A catalyst and method for catalytic purification of terephthalic acid waste gas

Abstract

This invention relates to a catalyst and method for the catalytic purification of terephthalic acid waste gas. The catalyst is primarily composed of titanium-aluminum composite oxides with good resistance to halogen poisoning. It is obtained by introducing Ce, which has excellent oxygen storage properties, into the amorphous titanium-aluminum composite oxide unit cells, and loading it with the highly active noble metal Pt and the dehalogenating agent Mn. This catalyst exhibits good catalytic oxidation activity for typical methyl acetate, benzene, and bromomethane in terephthalic acid waste gas, demonstrates relatively stable catalytic purification capacity for bromomethane, has low polybrominated byproducts, high selectivity for carbon dioxide, and is resistant to temperature and humidity, making it highly valuable for industrial applications.

Description

Technical Field

[0001] This invention belongs to the field of industrial waste gas treatment technology, specifically relating to a catalyst for the catalytic purification of terephthalic acid waste gas, and a method for purifying terephthalic acid waste gas using the catalyst. Background Technology

[0002] Purified terephthalic acid (PTA) is an important chemical raw material. Key production processes include oxidation and refining. The oxidation stage uses terephthalic acid as raw material, acetic acid as solvent, and bromide as a promoter, and oxidizes it in air under the action of a catalyst to obtain crude terephthalic acid. The refining stage involves catalytic hydrogenation of the crude terephthalic acid under high temperature and high pressure conditions, followed by impurity removal and other post-treatments to obtain the final product. Most of the PTA waste gas originates from the oxidation reaction process. The waste gas components include nitrogen, oxygen, water vapor, carbon monoxide, carbon dioxide, and VOCs (benzene, xylene, p-xylene, acetic acid, acetate esters, brominated hydrocarbons, etc.). The composition is complex and corrosive, making purification difficult and posing a significant threat to the environment.

[0003] Catalytic combustion is currently the most efficient method for purifying PTA waste gas. The waste gas enters a catalytic burner and is converted into carbon dioxide, water, bromine, and hydrogen bromide at 200–500℃. After bromine removal by an auxiliary spray tower, emissions can meet standards. The large-volume PTA waste gas treatment process is characterized by high temperature, oxygen deficiency, and the presence of water and halogens. General VOCs catalytic combustion catalysts are often insufficient for practical applications. The catalytic combustion of brominated hydrocarbons is particularly challenging, placing higher demands on catalyst performance. Currently, catalysts for PTA waste gas catalytic combustion mainly consist of noble metals Pd, Pt, and Ru catalysts, and non-noble metals Cu, Co, and Mn oxides. However, publicly available Pd and Pt catalysts either have poor bromine resistance or low selectivity. Ru-based catalysts are reported to produce RuO4 and vaporize in oxidation environments above 450℃. As for non-noble metal catalysts, their stability is a significant issue, preventing their industrial application. Summary of the Invention

[0004] The purpose of this invention is to address the characteristics of waste gas generated in the PTA industry, overcome the shortcomings of existing catalysts such as weak resistance to bromine poisoning, poor stability, and poor resistance to moisture, and provide a catalyst with excellent catalytic performance for the catalytic purification of PTA waste gas, as well as a method for purifying terephthalic acid waste gas using this catalyst.

[0005] To achieve the above objectives, the catalyst used in this invention for the catalytic purification of PTA waste gas is a titanium-aluminum composite oxide with good resistance to halogen poisoning. It is obtained by introducing Ce, which has excellent oxygen storage properties, into the amorphous titanium-aluminum composite oxide unit cell, and loading it with the highly active noble metal Pt and the dehalogen-resistant Mn. In the titanium-aluminum composite oxide, the molar ratio of Ti to Al is 1:1 to 1:12, and the loading amounts of Ce, Pt, and Mn are 1% to 20%, 1% to 5%, and 1% to 5% of the mass of the titanium-aluminum composite oxide, respectively.

[0006] In the above catalyst, it is further preferred that the molar ratio of Ti to Al in the titanium-aluminum composite oxide is 1:5 to 8, and the loadings of Ce, Pt, and Mn are 5% to 10%, 2%, and 2% to 4% of the mass of the titanium-aluminum composite oxide, respectively.

[0007] The preparation method of the catalyst for PTA waste gas catalytic purification of the present invention includes the following steps:

[0008] Step 1: Add aluminum isopropoxide to deionized water, heat to 80-100℃ and stir at a constant temperature until hydrolysis is achieved to obtain an aluminum solution; dissolve titanium oxysulfate in deionized water and add it dropwise to the aluminum solution, continue stirring at a constant temperature for 6-10 hours, let stand for aging for 12-24 hours, dry at 80-120℃ and calcine at 200-600℃ to obtain titanium-aluminum composite oxide;

[0009] Step 2: Dissolve cerium salt in deionized water, impregnate the titanium-aluminum composite oxide obtained in step 1 for 2-4 hours, then dry at 80-120℃ and calcine at 400-600℃ to obtain cerium-loaded titanium-aluminum composite oxide.

[0010] Step 3: Dissolve the platinum precursor and manganese salt in deionized water, and impregnate the cerium-supported titanium-aluminum composite oxide obtained in step 2 for 2-4 hours, followed by drying at 80-120°C and calcining at 200-600°C to obtain the catalyst.

[0011] In step 1 above, the preferred roasting temperature is 200℃.

[0012] In step 2 above, the cerium salt is any one of cerium nitrate, cerium chloride, cerium ammonium nitrate, cerium acetate, and cerium oxalate.

[0013] In step 2 above, the preferred calcination temperature is 600℃.

[0014] In step 3 above, the platinum precursor is any one of platinum nitrate, chloroplatinic acid, and tetraammineplatinum nitrate; the manganese salt is any one of manganese nitrate, manganese chloride, and manganese acetate.

[0015] In step 3 above, the preferred calcination temperature is 400℃.

[0016] The method for using the catalyst of this invention for catalytic purification of terephthalic acid waste gas is as follows: The catalyst is mixed with deionized water and ball-milled, and nitric acid and a dispersant are added dropwise to adjust the viscosity, obtaining a coating solution; cut cordierite honeycomb ceramics are impregnated and coated in the coating solution, dried at 80–120°C, and calcined at 400–600°C to obtain a coated honeycomb catalyst with a Pt loading of 1–2 g / L and a powder catalyst loading of 50–100 g / L; terephthalic acid waste gas is introduced into a catalytic combustion reactor filled with the coated honeycomb catalyst and subjected to combustion at 200–600°C for 5000–30000 h. -1 At air velocity, methyl acetate, xylene, and dibromomethane in the exhaust gas are catalytically combusted to produce carbon dioxide, water, hydrogen bromide, and elemental bromine.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] In this invention, the titanium-aluminum composite oxide is prepared by hydrolysis of titanium oxysulfate and aluminum isopropoxide. Ce is introduced into the titanium-aluminum composite oxide before it reaches its amorphous state via impregnation. Pt and Mn are supported by impregnation. The titanium-aluminum composite oxide support is more stable and has stronger bromine resistance. Introducing Ce, which has excellent oxygen storage properties, into the unit cell before the titanium-aluminum composite oxide reaches its amorphous state improves the catalyst's oxygen storage performance. The support of high-temperature stable Pt and Mn, which has good debromination ability, gives the catalyst better catalytic oxidation performance of brominated hydrocarbons. This catalyst exhibits good catalytic oxidation activity for typical methyl acetate, benzene, and bromomethane in PTA waste gas, has a relatively stable catalytic purification capacity for bromomethane, low polybrominated byproducts, high selectivity for carbon dioxide, and is resistant to temperature and humidity, making it highly valuable for industrial applications. Attached Figure Description

[0019] Figure 1 These are the stability curves of the catalysts prepared in Examples 1-10 and Comparative Examples 1-2 for the catalytic conversion of bromomethane.

[0020] Figure 2 These are the yield curves of polybrominated products after catalytic conversion of bromomethane by the catalysts prepared in Examples 1-10 and Comparative Examples 1-2. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0022] Example 1

[0023] In this embodiment, the molar ratio of Ti to Al in the titanium-aluminum composite oxide is 1:1, and the loadings of Ce, Pt, and Mn are 5%, 2%, and 4% of the mass of the titanium-aluminum composite oxide, respectively. The catalyst is prepared as follows:

[0024] Step 1: Weigh 40.8g of aluminum isopropoxide and add it to 200mL of water. Heat the solution to 80℃ and stir until it becomes a transparent gel to obtain an aluminum solution. Weigh 32.0g of titanium oxysulfate and dissolve it in 160mL of deionized water. Add the solution dropwise to the aluminum solution and continue stirring at 80℃ for 8 hours. Let it stand and age for 12 hours, dry it at 100℃ for 12 hours, and calcine it at 200℃ for 4 hours to obtain a titanium-aluminum composite oxide, denoted as TiAl-200.

[0025] Step 2: Weigh 4.27g of cerium nitrate hexahydrate and dissolve it in 130mL of water. Then add the TiAl-200 prepared in Step 1 and stir vigorously until it becomes a gel. Let it stand for 2 hours, dry it at 100℃ for 12 hours, and calcine it at 600℃ for 4 hours to obtain cerium-loaded titanium aluminum composite oxide, denoted as Ce5 / TiAl.

[0026] Step 3: Dilute 4 mL of 0.1 g / mL platinum nitrate aqueous solution and 5.21 g of 50% manganese nitrate aqueous solution with water to 100 mL, weigh 18.8 g of Ce5 / TiAl prepared in Step 2, add it to the solution and stir to impregnate for 2 hours, dry at 100℃ for 12 hours, and calcine at 400℃ for 4 hours to obtain the catalyst, denoted as Pt2Mn4 / Ce5 / TiAl.

[0027] Example 2

[0028] In this embodiment, the molar ratio of Ti to Al in the titanium-aluminum composite oxide is 1:2, and the loadings of Ce, Pt, and Mn are 5%, 2%, and 4% of the mass of the titanium-aluminum composite oxide, respectively. The catalyst is prepared as follows:

[0029] Step 1: Weigh 40.8g of aluminum isopropoxide and add it to 200mL of water. Heat the mixture to 80℃ and stir until it becomes a transparent gel to obtain an aluminum solution. Weigh 16.0g of titanium oxysulfate and dissolve it in 80mL of deionized water. Add the solution dropwise to the aluminum solution and continue stirring at 80℃ for 8 hours. Let it stand and age for 12 hours, dry it at 100℃ for 12 hours, and calcine it at 200℃ for 4 hours to obtain a titanium-aluminum composite oxide, denoted as TiAl2-200.

[0030] Step 2: Weigh 2.96g of cerium nitrate hexahydrate and dissolve it in 90mL of water. Then add the TiAl2-200 prepared in Step 1 and stir vigorously until it becomes a gel. Let it stand for 2 hours, dry it at 100℃ for 12 hours, and calcine it at 600℃ for 4 hours to obtain cerium-loaded titanium aluminum composite oxide, denoted as Ce5 / TiAl2.

[0031] Step 3: Dilute 4 mL of 0.1 g / mL platinum nitrate aqueous solution and 5.21 g of 50% manganese nitrate aqueous solution with water to 100 mL, weigh 18.8 g of Ce5 / TiAl2 prepared in Step 2, add it to the solution and stir to impregnate for 2 hours, dry at 100℃ for 12 hours, and calcine at 400℃ for 4 hours to obtain the catalyst, denoted as Pt2Mn4 / Ce5 / TiAl2.

[0032] Example 3

[0033] In this embodiment, the molar ratio of Ti to Al in the titanium-aluminum composite oxide is 1:6, and the loadings of Ce, Pt, and Mn are 5%, 2%, and 4% of the mass of the titanium-aluminum composite oxide, respectively. The catalyst is prepared as follows:

[0034] Step 1: Weigh 61.3g of aluminum isopropoxide and add it to 300mL of water. Heat the mixture to 80℃ and stir until it becomes a transparent gel to obtain an aluminum solution. Weigh 8.0g of titanium oxysulfate and dissolve it in 40mL of deionized water. Add the solution dropwise to the aluminum solution and continue stirring at 80℃ for 8 hours. Let it stand and age for 12 hours, dry it at 100℃ for 12 hours, and calcine it at 200℃ for 4 hours to obtain a titanium-aluminum composite oxide, denoted as TiAl6-200.

[0035] Step 2: Weigh 3.14g of cerium nitrate hexahydrate and dissolve it in 95mL of water. Then add the TiAl6-200 prepared in Step 1 and stir vigorously until it becomes a gel. Let it stand for 2 hours, dry it at 100℃ for 12 hours, and calcine it at 600℃ for 4 hours to obtain cerium-loaded titanium aluminum composite oxide, denoted as Ce5 / TiAl6.

[0036] Step 3: Dilute 4 mL of 0.1 g / mL platinum nitrate aqueous solution and 5.21 g of 50% manganese nitrate aqueous solution with water to 100 mL, weigh 18.8 g of Ce5 / TiAl6 prepared in Step 2, add it to the solution and stir to impregnate for 2 hours, dry at 100℃ for 12 hours, and calcine at 400℃ for 4 hours to obtain the catalyst, denoted as Pt2Mn4 / Ce5 / TiAl6.

[0037] Example 4

[0038] In this embodiment, the molar ratio of Ti to Al in the titanium-aluminum composite oxide is 1:12, and the loadings of Ce, Pt, and Mn are 5%, 2%, and 4% of the mass of the titanium-aluminum composite oxide, respectively. The catalyst is prepared as follows:

[0039] Step 1: Weigh 73.5g of aluminum isopropoxide and add it to 360mL of water. Heat the solution to 80℃ and stir until it becomes a transparent gel, obtaining an aluminum solution. Weigh 4.8g of titanium oxysulfate and dissolve it in 25mL of deionized water. Add the solution dropwise to the aluminum solution and continue stirring at 80℃ for 8 hours. Let the solution stand for aging for 12 hours, dry it at 100℃ for 12 hours, and calcine it at 200℃ for 4 hours to obtain a titanium-aluminum composite oxide, denoted as TiAl. 12 -200.

[0040] Step 2: Weigh 3.38g of cerium nitrate hexahydrate and dissolve it in 100mL of water, then add the TiAl prepared in Step 1. 12 After being vigorously stirred at -200°C until it forms a gel, it is allowed to stand for 2 hours, dried at 100°C for 12 hours, and calcined at 600°C for 4 hours to obtain a cerium-supported titanium-aluminum composite oxide, denoted as Ce5 / TiAl. 12 .

[0041] Step 3: Dilute 4 mL of 0.1 g / mL platinum nitrate aqueous solution and 5.21 g of 50% manganese nitrate aqueous solution with water to 100 mL, and weigh 18.8 g of Ce5 / TiAl prepared in Step 2. 12 Add the catalyst and stir for 2 hours, then dry at 100℃ for 12 hours and calcine at 400℃ for 4 hours to obtain the catalyst, denoted as Pt2Mn4 / Ce5 / TiAl. 12 .

[0042] Example 5

[0043] In this embodiment, the molar ratio of Ti to Al in the titanium-aluminum composite oxide is 1:6, and the loadings of Ce, Pt, and Mn are 10%, 2%, and 4% of the mass of the titanium-aluminum composite oxide, respectively. The catalyst is prepared as follows:

[0044] Step 1: Weigh 61.3g of aluminum isopropoxide and add it to 300mL of water. Heat the mixture to 80℃ and stir until it becomes a transparent gel to obtain an aluminum solution. Weigh 8.0g of titanium oxysulfate and dissolve it in 40mL of deionized water. Add the solution dropwise to the aluminum solution and continue stirring at 80℃ for 8 hours. Let it stand and age for 12 hours, dry it at 100℃ for 12 hours, and calcine it at 200℃ for 4 hours to obtain a titanium-aluminum composite oxide, denoted as TiAl6-200.

[0045] Step 2: Weigh 6.64g of cerium nitrate hexahydrate and dissolve it in 95mL of water. Then add TiAl6-200 prepared in Step 1 and stir vigorously until it becomes a gel. Let it stand for 2 hours, dry it at 100℃ for 12 hours, and calcine it at 600℃ for 4 hours to obtain cerium-loaded titanium aluminum composite oxide, denoted as Ce10 / TiAl6.

[0046] Step 3: Dilute 4 mL of 0.1 g / mL platinum nitrate aqueous solution and 5.21 g of 50% manganese nitrate aqueous solution with water to 100 mL, weigh 18.8 g of Ce10 / TiAl6 prepared in Step 2, add it to the solution and stir to impregnate for 2 hours, dry at 100℃ for 12 hours, and calcine at 400℃ for 4 hours to obtain the catalyst, denoted as Pt2Mn4 / Ce10 / TiAl6.

[0047] Example 6

[0048] In this embodiment, the molar ratio of Ti to Al in the titanium-aluminum composite oxide is 1:6, and the loadings of Ce, Pt, and Mn are 20%, 2%, and 4% of the mass of the titanium-aluminum composite oxide, respectively. The catalyst is prepared as follows:

[0049] Step 1: Weigh 61.3g of aluminum isopropoxide and add it to 300mL of water. Heat the mixture to 80℃ and stir until it becomes a transparent gel to obtain an aluminum solution. Weigh 8.0g of titanium oxysulfate and dissolve it in 40mL of deionized water. Add the solution dropwise to the aluminum solution and continue stirring at 80℃ for 8 hours. Let it stand and age for 12 hours, dry it at 100℃ for 12 hours, and calcine it at 200℃ for 4 hours to obtain a titanium-aluminum composite oxide, denoted as TiAl6-200.

[0050] Step 2: Weigh 14.9g of cerium nitrate hexahydrate and dissolve it in 95mL of water. Then add the TiAl6-200 prepared in Step 1 and stir vigorously until it becomes a gel. Let it stand for 2 hours, dry it at 100℃ for 12 hours, and calcine it at 600℃ for 4 hours to obtain the cerium-loaded titanium aluminum composite oxide, denoted as Ce20 / TiAl6.

[0051] Step 3: Dilute 4 mL of 0.1 g / mL platinum nitrate aqueous solution and 5.21 g of 50% manganese nitrate aqueous solution with water to 100 mL, weigh 18.8 g of Ce2O / TiAl6 prepared in Step 2, add it to the solution and stir to impregnate for 2 hours, dry at 100℃ for 12 hours, and calcine at 400℃ for 4 hours to obtain the catalyst, denoted as Pt2Mn4 / Ce2O / TiAl6.

[0052] Example 7

[0053] In this embodiment, the molar ratio of Ti to Al in the titanium-aluminum composite oxide is 1:6, and the loadings of Ce, Pt, and Mn are 10%, 2%, and 2% of the mass of the titanium-aluminum composite oxide, respectively. The catalyst is prepared as follows:

[0054] Step 1: Weigh 61.3g of aluminum isopropoxide and add it to 300mL of water. Heat the mixture to 80℃ and stir until it becomes a transparent gel to obtain an aluminum solution. Weigh 8.0g of titanium oxysulfate and dissolve it in 40mL of deionized water. Add the solution dropwise to the aluminum solution and continue stirring at 80℃ for 8 hours. Let it stand and age for 12 hours, dry it at 100℃ for 12 hours, and calcine it at 200℃ for 4 hours to obtain a titanium-aluminum composite oxide, denoted as TiAl6-200.

[0055] Step 2: Weigh 6.64g of cerium nitrate hexahydrate and dissolve it in 95mL of water. Then add TiAl6-200 prepared in Step 1 and stir vigorously until it becomes a gel. Let it stand for 2 hours, dry it at 100℃ for 12 hours, and calcine it at 600℃ for 4 hours to obtain cerium-loaded titanium aluminum composite oxide, denoted as Ce10 / TiAl6.

[0056] Step 3: Dilute 4 mL of 0.1 g / mL platinum nitrate aqueous solution and 2.61 g of 50% manganese nitrate aqueous solution with water to 100 mL, weigh 19.2 g of Ce10 / TiAl6 prepared in Step 2, add it to the solution and stir to impregnate for 2 hours, dry at 100℃ for 12 hours, and calcine at 400℃ for 4 hours to obtain the catalyst, denoted as Pt2Mn2 / Ce10 / TiAl6.

[0057] Example 8

[0058] In this embodiment, the molar ratio of Ti to Al in the titanium-aluminum composite oxide is 1:6, and the loadings of Ce, Pt, and Mn are 10%, 2%, and 4% of the mass of the titanium-aluminum composite oxide, respectively. The catalyst is prepared as follows:

[0059] Step 1: Weigh 61.3g of aluminum isopropoxide and add it to 300mL of water. Heat the mixture to 80℃ and stir until it becomes a transparent gel to obtain an aluminum solution. Weigh 8.0g of titanium oxysulfate and dissolve it in 40mL of deionized water. Add the solution dropwise to the aluminum solution and continue stirring at 80℃ for 8 hours. Let it stand and age for 12 hours, dry it at 100℃ for 12 hours, and calcine it at 200℃ for 4 hours to obtain a titanium-aluminum composite oxide, denoted as TiAl6-200.

[0060] Step 2: Weigh 6.64g of cerium nitrate hexahydrate and dissolve it in 95mL of water. Then add TiAl6-200 prepared in Step 1 and stir vigorously until it becomes a gel. Let it stand for 2 hours, dry it at 100℃ for 12 hours, and calcine it at 400℃ for 4 hours to obtain cerium-loaded titanium aluminum composite oxide, denoted as Ce10 / TiAl6.

[0061] Step 3: Dilute 4 mL of 0.1 g / mL platinum nitrate aqueous solution and 5.21 g of 50% manganese nitrate aqueous solution with water to 100 mL, weigh 18.8 g of Ce10 / TiAl6 prepared in Step 2, add it to the solution and stir to impregnate for 2 hours, dry at 100℃ for 12 hours, and calcine at 400℃ for 4 hours to obtain the catalyst, denoted as Pt2Mn4 / Ce10 / TiAl6.

[0062] Example 9

[0063] In this embodiment, the molar ratio of Ti to Al in the titanium-aluminum composite oxide is 1:6, and the loadings of Ce, Pt, and Mn are 10%, 2%, and 4% of the mass of the titanium-aluminum composite oxide, respectively. The catalyst is prepared as follows:

[0064] Step 1: Weigh 61.3g of aluminum isopropoxide and add it to 300mL of water. Heat the mixture to 80℃ and stir until it becomes a transparent gel to obtain an aluminum solution. Weigh 8.0g of titanium oxysulfate and dissolve it in 40mL of deionized water. Add the solution dropwise to the aluminum solution and continue stirring at 80℃ for 8 hours. Let it stand and age for 12 hours, dry it at 100℃ for 12 hours, and calcine it at 400℃ for 4 hours to obtain a titanium-aluminum composite oxide, denoted as TiAl6-400.

[0065] Step 2: Weigh 6.64g of cerium nitrate hexahydrate and dissolve it in 95mL of water. Then add TiAl6-400 prepared in Step 1 and stir vigorously until it becomes a gel. Let it stand for 2 hours, dry it at 100℃ for 12 hours, and calcine it at 600℃ for 4 hours to obtain cerium-loaded titanium aluminum composite oxide, denoted as Ce10 / TiAl6.

[0066] Step 3: Dilute 4 mL of 0.1 g / mL platinum nitrate aqueous solution and 5.21 g of 50% manganese nitrate aqueous solution with water to 100 mL, weigh 18.8 g of Ce10 / TiAl6 prepared in Step 2, add it to the solution and stir to impregnate for 2 hours, dry at 100℃ for 12 hours, and calcine at 400℃ for 4 hours to obtain the catalyst, denoted as Pt2Mn4 / Ce10 / TiAl6.

[0067] Example 10

[0068] In this embodiment, the molar ratio of Ti to Al in the titanium-aluminum composite oxide is 1:6, and the loadings of Ce, Pt, and Mn are 10%, 2%, and 4% of the mass of the titanium-aluminum composite oxide, respectively. The catalyst is prepared as follows:

[0069] Step 1: Weigh 61.3g of aluminum isopropoxide and add it to 300mL of water. Heat the solution to 80℃ and stir until it becomes a transparent gel to obtain an aluminum solution. Weigh 8.0g of titanium oxysulfate and dissolve it in 40mL of deionized water. Add the solution dropwise to the aluminum solution and continue stirring at 80℃ for 8 hours. Let it stand and age for 12 hours, dry it at 100℃ for 12 hours, and calcine it at 600℃ for 4 hours to obtain a titanium-aluminum composite oxide, denoted as TiAl6-600.

[0070] Step 2: Weigh 6.64g of cerium nitrate hexahydrate and dissolve it in 95mL of water. Then add TiAl6-600 prepared in Step 1 and stir vigorously until it becomes a gel. Let it stand for 2 hours, dry it at 100℃ for 12 hours, and calcine it at 600℃ for 4 hours to obtain cerium-loaded titanium aluminum composite oxide, denoted as Ce10 / TiAl6.

[0071] Step 3: Dilute 4 mL of 0.1 g / mL platinum nitrate aqueous solution and 5.21 g of 50% manganese nitrate aqueous solution with water to 100 mL, weigh 18.8 g of Ce10 / TiAl6 prepared in Step 2, add it to the solution and stir to impregnate for 2 hours, dry at 100℃ for 12 hours, and calcine at 400℃ for 4 hours to obtain the catalyst, denoted as Pt2Mn4 / Ce10 / TiAl6.

[0072] Comparative Example 1

[0073] Step 1: Weigh 81.8g of aluminum isopropoxide and add it to 400mL of water. Heat the mixture to 80℃ and stir at a constant temperature until it becomes a transparent gel. Stir at a constant temperature for 8 hours, let it stand and age for 12 hours, dry it at 100℃ for 12 hours, and calcine it at 200℃ for 4 hours to obtain the alumina precursor, denoted as Al-200.

[0074] Step 2: Weigh 3.33g of cerium nitrate hexahydrate and dissolve it in 100mL of water. Then add the Al-200 prepared in Step 1 and stir vigorously until it becomes a gel. Let it stand for 2 hours, dry it at 100℃ for 12 hours, and calcine it at 600℃ for 4 hours to obtain cerium-loaded alumina, denoted as Ce5 / Al.

[0075] Step 3: Dilute 4 mL of 0.1 g / mL platinum nitrate aqueous solution and 5.21 g of 50% manganese nitrate aqueous solution with water to 100 mL, weigh 18.8 g of Ce5 / Al prepared in Step 2, add it to the solution and stir to impregnate for 2 hours, dry at 100℃ for 12 hours, and calcine at 400℃ for 4 hours to obtain the catalyst, denoted as Pt2Mn4 / Ce5 / Al.

[0076] Comparative Example 2

[0077] Step 1: Weigh 61.3g of aluminum isopropoxide and add it to 300mL of water. Heat the mixture to 80℃ and stir for 8 hours. Let it stand for 12 hours to age, dry it at 100℃ for 12 hours, and calcine it at 200℃ for 4 hours to obtain the alumina precursor, denoted as Al-200. Weigh 8.0g of titanium oxysulfate and dissolve it in 40mL of deionized water. Heat the mixture to 80℃ and stir for 8 hours. Let it stand for 12 hours to age, dry it at 100℃ for 12 hours, and calcine it at 200℃ for 4 hours to obtain the titanium oxide precursor, denoted as Ti-200.

[0078] Step 2: Weigh 6.64g of cerium nitrate hexahydrate and dissolve it in 95mL of water. Then add Ti-200 and Al-200 prepared in Step 1 and stir vigorously until it becomes a gel. Let it stand for 2 hours, dry it at 100℃ for 12 hours, and calcine it at 600℃ for 4 hours to obtain cerium-loaded titanium-aluminum mixed oxide, denoted as Ce10 / Ti-Al6.

[0079] Step 3: Dilute 4 mL of 0.1 g / mL platinum nitrate aqueous solution and 5.21 g of 50% manganese nitrate aqueous solution with water to 100 mL, weigh 18.8 g of Ce10 / Ti-Al6 prepared in Step 2, add it to the solution and stir to impregnate for 2 hours, dry at 100℃ for 12 hours, and calcine at 400℃ for 4 hours to obtain the catalyst, denoted as Pt2Mn4 / Ce10 / Ti-Al6.

[0080] Example 11

[0081] The catalysts prepared in Examples 1-10 and Comparative Examples 1-2 were mixed with deionized water and ball-milled until the solid particle size was <15 μm. Nitric acid and polyacrylamide dispersant were added dropwise to adjust the viscosity to 200-300 mPa·s and the pH to 2-4 to obtain a coating solution. Cut cordierite honeycomb ceramics were repeatedly impregnated and coated in the coating solution, dried at 100°C for 4 hours, and calcined at 500°C for 4 hours to achieve a Pt loading of 1.5±0.1 g / L and a powder catalyst loading of approximately 75±5 g / L, thus obtaining a coated honeycomb catalyst. The coated honeycomb catalysts were loaded into fixed-bed reactors and their catalytic combustion performance was evaluated under the same conditions. The simulated reaction gas composition was: 0.05 vol.% methyl acetate, 0.05 vol.% benzene, 0.05 vol.% bromomethane, 2 vol.% oxygen, 2 vol.% water vapor, and the remainder nitrogen. The evaluation space velocity was 50000 h⁻¹. -1 The activity evaluation temperature was 200–400℃, conducted using a programmed temperature ramp method. The temperatures at which methyl acetate, benzene, and bromomethane achieved 95% conversion (T) were determined. 95The lower the temperature, the better the activity. Stability was evaluated at 400℃, measuring the conversion rate of bromomethane and the formation rate of byproducts. The |K| value of the trend line equation represents the stability trend; a smaller |K| value indicates a more stable catalyst, and a smaller |K| value indicates stronger resistance to bromine poisoning. To verify the catalyst's temperature and humidity resistance, the coated honeycomb catalyst was aged at 750℃ for 10 hours in a fixed-bed reactor with 10 vol.% water vapor, followed by performance evaluation using the method described above.

[0082] Table 1 shows the T values ​​of each catalyst for methyl acetate, benzene, and bromomethane. 95 And the carbon dioxide selectivity of the catalyst to bromomethane when running at 400°C for 70 hours. Figure 1 The conversion curves of bromomethane and the yield curves of polybrominated products for different catalysts running at 400℃ for 70 hours are shown. Figure 2 The conversion curves of bromomethane by different catalysts after running at 400℃ for 70 hours are shown.

[0083] Table 1. Catalytic activity of each catalyst for ethyl acetate, benzene, and bromomethane, and catalytic stability for bromomethane.

[0084]

[0085]

[0086] According to Table 1 and Figures 1-2 The test results show that in Examples 1-8, the catalysts all contained Ti, and their catalytic combustion activity and stability for bromomethane were far superior to those of Comparative Example 1. The catalyst in Example 5 exhibited the most suitable activity, stability, and polybromine yield for terephthalic acid waste gas. Meanwhile, the test data from Examples 5, 9, and 10 clearly indicate that treating the titanium-aluminum composite at 200°C and then introducing cerium, which has better oxygen storage properties, into the unit cell resulted in the best resistance to bromine poisoning. Compared to Comparative Example 2, which used a mixed oxide as a support, Example 5, which used a composite oxide as a support, clearly demonstrated superior catalytic performance. After aging the catalysts in Examples 5 and Comparative Examples 1-2 under moisture conditions, their performance decreased to some extent, but the To of the terephthalic acid waste gas in Example 5 after aging was the highest. 95 The catalyst exhibited the smallest decrease in temperature and humidity, the highest conversion rate for bromomethane and CO2 selectivity, the lowest polybromin yield, and the best stability, indicating that the catalyst of this invention has good temperature and humidity resistance. Based on the data, except for Example 5, the other examples also demonstrated excellent catalytic purification capabilities for PTA waste gas; therefore, this invention has promising prospects for industrialization.

Claims

1. A catalyst for catalytic purification of waste terephthalic acid gas, characterized by, The catalyst is a titanium-aluminum composite oxide as a carrier, loaded with Ce, Pt and Mn, wherein the molar ratio of Ti to Al is 1:1-1:12, and the loading of Ce, Pt and Mn is 1%-20%, 1%-5% and 1%-5% of the mass of the titanium-aluminum composite oxide respectively; The preparation method of the catalyst comprises the following steps: Step 1: measure aluminum isopropoxide into deionized water, heat to 80-100 DEG C and then constant temperature stirring until hydrolysis, to obtain an aluminum solution; measure titanyl sulfate and dissolve in deionized water, drop into the aluminum solution, continue constant temperature stirring for 6-10 hours, then stand for aging for 12-24 hours, 80-120 DEG C drying, 200-600 DEG C calcination, to obtain a titanium-aluminum composite oxide; Step 2: measure cerium salt and dissolve in deionized water, measure the titanium-aluminum composite oxide prepared in step 1 and immerse for 2-4 hours, then 80-120 DEG C drying, 400-600 DEG C calcination, to obtain a cerium-loaded titanium-aluminum composite oxide; Step 3: measure platinum precursor and manganese salt and dissolve in deionized water, measure the cerium-loaded titanium-aluminum composite oxide prepared in step 2 and immerse for 2-4 hours, then 80-120 DEG C drying, 200-600 DEG C calcination, to obtain the catalyst.

2. The catalyst for catalytic purification of terephthalic acid off-gas according to claim 1, characterized by, The molar ratio of Ti to Al in the titanium-aluminum composite oxide is 1:5-8, and the loading of Ce, Pt and Mn is 5%-10%, 2% and 2%-4% of the mass of the titanium-aluminum composite oxide respectively.

3. The catalyst for catalytic purification of terephthalic acid off-gas according to claim 1, characterized by, In step 1, the calcination temperature is 200 DEG C.

4. The catalyst for catalytic purification of terephthalic acid off-gas according to claim 1, characterized by, In step 2, the cerium salt is any one of cerium nitrate, cerium chloride, cerium ammonium nitrate and cerium acetate.

5. The catalyst for catalytic purification of terephthalic acid off-gas according to claim 1, characterized by, In step 2, the calcination temperature is 600 DEG C.

6. The catalyst for catalytic purification of terephthalic acid off-gas according to claim 1, characterized by, In step 3, the platinum precursor is any one of platinum nitrate, chloroplatinic acid and tetraammine platinum nitrate, and the manganese salt is any one of manganese nitrate, manganese chloride and manganese acetate.

7. The catalyst for catalytic purification of terephthalic acid off-gas according to claim 1, characterized by, In step 3, the calcination temperature is 400 DEG C.

8. A method for catalytic purification of waste terephthalic acid gas, characterized by, The catalyst of claim 1 is dispersed in water, acid and dispersant to obtain a coating liquid; the cordierite honeycomb ceramic is dipped in the coating liquid, dried at 80-120 DEG C and calcined at 400-600 DEG C to obtain a coated honeycomb catalyst with a Pt loading of 1-2 g / L and a powder catalyst loading of 50-100 g / L; terephthalic acid waste gas is introduced into a catalytic combustion reactor filled with the coated honeycomb catalyst, and catalytic combustion of methyl acetate, dimethylbenzene and bromoform in the waste gas is carried out at 200-600 DEG C, 5000-30000 h -1 Methyl acetate, dimethylbenzene and bromoform in the waste gas are catalytically combusted to produce carbon dioxide, water, hydrogen bromide and bromine at a space velocity.

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