Preparation method of high-temperature-resistant high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas and catalyst

Abstract

The invention relates to a preparation method of a high-temperature-resistant high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas and the catalyst, and belongs to the field of industrial waste gas treatment. The catalyst is prepared by taking noble metal, transition metal oxide and rare earth oxide as active components, taking honeycomb ceramic or metal honeycomb as a carrier and adopting a coating process. The preparation method comprises the following steps: firstly, preparing Ce < x > Zr < 0.6-x > La < y > Pr < 0.1-y > O < 2 > from lanthanum nitrate hexahydrate, praseodymium nitrate hexahydrate, cerium nitrate hexahydrate and zirconium nitrate pentahydrate, and then preparing La-Al < 2 > O < 3 > from the lanthanum nitrate hexahydrate and Al < 2 > O < 3 > through an equivalent-volume impregnation method, and then the CexZr < 0.6-x > La < y > Pr < 0.1-y > O2, La <-> Al < 2 > O < 3 > and noble metal are used together to prepare the catalyst which has the characteristics of high low-temperature activity, good thermal stability and high purification efficiency for high-airspeed catalytic combustion of acid ester volatile organic compounds.

Description

Technical Field

[0001] The present invention belongs to the field of industrial waste gas treatment, and in particular relates to a preparation method of a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas and the catalyst. Background Art

[0002] With tightening environmental regulations, eco-friendly and water-based coatings are gradually replacing solvent-based coatings and becoming a common industrial necessity. Compared to traditional paints, eco-friendly and water-based coatings currently use acid ester alcohol compounds and water instead of triphenyls and formaldehyde as diluents. They do not contain toxic and hazardous substances such as benzene, toluene, and formaldehyde. Compared with oil paints, these new eco-friendly coatings offer significant environmental advantages and are a key factor in achieving energy conservation and emission reduction. However, these new eco-friendly coatings still contain low-toxic volatile organic compounds (VOCs), such as ethyl acetate and ethanol acrylic acid, which require end-of-pipe treatment. Catalytic combustion technology is currently one of the most effective technologies for treating these VOCs. However, the catalytic process for these substances is complex and often accompanied by side reactions such as polymerization and acidolysis, making them difficult to treat. Furthermore, current catalysts for these substances have poor high-temperature resistance at high space velocities. Summary of the Invention

[0003] In response to the deficiencies in the prior art, the present invention proposes a method for preparing a high-temperature, high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas and a catalyst. The catalyst uses precious metals, transition metal oxides, and rare earth oxides as active components, ceramics as a carrier, and is prepared using a coating process. It has the characteristics of high low-temperature activity, good thermal stability, and high purification efficiency for the catalytic combustion of volatile organic compounds (VOCs) of acid esters in environmentally friendly coatings under high space-velocity conditions.

[0004] The present invention provides a method for preparing a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas, comprising the following steps: (1) Ce x Zr 0.6-x La y Pr 0.1-y O2 and La-Al2O3 are dissolved in water to obtain solution I; (2) Dissolve the aqueous solution of Pt(NO3)2 and the aqueous solution of Pd(NO3)2, ammonium molybdate tetrahydrate and ethylene glycol in water, which is called Solution II. (3) Add solution II dropwise to solution I, stir at room temperature for 1-2 hours, then heat in a water bath to 70-80°C and stir for 2-4 hours to obtain a catalyst precursor; place the catalyst precursor in an oven at 80-100°C and continue drying for 6-12 hours, then calcine at 500-650°C at a heating rate of 5-10°C / min for 2-6 hours to obtain a catalyst powder; then cool and grind with water for 8-12 hours to obtain a slurry; add a binder to the slurry to obtain a base coating slurry; (4) A carrier with a mesh size of 260-300 cpsi was immersed in the base coating slurry, and then the excess slurry in the carrier was blown out with 0.1 MPa compressed air. The carrier was dried at 100-120 °C for 2-6 h, and then calcined at 450-600 °C for 2-3 h. The catalyst was cooled to obtain a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst.

[0005] In a preferred embodiment, the Ce in step (1) x Zr 0.6-x La y Pr 0.1-y The preparation process of O2 is as follows: lanthanum nitrate hexahydrate, praseodymium nitrate hexahydrate, cerium nitrate hexahydrate and zirconium nitrate pentahydrate are mixed in a molar ratio of (2-3): (3-4): (23-42): (15-41), and then dissolved in water to obtain a mixed solution with a total mass concentration of the above four substances of 1-2 mol / L, and then a dispersant PEG6000 accounting for 1-3% of the total mass of the mixed solution is added, and the mixed solution is treated by ammonia coprecipitation method, aged for 24 hours, filtered, washed, dried at a temperature of 90-110 ° C for 6-12 hours, and finally calcined at a temperature of 550-600 ° C for 2-4 hours to obtain a modified composite oxide Ce. x Zr 0.6-x La y Pr 0.1-y O2, where the value ranges of x and y are: 0 <x≤0.6,0<y<0.1。

[0006] In a preferred embodiment, the preparation process of La-Al2O3 in step (1) is as follows: lanthanum nitrate hexahydrate is loaded on Al2O3 by an equal volume impregnation method, wherein the mass ratio of the lanthanum nitrate hexahydrate to the Al2O3 is 1:(7-12); then, the mixture is dried at 80-120°C for 1-2 hours, and finally, calcined at 450-600°C for 1-5 hours to obtain La-Al2O3; the specific surface area of ​​the Al2O3 is greater than 250m 2 / g, the pore volume of Al2O3 is greater than 60cm 3 / g.

[0007] In a preferred embodiment, the Ce in step (1) x Zr0.6-x La y Pr 0.1-y The mass ratio of O2 and La-Al2O3 is 5-7:3-5.

[0008] In a preferred embodiment, the mass of the water in step (1) is Ce x Zr 0.6-x La y Pr 0.1-y 2.2-2.5 times the total mass of O2 and La-Al2O3.

[0009] In a preferred embodiment, the total mass of the element Pt in the aqueous solution of Pt(NO3)2 and the element Pd in ​​the aqueous solution of Pd(NO3)2 in step (2) is the Ce in step (1). x Zr 0.6-x La y Pr 0.1-y The invention relates to a novel nanostructured carbon foam having a molecular weight of 0.45-0.8% of the total mass of O2 and La-Al2O3; the mass ratio of element Pt in the aqueous solution of Pt(NO3)2 and element Pd in ​​the aqueous solution of Pd(NO3)2 is (2.5-9):(1-7.5); the mass concentration of element Pt in the aqueous solution of Pt(NO3)2 and the mass concentration of element Pd in ​​the aqueous solution of Pd(NO3)2 are both 15%.

[0010] In a preferred embodiment, the mass ratio of the total mass of the element Pt in the aqueous solution of Pt(NO3)2 and the element Pd in ​​the aqueous solution of Pd(NO3)2, ammonium molybdate tetrahydrate and ethylene glycol in step (2) is (0.45-0.8):(0.7-0.8):(2.5~10.5).

[0011] In a preferred embodiment, the mass of water in step (2) is 2-2.5 times the total mass of the aqueous solution of Pt(NO3)2 and the aqueous solution of Pd(NO3)2, ammonium molybdate tetrahydrate and ethylene glycol.

[0012] In a preferred embodiment, the mass ratio of solution I to solution II in step (3) is (217-247):(8.7-49.6).

[0013] In a preferred embodiment, the solid content of the slurry in step (3) is 25-30%, and the particle size of the powder in the slurry is 5-20 μm.

[0014] In a preferred embodiment, the binder in step (3) is pseudo-boehmite or aluminum sol, and the binder accounts for 5-10% by mass of the slurry.

[0015] In a preferred embodiment, the carrier in step (4) is a honeycomb ceramic or metal honeycomb.

[0016] In a preferred embodiment, the coating loading of the high-temperature-resistant and high-space-velocity VOCs catalytic combustion catalyst in step (4) is 60-100 g / L.

[0017] In a preferred embodiment, the acid ester waste gas is prepared by the above-mentioned preparation method and is used as a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst.

[0018] The beneficial effects of the present invention are: The high-temperature resistant high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas provided by the present invention realizes low-temperature complete oxidation of VOCs in acid ester waste gas and exhibits excellent performance in high-temperature aging resistance; the auxiliary agent ethylene glycol is used to form a noble metal, transition metal and aluminum oxide, cerium zirconium lanthanum praseodymium composite oxide with special interfacial activity, thereby achieving high dispersion of active substances in the aluminum oxide and cerium zirconium lanthanum praseodymium composite oxide, and obtaining more active sites; in addition, ethylene glycol has a certain reducing ability during the catalyst synthesis process and the drying and calcining process, so that more oxygen vacancies appear in the aluminum oxide and cerium zirconium lanthanum praseodymium composite oxide, which assists in the catalytic oxidation of VOCs, thereby making the catalyst exhibit excellent low-temperature activity; then, by finely controlling the calcination temperature in the catalyst preparation process, the noble metal PtPd species and the transition metal oxide MoO x The highly dispersed form further forms a stronger interaction SMSI with alumina, cerium zirconium lanthanum praseodymium rare earth oxides, which makes the active metal have the ability to resist migration and agglomeration. Therefore, the catalyst shows excellent anti-aging ability after aging at 750 ° C for 24 hours.

[0019] The catalyst proposed in the present invention has the characteristics of low ignition temperature and good high-temperature stability for acid ester VOCs under high space velocity conditions, and can be widely used in petrochemical, pharmaceutical, papermaking, transportation, textile, coating, printing and other industrial industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a comparison chart of the anti-aging performance of the catalyst prepared in Example 1 for catalytic oxidation of ethyl acetate; Figure 2 This is a comparison chart of the anti-aging performance of the catalyst prepared in Example 1 for catalytic oxidation of toluene. DETAILED DESCRIPTION

[0021] The water used in the solution of the present invention is deionized water.

[0022] Preparation of Ce in the scheme of the present invention x Zr 0.6-x Lay Pr 0.1-y The ammonia co-precipitation method involving O2 uses ammonia water (mass concentration of 25-30%) to over-precipitate the system, and adjust the pH value of the system to between 8-10 by titration. Rapidly stir the precipitation and react for 8-12 hours; The Al2O3, Pt(NO3)2 aqueous solution and Pd(NO3)2 aqueous solution in the following examples and comparative examples of the present invention are all commercially available. The mass concentration of element Pt in the Pt(NO3)2 aqueous solution and the mass concentration of element Pd in ​​the Pd(NO3)2 aqueous solution are both 15%; the specification of Al2O3 is a specific surface area greater than 250m 2 / g, the pore volume of Al2O3 is greater than 60cm 3 / g.

[0023] Preparation of Ce in the scheme of the present invention x Zr 0.6-x La y Pr 0.1-y O2, where the value ranges of x and y are: 0 <x≤0.6,0<y<0.1。

[0024] Example 1 Preparation of Ce 0.36 Zr 0.24 La 0.02 Pr 0.04 O2 7.9742 g of lanthanum nitrate hexahydrate, 17.8869 g of praseodymium nitrate hexahydrate, 156.6168 g of cerium nitrate hexahydrate and 104.5227 g of zirconium nitrate pentahydrate were weighed, mixed and dissolved in water to form a mixture with a molar concentration of 1 mol / L, 6.5 g of PEG6000 as a dispersant was added to the mixture, and then excess ammonia water was added to the mixture to precipitate the mixture by ammonia coprecipitation. The solution containing the precipitate was aged overnight, filtered, washed with deionized water, and finally dried at 90 ° C for 6 h, and then calcined at 600 ° C for 2 h to obtain a modified composite oxide Ce. 0.36 Zr 0.24 La 0.02 Pr 0.04 O2; Preparation of La-Al2O3 95 g of Al2O3 and 13 g of lanthanum nitrate hexahydrate were weighed respectively, loaded by the equal volume impregnation method, then dried at 100°C for 2 h and calcined at 600°C for 2 h to obtain modified alumina La-Al2O3.

[0025] Preparation of catalyst 1 (1) 59.28g of Ce 0.36 Zr 0.24 La 0.02 Pr0.04 O2 and 39.52g of modified alumina La-Al2O3 were mixed and dissolved in 220g of deionized water, which was named Solution I; (2) 3.2 g of Pt(NO3)2 aqueous solution, 0.8 g of Pd(NO3)2 aqueous solution, 0.716 g of ammonium molybdate tetrahydrate and 10.5 g of ethylene glycol were dissolved in 30 g of deionized water, which was recorded as Solution II. Solution II was added dropwise to Solution I, stirred at room temperature for 1 h, heated in a water bath to 80 °C, stirred and dried for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in an oven at 80 °C and continued to be dried for 6 h. Finally, it was calcined in a muffle furnace at 600 °C at a heating rate of 5 °C / min for 4 h to obtain a catalyst powder. (3) Weigh 100 g of the above catalyst powder and add deionized water to grind for 8 h to obtain a slurry; the solid content of the slurry is 30% and the powder particle size is 5 μm; then add 10 g of pseudo-boehmite to the slurry and acid hydrolyze it to prepare a base coating slurry; (4) A cordierite honeycomb ceramic with a mesh size of 300 cpsi was used as a carrier, and the carrier was immersed in the base coating slurry so that the slurry was distributed on the pore structure of the cordierite honeycomb ceramic carrier. The excess slurry in the pores of the honeycomb ceramic carrier was blown out with 0.1 MPa compressed air. The catalyst was dried in an oven at 100°C for 2 h, calcined at 500°C for 2 h, and cooled to obtain a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst 1. The coating loading of the catalyst 1 was 80 g / L.

[0026] Example 2 Preparation of Ce 0.4 Zr 0.2 La 0.03 Pr 0.03 O2 13.2903 g of lanthanum nitrate hexahydrate, 12.7764 g of praseodymium nitrate hexahydrate, 174.2993 g of cerium nitrate hexahydrate and 87.1023 g of zirconium nitrate pentahydrate were weighed, mixed and dissolved in water to form a mixture with a molar concentration of 1 mol / L, 6.5 g of PEG6000 as a dispersant was added to the mixture, and then excess ammonia water was added to the above mixture. The mixture was precipitated by ammonia coprecipitation method, and the solution containing the precipitate was aged overnight, filtered, washed with deionized water, and finally dried at 90 ° C for 6 h, and then calcined at 600 ° C for 2 h to obtain a modified composite oxide Ce. 0.4 Zr 0.2 La 0.03 Pr 0.03 O2; Preparation of La-Al2O3 96 g Al2O3 and 11 g lanthanum nitrate hexahydrate were weighed respectively, loaded by equal volume impregnation method, then dried at 100°C for 2 h and calcined at 600°C for 2 h to obtain modified alumina La-Al2O3.

[0027] Preparation of catalyst 2 (1) 69.16 g of Ce 0.4 Zr 0.2 La 0.03 Pr 0.03 O2 and 29.64 g of modified alumina La-Al2O3 were mixed and dissolved in 220 g of deionized water, which was named solution I; (2) 3.2 g of Pt(NO3)2 aqueous solution, 0.8 g of Pd(NO3)2 aqueous solution, 0.716 g of ammonium molybdate tetrahydrate and 7 g of ethylene glycol were dissolved in 30 g of deionized water, which was recorded as Solution II. Solution II was added dropwise to Solution I, stirred at room temperature for 2 h, heated in a water bath to 70 °C, stirred and dried for 4 h to obtain a catalyst precursor, and then the catalyst precursor was placed in an oven at 100 °C for further drying for 6 h, and finally calcined in a muffle furnace at 600 °C at a heating rate of 5 °C / min for 4 h to obtain a catalyst powder. (3) Weigh 100 g of the above catalyst powder and add it to deionized water and grind it for 12 h to obtain a slurry; the solid content of the slurry is 30% and the powder particle size is 20 μm; then add 10 g of pseudo-boehmite to the slurry to prepare a base coating slurry; (4) A cordierite honeycomb ceramic with a mesh size of 300 cpsi was used as a carrier, and the carrier was immersed in the base coating slurry so that the slurry was distributed on the pore structure of the cordierite honeycomb ceramic carrier. The excess slurry in the pores of the honeycomb ceramic carrier was blown out with 0.1 MPa compressed air. The catalyst was dried in an oven at 120°C for 6 h, calcined at 500°C for 3 h, and cooled to obtain a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst 2. The coating loading of the catalyst 2 was 80 g / L.

[0028] Example 3 Preparation of Ce 0.45 Zr 0.15 La 0.02 Pr 0.04 O2 7.9742 g of lanthanum nitrate hexahydrate, 17.8869 g of praseodymium nitrate hexahydrate, 195.771 g of cerium nitrate hexahydrate and 62.7136 g of zirconium nitrate pentahydrate were weighed, mixed and dissolved in water to form a mixture with a molar concentration of 1 mol / L, 6.5 g of PEG6000 was added as a dispersant to the mixture, and then excess ammonia water was added to the mixture to precipitate the mixture by ammonia coprecipitation. The solution containing the precipitate was aged overnight, filtered, washed with deionized water, and finally dried at 90 ° C for 6 h, and then calcined at 550 ° C for 2 h to obtain a modified composite oxide Ce. 0.45 Zr 0.15 La 0.02 Pr 0.04 O2; Preparation of La-Al2O3 97 g Al2O3 and 8 g lanthanum nitrate hexahydrate were weighed respectively, loaded by equal volume impregnation method, then dried at 100°C for 2 h and calcined at 600°C for 2 h to obtain modified alumina La-Al2O3.

[0029] Preparation of catalyst 3 (1) 59.28g of Ce 0.45 Zr 0.15 La 0.02 Pr 0.04 O2 and 39.52g of modified alumina La-Al2O3 were mixed and dissolved in 220g of deionized water, which was named Solution I; (2) 3.6 g of Pt(NO3)2 aqueous solution, 0.4 g of Pd(NO3)2 aqueous solution, 0.716 g of ammonium molybdate tetrahydrate and 10.5 g of ethylene glycol were dissolved in 30 g of deionized water, which was recorded as Solution II. Solution II was added dropwise to Solution I, stirred at room temperature for 1 h, heated in a water bath to 80 °C, stirred and dried for 4 h to obtain a catalyst precursor, and then the catalyst precursor was placed in an oven at 100 °C for further drying for 10 h, and finally calcined in a muffle furnace at 550 °C at a heating rate of 5 °C / min for 4 h to obtain a catalyst powder. (3) Weigh 100 g of the above catalyst powder and add it to deionized water and grind it for 12 hours to obtain a slurry; the solid content of the slurry is 30%, and the powder particle size is 10 μm; then add 10 g of pseudo-boehmite to the slurry to prepare a base coating slurry; (4) A cordierite honeycomb ceramic with a mesh size of 300 cpsi was used as a carrier. The carrier was immersed in the base coating slurry so that the slurry was distributed on the pore structure of the cordierite honeycomb ceramic carrier. The excess slurry in the pores of the honeycomb ceramic carrier was blown out with 0.1 MPa compressed air. The catalyst was dried in an oven at 120°C for 6 h, calcined at 550°C for 4 h, and cooled to room temperature to obtain a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst 3. The coating loading of catalyst 3 was 80 g / L.

[0030] Example 4 Preparation of Ce 0.3 Zr 0.3 La 0.02 Pr 0.04 O2 7.9742 g of lanthanum nitrate hexahydrate, 17.8869 g of praseodymium nitrate hexahydrate, 131.356 g of cerium nitrate hexahydrate and 128.9113 g of zirconium nitrate pentahydrate were weighed, mixed and dissolved in water to form a mixture with a molar concentration of 1 mol / L, 6.5 g of PEG6000 as a dispersant was added to the mixture, and then excess ammonia water was added to the mixture to precipitate the mixture by ammonia coprecipitation. The solution containing the precipitate was aged overnight, filtered, washed with deionized water, and finally dried at 90 ° C for 6 h, and then calcined at 600 ° C for 2 h to obtain a modified composite oxide Ce. 0.3 Zr 0.3 La 0.02 Pr 0.04 O2; Preparation of La-Al2O3 94 g Al2O3 and 16 g lanthanum nitrate hexahydrate were weighed respectively, loaded by equal volume impregnation method, then dried at 100°C for 2 h and calcined at 600°C for 2 h to obtain modified alumina La-Al2O3.

[0031] Preparation of catalyst 4 (1) 59.28g of Ce 0.3 Zr 0.3 La 0.02 Pr 0.04 O2 and 39.52g of modified alumina La-Al2O3 were mixed and dissolved in 220g of deionized water, which was named Solution I; (2) 3 g of Pt(NO3)2 aqueous solution and 1 g of Pd(NO3)2 aqueous solution, 0.716 g of ammonium molybdate tetrahydrate and 10.5 g of ethylene glycol were dissolved in 30 g of deionized water, which was recorded as Solution II. Solution II was added dropwise to Solution I, stirred at room temperature for 1 h, heated in a water bath to 75 °C, stirred and dried for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in an oven at 90 °C and continued to be dried for 12 h. Finally, it was calcined in a muffle furnace at 600 °C at a heating rate of 5 °C / min for 2 h to obtain a catalyst powder. (3) Weigh 100 g of the above catalyst powder and add it to deionized water and grind it for 12 hours to obtain a slurry; the solid content of the slurry is 30%, and the powder particle size is 15 μm; then add 10 g of pseudo-boehmite to the slurry to prepare a base coating slurry; (4) A cordierite honeycomb ceramic with a mesh size of 300 cpsi was used as a carrier. The carrier was immersed in the base coating slurry so that the slurry was distributed on the pore structure of the cordierite honeycomb ceramic carrier. The excess slurry in the pores of the honeycomb ceramic carrier was blown out with 0.1 MPa compressed air. The catalyst was dried in an oven at 110°C for 4 h, calcined at 500°C for 3 h, and cooled to room temperature to obtain a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst 4. The coating loading of catalyst 4 was 80 g / L.

[0032] Example 5 18.6064 g of lanthanum nitrate hexahydrate, 7.6658 g of praseodymium nitrate hexahydrate, 88.4126 g of cerium nitrate hexahydrate and 170.7204 g of zirconium nitrate pentahydrate were weighed, mixed and dissolved in water to form a mixture with a molar concentration of 1 mol / L, 6.5 g of PEG6000 as a dispersant was added to the mixture, and then excess ammonia water was added to the mixture to precipitate the mixture by ammonia coprecipitation. The solution containing the precipitate was aged overnight, filtered, washed with deionized water, and finally dried at 90 ° C for 6 h, and then calcined at 550 ° C for 4 h to obtain a modified composite oxide Ce. 0.2 Zr 0.4 La 0.04 Pr 0.02 O2; Preparation of La-Al2O3 93 g of Al2O3 and 19 g of lanthanum nitrate hexahydrate were weighed respectively, loaded by the equal volume impregnation method, then dried at 100°C for 2 h and calcined at 550°C for 2 h to obtain modified alumina La-Al2O3.

[0033] Preparation of catalyst 5 (1) 59.28g of Ce 0.2 Zr 0.4 La 0.04 Pr 0.02 O2 and 39.52g of modified alumina La-Al2O3 were mixed and dissolved in 220g of deionized water, which was named Solution I; (2) 2.66 g of Pt(NO3)2 aqueous solution and 1.34 g of Pd(NO3)2 aqueous solution, 0.716 g of ammonium molybdate tetrahydrate and 10.5 g of ethylene glycol were dissolved in 30 g of deionized water, which was recorded as Solution II. Solution II was added dropwise to Solution I, stirred at room temperature for 1 h, heated in a water bath to 80 °C, stirred and dried for 2 h to obtain a catalyst precursor, and then the catalyst precursor was placed in an oven at 100 °C for further drying for 10 h, and finally calcined in a muffle furnace at 550 °C at a heating rate of 10 °C / min for 2 h to obtain a catalyst powder. (3) Weigh 100 g of the above catalyst powder and add it to deionized water and grind it for 12 h to obtain a slurry; the solid content of the slurry is 30% and the powder particle size is 5 μm; then add 10 g of pseudo-boehmite to the slurry to prepare a base coating slurry; (4) A cordierite honeycomb ceramic with a mesh size of 300 cpsi was used as a carrier. The carrier was immersed in the base coating slurry so that the slurry was distributed on the pore structure of the cordierite honeycomb ceramic carrier. The excess slurry in the pores of the honeycomb ceramic carrier was blown out with 0.1 MPa compressed air. The catalyst was dried in an oven at 105°C for 5 h, calcined at 550°C for 3 h, and cooled to obtain a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst 5. The coating loading of the catalyst 5 was 80 g / L.

[0034] Example 6 Preparation of Ce 0.24 Zr 0.36 La 0.02 Pr 0.04 O2 7.9742 g of lanthanum nitrate hexahydrate, 17.8869 g of praseodymium nitrate hexahydrate, 106.0952 g of cerium nitrate hexahydrate and 153.3 g of zirconium nitrate pentahydrate were weighed, mixed and dissolved in water to form a mixture with a molar concentration of 1 mol / L, 6.5 g of PEG6000 as a dispersant was added to the mixture, and then excess ammonia water was added to the above mixture to precipitate the mixture by ammonia coprecipitation method. The solution containing the precipitate was aged overnight, filtered, washed with deionized water, and finally dried at 90 ° C for 6 h, and then calcined at 550 ° C for 4 h to obtain the modified composite oxide Ce. 0.24 Zr 0.36 La 0.02 Pr 0.04 O2; Preparation of La-Al2O3 95 g of Al2O3 and 13 g of lanthanum nitrate hexahydrate were weighed respectively, loaded by the equal volume impregnation method, and then dried at 100°C for 2 h and calcined at 550°C for 2 h to obtain modified alumina La-Al2O3.

[0035] (1) 59.28g of Ce 0.24 Zr 0.36 La 0.02 Pr 0.04 O2 and 39.52g of modified alumina La-Al2O3 were mixed and dissolved in 220g of deionized water, which was named Solution I; (2) Dissolve 1 g of Pt(NO3)2 aqueous solution and 3 g of Pd(NO3)2 aqueous solution, 0.716 g of ammonium molybdate tetrahydrate and 10.5 g of ethylene glycol in 30 g of deionized water, which is called Solution II. Add Solution II dropwise into Solution I, stir at room temperature for 1 h, heat in a water bath to 80 °C, stir and dry for 4 h to obtain a catalyst precursor, then place the catalyst precursor in an oven at 95 °C and continue drying for 6 h. Finally, calcine in a muffle furnace at 500 °C at a heating rate of 10 °C / min for 2 h to obtain a catalyst powder. (3) Weigh 100 g of the above catalyst powder and add it to deionized water and grind it for 12 h to obtain a slurry; the solid content of the slurry is 25% and the powder particle size is 5 μm; then add 10 g of pseudo-boehmite to the slurry to prepare a base coating slurry; (4) A cordierite honeycomb ceramic with a mesh size of 300 cpsi was used as a carrier, and the carrier was immersed in the base coating slurry so that the slurry was distributed on the pore structure of the cordierite honeycomb ceramic carrier. The excess slurry in the pores of the honeycomb ceramic carrier was blown out with 0.1 MPa compressed air. The catalyst was dried in an oven at 110°C for 4 h, calcined at 500°C for 2 h, and cooled to obtain a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst 6. The coating loading of the catalyst 6 was 80 g / L.

[0036] Example 7 Preparation of Ce 0.36 Zr 0.24 La 0.03 Pr 0.03 O2 13.2903 g of lanthanum nitrate hexahydrate, 12.7764 g of praseodymium nitrate hexahydrate, 156.6168 g of cerium nitrate hexahydrate and 104.5227 g of zirconium nitrate pentahydrate were weighed, mixed and dissolved in water to form a mixture with a molar concentration of 1 mol / L, 6.5 g of PEG6000 as a dispersant was added to the mixture, and then excess ammonia water was added to the mixture to precipitate the mixture by ammonia coprecipitation. The solution containing the precipitate was aged overnight, filtered, washed with deionized water, and finally dried at 90 ° C for 6 h, and then calcined at 550 ° C for 4 h to obtain a modified composite oxide Ce. 0.36 Zr 0.24 La 0.03 Pr 0.03 O2; Preparation of La-Al2O3 95 g of Al2O3 and 13 g of lanthanum nitrate hexahydrate were weighed respectively, loaded by the equal volume impregnation method, and then dried at 100°C for 2 h and calcined at 550°C for 2 h to obtain modified alumina La-Al2O3.

[0037] Preparation of Catalyst 7 (1) 59.28g of Ce 0.36Zr 0.24 La 0.03 Pr 0.03 O2 and 39.52g of modified alumina La-Al2O3 were mixed and dissolved in 220g of deionized water, which was named Solution I; (2) 3.2 g of Pt(NO3)2 aqueous solution, 0.8 g of Pd(NO3)2 aqueous solution, 0.716 g of ammonium molybdate tetrahydrate and 10.5 g of ethylene glycol were dissolved in 30 g of deionized water, which was recorded as Solution II. Solution II was added dropwise to Solution I, stirred at room temperature for 1 h, heated in a water bath to 80 °C, stirred and dried for 4 h to obtain a catalyst precursor, and then the catalyst precursor was placed in an oven at 95 °C and continued to be dried for 6 h. Finally, it was calcined in a muffle furnace at 600 °C at a heating rate of 5 °C / min for 4 h to obtain a catalyst powder. (3) Weigh 100 g of the above catalyst powder and add it to deionized water and grind it for 12 h to obtain a slurry; the solid content of the slurry is 25% and the powder particle size is 5 μm; then add 7 g of pseudo-boehmite to the slurry and acid-hydrolyze it to obtain a base coating slurry; (4) A metal honeycomb with a mesh size of 260 cpsi was used as a carrier, and the carrier was immersed in the base coating slurry so that the slurry was distributed on the pore structure of the metal honeycomb carrier. The excess slurry in the pores of the honeycomb ceramic carrier was blown out with 0.1 MPa compressed air. The catalyst was dried in an oven at 110°C for 4 h, calcined at 550°C for 3 h, and cooled to obtain a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst 7. The coating loading of the catalyst 7 was 80 g / L.

[0038] Comparative Example 1 In step (2) of Example 1, ammonium molybdate tetrahydrate and ethylene glycol are not added when preparing solution II. Other contents are consistent with those in Example 1.

[0039] Comparative Example 2 In step (2) of Example 1, ethylene glycol was not added when preparing solution II, and other contents were consistent with those in Example 1.

[0040] Comparative Example 3 In step (1) of Example 1, 3.2 g of Pt(NO3)2 aqueous solution and 0.8 g of Pd(NO3)2 aqueous solution were replaced with 3.2 g of chloroplatinic acid aqueous solution and 0.8 g of chloropalladic acid aqueous solution. Other contents were consistent with those in Example 1.

[0041] Comparative Example 4 In step (2) of Example 1, when preparing solution II, the amount of the aqueous solution of Pt(NO3)2 and Pd(NO3)2 added was reduced, and the total amount of elemental Pt and Pd added in the aqueous solution of Pt(NO3)2 and Pd(NO3)2 was limited to 0.45 g. Other contents were consistent with those in Example 1.

[0042] Comparative Example 5 No Ce preparation 0.36 Zr 0.24 La 0.02 Pr 0.04 O2 and La-Al2O3, and 59.28g of Ce in step (1) of Example 1 0.36 Zr 0.24 La 0.02 Pr 0.04 O2 and 39.52g of modified alumina La-Al2O3 were replaced by 59.28g of CeO2 and 39.52g of Al2O3 respectively, and the other contents were consistent with those in Example 1.

[0043] The catalysts prepared in Examples 1-7 and Comparative Examples 1-5 were heated to 30000 h / min on the basis of the reaction of ethyl acetate and toluene at a volume space velocity of 30000 h / min. -1 The catalytic efficiency performance test was carried out at a concentration of 1000ppm and 1000ppm. Dry air was used as the carrier gas to simulate the exhaust gas environment. The exhaust gas concentration before and after passing through the catalyst was detected by gas chromatograph. The catalyst was aged at a high temperature of 750℃ for 24 hours. The test results are shown in Table 1 below: Table 1 Catalytic oxidation performance of toluene and ethyl acetate

[0044] Catalyst 1 prepared in Example 1 achieved efficient and complete catalytic oxidation of ethyl acetate, a representative example, at temperatures below 300°C. Complete oxidation of ethyl acetate was achieved at 270°C at a space velocity of 30,000 s. After aging at 750°C for 24 hours, the complete conversion temperature of ethyl acetate increased by only 10°C. Furthermore, in catalytic oxidation tests of toluene, a traditional paint solvent component, complete oxidation of toluene was achieved at 200°C at a space velocity of 30,000 s. After aging at 750°C for 24 hours, the complete conversion temperature of toluene remained at 200°C, showing virtually no degradation. By comparing Example 1, Example 2 and Comparative Example 2, it is found that ethylene glycol EG plays a crucial role in the catalyst synthesis process and plays a decisive role in the dispersion of the active metal of the catalyst. Therefore, it can be seen that the addition of ethylene glycol makes the active metal have more active sites. Although Example 2 contains about 1 / 3 less ethylene glycol than Example 1, the T99 of toluene of its fresh catalyst is 10°C lower than that of Example 1, but its toluene activity is lost to a certain extent during the high-temperature aging process; Examples 1 and Examples 3-7 perform more refined control on the calcination process of the catalyst, and find that under relatively higher temperatures and longer calcination times, when the catalyst is continuously aged at 750°C for 24h, the catalyst shows that both toluene and ethyl acetate have relatively good aging resistance; in Example 1, the catalyst shows the best aging resistance when calcined at 600°C for 4h, as shown in FIG. Figure 1 and Figure 2 As shown, where ΔT99 甲苯 0℃, ΔT99 乙酸乙酯 The temperature is 10°C. This is because under high temperature and long-term calcination atmosphere, the active metal and the carrier have a strong interaction, which makes the active metal more stably anchored on the carrier, preventing the migration and agglomeration of the active metal of the catalyst at high temperature. In Example 7, a metal honeycomb is used as the coating carrier. Although the toluene T99 activity is 5°C higher than that of the 300 cpsi ceramic honeycomb catalyst, the catalyst still has excellent activity and aging activity.

[0045] By comparing Example 1 with Comparative Examples 1, 2, and 3, it was found that changing the transition metal oxide additive ammonium molybdate, the dispersing reducing additive ethylene glycol, and the noble metal active component precursor in the catalyst all had significant effects and changes on the performance of the catalyst. Among them, the molybdenum additive was beneficial to the low-temperature oxidation activity of the catalyst in ethyl acetate and toluene, and ethylene glycol was helpful in dispersing the noble metal and the molybdenum additive. The noble metal nitrate compound had higher activity than the noble metal chloride, which was related to the poisoning of the catalyst by the chloride ions in the noble metal chloride, resulting in a relative shift of the catalyst activity toward high temperature. By comparing Example 1 with Comparative Example 4, the catalyst can still operate at high space velocity when the loading of precious metal is reduced and other conditions remain unchanged, although its complete oxidation temperature is 10°C higher. Its anti-aging ability is consistent with that of Example 1, which also provides a solution for some economical and applicable projects. By comparing Example 1 with Comparative Example 5, the catalytic efficiency of the ordinary cerium oxide used in Comparative Example 5 is much lower than that of the Ce in Example 1. x Zr 0.6-x La y Pr 0.1-yO2 cerium-zirconium solid solution compound, the compound is doped with a certain amount of zirconium Zr, lanthanum La and praseodymium Pr elements, so that the catalyst exhibits better low-temperature activity.

[0046] The above are only some preferred embodiments of the present invention and are not intended to limit the scope of the present invention. It should be understood that any modifications, equivalent substitutions, and changes made based on the present invention in the field of the present invention should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas, characterized in that: The following steps are involved: (1) Ce x Zr 0.6-x La y Pr 0.1-y O2 and La-Al2O3 are dissolved in water to obtain solution I; The Ce x Zr 0.6-x La y Pr 0.1-y O2 is a modified composite oxide obtained by treating lanthanum nitrate hexahydrate, praseodymium nitrate hexahydrate, cerium nitrate hexahydrate and zirconium nitrate pentahydrate through ammonia coprecipitation, wherein the value ranges of x and y are: 0 <x≤0.6,0<y<0.1; The La-Al2O3 is prepared by impregnating lanthanum nitrate hexahydrate and Al2O3 by an equal volume impregnation method, wherein the mass ratio of lanthanum nitrate hexahydrate to Al2O3 is 1:(7-12); the specific surface area of ​​Al2O3 is greater than 250m 2 / g, pore volume greater than 60cm 3 / g; The Ce x Zr 0.6-x La y Pr 0.1-y The mass ratio of O2 and La-Al2O3 is 5-7:3-5; (2) Dissolve the aqueous solution of Pt(NO3)2 and the aqueous solution of Pd(NO3)2, ammonium molybdate tetrahydrate and ethylene glycol in water, which is called Solution II. (3) adding solution II dropwise to solution I, stirring at room temperature and then heating in a water bath to obtain a catalyst precursor; drying and calcining the catalyst precursor, cooling it to obtain a catalyst powder, and then grinding it with water to obtain a slurry; adding a binder to the slurry to obtain a base coating slurry; (4) The carrier is immersed in the base coating slurry, and then the excess slurry in the carrier is blown out with 0.1 MPa compressed air. Finally, the carrier is dried, calcined, and cooled to obtain a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst.

2. The method for preparing a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas according to claim 1, characterized in that: Ce as described in step (1) x Zr 0.6-x La y Pr 0.1-y The preparation process of O2 is as follows: lanthanum nitrate hexahydrate, praseodymium nitrate hexahydrate, cerium nitrate hexahydrate and zirconium nitrate pentahydrate are mixed in a molar ratio of (2-3): (3-4): (23-42): (15-41), and then dissolved in water to obtain a mixture with a total concentration of the above four substances of 1-2 mol / L, and then 1-3% of the total mass of the mixture is added as a dispersant PEG6000, and the mixture is treated by ammonia coprecipitation method. After aging for 24 hours, the mixture is filtered and washed, dried at a temperature of 90-110 ° C for 6-12 hours, and finally calcined at a temperature of 550-600 ° C for 2-4 hours to obtain the modified composite oxide Ce x Zr 0.6-x La y Pr 0.1-y O2.

3. The method for preparing a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas according to claim 1, characterized in that: The preparation process of La-Al2O3 described in step (1) is as follows: lanthanum nitrate hexahydrate is loaded on Al2O3 by an equal volume impregnation method, then dried at 80-120°C for 1-2 hours, and finally calcined at 450-600°C for 1-5 hours to obtain La-Al2O3.

4. The method for preparing a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas according to claim 1, characterized in that: The mass of water in step (1) is Ce x Zr 0.6-x La y Pr 0.1-y 2.2-2.5 times the total mass of O2 and La-Al2O3.

5. The method for preparing a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas according to claim 1, characterized in that: The total mass of the element Pt in the aqueous solution of Pt(NO3)2 and the element Pd in ​​the aqueous solution of Pd(NO3)2 described in step (2) is the Ce described in step (1). x Zr 0.6-x La y Pr 0.1-y The mass ratio of element Pt in the aqueous solution of Pt(NO3)2 to element Pd in ​​the aqueous solution of Pd(NO3)2 is 2.5-9:1-7.5; the mass concentration of element Pt in the aqueous solution of Pt(NO3)2 and the mass concentration of element Pd in ​​the aqueous solution of Pd(NO3)2 are both 15%.

6. The method for preparing a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas according to claim 1, characterized in that: The mass ratio of the total mass of element Pt in the aqueous solution of Pt(NO3)2 and element Pd in ​​the aqueous solution of Pd(NO3)2, ammonium molybdate tetrahydrate and ethylene glycol in step (2) is (0.45-0.8):(0.7-0.8):(2.5-10.5); the mass of the water is 2-2.5 times the total mass of the aqueous solution of Pt(NO3)2 and the aqueous solution of Pd(NO3)2, ammonium molybdate tetrahydrate and ethylene glycol.

7. The method for preparing a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas according to claim 1, characterized in that: The mass ratio of solution I and solution II described in step (3) is (217-247):(8.7-49.6); the time of stirring at room temperature is 1-2 hours; the temperature of water bath heating is 70-80°C, and the time of water bath heating is 2-4 hours; the temperature of drying is 80-100°C, and the time of drying is 6-12 hours; the calcination is carried out at a temperature of 500-650°C for 2-6 hours at a heating rate of 5-10°C / min; and the grinding time is 8-12 hours.

8. The method for preparing a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas according to claim 1, characterized in that: The solid content of the slurry in step (3) is 25-30%, and the particle size of the powder in the slurry is 5-20 μm; the binder is pseudo-boehmite or aluminum sol, and the binder accounts for 5-10% of the slurry by mass.

9. The method for preparing a high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas according to claim 1, characterized in that: The carrier described in step (4) is a honeycomb ceramic or metal honeycomb, and the mesh number of the carrier is 260~300 cpsi; the drying temperature is 100~120℃, and the drying time is 2~6 hours; the calcination temperature is 450~600℃, and the calcination time is 2-3 hours; the coating loading of the high-temperature resistant and high-space-velocity VOCs catalytic combustion catalyst is 60~100 g / L.

10. A high-temperature-resistant and high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas produced by the preparation method according to any one of claims 1 to 9.

Images