WO2020103848A1

WO2020103848A1 - Environmentally-friendly high-temperature denitration catalyst and preparation method therefor

Info

Publication number: WO2020103848A1
Application number: PCT/CN2019/119602
Authority: WO
Inventors: 沈岳松; 陶兴军; 沈建宇; 陈蒙蒙
Original assignee: 南京工业大学
Priority date: 2018-11-21
Filing date: 2019-11-20
Publication date: 2020-05-28
Also published as: CN109513438B; CN109513438A

Abstract

An environmentally-friendly high-temperature denitration catalyst and a preparation method therefor. Said catalyst comprise a tungsten and zirconium composite oxide as a main catalyst component, one or more of barium, erbium, tin, iron, molybdenum, cobalt, copper, manganese, and lanthanum as a co-catalyst, a titanium white as a support component, and alumina as a forming auxiliary; with respect to the mass of the titanium white, the mass percentage of the main catalyst component is 8-20%, the mass percentage of the co-catalyst is 0-15%, and the mass percentage of the forming auxiliary is 5-30%; the element molar ratio of W to Zr in the tungsten and zirconium composite oxide is 1: (0.9-1.5). Said catalyst has a good high-temperature denitration effect and high thermal stability, has non-toxic components, and is environmentally friendly, and the preparation process is simple, being applicable to high-temperature NO_X removal of exhaust gas of a high-speed diesel engine and denitration of high-temperature exhaust gas in the petrochemical industry.

Description

Environment-friendly high-temperature denitration catalyst and preparation method thereof

Technical field

The invention relates to an environment-friendly high-temperature denitration catalyst and a preparation method thereof, which belong to the field of environmentally friendly catalytic materials and atmospheric pollution prevention and control, and are particularly suitable for the removal of high-temperature NO _X in the exhaust gas of medium and high-speed diesel engines and petrochemical industries.

Background technique

The diesel engine has the advantages of high power, low energy consumption, and good economic performance. However, its exhaust emissions are large and its composition is complex, so it has a great impact on the environment and human health. The main pollutants in diesel exhaust include: nitrogen oxides (NO _X ), hydrocarbons (HC), carbon monoxide (CO), and suspended particles (PM), among which NO _{X is} its main harmful component. The total amount of NO _X emissions in China is as high as 1 million tons every year, and it has been increasing year by year. The national control standards for NO _X emissions are becoming stricter. In 2016, the Ministry of Environmental Protection issued an opinion on "Solicitation of National Environmental Protection Standards" Limits and Measurement Methods for Exhaust Pollutants from Compression Ignition and Gas Fuel Ignition Engines and Automobiles (Phase VI of China) (Consultation Draft) ""Letter", formally soliciting opinions on diesel vehicle National Six Emissions Regulations, and it is planned to be implemented on January 1, 2020. With the increasingly strict emission control standards, the development of diesel exhaust purification technology is imminent. At present, the selective catalytic reduction technology (SCR) is commonly used in the aftertreatment technology of diesel exhaust, and the research of its main catalyst component is the core part in the related field of SCR technology.

At present, the use of domestic commercial SCR denitration catalysts is mostly monopolized abroad, and it is mainly concentrated on V ₂ O ₅ / MoO ₃ (WO ₃ ) / TiO ₂ ceramic carriers. The patents (201610654336.9), (201611251844.9), (201510807979.8), (201410404846.1), (201610297377.7), and (20161029 7377.7) are all related patents for vanadium-based exhaust gas denitration treatment technology, mainly based on vanadium. However, this system has the disadvantages of narrow active temperature window (300 ～ 410 ℃), poor high temperature activity, poor thermal stability, and easy SO ₂ poisoning, and the active component V ₂ O ₅ is a highly toxic substance, and the high temperature conditions It is easy to evaporate and vaporize, thus causing pollution to the human body and the environment. Patents (201611000833.3), (201610297377.7), (201611020271.9) (201611035444.4), (201110057115.0), (201110118922.9) are modified molecular sieve diesel exhaust gas denitration catalysts, of which the patent (201611000833.3) is modified with ferrous-La bimetallic ZSM- 5 Molecular sieve as main catalyst, CeO ₂ -ZrO ₂ solid solution as cocatalyst, SiO ₂ , TiO ₂ and γ-Al ₂ O ₃ as coating base materials, cordierite honeycomb ceramic as catalyst carrier, prepared with low temperature activity SCR catalyst. However, ZSM-5 molecular sieve catalyst has poor high-temperature structural stability, easy carbon deposition and metal deposition to reduce catalytic activity, and poisoning with heavy metals can cause permanent deactivation. The patents (201310208308.0), (201611235168.6), (201510401286.9), (201610652524.8), etc. use rare earth oxides or transition metal ions iron, manganese, copper, zirconium, etc. as the main active components to prepare denitration catalysts, but this series is prepared The catalyst has a narrow active temperature window, poor high temperature activity, and a complicated preparation process.

Summary of the invention

The main purpose of the present invention is to develop an environment-friendly high-temperature denitration catalyst suitable for high-temperature diesel engine high-temperature denitrification, with a view to replacing the commercial vanadium-titanium-based and molecular sieve type catalyst systems that are toxic and have low temperature activity and poor thermal stability; One purpose is to provide a method for preparing the above catalyst.

The technical scheme of the present invention is: an environment-friendly high-temperature denitration catalyst, characterized in that tungsten-zirconium composite oxide is the main catalyst component, and barium, erbium, tin, iron, molybdenum, cobalt, copper, manganese or lanthanum One or more of them are co-catalysts, with titanium dioxide as the carrier component and alumina as the co-forming agent; wherein, based on the quality of titanium dioxide, the mass percentage of the main catalyst component is 8% -20%, The co-catalyst mass percentage content is 0-15%, and the co-forming agent mass percentage content is 5-30%; the tungsten-zirconium composite oxide active component W and Zr element molar ratio is 1: (0.9-1.5) . .

The invention also provides a method for preparing the above environment-friendly high-temperature denitration catalyst, the specific steps of which are:

(1) Preparation of co-catalyst precursor ion solution

Screen and weigh one or more of soluble cocatalyst barium, erbium, tin, iron, molybdenum, cobalt, copper, manganese or lanthanum salt, add deionized water and mix, dissolve until the solution is clear and transparent by stirring. Assisted catalyst precursor ion solution;

(2) Preparation of catalytically modified composite carrier

Titanium dioxide is impregnated in equal volume with the promoter solution prepared in step (1), dried and pulverized, and then it is evenly mixed with the forming aid alumina to obtain a catalyst carrier, among which titanium dioxide, promoter and alumina The mass percentage is 1: (0% ~ 15%): (5% ~ 30%);

(3) Preparation of tungsten-zirconium composite ion precursor solution

Screen and weigh the soluble tungsten salt into deionized water and mix, then stir evenly until the solution is clear and transparent to obtain solution A;

Screen and weigh the soluble zirconium salt into deionized water and mix, then stir evenly until the solution is clear and transparent to obtain solution B;

Among them, the molar ratio of ions in solutions A and B is 1: (0.9 ～ 1.5). Add solution B to solution A. Stirring is needed during the dropwise addition to obtain a saturated solution of tungsten and zirconium ions;

(4) Preparation and pretreatment of catalyst body

Based on the quality of titanium dioxide, the mass percentage of the main active component of the catalyst is 8% to 20%, the tungsten-zirconium saturated ion solution prepared in step (3) is mixed with the catalyst carrier prepared in step (2), and organic The molding agent is poured into a mixer to mix and stir the mud, and the kneader is repeatedly kneaded. After the mud is stale, it is placed in the molding machine to be pre-extruded to prepare a catalyst mud with uniform humidity;

(5) Preparation of monolithic honeycomb catalyst

The catalyst sludge prepared in step (4) is subjected to training mud and pre-extrusion, and the prepared catalyst sludge is put into a molding machine, extruded into a honeycomb body through an abrasive tool, dried, and roasted, that is The catalyst is prepared.

Preferably, in step (1), the barium salt is barium acetate, barium nitrate or barium chloride; the erbium salt is erbium sulfate octahydrate or erbium chloride hexahydrate; the tin salt is tetrachloride pentahydrate Tin; the iron salt is iron sulfate, iron nitrate, iron acetate or iron chloride; the molybdenum salt is ammonium molybdate or ammonium paramolybdate; the cobalt salt is cobalt nitrate, cobalt acetate, cobalt oxalate or Cobalt sulfate; the copper salt is copper nitrate or copper chloride; the manganese salt is manganese acetate, manganese sulfate, manganese chloride or manganese nitrate; the lanthanum salt is lanthanum nitrate, lanthanum chloride or lanthanum acetate.

Preferably, the zirconium salt in step (3) is zirconium oxychloride or zirconium chloride; the tungsten salt is ammonium metatungstate, ammonium tungstate or ammonium paratungstate.

Preferably, the organic molding agent mentioned in step (4) is one or more of carboxymethyl cellulose, polyethylene oxide, carboxypropyl methyl cellulose or glycerin; the addition quality of the organic molding agent is titanium 0.1% ～ 2% of the quality of white powder.

The aging time described in the optional step (4) is 12-24 hours.

Preferably, the drying method described in step (5) is ordinary blast drying, the drying temperature is 30-80 ° C, and the drying time is 2-8 hours.

Preferably, the calcination temperature in step (5) is 500-800 ° C, and the calcination time is 2-5 hours.

Beneficial effect:

Compared with vanadium-titanium-based and molecular sieve catalysts, the present invention has the following beneficial effects:

(1) The catalyst has a large catalytic temperature window for diesel engine exhaust NO _X (400 ～ 600 ℃), and is especially suitable for the removal of high temperature NO _X in the exhaust gas of medium and high speed diesel engines;

(2) The selected main and co-catalyst components are inexpensive and environmentally friendly raw materials, and the preparation process is simple, which can reduce the harm to human health and environmental pollution,

(3) After the catalyst calcined at 700 ℃ for 2 hours at GHSV = 8000h ^-1, which for the NO _X removal activity in the temperature range of 370 ~ 600 ℃ window is still more than 90%, preferably having a visible High temperature denitration effect and thermal stability;

(4) When the ion molar ratio of the W / Zr solution is 1: 0.97, and the main active component of the catalyst accounts for 9.85% by mass of titanium dioxide, the catalyst has the best denitration effect. When GHSV = 8000h ^-1 , its denitration NO _X within a temperature range of 370 ~ 600 ℃ window activity can reach 94%;

BRIEF DESCRIPTION

FIG. 1 is a graph showing the change of NO _X removal activity of the catalysts prepared in Examples 1 to 6; wherein 1, 2, 3, 4, 5, 6 respectively represent Examples 1-6.

detailed description

Example 1

(1) Preparation of carrier

Taking the titanium dioxide / gamma alumina mass percentage as 1: 10%, weigh 30g titanium dioxide and 3g gamma alumina respectively, and mix them evenly to obtain a catalyst carrier;

(2) Preparation of tungsten-zirconium composite ion precursor solution

Screen and weigh 0.46g of ammonium paratungstate and 1.50g of deionized water, mix well until the solution is clear and transparent to obtain solution A;

Screen and weigh 2.26g of zirconium chloride and add 4.71g of deionized water to mix, stir evenly until the solution is clear and transparent to obtain solution B;

Among them, the ion molar ratio of solution A and B is 1: 1.5. Add solution B to solution A. Stirring is needed during the dropwise addition to obtain a saturated solution of tungsten and zirconium;

(3) Preparation and pretreatment of catalyst sludge

Based on the mass of the carrier, the mass percentage of the main active component of the catalyst is 9.24%, the tungsten-zirconium ion saturated solution prepared in step (2) and the catalyst prepared in step (1) are mixed with the carrier, and 0.03 g of carboxymethyl Cellulose is poured into a mixer to mix and knead the mud, which is kneaded repeatedly by a kneader. After the mud is aged for 12 hours, it is placed in a molding machine for pre-extrusion to prepare catalyst mud with uniform humidity;

(4) Preparation of monolithic catalysis

The catalyst sludge prepared in step (3) is subjected to training mud and pre-extrusion, and the prepared catalyst sludge is put into a molding machine, extruded into a honeycomb body through an abrasive tool, and blown through a drying box 30 After drying at ℃ for 8h and roasting at 500 ℃ for 5h, the preparation of monolithic catalyst is completed;

(5) Catalyst evaluation system

A small sample of 8 mL of the catalyst was taken into the catalyst performance evaluation reaction device, and simulated gas was passed to conduct activity evaluation. The simulated gas is composed of the measured exhaust gas of the diesel engine for vehicles. The composition is as follows: NO (930 ppm), NH ₃ (930 ppm), O ₂ (10.00%), and the rest is nitrogen. The volumetric space velocity of the gas is 8000h ^-1 . The prepared catalyst has a denitration activity higher than 93% within 400-600 ° C, and the catalyst has the best denitration activity at 9500% at 450 ° C and 500 ° C.

Example 2

(1) Preparation of precursor catalyst ion solution

Screen and weigh 1.51g erbium hexahydrate and 0.70g tin tetrachloride pentahydrate, dissolve in 5g deionized water, dissolve with stirring until the solution is clear and transparent, and help the catalyst precursor solution;

(2) Preparation of carrier

Weigh 30g of titanium dioxide and the same amount of co-catalyst solution prepared in step (1) to impregnate, after drying and pulverization, mix it with 1.5g of gamma alumina to obtain a catalyst carrier, of which titanium dioxide / co-catalyst / The mass percentage of gamma alumina is 1: 3%: 5%;

(3) Preparation of tungsten-zirconium composite ion precursor solution

Screen and weigh 4.14g of ammonium tungstate and 6.22g of deionized water, mix evenly until the solution is clear and transparent to obtain solution A;

Screen and weigh 5.73g of zirconium oxychloride and add 8.61g of deionized water to mix, stir evenly until the solution is clear and transparent to obtain solution B;

Among them, the ion molar ratio of A and B solutions is 1: 1.08. Add solution B to solution A. Stirring is required during the dropwise addition process to obtain a saturated solution of tungsten and zirconium;

(4) Preparation and pretreatment of catalyst sludge

Based on the quality of titanium dioxide, the mass percentage of the main active component of the catalyst is 20%, the tungsten-zirconium saturated solution prepared in step (3) and the catalyst mixed carrier prepared in step (2), and 0.15g of carboxypropyl Methyl cellulose is poured into a mixer to mix and knead the mud, which is kneaded repeatedly by a kneader. After the mud is stale for 24h, it is placed in a molding machine for pre-extrusion to prepare catalyst mud with uniform humidity;

(5) Preparation of monolithic catalysis

The catalyst sludge prepared in step (4) is subjected to training mud and pre-extrusion, and the prepared catalyst sludge is put into a molding machine, extruded into a honeycomb body through an abrasive tool, and blown through a drying box 80 After drying at ℃ for 2h and calcining at 800 ℃ for 2h, the preparation of monolithic catalyst is completed.

(6) Catalyst evaluation system

A small sample of 8 mL of the catalyst was taken into the catalyst performance evaluation reaction device, and simulated gas was passed to conduct activity evaluation. The simulated gas is based on the measured exhaust gas of diesel engines for vehicles. Its composition is as follows: NO (930 ppm), NH ₃ (930 ppm), O ₂ (10.00%), and the rest is nitrogen. The volumetric space velocity of the gas is 8000h ^-1 . The prepared catalyst has a denitration activity higher than 92% within 400-600 ° C, and the catalyst has the best denitration activity at 9250% at 450 ° C and 500 ° C.

Example 3

(1) Preparation of precursor catalyst ion solution

Screen and weigh 0.33g of barium nitrate and 0.15g of erbium chloride hexahydrate, dissolve it in 3g of deionized water, place it in a constant temperature water bath at 85 ° C and stir to dissolve until the solution is clear and transparent, which will help the catalyst precursor solution ;

(2) Preparation of carrier

Weigh 30g of titanium dioxide and the same volume of impregnated co-catalyst solution prepared in step (1), after drying and pulverization, mix it with 9g of gamma alumina to obtain a catalyst carrier, of which titanium dioxide / co-catalyst / The mass percentage of gamma alumina is 1: 1%: 30%;

(3) Preparation of tungsten-zirconium composite ion precursor solution

Screen and weigh 1.86g of ammonium metatungstate and 2.79g of deionized water, mix evenly until the solution is clear and transparent to obtain solution A;

Screen and weigh 2.19g of zirconium oxychloride and add 3.29g of deionized water to mix, stir evenly until the solution is clear and transparent to obtain solution B;

Among them, the molar ratio of ions in solutions A and B is 1: 1.08. Add solution B to solution A. Stirring is needed during the dropwise addition to obtain a saturated solution of tungsten and zirconium;

(4) Preparation and pretreatment of catalyst sludge

Based on the quality of titanium dioxide, the mass percentage of the main active component of the catalyst is 8.38%, the tungsten-zirconium saturated solution prepared in step (3) and the catalyst mixed carrier prepared in step (2), and 0.30 g of carboxymethyl Cellulose is poured into a mixer to mix and knead the mud, which is kneaded repeatedly by a kneader. After the mud is aged for 18 hours, it is placed in a molding machine for pre-extrusion to prepare catalyst mud with uniform humidity;

(5) Preparation of monolithic catalysis

The catalyst sludge prepared in step (4) is subjected to training mud and pre-extrusion, and the prepared catalyst sludge is put into a molding machine, extruded into a honeycomb body through an abrasive tool, and then blown through a drying box 60 After drying at ℃ for 5h and calcining at 700 ℃ for 2h, the preparation of monolithic catalyst is completed;

(6) Catalyst evaluation system

A small sample of 8 mL of the catalyst was taken into the catalyst performance evaluation reaction device, and simulated gas was passed to conduct activity evaluation. The simulated gas is based on the measured exhaust gas of diesel engines for vehicles. Its composition is as follows: NO (930 ppm), NH ₃ (930 ppm), O ₂ (10.00%), and the rest is nitrogen. The volumetric space velocity of the gas is 8000h ^-1 . The prepared catalyst has a denitration activity higher than 91% at 400-600 ° C, and the catalyst has the best catalytic denitration activity at 9500% at 450 ° C and 500 ° C.

Example 4

(1) Preparation of precursor catalyst ion solution

Screen and weigh 0.20 g of lanthanum nitrate hexahydrate and 0.38 g of ferric nitrate nonahydrate, dissolve in 2.50 g of deionized water, dissolve with stirring until the solution is clear and transparent, and help the catalyst precursor solution;

(2) Preparation of carrier

Weigh 30g of titanium dioxide and the same volume of impregnated catalyst solution prepared in step (1), after drying and pulverization, mix it with 6g of gamma alumina to obtain a catalyst carrier. Among them, titanium dioxide / cocatalyst / The mass percentage of gamma alumina is 1: 1%: 20%;

(3) Preparation of tungsten-zirconium composite ion precursor solution

Screen and weigh 2.07g of ammonium metatungstate and 4.50g of deionized water, mix evenly until the solution is clear and transparent to obtain solution A;

Screen and weigh 2.63g of zirconium oxychloride and add 3.95g of deionized water to mix, stir evenly until the solution is clear and transparent to obtain solution B;

Among them, the molar ratio of ions in solutions A and B is 1: 0.97. Add solution B to solution A. Stirring is needed during the dropwise addition to obtain a saturated solution of tungsten and zirconium;

(4) Preparation and pretreatment of catalyst sludge

Based on the quality of titanium dioxide, the mass percentage of the main active component of the catalyst is 9.85%, the tungsten-zirconium saturated solution prepared in step (3) and the catalyst mixed carrier prepared in step (2), and 0.15g of polyepoxy Ethane is poured into a mixer to mix and stir the mud, which is repeatedly kneaded by a kneader. After the mud is stale for 18h, it is placed in a molding machine for pre-extrusion to prepare catalyst mud with uniform humidity;

(5) Preparation of monolithic catalysis

(6) Catalyst evaluation system

A small sample of 8 mL of the catalyst was taken into the catalyst performance evaluation reaction device, and simulated gas was passed to conduct activity evaluation. The simulated gas is based on the measured exhaust gas of diesel engines for vehicles. Its composition is as follows: NO (930 ppm), NH ₃ (930 ppm), O ₂ (10.00%), and the rest is nitrogen. The volumetric space velocity of the gas is 8000h ^-1 . The prepared catalyst has a denitration activity higher than 94% at 370-600 ° C, and the catalyst has the best denitration activity at 500 ° C, 98.67%.

Example 5

(1) Preparation of precursor catalyst ion solution

Screen and weigh 3.54g of copper nitrate and 12.11g of 50% manganese nitrate solution, mix and dissolve until the solution is clear and transparent by stirring to obtain the catalyst precursor solution;

(2) Preparation of carrier

Weigh 30g of titanium dioxide and the same volume of impregnated catalyst solution prepared in step (1), after drying and pulverization, mix it with 4.5g of gamma alumina to obtain a catalyst carrier, of which titanium dioxide / cocatalyst / The mass percentage of gamma alumina is 1: 13%: 15%;

(3) Preparation of tungsten-zirconium composite ion precursor solution

Screen and weigh 3.16g of ammonium metatungstate and 6.87g of deionized water, mix evenly until the solution is clear and transparent to obtain solution A;

Screen and weigh 4.00g of zirconium oxychloride and add 6.00g of deionized water to mix, stir evenly until the solution is clear and transparent to obtain solution B;

(4) Preparation and pretreatment of catalyst sludge

Based on the quality of titanium dioxide, the mass percentage of the main active component of the catalyst is 15%, the tungsten-zirconium saturated solution prepared in step (3) and the catalyst mixed carrier prepared in step (2), and 0.60 g of glycerin are poured Mix and stir the mud in the mixer and knead it repeatedly by the kneader. After the mud is stale for 18h, put it into the molding machine to pre-extrude to prepare the catalyst mud with uniform humidity;

(5) Preparation of monolithic catalysis

The catalyst sludge prepared in step (4) is subjected to training mud and pre-extrusion, and the prepared catalyst sludge is put into a molding machine, extruded into a honeycomb body through an abrasive tool, and blown through a drying box 40 After drying at ℃ for 7h and calcining at 600 ℃ for 3h, the preparation of monolithic catalyst is completed;

(6) Catalyst evaluation system

A small sample of 8 mL of the catalyst was taken into the catalyst performance evaluation reaction device, and simulated gas was passed to conduct activity evaluation. The simulated gas is based on the measured exhaust gas of diesel engines for vehicles. Its composition is as follows: NO (930 ppm), NH ₃ (930 ppm), O ₂ (10.00%), and the rest is nitrogen. The volumetric space velocity of the gas is 8000h ^-1 . The prepared catalyst has a denitration activity higher than 92% within 400-600 ° C, and the catalyst has the best denitration activity at 500 ° C, 98.5%.

Example 6

(1) Preparation of precursor catalyst ion solution

Screen and weigh 8.73g of cobalt nitrate hexahydrate and 4.21 ammonium molybdate tetrahydrate, dissolve in 15g of deionized water, dissolve with stirring until the solution is clear and transparent, to help the catalyst precursor solution;

(2) Preparation of carrier

Weigh 30g of titanium dioxide and the same volume of impregnated catalyst solution prepared in step (2), after drying and pulverization, mix it with 3g of gamma alumina to obtain a catalyst carrier. Among them, titanium dioxide / cocatalyst / The mass percentage of gamma alumina is 1: 15%: 10%;

(3) Preparation of tungsten-zirconium composite ion precursor solution

Screen and weigh 4.21g of ammonium metatungstate and 9.15g of deionized water, mix well until the solution is clear and transparent to obtain solution A;

Screen and weigh 5.34g of zirconium oxychloride and add 8.02g of deionized water to mix, stir evenly until the solution is clear and transparent to obtain solution B;

(4) Preparation and pretreatment of catalyst sludge

Based on the quality of titanium dioxide, the mass percentage of the main active component of the catalyst is 20%, the tungsten-zirconium saturated solution prepared in step (3) and the catalyst mixed carrier prepared in step (2), and 0.15g of carboxymethyl Cellulose is poured into a mixer to mix and knead the mud, which is kneaded repeatedly by a kneader. After the mud is aged for 24 hours, it is placed in a molding machine for pre-extrusion to prepare catalyst mud with uniform humidity;

(5) Preparation of monolithic catalysis

(6) Catalyst evaluation system

A small sample of 8 mL of the catalyst was taken into the catalyst performance evaluation reaction device, and simulated gas was passed to conduct activity evaluation. The simulated gas is based on the measured exhaust gas of diesel engines for vehicles. Its composition is as follows: NO (930 ppm), NH ₃ (930 ppm), O ₂ (10.00%), and the rest is nitrogen. The volumetric space velocity of the gas is 8000h ^-1 . The prepared catalyst has a denitration activity higher than 90% within 400-600 ° C, and the catalyst has the best denitration activity at 500 ° C, which is 98.62%.

The graph of the change in NO _X removal activity of the catalysts prepared in Examples 1 to 6 above is shown in FIG. 1.

Claims

An environment-friendly high-temperature denitration catalyst characterized by a tungsten-zirconium composite oxide as the main catalyst component, and one or more of barium, erbium, tin, iron, molybdenum, cobalt, copper, manganese or lanthanum as Co-catalyst, with titanium dioxide as the carrier component, and alumina as the molding aid; wherein based on the quality of titanium dioxide, the mass percentage of the main catalyst component is 8% -20%, and the mass percentage of the promoter is 0 to 15%, the mass percentage of the molding aid is 5 to 30%; the molar ratio of the active component W of the tungsten-zirconium composite oxide to the Zr element is 1: (0.9-1.5). .
A method for preparing an environmentally friendly high-temperature denitration catalyst according to claim 1, the specific steps of which are:

(1) Preparation of co-catalyst precursor ion solution

Screen and weigh one or more of soluble cocatalyst barium, erbium, tin, iron, molybdenum, cobalt, copper, manganese or lanthanum salt, add deionized water and mix, dissolve until the solution is clear and transparent by stirring. Assisted catalyst precursor ion solution;

(2) Preparation of catalytically modified composite carrier

Titanium dioxide is impregnated in equal volume with the promoter solution prepared in step (1), dried and pulverized, and then it is evenly mixed with the forming aid alumina to obtain a catalyst carrier, among which titanium dioxide, promoter and alumina The mass percentage is 1: (0% ~ 15%): (5% ~ 30%);

(3) Preparation of tungsten-zirconium composite ion precursor solution

Screen and weigh the soluble tungsten salt into deionized water and mix, then stir evenly until the solution is clear and transparent to obtain solution A;

Screen and weigh the soluble zirconium salt into deionized water and mix, then stir evenly until the solution is clear and transparent to obtain solution B;

Among them, the molar ratio of ions in solutions A and B is 1: (0.9 ～ 1.5). Add solution B to solution A. Stirring is needed during the dropwise addition to obtain a saturated solution of tungsten and zirconium ions;

(4) Preparation and pretreatment of catalyst body

Based on the quality of titanium dioxide, the mass percentage of the main active component of the catalyst is 8% to 20%, the tungsten-zirconium saturated ion solution prepared in step (3) is mixed with the catalyst carrier prepared in step (2), and organic The molding agent is poured into a mixer to mix and stir the mud, and the kneader is repeatedly kneaded. After the mud is stale, it is placed in the molding machine to be pre-extruded to prepare a catalyst mud with uniform humidity;

(5) Preparation of monolithic honeycomb catalyst

The catalyst sludge prepared in step (4) is subjected to training mud and pre-extrusion, and the prepared catalyst sludge is put into a molding machine, extruded into a honeycomb body through an abrasive tool, dried, and roasted, that is The catalyst is prepared.
The method according to claim 2, wherein in step (1) the barium salt is barium acetate, barium nitrate or barium chloride; the erbium salt is erbium sulfate octahydrate or erbium chloride hexahydrate The tin salt is tin tetrachloride pentahydrate; the iron salt is iron sulfate, iron nitrate, iron acetate or iron chloride; the molybdenum salt is ammonium molybdate or ammonium paramolybdate; the cobalt The salt is cobalt nitrate, cobalt acetate, cobalt oxalate or cobalt sulfate; the copper salt is copper nitrate or copper chloride; the manganese salt is manganese acetate, manganese sulfate, manganese chloride or manganese nitrate; the lanthanum salt is nitric acid Lanthanum, lanthanum chloride or lanthanum acetate.
The method according to claim 2, wherein the zirconium salt in step (3) is zirconium oxychloride or zirconium chloride; the tungsten salt is ammonium metatungstate, ammonium tungstate or ammonium paratungstate.
The method according to claim 2, wherein the organic molding agent in step (4) is one of carboxymethyl cellulose, polyethylene oxide, carboxypropyl methyl cellulose or glycerin or Several kinds; the adding mass of the organic molding agent is 0.1% to 2% of the mass of the titanium dioxide.
The method according to claim 2, wherein the aging time in step (4) is 12-24 hours.
The method according to claim 2, characterized in that the drying method in step (5) is a common blast drying oven, the drying temperature is 30-80 ° C, and the drying time is 2-8h.
The method according to claim 2, characterized in that the calcination temperature in step (5) is 500-800 ° C, and the calcination time is 2-5 hours.