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CN-121972163-A - Granular tail gas combustion catalyst, preparation method thereof and tail gas purifying method

CN121972163ACN 121972163 ACN121972163 ACN 121972163ACN-121972163-A

Abstract

The invention discloses a granular tail gas combustion catalyst, a preparation method thereof and a tail gas purifying method. The granular catalyst comprises the following components of active components comprising Pt, bi, la and Hf, a carrier comprising powdery Al 2 O 3 and granular Al 2 O 3 , wherein the powdery Al 2 O 3 is obtained by mixing alpha' -AlOOH with rho-Al 2 O 3 and roasting. The active component is soaked and loaded on the powdery Al 2 O 3 , and then the soaking solution is prepared into slurry and coated on the granular Al 2 O 3 to obtain the catalyst. Bi. The addition of La and Hf inhibits the agglomeration of noble metal particles, and the powdery Al 2 O 3 has higher hydrothermal stability, so that the catalyst has better stability and longer service life when being used in the catalytic combustion reaction of fixed bed tail gas.

Inventors

  • KONG DEBIN
  • PAN SHIWEI
  • YANG ZHICHAO
  • XU QINGFENG
  • LUO LEI
  • LI ZUOJIN
  • SUN KANG
  • LI YUAN

Assignees

  • 万华化学集团股份有限公司

Dates

Publication Date
20260505
Application Date
20251209

Claims (10)

  1. 1. A catalyst for catalytic combustion of granular tail gas contains Pt, bi, la and Hf as active components and powdered Al 2 O 3 and granular Al 2 O 3 as carrier.
  2. 2. The catalyst according to claim 1, wherein the Pt content is 300 to 3000ppm, preferably 500 to 1500ppm, the bi content is 300 to 3000ppm, preferably 500 to 1500ppm, the la content is 300 to 2000ppm, preferably 500 to 1000ppm, the hf content is 300 to 2000ppm, preferably 500 to 1000ppm, and the active component content is calculated based on the mass sum of powdery Al 2 O 3 and granular Al 2 O 3 .
  3. 3. A method for preparing the granular exhaust gas catalytic combustion catalyst according to claim 1 or 2, comprising the steps of immersing a solution containing platinum salt, bismuth salt, lanthanum salt and hafnium salt in powdery Al 2 O 3 obtained by roasting a mixture of alpha' -AlOOH and rho-Al 2 O 3 , adding a binder to prepare slurry, coating the slurry on granular Al 2 O 3 , drying and reducing.
  4. 4. The method according to claim 3, wherein the preparation method of the powdery Al 2 O 3 comprises the steps of roasting a mixture of alpha '-AlOOH and rho-Al 2 O 3 , and preferably, the mass ratio of the alpha' -AlOOH in the mixture is 20-80%, preferably 40-60%.
  5. 5. The method according to claim 3 or 4, wherein the specific surface area of the powdery Al 2 O 3 is 100-450 m 2 /g, preferably 150-320 m 2 /g, the pore volume is 0.2-0.8 cm 3 /g, preferably 0.4-0.7 cm 3 /g, and the pore diameter is 3-12 nm, preferably 4-8 nm.
  6. 6. The method according to any one of claims 3 to 5, wherein the preparation method of the granular Al 2 O 3 comprises the steps of rolling and forming, aging and roasting a mixture of alpha ' -AlOOH and rho-Al 2 O 3 and water, wherein the mass ratio of the alpha ' -AlOOH in the mixture is preferably 20-80%, and the mass ratio of the alpha ' -AlOOH in the mixture is preferably 40-60%.
  7. 7. The method according to any one of claims 3-6, wherein the granular Al 2 O 3 has a spherical, ellipsoidal, elongated, preferably spherical shape, a size of 1-6 mm, preferably 3-6 mm, a specific surface area of 100-450 m 2 /g, preferably 150-320 m 2 /g, a pore volume of 0.2-0.8 cm 3 /g, preferably 0.4-0.7 cm 3 /g, a pore diameter of 3-12 nm, preferably 4-8 nm, and a water absorption of 30-60%, preferably 40-50%.
  8. 8. The method according to any one of claims 3-7, characterized in that the mass ratio of powdery Al 2 O 3 to granular Al 2 O 3 is 5-20%, preferably 5-15%.
  9. 9. A process for purifying exhaust gas in the presence of a catalyst according to claim 1 or 2 or a catalyst prepared by a process according to any one of claims 3 to 8, the reactor being in the form of a fixed bed.
  10. 10. The method according to claim 9, wherein the tail gas comprises oxygen, organic matter, CO, water=2-8%: 0-5%: 0-3%: 0-15%, nitrogen and other components, the ratio of organic matter to CO is different from 0, the space velocity is 1000-50000 h -1 , preferably 5000-30000 h -1 , and the temperature is 250-650 ℃, preferably 400-550 ℃.

Description

Granular tail gas combustion catalyst, preparation method thereof and tail gas purifying method Technical Field The invention relates to the fields of chemical tail gas treatment and catalysts, and comprises a tail gas combustion catalyst preparation method and a chemical tail gas treatment method. Background The tail gas of the chemical device contains a large amount of VOCs and CO, and the direct discharge to the atmosphere can cause the problem of environmental pollution. The existing treatment modes comprise a direct combustion method and a catalytic combustion method, and compared with the direct combustion method, the catalytic combustion method can realize flameless combustion at 400-600 ℃, and the heat released by the reaction can produce high-quality steam as a byproduct. The particulate exhaust gas combustion catalysts and the monolithic exhaust gas combustion catalysts can be classified according to the type of catalyst. CN109772309a discloses a monolithic catalyst for catalytic oxidation of ketobenzene-containing tail gas and a preparation method, wherein the active component of the catalyst is Pd or Pt or Pd and Pt with a certain proportion. The catalyst has higher ketone benzene tail gas combustion activity and stability, and can be used in the catalytic removal process of other VOCs gases containing phenol, ketone and the like. CN111111656a discloses a high-temperature resistant catalytic combustion catalyst for self-sustaining combustion of normal-temperature catalytic ignition VOCs, and a preparation method and application thereof. Comprises noble metal active components, oxygen storage material cerium zirconium solid solution and carrier. The catalyst can remove VOCs waste gas without external auxiliary heating energy, has good hydrothermal stability and high-temperature stability, and greatly simplifies the treatment of the VOCs waste gas. Taking a formaldehyde device as an example, the reaction flow is that methanol and air generate formaldehyde under the action of a catalyst, the generated formaldehyde is absorbed by water, the components in tail gas contain residual methanol, formaldehyde, CO and dimethyl ether, and the CO 2 and the water are generated after the catalyst is catalytically combusted, so that the emission index is reached. The catalytic combustion catalyst is granular platinum alumina, and the design life is 2 years. The service life of the conventional domestic catalyst is less than two years, the water resistance of the catalyst is poor, and various tail gas working conditions cannot be met. Therefore, there is a need to develop an exhaust gas combustion catalyst which can cope with complicated working conditions and has excellent stability. Disclosure of Invention The invention aims to provide a granular tail gas combustion catalyst, a preparation method thereof and a tail gas purification method, wherein the catalyst has good hydrothermal stability at high water concentration and high temperature, has high water resistance and prolongs the service life of the catalyst. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: A catalyst for catalytic combustion of granular tail gas is composed of active components including Pt, bi, la and Hf, and carrier including powdered Al 2O3 and granular Al 2O3. The Pt content is 300-3000 ppm, preferably 500-1500 ppm, the Bi content is 300-3000 ppm, preferably 500-1500 ppm, the La content is 300-2000 ppm, preferably 500-1000 ppm, the Hf content is 300-2000 ppm, preferably 500-1000 ppm, and the active component content is calculated based on the mass sum of powdery Al 2O3 and granular Al 2O3. A process for preparing the catalyst used for catalytic combustion of granular tail gas includes such steps as immersing the solution containing Pt, bi, la and Hf salts in the powder Al 2O3 prepared by calcining the mixture of alpha' -AlOOH and rho-Al 2O3, adding adhesive to obtain slurry, coating it on granular Al 2O3, drying and reduction. Preferably, the platinum salt comprises one or more of platinum nitrate, chloroplatinic acid, potassium tetrachloroplatinate, preferably chloroplatinic acid and/or platinum nitrate. Preferably, the bismuth salt comprises one or more of sodium bismuth oxide, potassium bismuth oxide, bismuth chloride and bismuth nitrate, preferably bismuth chloride and/or bismuth nitrate. Preferably, the lanthanum salt comprises one or more of lanthanum nitrate, lanthanum chloride and lanthanum carbonate, preferably lanthanum nitrate and/or lanthanum carbonate. Preferably, the hafnium salt comprises one or more of hafnium oxychloride, hafnium tetrachloride and hafnium sulfate, preferably hafnium oxychloride and/or hafnium tetrachloride. As a preferable scheme, nitric acid or hydrochloric acid is added into the solution to adjust the pH value to be 0.5-3, preferably 0.8-2. As a preferable scheme, the water content in the solution is 60-110%, preferably 75-95% of the saturated water a