate. Then, calcine the obtained white TiO2 precipitate in air at 500 °C for 5 h (heating rate: 5 °C / min) to obtain TiO2.

[0048] (2) Preparation of single-atom Cu / TiO2: Prepare a single-atom Cu / TiO2 catalyst with a Cu loading of 1 wt% by impregnation method (mass ratio of copper to TiO2 is 1:100): Take 1 g of TiO2 prepared in step (1) and disperse it evenly in 30 mL of deionized water to prepare a TiO2 suspension. Weigh 0.03775 g of copper nitrate trihydrate and dissolve it in 10 mL of deionized water. Add the copper nitrate aqueous solution to the TiO2 suspension and stir for 3 h. Place it in an oven at 90 °C and dry for 24 h.

[0049] Take 1 g of the obtained product and 0.56745 g of NaBH4 and dissolve them in 50 mL of deionized water, stir well for 35 min. After taking it out, wash it 5 times with deionized water and absolute ethanol, and finally place it in an oven at 90 °C and dry for 24 h to obtain a single-atom Cu / TiO2 catalyst rich in oxygen vacancies.

[0050] (3) Preparation of dual-atom Pt-Cu / TiO2 catalyst Take 1 g of Cu / TiO2 catalyst and disperse it in 30 mL of deionized water, denoted as solution A; weigh 0.00159 g of chloroplatinic acid (mass ratio of Pt to Cu / TiO2 is 0.06:100), dissolve it in 10 mL of deionized water, denoted as solution B; Drop solution B into solution A, adjust the pH of the solution to 10 with ammonia water, stir magnetically for 3 h; place it in an oven at 90 °C and dry for 24 h. Place it in a muffle furnace and calcine it at 500 °C for 5 h to prepare a Pt-Cu / TiO2 catalyst.

[0051] (4) Catalytic activity test The propane oxidation catalytic reaction is carried out in a fixed-bed reactor operating at atmospheric pressure. The catalyst (100 mg; 80 mesh) is inserted into the center of a 500 mm long quartz tube with an inner diameter of 10 mm, and quartz wool is inserted at both ends of the catalyst. The propane content in the feed gas is 500 ppm, and the balanced gas mixture is 40 vol% O2, 10 vol% C3H8, and N2, (weight hourly space velocity (WHSV = 60000 mL⋅h -1 ⋅g −1 ). A gas chromatograph equipped with a flame ionization detector (FID) is used for on-line analysis of the propane and reaction product concentrations.

[0052] Figure 8 This is a comparison chart of the catalytic activity of Pt-Cu / TiO2 for propane oxidation with temperature change in Example 3 of the present invention. It can be seen that the Pu-Cu / TiO2 catalyst has a propane removal efficiency of 100% at 270 °C.

[0053] Figure 9 This is a test chart of the catalytic stability of Pt-Cu / TiO2 prepared in Example 3 of the present invention. It can be seen that the catalyst maintains a stability of 90% after being used for 48 hours T 90 stability is maintained at 90%.

[0054] (6) Sulfur resistance test The sulfur resistance test is carried out in a fixed-bed reactor operating at atmospheric pressure. The catalyst (100 mg; 80 mesh) is inserted into the center of a 500 mm long quartz tube with an inner diameter of 10 mm, and quartz wool is inserted at both ends of the catalyst. The propane content in the feed gas is 500 ppm, 500 ppm SO2; the balanced gas mixture is 30 vol% O2, 10 vol% SO2, 10 vol% C3H8, and N2 (weight hourly space velocity (WHSV = 60000 mL⋅h -1 ⋅g −1 ). A gas chromatograph equipped with a flame ionization detector (FID) is used for on-line analysis of the propane and reaction product concentrations.

[0055] Figure 10 This is a sulfur resistance test chart of Pt-Cu / TiO2 prepared in Example 3 of the present invention. During the test of propane catalytic oxidation, SO2 is introduced, and there is no obvious change in the propane conversion rate.

[0056] Comparative Example 1: The catalyst preparation steps are the same as those in Example 1. Compared with Example 1, NaBH4 reduction is not used in the preparation process of Cu / TiO2.

[0057] Figure 11This is the comparative graph of the catalytic activity of Pt-Cu / TiO₂ in Comparative Example 1 of the present invention for propane oxidation varying with temperature. The test conditions and methods are the same as those in Example 1. It can be seen that the propane conversion rate reaches 90% at T = 261 °C.

[0058] Figure 12 This is the sulfur resistance test graph of Pt-Cu / TiO₂ in Comparative Example 1 of the present invention. SO₂ was introduced during the test of propane catalytic oxidation for the catalyst, and the test conditions and methods are the same as those in Example 1. It can be seen that the propane conversion rate decreased significantly.

[0059] Comparative Example 2: The preparation method of the catalyst is the same as that in Example 1. Compared with Example 1, ammonia water was not used to adjust the pH when impregnating Pt on Cu / TiO₂.

[0060] Figure 13 This is the comparative graph of the catalytic activity of Pt-Cu / TiO₂ in Comparative Example 2 of the present invention for propane oxidation varying with temperature. The test conditions and methods are the same as those in Example 1. At T = 269 °C, the propane conversion rate reaches 90%.

[0061] Figure 14 This is the sulfur resistance test graph of Pt-Cu / TiO₂ in Comparative Example 2 of the present invention. SO₂ was introduced during the test of propane catalytic oxidation for the catalyst, and the test conditions and methods are the same as those in Example 1. It can be seen that the propane conversion rate decreased significantly.

[0062] Comparative Example 3: The preparation of single-atom Cu / TiO₂ is consistent with the preparation method of Cu / TiO₂ in Example 1. The single-atom Cu / TiO₂ catalyst with a Cu loading of 0.1 wt% was prepared by the impregnation method: Take 1 g of TiO₂ prepared in Example 1 and disperse it evenly in deionized water to obtain a TiO₂ suspension. Weigh 0.003775 g of copper nitrate trihydrate and dissolve it in 10 mL of deionized water. Add the copper nitrate aqueous solution to the TiO₂ suspension and stir for 1 h. Place it in an oven and dry at 70 °C for 8 h.

[0063] Weigh 1 g of the obtained product and 0.18915 g of NaBH₄ and dissolve them in 50 mL of deionized water and stir well for 15 min. Wash with deionized water and absolute ethanol three times, and finally place it in an oven at 70 °C and dry for 8 h to obtain a single-atom Cu / TiO₂ catalyst rich in oxygen vacancies.

[0064] Figure 15 This is the comparative graph of the catalytic activity of Cu / TiO₂ in Comparative Example 3 of the present invention for propane oxidation varying with temperature. The test conditions and methods are the same as those in Example 1. At T = 310 °C. The propane conversion rate reaches 90%.

[0065] Figure 16 This is the test chart of the sulfur resistance of Cu / TiO₂ in Comparative Example 3 of the present invention. During the test of propane catalytic oxidation, SO₂ was introduced into the catalyst. The test conditions and methods were the same as those in Example 1. It can be seen that the propane conversion rate decreased significantly.

[0066] Comparative Example 4: Preparation of single-atom Pt / TiO₂. The preparation method of the support and the loading amount of Pt were the same as those in Example 1.

[0067] A catalyst of single-atom Pt / TiO₂ with a Pt loading of 0.02 wt% was prepared by the impregnation method: Take 1 g of TiO₂ prepared in Example 1 and disperse it evenly in 30 mL of deionized water to obtain a TiO₂ suspension, denoted as Solution A. Weigh 0.000531 g of chloroplatinic acid and dissolve it in 10 mL of deionized water (the mass ratio of Pt to TiO₂ is 0.02:100), denoted as Solution B; add Solution B dropwise into Solution A, adjust the pH of the solution to 8 with ammonia water, stir magnetically for 1 h, place it in an oven at 70 °C, and dry it for 8 h. Then place it in a muffle furnace and calcine it at 400 °C for 3 h to obtain a single-atom Pt / TiO₂ catalyst.

[0068] Figure 17 This is the comparison chart of the catalytic activity of Pt / TiO₂ for propane oxidation with temperature change in Comparative Example 4 of the present invention. The test conditions and methods were the same as those in Example 1. At T = 290 °C, the propane conversion rate reached 90%.

[0069] Figure 18 This is the test chart of the sulfur resistance of Pt / TiO₂ in Comparative Example 4 of the present invention. During the test of propane catalytic oxidation, SO₂ was introduced into the catalyst. The test conditions and methods were the same as those in Example 1. It can be seen that the propane conversion rate decreased significantly.

[0070] The actual results show that compared with Comparative Examples 1-4, the Pt-Cu / TiO₂ catalysts prepared in Examples 1, 2, and 3 exhibit excellent catalytic performance and sulfur resistance for propane catalytic oxidation.

[0071] The present invention has been disclosed in the above preferred embodiments, but it is not intended to limit the present invention. Any technical solutions obtained by adopting equivalent substitution or equivalent transformation shall fall within the protection scope of the present invention.

Claims

1. Application of an atomically dispersed dual-active site Pt-Cu / TiO2 catalyst in propane oxidation catalysis, characterized in that: The catalyst uses TiO2 as a carrier and Pt and Cu as dual-loaded catalytic active components, the active component Cu loading is 0.1-1wt% of the TiO2 carrier mass, the Pt loading is 0.02-0.06wt% of the sum of the Cu and TiO2 masses, and a Pt-O-Cu dual active site is formed on the catalyst surface.

2. The use according to claim 1, characterized in that: The catalyst is obtained according to the following preparation method: The catalyst carrier TiO2 was prepared by a sol-gel method using tetrabutyl titanate as a titanium precursor and poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) as a template. Using copper nitrate as a Cu precursor, Cu was loaded onto the catalyst carrier TiO2 by an impregnation method to obtain a single-atom Cu / TiO2 precursor; NaBH4 was used to construct oxygen vacancies on the surface of the single-atom Cu / TiO2 precursor to obtain a single-atom Cu / TiO2 catalyst rich in oxygen vacancies; Using chloroplatinic acid as a Pt precursor, Pt was loaded onto a single-atom Cu / TiO2 catalyst rich in oxygen vacancies by an impregnation method to obtain a diatomic Pt-Cu / TiO2 catalyst.

3. The use according to claim 2, characterized in that: The catalyst carrier TiO2 is prepared by a sol-gel method, comprising: Stir poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol), tetrahydrofuran, acetic acid and concentrated hydrochloric acid to form a transparent solution, quickly add tetrabutyl titanate, and continue stirring until a golden yellow solution is formed; The golden yellow solution is kept warm and dried to obtain a hydrogel, the hydrogel is dried to obtain a white precipitate, and the white precipitate is calcined in air to obtain a TiO2 carrier.

4. The use according to claim 3, characterized in that: The ratio of the added amounts of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol), tetrahydrofuran, acetic acid, concentrated hydrochloric acid and tetrabutyl titanate is 1.6g-4.8g:30-90mL:2.4-7.2mL:1.5-4.5mL:0.01-0.03mol.

5. The use according to claim 2, characterized in that: In the step of preparing the single-atom Cu / TiO2 precursor, the amount of copper nitrate added is such that the copper loading is 0.1~1wt% of the mass of the TiO2 carrier.

6. The use according to claim 2, characterized in that: In the step of constructing oxygen vacancies on the surface of the single-atom Cu / TiO2 precursor using NaBH4, the mass ratio of NaBH4 to the single-atom Cu / TiO2 precursor is 0.18915-0.56745:

1.

7. The use according to claim 2, characterized in that: In the step of preparing the diatomic Pt-Cu / TiO2 catalyst by impregnation method, the amount of chloroplatinic acid added is such that the Pt loading is 0.02-0.06wt% of the mass of the single-atom Cu / TiO2 catalyst rich in oxygen vacancies.

8. The use according to claim 2, characterized in that: The preparation steps of the single-atom Cu / TiO2 catalyst rich in oxygen vacancies specifically include: Uniformly dispersing TiO2 in deionized water to prepare a TiO2 suspension; Dissolve copper nitrate in deionized water, add it to the TiO2 suspension, stir evenly, and obtain a single-atom Cu / TiO2 precursor; The single-atom Cu / TiO2 precursor is immersed in a NaBH4 solution and stirred thoroughly to obtain a single-atom Cu / TiO2 catalyst rich in oxygen vacancies.

9. The use according to claim 2, characterized in that: The preparation steps of the diatomic Pt-Cu / TiO2 catalyst specifically include: The single-atom Cu / TiO2 catalyst rich in oxygen vacancies was dispersed in deionized water to obtain solution A; Dissolve chloroplatinic acid in deionized water to obtain solution B; Solution B was added dropwise into solution A, and the pH value of the solution was adjusted to 8-10 with aqueous ammonia. After magnetic stirring, the solution was dried and calcined to obtain a diatomic Pt-Cu / TiO2 catalyst.

10. The use according to claim 1, characterized in that: The catalyst has the property of resisting sulfur poisoning in propane oxidation catalysis.

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