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CN-121972164-A - Supported catalyst and preparation method thereof

CN121972164ACN 121972164 ACN121972164 ACN 121972164ACN-121972164-A

Abstract

The invention provides a supported catalyst and a preparation method thereof. The supported catalyst comprises an alumina carrier and an active metal component, wherein the active metal component comprises vanadium species and platinum nanoparticles, the surface of the alumina carrier comprises oxygen vacancies, the adjacent area of the oxygen vacancies comprises a vanadium species enrichment area, the mass ratio of the alumina carrier, the vanadium species and the platinum nanoparticles is 85-95 percent, 1-10 percent and 0.5-5 percent, the molar ratio of the vanadium species comprises V 4+ and V 5+ ,V 4+ /(V 4+ +V 5+ ) is more than or equal to 0.65, and the platinum nanoparticles are attached to the vanadium species enrichment area. The technical scheme solves the problems of low catalytic activity, poor stability and complex preparation process of the flue gas denitrification catalyst by the catalytic oxidation method in the prior art.

Inventors

  • WU GUOYU

Assignees

  • 中铝科学技术研究院有限公司

Dates

Publication Date
20260505
Application Date
20260403

Claims (10)

  1. 1. A supported catalyst is characterized in that the supported catalyst comprises an alumina carrier and an active metal component, the active metal component comprises a vanadium species and platinum nanoparticles; the surface of the alumina support comprises oxygen vacancies, the adjacent regions of which comprise vanadium species enriched regions; The mass ratio of the alumina carrier to the vanadium species to the platinum nano particles is 85-95%, 1-10% and 0.5-5%; The molar ratio of the vanadium species including V 4+ to V 5+ ,V 4+ /(V 4+ +V 5+ ) is more than or equal to 0.65; The platinum nanoparticles are attached to the vanadium species enriched region.
  2. 2. The supported catalyst according to claim 1, wherein the concentration of oxygen vacancies is 1.0x 18 ~5.0×10 19 /cm -3 ;V 4+ /(V 4+ +V 5+ ) and the molar ratio is 0.65-0.75, the particle size of the platinum nanoparticles is 1-3 nm, and the Pt 4f binding energy of platinum is shifted negatively by 0.5-1.5 eV relative to the standard value of pure platinum.
  3. 3. The supported catalyst according to claim 1 or 2, wherein the specific surface area of the alumina carrier is 480-800 m2/g, and the pore size distribution of the alumina carrier is concentrated at 3-10 nm.
  4. 4. A method for preparing the supported catalyst according to any one of claims 1 to 3, comprising: Step S1, mixing raw materials comprising sodium aluminate solution and surfactant, and then dropwise adding H 2 O 2 solution for precipitation reaction to obtain aluminum hydroxide; s2, carrying out a composite reaction on the raw materials comprising the aluminum hydroxide, the ammonium carbonate and the ammonium bicarbonate to obtain an aluminum ammonium carbonate precursor; Step S3, mixing raw materials comprising ammonium vanadate, ammonium metavanadate and the ammonium aluminum carbonate precursor under alkaline conditions, and then sequentially drying and programming to raise the temperature to obtain a catalyst intermediate; Step S4, mixing raw materials comprising the catalyst intermediate, platinum salt, a first dispersing agent and a pH regulator to obtain a suspension; Step S5, mixing raw materials comprising a reducing agent and a second dispersing agent to obtain a mixed solution; And S6, dropwise adding the suspension into the mixed solution for reaction, and then sequentially carrying out filtration, washing, drying and programmed heat treatment to obtain the supported catalyst.
  5. 5. The method for preparing a supported catalyst according to claim 4, wherein in the step S1, In the sodium aluminate solution, calculated in an oxide form, the mass concentration of Na 2 O is 130-160 g/L, the mass concentration of Al 2 O 3 is 150-240 g/L, and the caustic ratio alpha K is 1.2-1.4; And/or the surfactant is stearic acid ethanol solution, wherein the ratio of the mass of stearic acid to the volume of ethanol is 0.05g:30 mL-5 g:100mL; And/or the solute content of the H 2 O 2 solution is 5-30wt%, and the volume ratio of the sodium aluminate solution to the H 2 O 2 solution is 100-600:10-30; and/or stirring in the process of dropwise adding the H 2 O 2 solution, wherein the stirring speed is 500-800 rpm, and the stirring time is 15-30 min.
  6. 6. The method for preparing a supported catalyst according to claim 4, wherein in the step S2, The total molar concentration of the ammonium carbonate and the ammonium bicarbonate is 1.5-3.0 mol/L; And/or the molar ratio of the ammonium carbonate to the ammonium bicarbonate is 1:0.5-2.
  7. 7. The method for preparing a supported catalyst according to claim 4, wherein in the step S3, The molar ratio of the ammonium vanadate to the ammonium metavanadate is 1:0.5-2.5; and/or the mixing temperature is 20-50 ℃, and the mixing time is 30-180 min; and/or adjusting the alkaline condition to pH=9.5-10.5 by ammonia water; And/or, the programmed heating process comprises the following steps: Raising the temperature from room temperature to 100-150 ℃ at a temperature raising rate of 5-10 ℃ and preserving the heat for 1-3 hours; Raising the temperature from 100-150 ℃ to 300-350 ℃ at the temperature raising rate of 5-10 ℃ and preserving the temperature for 0.5-1 h; heating from 300-350 ℃ to 450-500 ℃ at a heating rate of 2-5 ℃ per minute, and preserving heat for 0.5-1 h; Heating from 450-500 ℃ to 600-800 ℃ at a heating rate of 2-5 ℃ per minute, and preserving heat for 0.5-1 h; and/or, the molar ratio of V 4+ /V 5+ in the catalyst intermediate is more than or equal to 0.65.
  8. 8. The method for preparing a supported catalyst according to claim 4, wherein in the step S4, The platinum salt is selected from any one or more of chloroplatinic acid, chloroplatinate, [ Pt (acac) 2 ], platinum (II) alkoxide, tetramine platinum (II) chloride, platinum nitrate, diammine platinum dinitrate and [ Pt (CH 3 NH 2 ) 4 ][PtCl 4 ]; And/or the first dispersant is selected from any one or more of polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), polyvinyl alcohol (PVA), sodium Polyacrylate (PAAS), polyethylene oxide (PEO), nonionic Polyacrylamide (PAM), sodium Dodecyl Benzene Sulfonate (SDBS) and Tween (Tween); and/or the pH regulator is a mixed solution of ammonium chloride and ammonia water; and/or the pH of the suspension is 10+/-0.2.
  9. 9. The method for preparing the supported catalyst according to claim 4, wherein in the step S5, the reducing agent is selected from any one or more of ascorbic acid, formic acid, sodium formate, glucose, ethylene glycol, hydrazine hydrate and sodium borohydride; and/or the second dispersant is selected from any one or more of ammonium polyacrylate, sodium polyacrylate, polyacrylic acid, polymethacrylate and polymaleic acid.
  10. 10. The method for preparing a supported catalyst according to claim 4, wherein in the step S5, the dropping speed of the suspension is 5-30 ml/min, the reaction temperature is 10-20 ℃, and the reaction time is 30-150 min; And/or, in step S6, the process of the programmed heat treatment includes: Raising the temperature from room temperature to 100-150 ℃ at a temperature raising rate of 5-10 ℃ and preserving the heat for 1.5-3 hours; Raising the temperature from 100-150 ℃ to 300-350 ℃ at the temperature raising rate of 5-10 ℃ and preserving the temperature for 1-1.5 h; Heating from 300-350 ℃ to 550-600 ℃ at a heating rate of 2-5 ℃ per minute, and preserving heat for 0.5-1 h; Heating from 550-600 ℃ to 800-1000 ℃ at a heating rate of 2-5 ℃ per minute, and preserving heat for 0.25-1 h.

Description

Supported catalyst and preparation method thereof Technical Field The invention relates to the technical field of catalyst preparation, in particular to a supported catalyst and a preparation method thereof. Background With the increasingly strict environmental protection requirements, the flue gas denitrification technology has become an important means for controlling the atmospheric pollution. The catalytic oxidation method is used as a high-efficiency flue gas denitrification technology, and converts nitrogen oxides in the flue gas into harmless substances through the action of a catalyst, so that the method has the advantages of low reaction temperature, good selectivity and the like, and is widely applied to industrial flue gas treatment. The supported catalyst is a core material for flue gas denitrification by a catalytic oxidation method due to the characteristics of high dispersity of active components, good stability of a carrier and the like. Currently, supported catalysts for flue gas denitrification mainly include vanadium-titanium based catalysts and noble metal catalysts. The Chinese patent application with the publication number of CN111420660A discloses a noble metal composite vanadium-titanium catalyst for purifying organic waste gas in coal-fired flue gas, and the catalyst shows a certain oxidation performance in high-sulfur, high-nitrogen and high-ammonia flue gas. Chinese patent CN112844402B discloses a nano Co 3O4 supported catalyst, which has the characteristic of high low-temperature activity, but is mainly used for catalytic oxidation of VOCs. Chinese patent CN118743990B discloses a supported noble metal catalyst comprising noble metal active components such as platinum, palladium, rhodium, etc., having higher catalytic activity. Chinese patent CN119481118B discloses a preparation method of a supported catalyst, in which a carrier precursor is prepared by precipitation reaction of vanadate and ammonium salt, and then a noble metal compound is supported. However, the existing flue gas denitrification catalyst by the catalytic oxidation method still has a plurality of problems that firstly, the catalytic activity is not high, particularly, high-efficiency nitrogen oxide conversion is difficult to realize under the low-temperature condition, secondly, the stability of the catalyst is poor, active component loss and carrier structure damage easily occur in a complex flue gas environment, so that the catalytic performance is fast attenuated, and thirdly, the preparation process of the existing catalyst is complex, multi-step reaction and severe preparation conditions are involved, and the production cost and the process control difficulty are increased. These problems severely restrict the industrial application and popularization of the catalytic oxidation flue gas denitrification technology. Disclosure of Invention The invention mainly aims to provide a supported catalyst and a preparation method thereof, which are used for solving the problems of low catalytic activity, poor stability and complex preparation process of a catalytic oxidation flue gas denitrification catalyst in the prior art. In order to achieve the above object, according to one aspect of the present invention, there is provided a supported catalyst comprising an alumina carrier and an active metal component, the active metal component comprising a vanadium species and platinum nanoparticles, the surface of the alumina carrier comprising oxygen vacancies, the vicinity of the oxygen vacancies comprising a vanadium species enriched region, the mass ratio of the alumina carrier, the vanadium species and the platinum nanoparticles being 85 to 95%:1 to 10%:0.5 to 5%, the molar ratio of the vanadium species comprising V 4+ to V 5+,V4+/(V4++V5+) being equal to or greater than 0.65, the platinum nanoparticles being attached to the vanadium species enriched region. Further, the concentration of the oxygen vacancies is 1.0X10 18~5.0×1019/cm -3;V4+/(V4++V5+), the molar ratio is 0.65-0.75, the particle size of the platinum nano-particles is 1-3 nm, and the Pt 4f binding energy of the platinum is shifted negatively by 0.5-1.5 eV relative to the standard value of pure platinum. Further, the specific surface area of the alumina carrier is 480-800 m < 2 >/g, and the pore size distribution of the alumina carrier is concentrated to 3-10 nm. According to another aspect of the invention, the preparation method of the supported catalyst comprises the steps of S1, mixing raw materials comprising sodium aluminate solution and surfactant, dropwise adding H 2O2 solution for precipitation reaction to obtain aluminum hydroxide, S2, carrying out composite reaction on raw materials comprising aluminum hydroxide, ammonium carbonate and ammonium bicarbonate to obtain an ammonium aluminum carbonate precursor, S3, mixing raw materials comprising ammonium vanadate, ammonium metavanadate and ammonium aluminum carbonate precursor under alkaline conditio