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In-situ regeneration system and method of Cu-based molecular sieve denitrification catalyst for diesel vehicle exhaust gas purification

A denitration catalyst and in-situ regeneration technology, which is applied in the direction of molecular sieve catalyst, catalyst regeneration/reactivation, physical/chemical process catalyst, etc., can solve the problems that are not suitable for off-line cleaning regeneration, inconvenient disassembly, difficult regeneration, etc., and achieve regeneration cost Low, short regeneration time, low-cost regeneration effect

Active Publication Date: 2021-04-06
SHAOXING UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For diesel vehicles, the aftertreatment system is not easy to disassemble, so it is not suitable for off-line cleaning and regeneration
Studies have shown that there are two main reasons for the sulfur poisoning of Cu-based catalysts in diesel vehicles. One is the generated (NH 4 ) 2 SO 4 species poison the active sites or block the pores of the molecular sieve, and the two active Cu species sulfide into inert CuSO 4 , the latter compared to (NH 4 ) 2 SO 4 More mulching and clogging, and harder to regenerate

Method used

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  • In-situ regeneration system and method of Cu-based molecular sieve denitrification catalyst for diesel vehicle exhaust gas purification

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] Fresh Cu / SAPO-34 catalyst was heated at a temperature of 300 °C, the ratio of ammonia to nitrogen was 1:1, NO x The concentration is 500ppm, SO 2 The concentration is 100ppm, the space velocity is 80,000h -1 The denitrification efficiency of the catalyst dropped from 98% to 50% after running for 36 hours under the exhaust gas condition.

[0036] The regenerative device process flow of the present invention is as followsfigure 1 As shown, the hot ammonia gas is fed through the external nozzle in front of the catalyst, the concentration is 3000ppm, the temperature is 450°C, and the hot ammonia gas is fed for 1 hour.

[0037] The denitrification efficiency of the Cu / SAPO-34 catalyst recovered to 96.5% after the feed was stopped, and no ammonia slip was detected during the regeneration process.

Embodiment 2

[0039] The fresh Cu / SSZ-13 catalyst was heated at a temperature of 350 °C, with an ammonia-to-nitrogen ratio of 1:1, NO x The concentration is 500ppm, SO 2 The concentration is 150ppm, the space velocity is 100,000h -1 The denitrification efficiency of the catalyst dropped from 99% to 41% after running for 48 hours under the exhaust gas condition.

[0040] The regenerative device process flow of the present invention is as follows figure 1 As shown, hot diesel steam is fed through the external injection nozzle in front of the catalyst, the concentration is 5000ppm, the temperature is 550°C, and the hot diesel steam is fed for 1 hour.

[0041] The denitrification efficiency of the Cu / SSZ-13 catalyst recovered to 92.4% after the feed was stopped, and no diesel vapor escape was detected during the regeneration process.

Embodiment 3

[0043] The fresh Cu / ZSM-5 catalyst was heated at a temperature of 250°C, with an ammonia-to-nitrogen ratio of 1:1, NO x The concentration is 500ppm, SO 2 The concentration is 100ppm, the space velocity is 60,000h -1 The denitrification efficiency of the catalyst dropped from 95% to 32% after running for 72 hours under the exhaust gas condition.

[0044] The regenerative device process flow of the present invention is as follows figure 1 As shown, hot diesel reformed gas is introduced from the external injection nozzle in front of the catalyst, the concentration is 4000ppm, the temperature is 500°C, and the hot diesel reformed gas is introduced for 1.5 hours.

[0045] The denitrification efficiency of the Cu / ZSM-5 catalyst recovered to 91.9% after the feed was stopped, and no diesel vapor escape was detected during the regeneration process.

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Abstract

An in-situ regeneration system and method for a Cu-based molecular sieve denitrification catalyst for diesel vehicle exhaust purification, when the SCR purifier outlet NO x When the concentration is close to the emission limit, start in-situ regeneration; in addition to normal spraying of urea, an additional reducing gas at a certain temperature is introduced into the SCR purifier to remove the sulfur species deposited on the surface and inside of the catalyst pores, and realize the in-situ catalyst Regeneration, continue to pass the reducing gas for 0.5-1.5h, that is, complete the regeneration of the SCR catalyst; the process of the present invention utilizes the reducing atmosphere to reduce (NH 4 ) 2 SO 4 and CuSO 4 The decomposition temperature is high, and the sulfur species deposited on the catalyst can be removed in situ to quickly realize the in situ regeneration of the catalyst and ensure the normal driving of the vehicle during the regeneration process.

Description

technical field [0001] The invention belongs to the technical field of SCR denitrification catalyst regeneration, and in particular relates to an in-situ regeneration method of a Cu-based molecular sieve denitrification catalyst used for purifying diesel vehicle exhaust. Background technique [0002] Haze weather has brought great harm to people's physical and mental health. According to expert argumentation, 31.1% of smog comes from vehicle exhaust emissions, of which strong oxidizing nitrogen oxides (NO x ) is the main factor causing the secondary particle explosion. Proven: NH 3 -SCR system is to control diesel vehicle exhaust NO x The best technology, the principle is to use NH 3 selectively NO x Catalytic reduction to harmless N 2 . With the introduction of more stringent emission regulations (National VI), SCR catalysts are required to have high denitrification rate and high N in the range of 150-550 °C 2 Selective, and at the same time, it has the performance ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01J29/46B01J29/56B01J29/85B01J29/90B01J38/04B01J38/08B01J38/10B01D53/96
CPCB01D53/96B01J29/46B01J29/56B01J29/85B01J29/90B01J38/04B01J38/08B01J38/10
Inventor 刘雪松余琪璠杨敏陈朝贵李建法
Owner SHAOXING UNIVERSITY
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