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

Abstract

The application 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 takes noble metal, transition metal oxide and rare earth oxide as active components, takes honeycomb ceramic or metal honeycomb as a carrier, and is prepared by adopting a coating process. First, Ce x Zr 0.6‑x La y Pr 0.1‑ y O2 is prepared by using lanthanum nitrate hexahydrate, praseodymium nitrate hexahydrate, cerium nitrate hexahydrate and zirconium nitrate pentahydrate; then, La-Al2O3 is prepared by using lanthanum nitrate hexahydrate and Al2O3 through an equal-volume impregnation method; and finally, the catalyst is prepared by using Ce x Zr 0.6‑x La y Pr 0.1‑ y O2, La-Al2O3 and noble metal. The catalyst has the characteristics of high low-temperature activity, good thermal stability and high purification efficiency for catalytic combustion of volatile organic compounds of acid esters at high space velocity.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of industrial waste gas treatment, and particularly 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. BACKGROUND

[0002] Environment-friendly coatings and water-based coatings will gradually replace solvent-based coatings and become the demand of daily industry. Compared with traditional paints, environment-friendly coatings and water-based coatings are new environment-friendly coatings using acid ester alcohol compounds and water instead of triphenyl and formaldehyde as diluents, and do not contain benzene, toluene, formaldehyde and other toxic and harmful air. Compared with paints, the environment-friendly coatings have obvious environmental advantages and are an important guarantee for energy saving and emission reduction. However, these new environment-friendly coatings still have low-toxicity volatile organic compounds such as ethyl acetate and ethanol propylene acid as representatives which need to be treated at the end, and the catalytic combustion technology is one of the most effective technologies for treating such volatile organic compounds (VOCs). However, the catalytic process of such substances is complex, and is often accompanied by some side reactions such as polymerization, acidolysis and the like, which are difficult to handle, and the current catalysts have poor high-temperature resistance under high space velocity conditions. SUMMARY

[0003] In view of the deficiencies in the prior art, the application provides a preparation method of a high-temperature-resistant high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas and the catalyst. The catalyst uses noble metals, transition metal oxides and rare earth oxides as active components, uses ceramic as a carrier, and is prepared by a coating process. The catalyst has the characteristics of high low-temperature activity, good thermal stability and high purification efficiency for catalytic combustion of volatile organic compounds (VOCs) of acid esters in environment-friendly coatings under high space velocity conditions.

[0004] The application provides a preparation method of a high-temperature-resistant high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas, which comprises the following steps:

[0005] (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;

[0006] (2) Pt(NO3)2 aqueous solution and Pd(NO3)2 aqueous solution, ammonium molybdate tetrahydrate and ethylene glycol are dissolved in water to obtain solution II;

[0007] (3) drop solution II into solution I, stir at room temperature for 1-2 h, then heat in water bath to 70-80℃ and stir for 2-4 h to obtain a catalyst precursor; place the catalyst precursor in an oven at 80-100℃ and continue drying for 6-12 h, then calcine at 500-650℃ with a temperature rising rate of 5-10℃ / min for 2-6 h to obtain a catalyst powder; then cool and grind with water for 8-12 h to obtain a slurry; add a binder to the slurry to obtain a base coating slurry;

[0008] (4) immerse a carrier with a pore number of 260-300 cpsi in the base coating slurry, then blow off the excess slurry in the carrier with compressed air at 0.1 MPa, dry at 100-120℃ for 2-6 h, then calcine at 450-600℃ for 2-3 h, and cool to obtain a high-temperature and high-air-speed VOCs catalytic combustion catalyst.

[0009] In one preferred embodiment, the Ce x Zr 0.6-x La y Pr 0.1-y O2

[0010] The preparation process is as follows: mix lanthanum nitrate hexahydrate, praseodymium nitrate hexahydrate, cerium nitrate hexahydrate and zirconium nitrate pentahydrate in a molar ratio of (2-3):(3-4):(23-42):(15-41), dissolve to obtain a mixed solution with a total mass concentration of 1-2 mol / L, then add a dispersant PEG6000 accounting for 1-3% of the total mass of the mixed solution, treat the mixed solution by ammonia coprecipitation, filter and wash after aging for 24 h, dry at 90-110℃ for 6-12 h, and finally calcine at 550-600℃ for 2-4 h to obtain the modified composite oxide Ce x Zr 0.6-x La y Pr 0.1-y O2, wherein the value ranges of x and y are 0

[0011] In one preferred embodiment, the preparation process of La-Al2O3 in step (1) is as follows: load lanthanum nitrate hexahydrate on Al2O3 by an equal-volume impregnation method, and the mass ratio of the lanthanum nitrate hexahydrate to the Al2O3 is 1:(7-12); then dry at 80-120℃ for 1-2 h, and finally calcine at 450-600℃ for 1-5 h to obtain La-Al2O3; the specific surface area of the Al2O3 is greater than 250 m 2 / g, and the pore volume of the Al2O3 is greater than 60 cm 3 / g.

[0012] In one preferred embodiment, the mass of water in step (1) is 2-2.5 times the mass of 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.

[0013] In one preferred embodiment, the mass of water in step (1) is 2-2.5 times the mass of 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.

[0014] In one preferred embodiment, 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 in step (2) is 0.45-0.8% of the total mass of 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.

[0015] In one preferred embodiment, 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, the mass of ammonium molybdate tetrahydrate and the mass of ethylene glycol in step (2) is (0.45-0.8):(0.7-0.8):(2.5~10.5).

[0016] In one 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.

[0017] In one preferred embodiment, the mass ratio of solution I and solution II in step (3) is (217-247):(8.7-49.6).

[0018] In one preferred embodiment, the solid content in the slurry in step (3) is 25~30%, and the particle size of the powder in the slurry is 5-20μm.

[0019] In one preferred embodiment, the binder in step (3) is pseudo-boehmite or aluminum sol, and the mass percentage of the binder in the slurry is 5-10%.

[0020] In a preferred embodiment, the carrier in step (4) is honeycomb ceramic or metal honeycomb.

[0021] In a preferred embodiment, the coating load of the high-temperature-resistant high-space-velocity VOCs catalytic combustion catalyst in step (4) is 60-100 g / L.

[0022] In a preferred embodiment, the high-temperature-resistant high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas is prepared by the above preparation method.

[0023] The beneficial effects of the present application are:

[0024] The high-temperature-resistant high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas provided by the present application realizes the low-temperature complete oxidation of acid ester waste gas VOCs and exhibits excellent performance in high-temperature aging resistance; the additive ethylene glycol enables the noble metal, transition metal, and alumina, cerium-zirconium-lanthanum-praseodymium composite oxide to form a special interfacial activity, realizes the high dispersion of the active substance in the alumina, cerium-zirconium-lanthanum-praseodymium composite oxide, and obtains more active sites; in addition, ethylene glycol has a certain reducing capacity in the catalyst synthesis process and the drying and calcination process, so that the alumina, cerium-zirconium-lanthanum-praseodymium composite oxide has more oxygen vacancies, which helps the catalytic oxidation of VOCs, so that the catalyst exhibits excellent low-temperature activity; then, the calcination temperature in the catalyst preparation process is finely regulated and controlled, the high dispersion form of the noble metal PtPd species and the transition metal oxide MoO x further forms a stronger mutual interaction SMSI with the alumina, cerium-zirconium-lanthanum-praseodymium rare earth oxide solid, so that the active metal has the ability to resist migration and agglomeration, and therefore the catalyst exhibits excellent anti-aging ability after aging at 750 DEG C for 24 h.

[0025] The catalyst provided by the present application has the characteristics of low light-off temperature and good high-temperature stability under high-space-velocity conditions of acid ester VOCs, and can be widely applied to petrochemical, pharmaceutical, papermaking, transportation, textile, coating, printing, and other industrial industries. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The anti-aging performance comparison chart of the catalyst prepared in Example 1 for catalytic oxidation of ethyl acetate;

[0027] Figure 2 The anti-aging performance comparison chart of the catalyst prepared in Example 1 for catalytic oxidation of toluene. DETAILED DESCRIPTION

[0028] The water in the scheme of the present application is all deionized water.

[0029] The Ce x Zr 0.6-x La y Pr 0.1-y O2 is prepared by the ammonia co-precipitation method, and ammonia water (mass concentration of 25-30%) is used for excessive precipitation of the system, the pH value of the system is adjusted to 8-10 through titration, and the system is precipitated through rapid stirring, and the reaction is carried out for 8-12 h.

[0030] The Al2O3, the Pt(NO3)2 aqueous solution and the Pd(NO3)2 aqueous solution in the following examples and comparative examples of the present application are all commercially available, the mass concentration of the element Pt in the Pt(NO3)2 aqueous solution and the mass concentration of the element Pd in the Pd(NO3)2 aqueous solution are both 15%; the specification of the Al2O3 is that the specific surface area is greater than 250 m 2 / g, and the pore volume of the Al2O3 is greater than 60 cm 3 / g.

[0031] The Ce x Zr 0.6-x La y Pr 0.1-y O2 is prepared by the ammonia co-precipitation method, and ammonia water (mass concentration of 25-30%) is used for excessive precipitation of the system, the pH value of the system is adjusted to 8-10 through titration, and the system is precipitated through rapid stirring, and the reaction is carried out for 8-12 h.

[0032] Example 1

[0033] The Ce 0.36 Zr 0.24 La 0.02 Pr 0.04 O2 is prepared by the ammonia co-precipitation method, and ammonia water (mass concentration of 25-30%) is used for excessive precipitation of the system, the pH value of the system is adjusted to 8-10 through titration, and the system is precipitated through rapid stirring, and the reaction is carried out for 8-12 h.

[0034] 7.9742g of lanthanum nitrate hexahydrate, 17.8869g of praseodymium nitrate hexahydrate, 156.6168g of cerium nitrate hexahydrate and 104.5227g of zirconium nitrate pentahydrate are weighed, mixed and dissolved in water to form a mixed solution with a molar concentration of 1mol / L, 6.5g of PEG6000 is added as a dispersant to the mixed solution, then excess ammonia water is added to the mixed solution to precipitate the mixed solution by the ammonia co-precipitation method, the solution containing the precipitate is aged overnight, filtered, washed with deionized water, and finally dried at 90℃ for 6h and calcined at 600℃ for 2h to obtain the modified composite oxide Ce 0.36 Zr 0.24 La 0.02 Pr 0.04 O2.

[0035] The La-Al2O3

[0036] 95 g of Al2O3 and 13 g of lanthanum nitrate hexahydrate were weighed respectively, loaded by equal-volume impregnation, dried at 100 ℃ for 2 h, and calcined at 600 ℃ for 2 h to obtain modified alumina La-Al2O3.

[0037] Preparation of catalyst 1

[0038] (1) 59.28 g of Ce 0.36 Zr 0.24 La 0.02 Pr 0.04 O2 and 39.52 g of modified alumina La-Al2O3 were mixed and dissolved in 220 g of deionized water to form solution I;

[0039] (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 to form solution II; solution II was added dropwise to solution I, stirred at room temperature for 1 h, and then heated in a water bath to 80 ℃ and stirred to dryness for 2 h to obtain a catalyst precursor; then the catalyst precursor was placed in an oven at 80 ℃ for continuous drying for 6 h, and finally calcined at 600 ℃ in a muffle furnace at a heating rate of 5 ℃ / min for 4 h to obtain a catalyst powder;

[0040] (3) 100 g of the above catalyst powder was weighed and added with deionized water for grinding for 8 h to obtain a slurry; the solid content of the slurry was 30%, and the powder particle size was 5 μm; 10 g of pseudo-boehmite was further added to the slurry, and an acid solution was prepared to form a base coating slurry;

[0041] (4) a cordierite honeycomb ceramic with a pore number of 300 cpsi was used as a carrier, the carrier was immersed in the base coating slurry, the slurry was distributed on the pore structure of the cordierite honeycomb ceramic carrier, and the excess slurry in the pores of the honeycomb ceramic carrier was blown out by compressed air at 0.1 MPa; the carrier was dried at 100 ℃ in an oven for 2 h and calcined at 500 ℃ for 2 h, and then cooled to obtain a high-temperature and high-air-speed VOCs catalytic combustion catalyst 1; the coating load of the catalyst 1 was 80 g / L.

[0042] Example 2

[0043] Preparation of Ce 0.4 Zr 0.2 La 0.03 Pr 0.03 O2

[0044] Take 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, mix and dissolve in water to form a mixed solution with a molar concentration of 1 mol / L, then add 6.5 g of PEG6000 as a dispersant to the mixed solution, and then add excess ammonia water to the mixed solution, and precipitate the mixed solution by ammonia coprecipitation, and then let the solution containing the precipitate stand overnight, filter, wash with deionized water, and finally dry at 90°C for 6h and calcine at 600°C for 2h to obtain a modified composite oxide Ce 0.4 Zr 0.2 La 0.03 Pr 0.03 O2;

[0045] Preparation of La-Al2O3

[0046] Take 96 g of Al2O3 and 11 g of lanthanum nitrate hexahydrate respectively, load by equal volume impregnation method, then dry at 100°C for 2h and calcine at 600°C for 2h to obtain modified alumina La-Al2O3.

[0047] Preparation of catalyst 2

[0048] (1) Mix 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, and dissolve in 220 g of deionized water to form solution I;

[0049] (2) Dissolve 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 in 30 g of deionized water to form solution II; add solution II dropwise to solution I, stir at room temperature for 2h, then heat in a water bath to 70°C and stir to dry for 4h to obtain a catalyst precursor, then place the catalyst precursor in an oven and continue to dry at 100°C for 6h, and finally calcine the catalyst precursor in a muffle furnace at 600°C with a temperature rising rate of 5°C / min for 4h to obtain a catalyst powder;

[0050] (3) Take 100 g of the above catalyst powder and add deionized water to grind for 12h to obtain a slurry; the solid content of the slurry is 30%, and the powder particle size is 20μm; then add 10 g of pseudo-boehmite to the slurry to prepare a base coating slurry;

[0051] (4) use the 300 cpsi cordierite honeycomb ceramic as the carrier, immerse the carrier in the base coating slurry, distribute the slurry on the pore structure of the cordierite honeycomb ceramic carrier, and blow out the excess slurry in the pores of the honeycomb ceramic carrier with 0.1 MPa compressed air, dry in an oven at 120°C for 6 h, calcine at 500°C for 3 h, and cool to obtain the high-temperature-resistant high-air-speed VOCs catalytic combustion catalyst 2, and the coating load of the catalyst 2 is 80 g / L.

[0052] Example 3

[0053] Preparation of Ce 0.45 Zr 0.15 La 0.02 Pr 0.04 O2

[0054] Take 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, mix and dissolve in water to obtain a mixed solution with a molar concentration of 1 mol / L, add 6.5 g of PEG6000 as a dispersant to the mixed solution, then add excess ammonia water to the mixed solution, and precipitate the mixed solution by ammonia coprecipitation. The solution containing the precipitate is aged overnight, filtered, washed with deionized water, and finally dried at 90°C for 6 h and calcined at 550°C for 2 h to obtain the modified composite oxide Ce 0.45 Zr 0.15 La 0.02 Pr 0.04 O2.

[0055] Preparation of La-Al2O3

[0056] Take 97 g of Al2O3 and 8 g of lanthanum nitrate hexahydrate respectively, load by equal-volume impregnation method, then dry at 100°C for 2 h and calcine at 600°C for 2 h to obtain the modified alumina La-Al2O3.

[0057] Preparation of catalyst 3

[0058] (1) Mix 59.28 g of Ce 0.45 Zr 0.15 La 0.02 Pr 0.04 O2 and 39.52 g of modified alumina La-Al2O3, and dissolve in 220 g of deionized water to obtain solution I;

[0059] (2) 3.6 g of Pt(NO3)2 aqueous solution and 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 to form solution II; solution II was added dropwise into solution I, and after stirring at room temperature for 1 h, water bath heating was performed to 80℃, and stirring and drying were performed for 4 h to obtain a catalyst precursor, then the catalyst precursor was placed in an oven for further drying at 100℃ for 10 h, and finally calcination was performed at 550℃ in a muffle furnace at a temperature increasing rate of 5℃ / min for 4 h to obtain a catalyst powder;

[0060] (3) 100 g of the above catalyst powder was weighed and added into deionized water for grinding for 12 h to obtain a slurry; the solid content of the slurry was 30%, and the powder particle size was 10 μm; 10 g of pseudo-boehmite was further added into the slurry to prepare a base coating slurry;

[0061] (4) a cordierite honeycomb ceramic with a pore number of 300 cpsi was used as a carrier, the carrier was immersed in the base coating slurry, the slurry was distributed on the pore structure of the cordierite honeycomb ceramic carrier, and the excess slurry in the pores of the honeycomb ceramic carrier was blown out by using 0.1 MPa compressed air, drying was performed at 120℃ in an oven for 6 h, calcination was performed at 550℃ for 4 h, and cooling was performed to room temperature to obtain a high-temperature and high-air-speed VOCs catalytic combustion catalyst 3, and the coating load of the catalyst 3 was 80 g / L.

[0062] Example 4

[0063] Preparation of Ce 0.3 Zr 0.3 La 0.02 Pr 0.04 O2

[0064] 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 mixed solution with a molar concentration of 1 mol / L, 6.5 g of PEG6000 was added as a dispersant to the mixed solution, and then excess ammonia water was added to the mixed solution to perform ammonia coprecipitation, the solution containing the precipitate was aged overnight, filtered, washed with deionized water, and finally dried at 90℃ for 6 h and calcined at 600℃ for 2 h to obtain a modified composite oxide Ce 0.3 Zr 0.3 La 0.02 Pr 0.04 O2.

[0065] Preparation of La-Al2O3

[0066] 94 g of Al2O3 and 16 g of lanthanum nitrate hexahydrate were weighed respectively, loaded by equal-volume impregnation method, then dried at 100 ℃ for 2 h and calcined at 600 ℃ for 2 h to obtain modified alumina La-Al2O3.

[0067] Preparation of catalyst 4

[0068] (1) 59.28 g of Ce 0.3 Zr 0.3 La 0.02 Pr 0.04 O2 and 39.52 g of modified alumina La-Al2O3 were mixed and dissolved in 220 g of deionized water to form solution I;

[0069] (2) 3 g of Pt(NO3)2 aqueous solution, 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 to form solution II; solution II was added dropwise to solution I, stirred at room temperature for 1 h, then heated to 75 ℃ in a water bath and stirred to dryness for 2 h to obtain a catalyst precursor, then the catalyst precursor was placed in an oven for further drying at 90 ℃ for 12 h, and finally calcined at 600 ℃ in a muffle furnace at a heating rate of 5 ℃ / min for 2 h to obtain a catalyst powder;

[0070] (3) 100 g of the above catalyst powder was weighed and added to deionized water for grinding for 12 h to obtain a slurry; the solid content of the slurry was 30%, and the powder particle size was 15 μm; 10 g of pseudo-boehmite was further added to the slurry to prepare a base coating slurry;

[0071] (4) A cordierite honeycomb ceramic with a pore number of 300 cpsi was used as a carrier, the carrier was immersed in the base coating slurry, the slurry was distributed on the pore structure of the cordierite honeycomb ceramic carrier, and the excess slurry in the pores of the honeycomb ceramic carrier was blown out by compressed air at 0.1 MPa, dried at 110 ℃ in an oven for 4 h, calcined at 500 ℃ for 3 h, and cooled to room temperature to obtain a high-temperature and high-air-speed VOCs catalytic combustion catalyst 4; the coating load of the catalyst 4 was 80 g / L.

[0072] Example 5

[0073] 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 mixed solution with a molar concentration of 1 mol / L, 6.5 g of PEG6000 was added as a dispersant, and then excess ammonia water was added to the mixed solution by ammonia coprecipitation method. The solution containing the precipitate was aged overnight, filtered, washed with deionized water, and finally dried at 90 ℃ for 6 h and calcined at 550 ℃ for 4 h to obtain a modified composite oxide Ce0.2 Zr 0.4 La 0.04 Pr 0.02 O2;

[0074] Preparation of La-Al2O3

[0075] 93g of Al2O3 and 19g of lanthanum nitrate hexahydrate were weighed respectively, loaded by equal-volume impregnation, dried at 100℃ for 2h, and calcined at 550℃ for 2h to obtain modified alumina La-Al2O3.

[0076] Preparation of catalyst 5

[0077] (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 to form solution I;

[0078] (2) 2.66g of Pt(NO3)2 aqueous solution, 1.34g of Pd(NO3)2 aqueous solution, 0.716g of ammonium molybdate tetrahydrate, and 10.5g of ethylene glycol were dissolved in 30g of deionized water to form solution II; solution II was added dropwise to solution I, stirred at room temperature for 1h, and then heated in a water bath to 80℃ and stirred to dryness for 2h to obtain a catalyst precursor; the catalyst precursor was then placed in an oven and dried at 100℃ for 10h; finally, the catalyst precursor was calcined at 550℃ in a muffle furnace at a temperature rising rate of 10℃ / min for 2h to obtain a catalyst powder;

[0079] (3) 100g of the above catalyst powder was weighed and added to deionized water for grinding for 12h to obtain a slurry; the solid content of the slurry was 30%, and the powder particle size was 5μm; 10g of pseudoboehmite was further added to the slurry to prepare a base coating slurry;

[0080] (4) a cordierite honeycomb ceramic with a pore number of 300cpsi was used as a carrier, the carrier was immersed in the base coating slurry, the slurry was distributed on the pore structure of the cordierite honeycomb ceramic carrier, and the excess slurry in the pores of the honeycomb ceramic carrier was blown out by compressed air at 0.1MPa; the carrier was dried at 105℃ in an oven for 5h and calcined at 550℃ for 3h to obtain a high-temperature and high-air-speed VOCs catalytic combustion catalyst 5; the coating load of the catalyst 5 was 80g / L.

[0081] Example 6

[0082] Preparation of Ce 0.24 Zr 0.36 La 0.02 Pr 0.04 O2

[0083] Weigh 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, mix and dissolve in water to form a mixed solution with a molar concentration of 1 mol / L, add 6.5 g of PEG6000 as a dispersant to the mixed solution, then add excess ammonia water to the mixed solution, and precipitate the mixed solution by ammonia coprecipitation. The solution containing the precipitate is aged overnight, filtered, washed with deionized water, and finally dried at 90°C for 6 h and calcined at 550°C for 4 h to obtain a modified composite oxide Ce 0.24 Zr 0.36 La 0.02 Pr 0.04 O2;

[0084] Preparation of La-Al2O3

[0085] Weigh 95 g of Al2O3 and 13 g of lanthanum nitrate hexahydrate respectively, load by equal volume impregnation method, then dry at 100°C for 2 h and calcine at 550°C for 2 h to obtain modified alumina La-Al2O3.

[0086] (1) Dissolve 59.28 g of Ce 0.24 Zr 0.36 La 0.02 Pr 0.04 O2 and 39.52 g of modified alumina La-Al2O3 in 220 g of deionized water to form solution I;

[0087] (2) Dissolve 1 g of Pt(NO3)2 aqueous solution, 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 to form solution II; add solution II dropwise to solution I, stir at room temperature for 1 h, then heat in a water bath to 80°C and stir to dry for 4 h to obtain a catalyst precursor, then place the catalyst precursor in an oven at 95°C for further drying for 6 h, and finally calcine the catalyst precursor in a muffle furnace at 500°C at a heating rate of 10°C / min for 2 h to obtain a catalyst powder;

[0088] (3) Grind 100 g of the above catalyst powder in deionized water 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 pseudoboehmite to the slurry to prepare a base coating slurry;

[0089] (4) use the 300 cpsi cordierite honeycomb ceramics as the carrier, immerse the carrier in the base coating slurry, make the slurry distribute on the pore structure of the cordierite honeycomb ceramics carrier, and blow out the excess slurry in the pores of the honeycomb ceramics carrier with 0.1 MPa compressed air, dry in the oven at 110°C for 4 h, calcine at 500°C for 2 h, and cool to obtain the high-temperature-resistant high-air-speed VOCs catalytic combustion catalyst 6, and the coating load of the catalyst 6 is 80 g / L.

[0090] Example 7

[0091] Preparation of Ce 0.36 Zr 0.24 La 0.03 Pr 0.03 O2

[0092] Take 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, mix and dissolve in water to obtain a mixed solution with a molar concentration of 1 mol / L, add 6.5 g of PEG6000 as a dispersant to the mixed solution, then add excess ammonia water to the mixed solution, and precipitate the mixed solution by ammonia coprecipitation, let the solution containing the precipitate stand overnight, filter, wash with deionized water, and finally dry at 90°C for 6 h and calcine at 550°C for 4 h to obtain the modified composite oxide Ce 0.36 Zr 0.24 La 0.03 Pr 0.03 O2.

[0093] Preparation of La-Al2O3

[0094] Take 95 g of Al2O3 and 13 g of lanthanum nitrate hexahydrate respectively, load by equal-volume impregnation method, then dry at 100°C for 2 h and calcine at 550°C for 2 h to obtain the modified alumina La-Al2O3.

[0095] Preparation of catalyst 7

[0096] (1) Mix 59.28 g of Ce 0.36 Zr 0.24 La 0.03 Pr 0.03 O2 and 39.52 g of modified alumina La-Al2O3, and dissolve in 220 g of deionized water to obtain solution I;

[0097] (2) 3.2 g of Pt(NO3)2 aqueous solution and 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 to form a solution II; the solution II was added dropwise into the solution I, stirred at room temperature for 1 h, heated in water bath to 80℃ and stirred to dry for 4 h to obtain a catalyst precursor, then the catalyst precursor was placed in an oven at 95℃ and dried for another 6 h, finally calcined at 600℃ in a muffle furnace at a heating rate of 5℃ / min for 4 h to obtain a catalyst powder;

[0098] (3) 100 g of the catalyst powder was weighed and added into deionized water for grinding for 12 h to obtain a slurry; the solid content of the slurry was 25%, and the powder particle size was 5 μm; 7 g of pseudo-boehmite was further added into the slurry, and a basic coating slurry was prepared after acidolysis;

[0099] (4) a metal honeycomb with a pore number of 260 cpsi was used as a carrier, the carrier was immersed in the basic coating slurry, the slurry was distributed on the pore structure of the metal honeycomb carrier, and the excess slurry in the pores of the honeycomb ceramic carrier was blown out by using 0.1 MPa compressed air, dried in an oven at 110℃ for 4 h, calcined at 550℃ for 3 h, and cooled to obtain a high-temperature and high-air-speed VOCs catalytic combustion catalyst 7, and the coating load of the catalyst 7 was 80 g / L.

[0100] Comparative Example 1

[0101] In step (2) of Example 1, the ammonium molybdate tetrahydrate and the ethylene glycol were not added in the preparation of the solution II, and the other contents were consistent with those in Example 1.

[0102] Comparative Example 2

[0103] In step (2) of Example 1, the ethylene glycol was not added in the preparation of the solution II, and the other contents were consistent with those in Example 1.

[0104] Comparative Example 3

[0105] 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 by 3.2 g of chloroplatinic acid aqueous solution and 0.8 g of chloropalladic acid aqueous solution, and the other contents were consistent with those in Example 1.

[0106] Comparative Example 4

[0107] In step (2) of Example 1, the addition amount of the Pt(NO3)2 and Pd(NO3)2 aqueous solutions was reduced, and the total addition amount of the elements Pt and Pd in the Pt(NO3)2 and Pd(NO3)2 aqueous solutions was limited to 0.45 g, and the other contents were consistent with those in Example 1.

[0108] Comparative Example 5

[0109] Ce is not prepared 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 with 59.28g of CeO2 and 39.52g of Al2O3, respectively. All other contents were the same as in Example 1.

[0110] The catalysts prepared in Examples 1-7 and Comparative Examples 1-5 were used to process representative waste gases of ethyl acetate and toluene at a volume hourly space velocity of 30,000 h⁻¹. -1 Catalytic efficiency performance was tested at a concentration of 1000 ppm. Dry air was used as the carrier gas to simulate the exhaust gas environment. The concentration of exhaust gas before and after passing through the catalyst was detected by gas chromatography. The catalyst was aged at 750℃ for 24 hours. The test results are shown in Table 1 below:

[0111] Table 1. Catalytic performance of the catalysts in the oxidation of toluene and ethyl acetate

[0112]

[0113] Catalyst 1, prepared in Example 1, achieves highly efficient and complete catalytic oxidation of ethyl acetate at temperatures below 300°C. Ethyl acetate is completely oxidized at 270°C with a space velocity of 30,000, and after aging at 750°C for 24 hours, the complete conversion temperature of ethyl acetate only increases by 10°C. Furthermore, in the catalytic oxidation test of toluene, a traditional paint solvent, complete oxidation of toluene is achieved at 200°C with a space velocity of 30,000, and after aging at 750°C for 24 hours, the complete conversion temperature of toluene remains at 200°C, showing almost no degradation.

[0114] It is found by comparing Example 1, Example 2 and Comparative Example 2 that ethylene glycol EG plays a crucial role in the synthesis of the catalyst and has a decisive effect on the dispersion of the active metal of the catalyst, so it can be seen that the addition of ethylene glycol makes the active metal have more active sites. Although Example 2 is about 1 / 3 less than Example 1 in ethylene glycol, the T99 of the fresh catalyst for toluene is 10℃ lower than that of Example 1, but the toluene activity of the catalyst has a certain loss during the high-temperature aging process; the calcination process of the catalyst in Example 1 and Example 3-7 is more finely controlled, and it is found that the catalyst has relatively good anti-aging ability for toluene and ethyl acetate under the condition of 750℃ continuous aging for 24h at a relatively higher temperature and a higher calcination time; the catalyst in Example 1 shows the best anti-aging performance under the condition of calcination at 600℃ for 4h, as shown in Figure 1 and Figure 2 , wherein ΔT99 甲苯 is 0℃, and ΔT99 乙酸乙酯 is 10℃, which is due to the strong interaction between the active metal and the carrier under the high-temperature and long-time calcination atmosphere, so that the active metal is more stably anchored on the carrier, preventing the migration and agglomeration of the active metal of the catalyst at high temperature; although the toluene T99 activity of the catalyst in Example 7 is 5℃ higher than that of the ceramic honeycomb catalyst with 300cpsi, the catalyst still has excellent activity and aging activity.

[0115] It is found by comparing Example 1 with Comparative Example 1, Comparative Example 2 and Comparative Example 3 that changing the transition metal oxide additive ammonium molybdate in the catalyst, the dispersing and reducing additive ethylene glycol, and the precious metal active component precursor all have obvious effects and changes on the performance of the catalyst, among which the molybdenum additive is beneficial to the low-temperature oxidation activity of the catalyst for ethyl acetate and toluene, ethylene glycol is helpful to the dispersion of the precious metal and the molybdenum additive, and the precious metal nitrate compound has higher activity than the precious metal chloride, which is related to the poisoning of the chloride ion in the chloride precious metal to the catalyst, resulting in the relatively high temperature shift of the activity of the catalyst;

[0116] By comparing Example 1 with Comparative Example 4, it is found that the catalyst can still work at high space velocity under the condition of reducing the loading amount of the precious metal and keeping other conditions unchanged, although the complete oxidation temperature is 10℃ higher, and the anti-aging ability is consistent with that of Example 1, which also provides a solution for some economic and applicable projects;

[0117] By comparing Example 1 with Comparative Example 5, it is found that the catalytic efficiency of the ordinary cerium oxide in Comparative Example 5 is much lower than that of Ce x Zr 0.6-x La y Pr 0.1-yO2 cerium zirconium solid solution compound, the compound is doped by certain amount of zirconium Zr, lanthanum La and praseodymium Pr elements, so that the catalyst shows better low temperature activity.

[0118] The above merely preferred embodiments of the present application, not for limiting the scope of the application. It should be understood that the present application in the field, according to the concept of the present application to improve and change while any modification, equivalent replacement, change, etc. should belong to the appended claims of the present application within the scope of the protection.

Claims

1. A method for preparing a high-temperature, high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas, characterized in that, Includes the following steps: (1) Ce x Zr 0.6-x La y Pr 0.1-y O2 and La-Al2O3 dissolve 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 with ammonia co-precipitation, where the values ​​of x and y range from 0 to 10. <x≤0.6,0<y<0.1; The La-Al2O3 is prepared by an equal-volume impregnation method using lanthanum nitrate hexahydrate and Al2O3, wherein the mass ratio of lanthanum nitrate hexahydrate to Al2O3 is 1:(7-12); and the specific surface area of ​​the Al2O3 is greater than 250 m². 2 / g, pore volume greater than 60cm³ 3 / g; The Ce 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 dissolved in water to obtain a mixed solution with a total concentration of 1-2 mol / L. Then, 1-3% of the total mass of the mixed solution is added as a dispersant PEG6000. The mixed solution is treated by ammonia co-precipitation, aged for 24 hours, filtered, washed, dried at 90-110℃ for 6-12 hours, and finally calcined at 550-600℃ for 2-4 hours to obtain the modified composite oxide Ce. x Zr 0.6-x La y Pr 0.1-y O2; The Ce x Zr 0.6-x La y Pr 0.1-y The mass ratio of O2 to La-Al2O3 is 5-7:3-5; (2) Dissolve the aqueous solutions of Pt(NO3)2 and Pd(NO3)2, ammonium molybdate tetrahydrate and ethylene glycol in water, and label it as solution II; (3) Add solution II dropwise to solution I, stir at room temperature and heat in a water bath to obtain a catalyst precursor; dry and calcine the catalyst precursor, cool it to obtain catalyst powder, then add water and grind it to obtain a slurry; add a binder to the slurry to obtain a basic coating slurry; the water bath heating temperature is 70~80℃ and the water bath heating time is 2~4h. (4) The carrier is immersed in the base coating slurry, and then the excess slurry in the carrier is blown out with compressed air at 0.1 MPa. Finally, the carrier is dried, calcined, and cooled to obtain a high-temperature and high-space-velocity VOCs catalytic combustion catalyst.

2. The preparation method of the high-temperature, 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 in step (1) is as follows: Lanthanum nitrate hexahydrate is loaded onto Al2O3 by equal volume impregnation, then dried at 80-120℃ for 1-2h, and finally calcined at 450-600℃ for 1-5h to obtain La-Al2O3.

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

4. The preparation method of the high-temperature, high-space-velocity VOCs catalytic combustion catalyst for acid ester waste gas according to claim 1, characterized in that, 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 mentioned in step (2) is the same as the mass of element Ce mentioned in step (1). x Zr 0.6-x La y Pr 0.1-y The total mass of O2 and La-Al2O3 is 0.45-0.8%; 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%.

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

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

7. The preparation method of the high-temperature, 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 5-20μm; the binder is boehmite or aluminum sol, and the binder accounts for 5-10% of the slurry mass.

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

9. A high-temperature, high-space-velocity VOCs catalytic combustion catalyst for ester-based waste gas prepared by the preparation method according to any one of claims 1 to 8.

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