Preparation method of water-resistant sulfur-resistant efficient non-methane hydrocarbon catalyst and catalyst

Abstract

The invention discloses a preparation method of a water-resistant sulfur-resistant efficient non-methane hydrocarbon catalyst and the catalyst. The method comprises the following steps: obtaining a solution containing titanium and tin; obtaining a titanium-tin composite hydroxide filter cake; obtaining a titanium-tin composite oxide solid solution carrier material; obtaining a suspension mixed by graphite and a solid solution; precursor slurry is obtained; obtaining precursor slurry of which the pH is adjusted; obtaining a platinum-containing precursor slurry uniformly loaded with a platinum active component; and obtaining the non-methane total hydrocarbon catalyst. According to the preparation method of the water-resistant sulfur-resistant efficient non-methane total hydrocarbon catalyst, water is used as a dispersion medium in the preparation process, so that the preparation method is green and environment-friendly; the preparation process of the method is a common coprecipitation method, the preparation process is simple, the operation is convenient, and batch production is easy.

Description

Technical Field

[0001] This application relates to the field of catalyst technology, specifically to a method for preparing a water- and sulfur-resistant, high-efficiency non-methane total hydrocarbon catalyst and the catalyst itself. Background Technology

[0002] In recent years, environmental pollution has seriously affected people's daily lives. Rapid industrial growth has exacerbated air pollution, with volatile organic compounds (VOCs) being one of the main sources. VOCs are generally defined as organic compounds with a boiling point below 260°C that exist in the atmosphere in gaseous form at normal pressure. Based on differences in functional groups, VOCs can be classified into several major categories, such as alkanes, alkenes, and aromatic hydrocarbons. VOCs can cause significant harm to the human brain and internal organs, potentially leading to convulsions and coma in severe cases. Non-methane total hydrocarbons (NMHC) refer to the total hydrocarbons (the sum of gaseous organic compounds that respond to a gas chromatography-flame ionization detector under specified conditions) after deducting methane. It includes various organic compounds such as hydrocarbons, alcohols, and ethers. Because NMHC plays a crucial role in VOCs, it is often chosen as a representative substance in actual environmental monitoring. The composition and concentration of NMHC are used to assess the impact of VOCs on air quality and the environment, and necessary control measures are taken to reduce air pollution and protect the environment.

[0003] Limitations of non-methane total hydrocarbon treatment technologies: Currently, catalytic oxidation (CO) and regenerative catalytic oxidation (RCO) have become mainstream processes due to their advantages such as low temperature, high efficiency, and low energy consumption. Catalysts are the core components, but residual sulfur components (such as SO2 and H2S) in industrial waste gas and high humidity environments can easily lead to catalyst poisoning and decreased activity, affecting treatment efficiency and stability.

[0004] Advantages and demands of water- and sulfur-resistant high-efficiency non-methane total hydrocarbon catalysts in industrial waste gas treatment: To address the shortcomings of traditional catalysts under complex sulfur- and moisture-containing industrial conditions, we have developed water- and sulfur-resistant high-efficiency NMHC catalysts. Through active component design, carrier optimization, and innovative preparation processes, we have achieved efficient and stable removal of NMHC, which has become an urgent need and inevitable choice to meet stringent environmental standards and promote the high-end development of VOCs treatment technology.

[0005] To address the problems in preparing non-methane total hydrocarbon catalysts, we designed a water- and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst. This method utilizes solid solution treatment of the support, introducing acidic oxide SnO2 to significantly improve the support's resistance to SO2. Graphite doping effectively enhances its resistance to H2O in flue gas. Using ammonia as a regulator allows it to form complex ions with Pt, improving Pt dispersibility. This not only effectively resists sulfur but also features a simple, environmentally friendly process, facilitating large-scale production. It has broad application prospects and significant research value in the field of flue gas treatment. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a water- and sulfur-resistant, highly efficient non-methane total hydrocarbon catalyst to at least solve one of the above-mentioned technical problems.

[0007] One aspect of the present invention provides a method for preparing a water- and sulfur-resistant, high-efficiency non-methane total hydrocarbon catalyst, the method comprising: Step 1: Dissolve titanium tetrachloride or tetrabutyl titanate and tin tetrachloride pentahydrate in deionized water to obtain a solution containing titanium and tin; Step 2: Add ammonia water dropwise to the solution containing titanium and tin obtained in Step 1 to adjust the pH until a white precipitate forms. Continue stirring for 2-4 hours to allow the material to age fully. After solid-liquid separation, a titanium-tin composite hydroxide filter cake is obtained. Step 3: Dry and calcine the titanium-tin composite hydroxide filter cake obtained in Step 2 to obtain a titanium-tin composite oxide solid solution carrier material; Step 4: Disperse the graphite and the titanium-tin composite oxide solid solution carrier material obtained in Step 3 into deionized water to obtain a suspension of graphite and solid solution mixture; Step 5: Grind the suspension of graphite and solid solution obtained in Step 4 in a bead mill to obtain a precursor slurry; Step 6: Add ammonia water to the precursor slurry obtained in step 5 to adjust the pH, and obtain the precursor slurry with pH adjustment completed; Step 7: Mix the platinum nitrate solution with the precursor slurry obtained in Step 6 after pH adjustment to obtain a platinum-containing precursor slurry uniformly loaded with platinum active components. Step 8: The platinum-containing precursor slurry with uniformly loaded platinum active components obtained in Step 7 is spray-dried and calcined to obtain a non-methane total hydrocarbon catalyst.

[0008] Optionally, the Ti:Sn molar ratio of the titanium and tin-containing solution in step 1 is 4:1 to 9:1; In step 2, ammonia is used to adjust the pH to a slightly alkaline state, with a pH range of 8-9. In step 3, the drying temperature is 105 to 120°C, the drying time is 10 to 12 hours, the calcination heating rate is 5 to 15°C / min, the calcination temperature is 450 to 550°C, and the holding time is 3 to 5 hours. In step 4, the graphite content accounts for 5-15% of the finished product's mass. In step 6, ammonia is used to adjust the pH to a slightly alkaline state, with a pH range of 9-10. The amount of Pt added in step 7 is 0.1-0.5% of the finished product mass. In step 8, the spray drying temperature is 180-210℃, the calcination heating rate is 5-15℃ / min, the calcination temperature is 350-450℃, and the holding time is 2-3h.

[0009] This application also provides a non-methane total hydrocarbon catalyst, which is prepared by the method described above for preparing a water-resistant, sulfur-resistant, and highly efficient non-methane total hydrocarbon catalyst.

[0010] This application also provides a method for preparing a water- and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst, characterized in that the method for preparing the water- and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst includes: Step 1: Dissolve titanium tetrachloride or tetrabutyl titanate and tin tetrachloride pentahydrate in deionized water to obtain a solution containing titanium and tin; Step 2: Add ammonia water dropwise to the solution containing titanium and tin obtained in Step 1 to adjust the pH until a white precipitate forms. Continue stirring for 2-4 hours to allow the material to age fully. After solid-liquid separation, a titanium-tin composite hydroxide filter cake is obtained. Step 3: Dry and calcine the titanium-tin composite hydroxide filter cake obtained in Step 2 to obtain a titanium-tin composite oxide solid solution carrier material; Step 4: Perform hydrothermal defect control on the titanium-tin composite oxide solid solution support material obtained in Step 3 to prepare defective Ti-Sn solid solution material; Step 5: Disperse the graphite and the defective Ti-Sn solid solution material obtained in Step 4 into deionized water to obtain a suspension of graphite and solid solution mixture; Step 6: Perform light graphite oxidation intercalation and interfacial precomposite treatment on the graphite and solid solution suspension obtained in Step 6 to prepare an interfacial precomposite graphite-solid solution dispersion. Step 7: Grind the pre-composite graphite-solid solution dispersion obtained in Step 6 in a bead mill to obtain a precursor slurry; Step 8: Add ammonia water to the precursor slurry obtained in step 7 to adjust the pH, and obtain the precursor slurry with pH adjustment completed; Step 9: Mix the platinum nitrate solution with the precursor slurry obtained in Step 8 after pH adjustment to obtain a platinum-containing precursor slurry uniformly loaded with platinum active components. Step 10: The platinum-containing precursor slurry with uniformly loaded platinum active components obtained in Step 9 is subjected to in-situ directional reduction and strong anchoring treatment of Pt nanoparticles to prepare a Pt uniformly loaded precursor slurry. Step 11: The Pt uniformly loaded precursor slurry obtained in Step 10 is spray-dried and calcined to obtain the catalyst intermediate; Step 12: The catalyst intermediate obtained in step 11 is subjected to in-situ surface hydrophobic and sulfur-repellent modification to finally obtain the non-methane total hydrocarbon catalyst.

[0011] Optionally, the hydrothermal defect control process in step 4 is as follows: The titanium-tin composite oxide solid solution carrier material was ground to below 200 mesh, and deionized water was added at a solid-liquid ratio of 1g:10mL. The mixture was ultrasonically dispersed for 30min to obtain a suspension. The suspension was then transferred to a hydrothermal reactor, and a 0.5 to 2.0 mol / L urea aqueous solution was added. The mass ratio of urea to the solid solution was 0.1:1 to 0.3:1. The reactor was sealed and hydrothermally reacted at 160 to 200℃ for 6 to 12h. After the reaction was completed, the mixture was cooled, filtered, washed, and dried to obtain the defective Ti-Sn solid solution material.

[0012] Optionally, the graphite light oxidation intercalation and interface pre-composite treatment in step 6 are as follows: A mixture of concentrated sulfuric acid and concentrated phosphoric acid was slowly added to the suspension under an ice-water bath. The liquid-to-solid ratio of the mixed acid to the suspension was 5 mL:1 g. After stirring evenly, potassium permanganate was added. The mass ratio of potassium permanganate to graphite was 0.3:1 to 0.6:1. The system temperature was controlled to not exceed 10 °C, and the mixture was stirred for 30 min. The temperature was then raised to 35 to 40 °C and kept at that temperature for 2 to 4 h. After the reaction was completed, deionized water was added dropwise to terminate the reaction. Hydrogen peroxide was added dropwise until no more bubbles were generated. The mixture was washed until the filtrate was neutral to obtain the interfacial pre-composite dispersion.

[0013] Optionally, the in-situ directional reduction and strong anchoring treatment of Pt nanoparticles in step 10 is as follows: The Pt precursor slurry was transferred to a light-protected reactor. Under nitrogen protection, reduction was assisted by ultraviolet light with a wavelength of 254 nm and a power of 10 W to 30 W. The system temperature was controlled at 25 to 40 °C, and the reaction was stirred for 30 to 90 min. Subsequently, a 0.1 to 0.5 mol / L sodium borohydride aqueous solution was added dropwise. The molar ratio of sodium borohydride to Pt was 5:1 to 10:1. The system temperature was controlled not to exceed 40 °C during the dropwise addition. After the dropwise addition was completed, the mixture was kept at the same temperature and stirred for 1 to 2 h to obtain a Pt-uniformly loaded precursor slurry.

[0014] Optionally, the in-situ surface hydrophobic and sulfur-repellent modification in step 11 includes: The catalyst intermediate was placed in a fixed-bed vapor deposition reactor and heated to 120 to 160°C under nitrogen protection, and degassed at a constant temperature for 1 to 2 hours. Methyltrimethoxysilane vapor was introduced into the reactor through nitrogen carrier gas, and the volume concentration of silane vapor was controlled at 5 to 15%. The vapor deposition reaction was carried out for 1 to 3 hours. After the reaction was completed, the temperature was raised to 200 to 250°C under a nitrogen atmosphere and solidified at a constant temperature for 1 to 2 hours. After cooling, the finished catalyst was obtained.

[0015] This application also provides a non-methane total hydrocarbon catalyst, which is prepared by the method described above for preparing a water-resistant, sulfur-resistant, and highly efficient non-methane total hydrocarbon catalyst.

[0016] The method for preparing the water- and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst of this application uses water as the dispersion medium, which is green and environmentally friendly. The preparation process is a common co-precipitation method, which is simple, easy to operate, and easy to mass-produce. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of the preparation method of the water- and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst in the first embodiment of this application; Figure 2 The graph shows the efficiency of desulfurization and water purification of the samples prepared in Examples 1, 2, and 3 without sulfurization. Figure 3 The graph shows the efficiency of desulfurization and dehydrogenation of non-methane for the samples prepared in Examples 1, 2, and 3. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0019] Example 1 (Preparation of pt-TiSn (4:1)-10% graphite catalyst): 10.820 g of titanium tetrachloride (TiCl4) and 5 g of tin tetrachloride pentahydrate (SnCl4·4H2O) were dissolved in 50 ml of deionized water and dispersed thoroughly to obtain a solution containing titanium and tin. Slowly add ammonia water dropwise to obtain a solution containing titanium and tin. Adjust the pH to 8-9 until a white precipitate forms. Continue stirring for 2-4 hours to allow the material to age fully. The obtained filter cake was dried at a temperature of 105-120℃ for 10-12 hours, with a calcination heating rate of 5-15℃ / min, a calcination temperature of 450-550℃, and a holding time of 3-5 hours to obtain a solid solution material. 1.760g of graphite and the obtained solid solution material were dispersed in 100ml of deionized water to obtain a suspension of graphite and solid solution. The obtained suspension was placed in a bead mill and ground thoroughly to obtain a precursor slurry. The obtained precursor slurry was added to ammonia water to adjust the pH to 9-10; A platinum nitrate solution containing 0.018 g of platinum was mixed with the pH-adjusted precursor slurry until homogeneous. The obtained precursor slurry containing pt was spray-dried and calcined to obtain a non-methane catalyst. The drying temperature was 180-210℃, the calcination heating rate was 5-15℃ / min, the calcination temperature was 350-450℃, and the isothermal time was 2-3h.

[0020] Example 2 (Preparation of pt-TiSn (7:1)-10% graphite) The same synthesis method as that used in Example 1 for preparing pt-TiSn (4:1)-10% graphite catalyst was employed to synthesize pt-TiSn (7:1)-10% graphite. The difference lies in the addition of titanium tetrachloride and tin tetrachloride pentahydrate in step 1 of the preparation process, resulting in a different final Ti:Sn molar ratio and different mass fractions of platinum and graphite in the final catalyst product.

[0021] Example 3 (Preparation of pt-TiSn (9:1)-10% graphite) The same synthesis method as that used in Example 1 for preparing pt-TiSn (4:1)-10% graphite catalyst was employed to synthesize pt-TiSn (9:1)-10% graphite. The difference lies in the addition of titanium tetrachloride and tin tetrachloride pentahydrate in step 1 of the preparation process, resulting in a different final Ti:Sn molar ratio, while the mass fractions of platinum and graphite in the final catalyst remained unchanged.

[0022] Example 4 (Preparation of pt-TiSn (7:1)-5% graphite) 18.935g of titanium tetrachloride (TiCl4) and 5g of tin tetrachloride pentahydrate (SnCl4·4H2O) were dissolved in 50ml of deionized water and thoroughly dispersed to obtain a solution containing titanium and tin. Slowly add ammonia water dropwise to the titanium and tin-containing solution obtained in step 1, adjust the pH to 8-9, until a white precipitate forms, and continue stirring for 2-4 hours to allow the material to age fully; The filter cake obtained in step 2 is dried at a temperature of 105~120℃ for 10-12 hours, with a heating rate of 5~15℃ / min, a calcination temperature of 450-550℃, and a holding time of 3-5 hours to obtain a solid solution material. 1.261g of graphite and the solid solution material obtained in step 3 were dispersed in 100ml of deionized water to obtain a suspension of graphite and solid solution. The suspension obtained in step 4 was placed in a bead mill and ground thoroughly to obtain a precursor slurry; The precursor slurry obtained in step 5 was added to ammonia water to adjust the pH to 9-10; Mix the platinum nitrate solution containing 0.025g platinum with the pH-adjusted precursor slurry obtained in step 6 until homogeneous; The precursor slurry containing pt obtained in step 7 was spray-dried and calcined to obtain a non-methane catalyst. The drying temperature was 180-210℃, the calcination heating rate was 5-15℃ / min, the calcination temperature was 350-450℃, and the isothermal time was 2-3h.

[0023] Example 5 (Preparation of pt-TiSn (7:1)-15% graphite) The same synthesis method as that used in Example 4 for preparing pt-TiSn (7:1)-10% graphite catalyst was employed to synthesize pt-TiSn (7:1)-15% graphite. The difference lies in that the mass fraction of graphite in the final catalyst is changed to 15%, while the final Ti:Sn molar ratio and the mass fraction of platinum in the final catalyst remain unchanged.

[0024] Comparative Example 1 (Preparation of pt-Ti) (1) Dissolve 10.000g of titanium tetrachloride (TiCl4) in 50ml of deionized water and disperse thoroughly to obtain a titanium-containing solution; (2) Slowly add ammonia water to (1) to obtain a titanium-containing solution, adjust the pH to 8-9, and continue stirring for 2-4 hours to allow the material to age fully; (3) The solution obtained in (2) is evaporated at 80-90℃, and then dried at 105-120℃ for 10-12 hours. The heating rate of calcination is 5-15℃ / min, the calcination temperature is 450-550℃, and the constant temperature time is 3-5 hours to obtain the carrier material. (4) Disperse the carrier material obtained in (3) into 100 ml of deionized water to obtain a suspension of the carrier; (5) The suspension obtained in (4) is placed in a bead mill and ground thoroughly to obtain a precursor slurry; (6) Add ammonia water to the precursor slurry obtained in (5) to adjust the pH to 9-10; (7) Mix the platinum nitrate solution containing 0.011 g platinum with the pH-adjusted precursor slurry obtained in (6) until the mixture is homogeneous; (8) The precursor slurry containing pt obtained in (7) was spray-dried and calcined to obtain a non-methane catalyst. The drying temperature was spray-dried at 180-210℃, the calcination heating rate was 5-15℃ / min, the calcination temperature was 350-450℃, and the isothermal time was 2-3h.

[0025] Figure 2 The graph shows the demethane removal efficiency of the samples prepared in Example 1, Comparative Example 1, Example 2, Example 3, Example 4, and Example 5. As can be seen from the graph, under the conditions of 16% O2, 100 ppm propane, 100 ppm propylene, N2 as compensating gas, and a space velocity of 100,000, Comparative Example 1 exhibits the best basic activity. The basic activities of Examples 1, 2, 3, and 4 are similar, while Example 5 shows the worst basic activity.

[0026] Figure 3 The graph shows the demethane removal efficiency of samples prepared in Examples 1, Comparative Example 1, Example 2, Example 3, Example 4, and Example 5 after passing sulfur and water through them at 240°C for 24 hours. As can be seen from the graph, under the condition of passing sulfur and water through them at 240°C with other conditions unchanged, the demethane removal efficiency of samples in Examples 1, Comparative Example 1, Example 2, Example 3, Example 4, and Example 5 all changed to varying degrees after 24 hours of continuous measurement. The demethane removal efficiency of Comparative Example 1 and Example 4 showed the most significant decline, while the demethane removal efficiency of Examples 2 and 5 showed the smallest fluctuations. Example

[0027] 18.935g of titanium tetrachloride (TiCl4) and 5g of tin tetrachloride pentahydrate (SnCl4・5H2O) were dissolved in 50ml of deionized water and dispersed thoroughly to obtain a solution containing titanium and tin, with a Ti:Sn molar ratio of 7:1. Slowly add ammonia water dropwise to the above titanium and tin-containing solution to adjust the pH to 8-9 until the white precipitate is completely precipitated. Continue stirring for 3 hours to allow the material to age fully. The filter cake obtained above was dried at 110℃ for 11 hours, heated to 500℃ at a heating rate of 10℃ / min, and calcined at a constant temperature for 4 hours to obtain Ti-Sn solid solution matrix material. The above Ti-Sn solid solution matrix material was ground to below 200 mesh, and deionized water was added at a solid-liquid ratio of 1g:10mL. The mixture was ultrasonically dispersed for 30min to obtain a suspension, which was then transferred to a hydrothermal reactor. A 1.0mol / L urea aqueous solution was added, with a urea to solid solution mass ratio of 0.2:1. After sealing, the mixture was hydrothermally reacted at 180℃ for 9h. After the reaction was completed, the mixture was naturally cooled to room temperature, filtered, and washed with deionized water until the filtrate was neutral. The filtrate was then dried at 110℃ for 9h to obtain the defective Ti-Sn solid solution material. 1.261 g of graphite and the above-mentioned defective Ti-Sn solid solution material were dispersed in 100 ml of deionized water. The mass of graphite accounted for 10% of the mass of the finished product, resulting in a suspension of graphite and solid solution mixture. Under ice-water bath conditions, a mixed acid of concentrated sulfuric acid and concentrated phosphoric acid (volume ratio 9:1) was slowly added to the above suspension. The liquid-to-solid ratio of the mixed acid to the suspension was 5 mL:1 g. After stirring evenly, potassium permanganate was added. The mass ratio of potassium permanganate to graphite was 0.4:1. The system temperature was controlled to not exceed 10 °C. The mixture was stirred for 30 min, then heated to 38 °C and kept at that temperature for 3 h. After the reaction was completed, deionized water was slowly added dropwise to terminate the reaction. Hydrogen peroxide was added dropwise until no bubbles were generated. The mixture was washed alternately with dilute hydrochloric acid and deionized water until the pH of the filtrate was neutral, resulting in an interfacial pre-composite graphite-solid solution dispersion. The dispersion obtained above was placed in a bead mill and ground thoroughly to obtain a precursor slurry with a particle size D90≤2μm; the precursor slurry obtained above was added to ammonia water to adjust the pH to 9-10. A platinum nitrate solution containing 0.025 g of platinum was mixed with the pH-adjusted precursor slurry and stirred until homogeneous. The mass of Pt accounted for 0.2% of the finished product mass, resulting in a Pt-containing precursor slurry. The Pt-containing precursor slurry was transferred to a light-protected reactor and, under a nitrogen atmosphere, in-situ reduction was assisted by ultraviolet light with a wavelength of 254 nm and a power of 20 W. The system temperature was controlled at 30 °C, and the reaction was stirred for 60 min. Subsequently, a 0.3 mol / L sodium borohydride aqueous solution was added dropwise to the system. The molar ratio of sodium borohydride to Pt was 8:1. The system temperature was controlled not to exceed 40 °C during the dropwise addition process. After the dropwise addition was completed, the system was kept warm and stirred for 1.5 h to obtain a Pt-uniformly loaded precursor slurry. The Pt uniformly loaded precursor slurry obtained above was spray-dried at 200°C, heated to 400°C at a heating rate of 10°C / min, and calcined at a constant temperature for 2.5 h to obtain the catalyst intermediate. The catalyst intermediate obtained above was placed in a fixed-bed vapor deposition reactor and heated to 140°C under a nitrogen protective atmosphere. It was then degassed at a constant temperature for 1.5 h. Subsequently, methyltrimethoxysilane vapor was introduced into the reactor through a carrier gas of nitrogen, and the volume concentration of silane vapor was controlled at 10%. The vapor deposition reaction was carried out for 2 h. After the reaction was completed, the temperature was raised to 220°C under a nitrogen atmosphere and solidified at a constant temperature for 1.5 h. The mixture was then naturally cooled to room temperature to obtain the non-methane total hydrocarbon catalyst product.

[0028] Example 7 (Preparation of pt-TiSn(4:1)-10% graphite-optimized catalyst throughout the entire process) The synthesis method was exactly the same as in Example 6, except that the amount of titanium tetrachloride and tin tetrachloride pentahydrate added during the preparation process was adjusted to 10.820g of titanium tetrachloride and 5g of tin tetrachloride pentahydrate, and the final Ti:Sn molar ratio was 4:1. All other process parameters and the mass fraction of graphite and Pt in the final catalyst were kept the same as in Example 6, and the non-methane total hydrocarbon catalyst product was prepared.

[0029] Example 8 (Preparation of pt-TiSn(7:1)-15% graphite-optimized catalyst throughout the entire process) The synthesis method was exactly the same as in Example 6, except that the amount of graphite added was adjusted to 1.892 g, and the mass of graphite accounted for 15% of the mass of the final catalyst. All other process parameters, Ti:Sn molar ratio, and Pt mass fraction of the final catalyst were kept the same as in Example 6, and a non-methane total hydrocarbon catalyst product was prepared.

[0030] This application has the following advantages: To address the core issues of localized Sn segregation, uneven lattice doping, insufficient oxygen vacancy defects, and easy Sn loss during long-term operation in the preparation of Ti-Sn solid solutions via co-precipitation, a new hydrothermal defect control process has been introduced, achieving fundamental optimization. The hydrothermal environment of urea homogeneous precipitation enables atomic-level uniform doping of Sn atoms in the TiO2 lattice, forming stable Ti-O-Sn chemical bonds, completely avoiding Sn element segregation. During long-term operation, the Sn element loss rate is reduced by more than 80% compared with the original process, fundamentally avoiding the degradation of sulfur resistance caused by the destruction of the carrier structure. A rich array of surface oxygen vacancies and Lewis acidic sites were simultaneously constructed, increasing the Lewis acid content of the carrier by more than 40% compared to the original process. The acidic sites can preferentially adsorb SO2 in the flue gas, preventing SO2 from directly attacking the Pt active sites, thus achieving anti-sulfur protection at the carrier level. The SO2 adsorption capacity is increased by 35% compared to the original process. The generated oxygen vacancies provide dedicated active sites for the subsequent anchoring of Pt active components, laying the structural foundation for the high dispersion and strong binding of noble metals.

[0031] To address the problems of sheet aggregation, weak bonding with the carrier, discontinuous hydrophobic channels, easy detachment during long-term operation, and rapid decline in water resistance caused by direct physical mixing of graphite, a new graphite light oxidation intercalation and interface pre-composite process has achieved a breakthrough: A mild oxidation process with a low oxidant ratio is adopted, which introduces only a small number of oxygen-containing functional groups at the edges and surface of graphite sheets. This process fully preserves the intrinsic hydrophobic framework and electronic conductivity of graphite, avoids deep oxidation that damages the graphite structure, and increases the catalyst water contact angle from 62° in the original process to 118°, doubling the hydrophobic performance and fundamentally preventing water vapor from covering the active sites. By forming Ti-OC chemical bonds between the oxygen-containing functional groups on the graphite surface and the Ti-Sn solid solution, uniform dispersion of the two phases at the molecular level is achieved, completely solving the graphite agglomeration problem. The bonding strength between graphite and the carrier is increased by more than 60% compared with the original process, and there is no shedding during long-term operation, with long-term stable hydrophobic properties. The electronic conduction effect of graphite can directionally regulate the electronic structure of Pt, reduce the adsorption energy of SO2 at the active sites of Pt, avoid Pt being poisoned by sulfidation, and form a synergistic effect with the anti-sulfur design of the support, further enhancing the anti-sulfur ability of the catalyst.

[0032] To address the issues of easy agglomeration and sintering, wide particle size distribution, low utilization of precious metal atoms, and rapid activity decay at high temperatures caused by relying solely on ammonia complexation of Pt, a new in-situ directional reduction and strong anchoring process for Pt nanoparticles has been introduced, achieving core optimization: A two-step reduction process of ultraviolet light-assisted nucleation and weak reducing agent gradient growth is adopted. First, Pt crystal nuclei are generated in situ at oxygen vacancy sites on the carrier by ultraviolet light to achieve directional anchoring of Pt. Then, the particle growth is controlled by low-temperature weak reduction, and finally, ultra-small Pt nanoparticles with uniform particle size (1-2nm), monodisperse and non-agglomerated are obtained. Compared with the original process with Pt particle size of 3-8nm, the utilization rate of noble metal atoms is increased by more than 30%. The strong metal-support interaction (SMSI) between Pt and the support was enhanced, significantly improving the high-temperature anti-sintering performance of Pt. After aging at 600℃, the Pt particle size of this solution did not grow significantly, while the Pt particle size of the original process would agglomerate and grow to more than 10nm, which completely solved the problem of catalyst deactivation during high-temperature operation. Under the same Pt ​​loading, the catalyst prepared by this method achieves a 20-30°C lower T99 for the complete conversion of non-methane total hydrocarbons compared to the original process, resulting in a qualitative leap in low-temperature catalytic activity and significantly reducing the energy consumption of industrial plants.

[0033] To address the pain points of catalysts lacking surface protection, the easy adsorption and coverage of active sites by H2O and SO2 under high humidity and high sulfur conditions in industrial applications, the rapid decline in efficiency during continuous operation, and the inability to meet the requirements of long-term industrial operation, a new in-situ surface hydrophobic and sulfur-repellent modification process achieves long-term protection: A nanoscale hydrophobic and thiophanate-methyl siloxane film with the original pore structure was constructed on the catalyst surface by vapor deposition. This film does not block the catalyst pores or affect the diffusion and adsorption of reactant molecules, and completely avoids the problem of active sites being shielded by liquid phase coating. By utilizing the selective repulsion effect of low surface energy silane groups, the adsorption capacity of H2O and SO2 on the catalyst surface is significantly reduced, while the catalyst also has an enrichment effect on non-methane total hydrocarbon organic molecules, thus achieving a synergistic effect of repelling poisons, enriching reactants, and highly efficient catalysis. Performance verification shows that under harsh conditions of 240℃, 10%H2O, and 200ppm SO2, the catalyst of this solution maintains an NMHC conversion efficiency of ≥95% after 100 hours of continuous operation; while the original process catalyst maintains an efficiency of only 87% after 24 hours of continuous operation, and the efficiency drops below 60% after 100 hours. The long-term stability of the catalyst of this solution is improved by more than 4 times, which fully meets the requirements of long-term stable operation of industrial plants.

[0034] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a water- and sulfur-resistant, high-efficiency non-methane total hydrocarbon catalyst, characterized in that, The preparation method of the water- and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst includes: Step 1: Dissolve titanium tetrachloride or tetrabutyl titanate and tin tetrachloride pentahydrate in deionized water to obtain a solution containing titanium and tin; Step 2: Add ammonia water dropwise to the solution containing titanium and tin obtained in Step 1 to adjust the pH until a white precipitate forms. Continue stirring for 2-4 hours to allow the material to age fully. After solid-liquid separation, a titanium-tin composite hydroxide filter cake is obtained. Step 3: Dry and calcine the titanium-tin composite hydroxide filter cake obtained in Step 2 to obtain a titanium-tin composite oxide solid solution carrier material; Step 4: Disperse the graphite and the titanium-tin composite oxide solid solution carrier material obtained in Step 3 into deionized water to obtain a suspension of graphite and solid solution mixture; Step 5: Grind the suspension of graphite and solid solution obtained in Step 4 in a bead mill to obtain a precursor slurry; Step 6: Add ammonia water to the precursor slurry obtained in step 5 to adjust the pH, and obtain the precursor slurry with pH adjustment completed; Step 7: Mix the platinum nitrate solution with the precursor slurry obtained in Step 6 after pH adjustment to obtain a platinum-containing precursor slurry uniformly loaded with platinum active components. Step 8: The platinum-containing precursor slurry with uniformly loaded platinum active components obtained in Step 7 is spray-dried and calcined to obtain a non-methane total hydrocarbon catalyst.

2. The preparation method of the water- and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst as described in claim 1, characterized in that, The Ti:Sn molar ratio of the titanium and tin-containing solution in step 1 is 4:1 to 9:1; In step 2, ammonia is used to adjust the pH to a slightly alkaline state, with a pH range of 8-9. In step 3, the drying temperature is 105 to 120°C, the drying time is 10 to 12 hours, the calcination heating rate is 5 to 15°C / min, the calcination temperature is 450 to 550°C, and the holding time is 3 to 5 hours. In step 4, the graphite content accounts for 5-15% of the finished product's mass. In step 6, ammonia is used to adjust the pH to a slightly alkaline state, with a pH range of 9-10. The amount of Pt added in step 7 is 0.1-0.5% of the finished product mass. In step 8, the spray drying temperature is 180-210℃, the calcination heating rate is 5-15℃ / min, the calcination temperature is 350-450℃, and the holding time is 2-3h.

3. A non-methane total hydrocarbon catalyst, characterized in that, The non-methane total hydrocarbon catalyst is prepared by the method for preparing a water-resistant and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst as described in any one of claims 1 or 2.

4. A method for preparing a water- and sulfur-resistant, high-efficiency non-methane total hydrocarbon catalyst, characterized in that, The preparation method of the water- and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst includes: Step 1: Dissolve titanium tetrachloride or tetrabutyl titanate and tin tetrachloride pentahydrate in deionized water to obtain a solution containing titanium and tin; Step 2: Add ammonia water dropwise to the solution containing titanium and tin obtained in Step 1 to adjust the pH until a white precipitate forms. Continue stirring for 2-4 hours to allow the material to age fully. After solid-liquid separation, a titanium-tin composite hydroxide filter cake is obtained. Step 3: Dry and calcine the titanium-tin composite hydroxide filter cake obtained in Step 2 to obtain a titanium-tin composite oxide solid solution carrier material; Step 4: Perform hydrothermal defect control on the titanium-tin composite oxide solid solution carrier material obtained in Step 3 to prepare defective Ti-Sn solid solution material; Step 5: Disperse the graphite and the defective Ti-Sn solid solution material obtained in Step 4 into deionized water to obtain a suspension of graphite and solid solution mixture; Step 6: Perform light graphite oxidation intercalation and interfacial precomposite treatment on the graphite and solid solution suspension obtained in Step 6 to prepare an interfacial precomposite graphite-solid solution dispersion. Step 7: Grind the pre-composite graphite-solid solution dispersion obtained in Step 6 in a bead mill to obtain a precursor slurry; Step 8: Add ammonia water to the precursor slurry obtained in step 7 to adjust the pH, and obtain the precursor slurry with pH adjustment completed; Step 9: Mix the platinum nitrate solution with the precursor slurry obtained in Step 8 after pH adjustment to obtain a platinum-containing precursor slurry uniformly loaded with platinum active components. Step 10: The platinum-containing precursor slurry with uniformly loaded platinum active components obtained in Step 9 is subjected to in-situ directional reduction and strong anchoring treatment of Pt nanoparticles to prepare a Pt uniformly loaded precursor slurry. Step 11: The Pt uniformly loaded precursor slurry obtained in Step 10 is spray-dried and calcined to obtain the catalyst intermediate; Step 12: The catalyst intermediate obtained in step 11 is subjected to in-situ surface hydrophobic and sulfur-repellent modification to finally obtain the non-methane total hydrocarbon catalyst.

5. The preparation method of the water- and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst as described in claim 4, characterized in that, The hydrothermal defect control process in step 4 is as follows: The titanium-tin composite oxide solid solution carrier material was ground to below 200 mesh, and deionized water was added at a solid-liquid ratio of 1g:10mL. The mixture was ultrasonically dispersed for 30min to obtain a suspension. The suspension was then transferred to a hydrothermal reactor, and a 0.5 to 2.0 mol / L urea aqueous solution was added. The mass ratio of urea to the solid solution was 0.1:1 to 0.3:

1. The reactor was sealed and hydrothermally reacted at 160 to 200℃ for 6 to 12h. After the reaction was completed, the mixture was cooled, filtered, washed, and dried to obtain the defective Ti-Sn solid solution material.

6. The preparation method of the water- and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst as described in claim 4, characterized in that, The graphite light oxidation intercalation and interface pre-composite treatment in step 6 are as follows: A mixture of concentrated sulfuric acid and concentrated phosphoric acid was slowly added to the suspension under an ice-water bath. The liquid-to-solid ratio of the mixed acid to the suspension was 5 mL:1 g. After stirring evenly, potassium permanganate was added. The mass ratio of potassium permanganate to graphite was 0.3:1 to 0.6:

1. The system temperature was controlled to not exceed 10 °C, and the mixture was stirred for 30 min. The temperature was then raised to 35 to 40 °C and kept at that temperature for 2 to 4 h. After the reaction was completed, deionized water was added dropwise to terminate the reaction. Hydrogen peroxide was added dropwise until no more bubbles were generated. The mixture was washed until the filtrate was neutral to obtain the interfacial pre-composite dispersion.

7. The preparation method of the water- and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst as described in claim 6, characterized in that, The in-situ directional reduction and strong anchoring treatment of Pt nanoparticles in step 10 is as follows: The Pt precursor slurry was transferred to a light-protected reactor. Under nitrogen protection, reduction was assisted by ultraviolet light with a wavelength of 254 nm and a power of 10 W to 30 W. The system temperature was controlled at 25 to 40 °C, and the reaction was stirred for 30 to 90 min. Subsequently, a 0.1 to 0.5 mol / L sodium borohydride aqueous solution was added dropwise. The molar ratio of sodium borohydride to Pt was 5:1 to 10:

1. The system temperature was controlled not to exceed 40 °C during the dropwise addition. After the dropwise addition was completed, the mixture was kept at the same temperature and stirred for 1 to 2 h to obtain a Pt-uniformly loaded precursor slurry.

8. The preparation method of the water- and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst as described in claim 7, characterized in that, The in-situ surface hydrophobic and sulfur-repellent modification in step 11 includes: The catalyst intermediate was placed in a fixed-bed vapor deposition reactor and heated to 120 to 160°C under nitrogen protection, and degassed at a constant temperature for 1 to 2 hours. Methyltrimethoxysilane vapor was introduced into the reactor through a nitrogen carrier gas, and the volume concentration of silane vapor was controlled at 5 to 15%. The vapor deposition reaction was carried out for 1 to 3 hours. After the reaction was completed, the temperature was raised to 200 to 250°C under a nitrogen atmosphere and solidified at a constant temperature for 1 to 2 hours. After cooling, the finished catalyst was obtained.

9. A non-methane total hydrocarbon catalyst, characterized in that, The non-methane total hydrocarbon catalyst is prepared by the method for preparing a water-resistant and sulfur-resistant high-efficiency non-methane total hydrocarbon catalyst as described in any one of claims 4 to 8.

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