Catalyst for selective catalytic reduction of ammonia to remove NOx and preparation method thereof

A selectivity and catalyst technology, applied in physical/chemical process catalysts, chemical instruments and methods, organic compounds/hydrides/coordination complex catalysts, etc., can solve catalytic activity reduction, copper and iron loss, hydrothermal stability In order to achieve high NOx conversion efficiency, improve kinetic distribution, high temperature activity and hydrothermal stability

Active Publication Date: 2018-09-14
NINGBO HIGH TECH ZONE YONGSHI TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage of this catalyst is that the catalyst has a narrow operating temperature range and poor hydrothermal stability. In actual work, due to the presence of water in the exhaust gas of diesel engines, copper and iron are easily lost in the pores of the molecular sieve, and the catalytic activity decreases rapidly.

Method used

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  • Catalyst for selective catalytic reduction of ammonia to remove NOx and preparation method thereof
  • Catalyst for selective catalytic reduction of ammonia to remove NOx and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] The preparation method of the molecular sieve-loaded catalyst used for ammonia selective catalytic reduction to remove NOx comprises the following steps in sequence:

[0030] 1. Pre-calcining: Calcining the ZSM-35 molecular sieve at a temperature of 120°C for 0.5 hours. Through the pre-calcination treatment, the organic matter of the molecular sieve channel and the template agent on the surface is removed, which is more conducive to the subsequent ion exchange.

[0031] 2. Ion exchange: Disperse the pre-calcined ZSM-35 molecular sieve into water at room temperature to form a molecular sieve slurry; at the same time, in another reaction kettle, dissolve copper chloride at room temperature, and then pour it into the molecular sieve slurry. Stirring constantly, stir for 3 hours. Wherein, the weight ratio of copper ion to ZSM-35 molecular sieve is 1%.

[0032] 3. The molecular sieve after cation exchange is washed with deionized water, then dried at 50° C. for 3 hours, an...

Embodiment 2

[0035] This example is basically the same as Example 1, the only difference being that the molecular sieve is Cu-ZSM-5 molecular sieve.

Embodiment 3

[0037] This embodiment is basically the same as Embodiment 1, the only difference being that the molecular sieve is a Beta molecular sieve.

[0038] The performance test results of the molecular sieve supported catalyst prepared in Examples 1-3 are shown in Table 1 below:

[0039] Table 1

[0040]

[0041] The reaction space velocity is 90000(h -1 ), 800ppmNH 3 , 800ppmNO, 8%O 2 ,

[0042] It can be seen from Table 1 that the catalyst prepared in Example 1 can have high NOx conversion efficiency under conditions of wider temperature range and high space velocity.

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Abstract

The invention discloses a preparation method of a catalyst for NOx removal based on ammonia selective catalytic reduction. The preparation method includes the steps of (1), subjecting a molecular sieve and a salt solution containing one or multiple metal cations to cation exchange by an ion exchange method; (2), after the ion exchange, washing the molecular sieve by deionized water, drying the molecular sieve at the temperature of 50-200 DEG C, and calcining the same at the temperature of 200-600 DEG C so as to achieve stable binding of the cations exchanged into the molecular sieve; (3), dispersing the molecular sieve processed in the step (2) in water, adding in a certain proportion of hollow aluminum oxide pellet powder according to the mass ratio of the molecular sieve to the hollow aluminum oxide pellet powder 2:1-15:1, adding in binders and thickeners after full dispersing, and coating the solution to a cordierite monolith honeycomb carrier to form a catalyst coating tens of micrometers in thickness on walls of pores of the honeycomb carrier. With the molecular sieve loaded, the catalyst prepared by the method has the advantages of high high-temperature activity and hydrothermal stability.

Description

technical field [0001] The invention belongs to the technical field of tail gas denitrification catalysts, in particular, the invention relates to a molecular sieve-loaded catalyst used for ammonia selective catalytic reduction to remove NOx and a preparation method thereof. Background technique [0002] Diesel vehicle engine exhaust contains harmful gases such as hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), and particulate matter (PM). The exhaust itself has a certain temperature and first passes through a direct oxidation catalyst (DOC). Finally, hydrocarbons and carbon monoxide are oxidized into harmless gases such as carbon dioxide and water, nitrogen oxides and particulate matter cannot be converted, and then enter the selective catalytic reduction denitrification catalyst (SCR catalyst), and urea is injected between the two catalysts Solution, urea is decomposed into ammonia and carbon dioxide, wherein ammonia reacts with nitrogen oxides under the ac...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01J31/28B01J35/04
CPCB01J31/28B01J35/04
Inventor 张保才王新昕张楚宁
Owner NINGBO HIGH TECH ZONE YONGSHI TECH CO LTD
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