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Urea scr catalyst based on ion exchange molecular sieve

A technology of SCR catalyst and ion exchange, applied in molecular sieve catalysts, physical/chemical process catalysts, separation methods, etc., can solve problems such as escape, incomplete pyrolysis and hydrolysis of urea, and reduced activity, so as to avoid uneven coating Effect

Active Publication Date: 2016-08-31
SICHUAN MIANYANG HUAYUANHANGSHENG ENVIRONMENTAL TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the case of low exhaust gas temperature or limited installation space, due to incomplete pyrolysis and hydrolysis of urea, sufficient ammonia cannot be generated, resulting in reduced purification efficiency
The operating temperature range of existing SCR catalysts is narrow, that is, the activity decreases at high or low temperatures
In addition, due to the dynamic characteristics and reasons of various engines and catalysts, the reducing agent ammonia is very likely to react incompletely and escape from the outlet, causing secondary pollution

Method used

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  • Urea scr catalyst based on ion exchange molecular sieve
  • Urea scr catalyst based on ion exchange molecular sieve

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] This embodiment provides a urea SCR catalyst based on ion exchange molecular sieve, and its preparation process includes:

[0037] Step 1: Take 1000g of HZSM-5 molecular sieve particles and mix them with water to make a molecular sieve slurry. The water content of the molecular sieve slurry is suitable for mixing with the copper ion solution. The active agent copper nitrate solution containing copper ions is added to the molecular sieve slurry and mixed to obtain a mixed slurry. The copper nitrate solution is made by adding 113.3 g of copper nitrate trihydrate into water so that the content of the active component copper ions in the mixed slurry is 3%.

[0038] Step 2: Adjust the pH value of the mixed slurry to 8.9, keep the mixed slurry weakly alkaline, and stir for 20 hours to obtain an active slurry that has completed ion exchange.

[0039] Step 3: After the active slurry is filtered, it is dispersed into small pieces with a blue color; the small pieces of filter cake are ...

Embodiment 2

[0043] This embodiment provides a urea SCR catalyst based on ion exchange molecular sieve, and its preparation process includes:

[0044] Step 1: Take 1000g of HZSM-5 molecular sieve particles and mix them with water to make a molecular sieve slurry. The water content of the molecular sieve slurry is suitable for mixing with the copper ion solution. The active agent copper nitrate solution containing copper ions is added to the molecular sieve slurry and mixed to obtain a mixed slurry. The copper nitrate solution is made by adding 302.4 g of copper nitrate trihydrate into water so that the content of the active component copper ions in the mixed slurry is 8%.

[0045] Step 2: Adjust the pH value of the mixed slurry to 9.0, keep the mixed slurry weakly alkaline, and stir for 25 hours to obtain an active slurry that has completed ion exchange.

[0046] Step 3: After the active slurry is filtered, it is dispersed into small pieces with a blue color; the small pieces of filter cake are ...

Embodiment 3

[0050] This embodiment provides a urea SCR catalyst based on ion exchange molecular sieve, and its preparation process includes:

[0051] Step 1: Take 1000g of HZSM-5 molecular sieve particles and mix them with water to make a molecular sieve slurry. The water content of the molecular sieve slurry is suitable for mixing with the copper ion solution. The active agent copper nitrate solution containing copper ions is added to the molecular sieve slurry and mixed to obtain a mixed slurry. The copper nitrate solution is made by adding 188.9 g of copper nitrate trihydrate into water so that the content of the active component copper ion in the mixed slurry is 5%.

[0052] Step 2: Adjust the pH of the mixed slurry to 9.1, keep the mixed slurry weakly alkaline, and stir for 20 hours; to obtain an active slurry that has completed ion exchange.

[0053] Step 3: After the active slurry is filtered, it is dispersed into small pieces with a blue color; the small pieces of filter cake are dried ...

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Abstract

The invention discloses a urea SCR catalyst based on an ion exchange molecular sieve. A preparation process of the catalyst comprises the following steps: uniformly mixing molecular sieve particles and water to prepare molecular sieve slurry; adding active agent solution containing copper ions in the molecular sieve slurry and mixing uniformly to obtain mixed slurry; adjusting the pH value of the mixed slurry to 8.9-9.1, keeping the mixed slurry to be alkalescent, and stirring for 10-30h; filtering the active slurry, drying and calcining; cooling the catalyst powder obtained after calcining and grinding into slurry which is catalyst slurry, coating a carrier with the catalyst slurry and calcining. The method changes the coating mode of the active components on the carrier, and the disadvantages in the traditional impregnation technology that the coating uniformity is poor, the coating amount is insufficient, the active surface area of the catalyst is reduced because pores of the carrier are blocked, the catalytic performance is reduced, the exhaust back pressure is increased and the oil consumption of the whole vehicle is increased are avoided.

Description

Technical field [0001] The invention relates to the technical field of automobile exhaust gas treatment, in particular to a urea SCR catalyst based on ion exchange molecular sieve. Background technique [0002] The exhaust from locomotives is one of the main sources of air pollution. The main pollutant of medium- and heavy-duty diesel vehicles is nitrogen oxides, and their emissions are extremely harmful to the ecological environment and human health. Nitrogen oxides in combustion exhaust gas are usually produced by the reaction of nitrogen compounds in fuel and nitrogen and oxygen in the air at high temperatures. Taking internal combustion engines, especially diesel engines and other oxy-fuel combustion engines as an example, the exhaust gas contains pollutants carbon monoxide (CO), hydrocarbons (HC), carbon particles and nitrogen oxides. In the case of a gasoline engine, oxygen in the air and fuel are mixed and burned in a chemical ratio. There are no carbon particles in the ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01J29/46B01D53/94B01D53/56
CPCY02A50/20Y02T10/12
Inventor 华家本李世宁魏东胡长青胡俊
Owner SICHUAN MIANYANG HUAYUANHANGSHENG ENVIRONMENTAL TECH
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