PtCo (x%) / TiO2 catalyst for catalytic combustion of vinyl chloride and preparation method and application of PtCo (x%) / TiO2 catalyst
The PtCo(x%)/TiO2 catalyst prepared by equal volume impregnation method uses TiO2 support to wrap Pt and Co species, enhance oxidation performance and acidic sites, solve the problems of reduced catalyst activity and generation of polychlorinated by-products, and realize chlorine Ethylene is highly efficient and fully oxidized and has low temperature emissions.
Patent Information
- Application Number
- CN202411429292.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-14
- Publication Date
- 2024-12-13
AI Technical Summary
During the catalytic combustion process, existing catalysts are prone to produce polychlorinated by-products and platinum species poisoning, resulting in reduced activity and incomplete oxidation, and it is difficult to effectively degrade chlorine-containing volatile organic compounds.
The PtCo(x%)/TiO2 catalyst was prepared by equal volume impregnation method, and the Pt and Co species were encapsulated through the TiO2 support, which enhanced oxidative performance and acidic sites, and inhibited the formation of polychlorinated by-products.
It improves the activity, selectivity and stability of the catalyst, avoids the formation of polychlorinated by-products, and achieves complete oxidation of vinyl chloride and low-temperature emissions.
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Abstract
Description
Technical Field
[0001] The present invention relates to a PtCo(x%) / TiO2 catalyst for catalytic combustion of vinyl chloride. 2 Catalyst and preparation method and application thereof, specifically, preparation of PtCo(x%) / TiO by equal volume impregnation method 2 Catalyst, belongs to the field of air pollution control. Background Art
[0002] Chlorinated volatile organic compounds (CVOCs) are important intermediates in industrial processes. Factories will inevitably release these compounds, causing serious harm to human health. At present, my country has formulated strict standards for the emission of air pollutants. For example, the "Emission Standards for Pollutants from Caustic Soda and Polyvinyl Chloride Industries" (GB 15581-2016) clearly stipulates that the emission concentration limit of vinyl chloride (VC) is 10 mg / m 3 The emission concentration limit of dichloroethane (DCE) is 5 mg / m 3 .
[0003] At present, the commonly used CVOCs catalytic combustion catalysts are mostly supported precious metal catalysts, transition metal oxide catalysts, perovskite catalysts and solid acid catalysts. Among them, precious metal catalysts (such as supported Pt, Pd and Ru catalysts) usually have high catalytic activity and thus have received extensive attention in industrial applications. Platinum-based catalysts have been widely studied due to their unique redox ability, which is conducive to the deep oxidation of chlorinated hydrocarbons and has high catalytic activity. For example, the Pt / CeO 2 -Al 2 O 3 The catalyst has excellent dichloromethane catalytic activity due to the formation of Ce-Pt-O solid solution. However, due to the lack of acidic sites, especially Bronsted acidic sites, the platinum species will be deactivated by poisoning by the formed chlorine species and produce a large amount of polychlorinated by-products. 2 Due to its excellent electron transfer ability, thermal stability and acidity, it is used for the effective degradation of CVOCs. At the same time, the supported bimetallic catalyst shows a unique synergistic effect, which is expected to maintain the reactivity of Pt species by removing chlorine species and reducing polychlorinated byproducts.
[0004] Although the various catalysts mentioned in the literature have their own advantages, there are still some inevitable problems. On the one hand, excessive redox ability during catalytic combustion is prone to produce polychlorinated byproducts, leading to secondary pollution; on the other hand, surface chlorine species poisoning can lead to the deactivation of the active center of the catalyst, thereby reducing its activity and producing incomplete oxidation byproducts. Therefore, the development of catalysts with balanced redox ability and acidity has great practical application prospects. Summary of the invention
[0005] The object of the present invention is to provide a Pt-based catalyst for catalytic combustion of vinyl chloride and a preparation method thereof, so as to overcome the shortcomings of existing catalysts.
[0006] The PtCo(x%) / TiO2 used for catalytic combustion reaction of vinyl chloride according to the present invention 2 The composition and weight percentage content of the catalyst are: Pt 1% Co 1~20% TiO 2 79~98%
[0007] The PtCo(x%) / TiO2 used for catalytic combustion reaction of vinyl chloride according to the present invention 2 TiO in Catalysts 2 The carrier is prepared by a sol-gel method, which specifically includes the following steps: dissolving a certain amount of tetrabutyl titanate in a mixed solution of anhydrous ethanol and glacial acetic acid, slowly dropping a mixed solution of anhydrous ethanol, water and ammonia water into the above solution, vigorously stirring for 6 to 12 hours under heating in a water bath at 25 to 60°C, standing and aging at room temperature for 12 to 24 hours, then drying at 80 to 120°C for 8 to 12 hours, and then calcining at 500°C for 2 to 6 hours.
[0008] The PtCo(x%) / TiO2 used for catalytic combustion reaction of vinyl chloride according to the present invention 2 The catalyst was prepared by an equal volume impregnation method, which specifically includes the following steps: mixing the required amount of platinum precursor solution, cobalt nitrate and a certain amount of deionized water, and slowly dropping them into a certain mass of TiO 2 The mixture is ultrasonically stirred for 30 minutes to 2 hours, taken out and aged at room temperature for 12 to 24 hours, dried at 80 to 120°C for 8 to 12 hours, and then calcined at 500°C for 2 to 6 hours.
[0009] The PtCo(x%) / TiO 2 The catalyst is used in the catalytic combustion reaction of vinyl chloride. The catalytic reaction conditions are: the concentration of vinyl chloride is 1000-4000 ppm, and the reaction space velocity is 30000-60000 mL·g-1 ·h -1 .
[0010] The significant advantage of the preparation method of the catalyst of the present invention is that Pt and Co are co-loaded on TiO 2 On the support, PtCo(x%) / TiO was prepared 2 Catalyst, when the cobalt content is 1%, Pt and Co species are replaced by TiO 2 The thin cover layer of the support wraps the PtCo species with the TiO 2 There is a strong interaction between them, which can maintain the catalyst structure before and after the reaction, inhibit the deactivation of platinum species, and make the catalyst have better activity and stability.
[0011] The significant advantage of the preparation method of the catalyst of the present invention is that the bimetallic synergy between PtCo species and the interaction between the carriers produce more oxygen vacancies, thereby enhancing the oxidation performance of the catalyst, which is beneficial to the deep oxidation of chlorine-containing byproducts. 2 The Brønsted acid sites on the surface are beneficial to the removal of chlorine species, which greatly suppresses the production of chlorine-containing by-products and greatly improves the selectivity of the catalyst.
[0012] One of the significant advantages of the catalyst of the present invention is that it does not generate more toxic polychlorinated by-products, thus avoiding secondary pollution, and can completely oxidize vinyl chloride into hydrogen chloride or chlorine, carbon dioxide and water at a relatively low reaction temperature, which is then absorbed by alkaline solution to achieve standard emission of vinyl chloride waste gas.
[0013] The second significant advantage of the catalyst of the present invention is that PtCo(x%) / TiO is prepared by an equal volume impregnation method. 2 The catalyst can significantly improve the activity, selectivity and stability of the catalyst, and the preparation method is simple and easy to implement industrialization. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 is the Co content for 1 wt.% PtCo(x%) / TiO 2 The influence of catalyst on vinyl chloride catalytic activity; Figure 2 is the reaction space velocity for 1 wt.% PtCo(1%) / TiO 2 The influence of catalyst on vinyl chloride catalytic activity; Figure 3 is the effect of vinyl chloride concentration on 1 wt.% PtCo(1%) / TiO 2 The influence of catalyst on vinyl chloride catalytic activity; Figure 4 shows 1 wt.% PtCo(1%) / TiO 224-hour stability of the catalyst in catalytic combustion of vinyl chloride (4a) and the corresponding CO 2 Selectivity (4b). DETAILED DESCRIPTION
[0015] The present invention will be described in detail below with reference to specific embodiments, but this does not limit the protection scope of the present invention.
[0016] Comparative Example TiO 2 Preparation of the carrier: 4.25 g of tetrabutyl titanate was dissolved in a solution of 20 mL of anhydrous ethanol and 1.37 g of glacial acetic acid to obtain solution A; 10 mL of anhydrous ethanol was mixed with 10 mL of water and 2 mL of aqueous ammonia (28 wt.%) to obtain solution B; solution B was slowly added dropwise to solution A, stirred vigorously for 10 hours under heating in a water bath at 60 °C, aged at room temperature for 12 hours, then dried at 80 °C for 12 hours, and then calcined at 500 °C for 4 hours.
[0017] 1 wt.% Pt / TiO 2 Catalyst preparation: 0.306 g of Pt(NO 3 ) 2 The precursor solution (Pt content of 6.6 wt.%) was mixed with 2.1 g of deionized water and slowly added dropwise to 2 g of TiO 2 The mixture was ultrasonically stirred for 1 hour, taken out and aged at room temperature for 12 hours, dried at 80°C for 12 hours, and then calcined at 500°C for 4 hours. Example
[0018] 1 wt.% PtCo(1%) / TiO 2 Catalyst preparation: 0.309 g of Pt(NO 3 ) 2 Precursor solution (Pt content 6.6 wt.%), 0.101 g of cobalt nitrate and 2.1 g of deionized water were mixed and slowly added dropwise to 2 g of TiO 2 The mixture was ultrasonically stirred for 1 hour, taken out and aged at room temperature for 12 hours, dried at 80°C for 12 hours, and then calcined at 500°C for 4 hours.
[0019] The catalytic performance evaluation conditions are as follows: the catalytic oxidation activity of CVOCs was tested in a fixed bed reactor. 240 mg of catalyst (40-60 mesh) was placed at the bottom and diluted with the same amount of quartz sand. The flow rate of dry air was controlled at 120 mL min -1 , corresponding to 30000 mL g -1 ·h -1The weight hourly space velocity was 1000 ppm. The concentration of vinyl chloride was 1000 ppm. During the test experiment, the reactor temperature was heated from 100 °C to 550 °C. The composition of the tail gas was analyzed by an online gas chromatograph with a flame ionization detector.
[0020] Change 1 wt.% PtCo(x%) / TiO 2 The Co contents in the catalysts are 1, 5, 10 and 20% respectively. 1 wt.%PtCo(x%) / TiO 2 The other preparation processes of the catalyst were the same as those of 1 wt.% PtCo(1%) / TiO 2 The catalyst is the same.
[0021] Effect of Co content on 1 wt.% PtCo(x%) / TiO 2 The influence of catalyst on vinyl chloride catalytic activity Figure 1 shown. Example
[0022] The reaction space velocity was changed to 30000, 40000, 50000 and 60000 mL·g -1 ·h -1 1 wt.% PtCo(1%) / TiO 2 The preparation process of the catalyst and the performance evaluation conditions of other catalysts are the same as those in Example 1.
[0023] Effect of reaction space velocity on 1 wt.% PtCo(1%) / TiO 2 The influence of catalyst on vinyl chloride catalytic activity Figure 2 shown. Example
[0024] The concentration of vinyl chloride was changed to 1000, 2000, 3000 and 4000 ppm. 1 wt.% PtCo(1%) / TiO 2 The preparation process of the catalyst and the performance evaluation conditions of other catalysts are the same as those in Example 1.
[0025] Effect of vinyl chloride concentration on 1 wt.% PtCo(1%) / TiO 2 The influence of catalyst on vinyl chloride catalytic activity Figure 3 shown. Example
[0026] 0.24 g of 1 wt.% PtCo(1%) / TiO prepared in Example 1 was added 2 The catalyst was placed in a quartz tube fixed bed reactor, with air as the oxidant, at a vinyl chloride concentration of 1000 ppm and a reaction space velocity of 30000 mL g -1 ·h-1 The catalytic combustion reaction of vinyl chloride was carried out for 24 hours under the conditions of reaction temperature of 360 °C to investigate the high temperature stability of the catalyst. The experimental results are shown in Figure 4. As can be seen from Figure 4, within the reaction time of 24 hours, the conversion rate of vinyl chloride achieved 100% conversion rate and was stable. No polychlorinated by-products were produced during the reaction process, and CO 2 The selectivity is 100%. Therefore, the catalyst has excellent high temperature stability.
Claims
1. A PtCo(x%) / TiO2 catalyst for catalytic combustion of vinyl chloride, characterized in that: The composition and weight percentage content of the catalyst are: Pt 1% Co 1~20% TiO2 79~98%.
2. The PtCo(x%) / TiO2 catalyst for catalytic combustion of vinyl chloride according to claim 1, characterized in that: The TiO2 carrier is prepared by a sol-gel method, which specifically includes the following steps: dissolving a certain amount of tetrabutyl titanate in a mixed solution of anhydrous ethanol and glacial acetic acid, slowly dropping a mixed solution of anhydrous ethanol, water and ammonia water into the above solution, vigorously stirring for 6 to 12 hours under water bath heating at 25 to 60°C, standing and aging at room temperature for 12 to 24 hours, then drying at 80 to 120°C for 8 to 12 hours, and then calcining at 500°C for 2 to 6 hours.
3. A method for preparing the PtCo(x%) / TiO2 catalyst for catalytic combustion of vinyl chloride as claimed in claim 1 and claim 2, characterized in that: The preparation method is an equal volume impregnation method, which specifically includes the following steps: mixing a required amount of platinum precursor solution, cobalt nitrate and a certain amount of deionized water, slowly dropping them onto a certain mass of TiO2 carrier, ultrasonically stirring the mixture for 30 minutes to 2 hours, taking it out and standing it for aging at room temperature for 12 to 24 hours, drying it at 80 to 120°C for 8 to 12 hours, and then calcining it at 500°C for 2 to 6 hours.
4. The use of the PtCo(x%) / TiO2 catalyst for catalytic combustion of vinyl chloride according to claim 1, characterized in that: The catalytic reaction conditions are: the concentration of vinyl chloride is 1000-4000 ppm, and the reaction space velocity is 30000-60000 mL·g -1 ·h -1 .