SCR catalyst for diesel exhaust purification and preparation method of SCR catalyst

An SCR catalyst and exhaust gas purification technology, applied in physical/chemical process catalysts, molecular sieve catalysts, chemical instruments and methods, etc., can solve the problems of low temperature activity drop, activity drop, etc., and achieve high hydrothermal stability and wide active temperature window. , The effect of good resistance to hydrothermal aging

Active Publication Date: 2017-07-28
SINOCAT ENVIRONMENTAL TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

CN103127951A patent discloses a catalyst with Cu and Fe as active components and ZSM-5\Y molecular sieve as carrier. The catalyst has a wide activity temperature window, but its low-temperature activity drops sharply after hydrothermal aging at 670°C for 64h
Although the current copper-based zeolite SCR catalyst has good activity in the low temperature stage (US8101147B2), but the ammoxidation reaction will occur in the high temperature stage above 450 ° C, resulting in a sharp decline in activity

Method used

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  • SCR catalyst for diesel exhaust purification and preparation method of SCR catalyst
  • SCR catalyst for diesel exhaust purification and preparation method of SCR catalyst
  • SCR catalyst for diesel exhaust purification and preparation method of SCR catalyst

Examples

Experimental program
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Effect test

Embodiment 1

[0047] Configure 1000mL neodymium nitrate solution, Nd in the solution 4+ The concentration is 0.2mol / L, heated to 70°C, 50g SAPO-34 molecular sieve powder is added while maintaining strong stirring, and ion exchange is carried out in a constant temperature reactor at 70°C, and the exchange time is 10h. The obtained slurry was filtered with filter cloth and washed with deionized water for three times. The obtained molecular sieve sludge was dried at a drying temperature of 105℃, air atmosphere, and the drying time was 24h. The dried molecular sieve sludge was twisted and finely passed through 100 mesh. screen. The powder obtained is recorded as Nd-SAPO-34.

[0048] Configure 500mL copper nitrate solution, Cu in the solution 2+ The concentration is 0.6mol / L, heated to 70°C, add 50g of Nd-SAPO-34 molecular sieve powder while maintaining vigorous stirring, and perform ion exchange in a constant temperature reactor at 70°C. The exchange time is 2h. The obtained slurry was filtered w...

Embodiment 2

[0058] Prepare 1000mL of 0.1mol / L praseodymium nitrate solution, add 50g SAPO-34 molecular sieve powder and carry out ion exchange for 12h in a constant temperature reactor at 70°C. The obtained slurry is filtered, washed, and dried to obtain Pr-SAPO-34. Configure 500mL copper nitrate solution with a concentration of 0.6mol / L, add 50g Pr-SAPO-34 molecular sieve powder and carry out ion exchange for 3h in a constant temperature reactor at 70°C. The obtained slurry is filtered, washed, and dried. Repeat this ion exchange operation twice. The obtained molecular sieve powder is calcined in an air atmosphere. Other catalyst preparation processes and test conditions are the same as in Example 1. The resulting sample is referred to as S2.

Embodiment 3

[0060] Configure 1000mL of 0.2mol / L yttrium nitrate solution, add 50g SAPO-34 molecular sieve powder and carry out ion exchange in a constant temperature reactor at 70°C for 10h. The obtained slurry is filtered, washed, and dried to obtain Y-SAPO-34. Configure 500mL copper nitrate solution with a concentration of 0.2mol / L, add 50g Y-SAPO-34 molecular sieve powder and carry out ion exchange in a constant temperature reactor at 70°C for 3h. The obtained slurry is filtered, washed, and dried. Repeat this ion exchange operation four times. The obtained molecular sieve powder is calcined in an air atmosphere. Then the slurry is prepared, coated on the cordierite ceramic carrier, and then dried and calcined to obtain the monolithic SCR catalyst. The other operations are the same as in Example 1. The resulting sample is referred to as S3.

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Abstract

The invention discloses an SCR catalyst for diesel exhaust denitration and purification and a preparation method of the SCR catalyst. The catalyst is prepared from a transition or rare-earth metal element-modified zeolite molecular sieve as a carrier and metal elements such as Cu and Fe as active components. The preparation method comprises the steps of carrying out modified pretreatment of the zeolite molecular sieve; carrying out multiple liquid ion exchange; filtering and washing; drying and roasting; and finally pulping and coating a ceramic matrix to form a whole SCR catalyst. By adopting the modified zeolite molecular sieve as the carrier and nontoxic Cu and Fe as the active components, the SCR catalyst is harmless to a human body and friendly to the environment. Compared with an existing conventional method, the preparation method has the advantages that the ratios of species Cu and Fe at exchange sites in the prepared catalyst are obviously improved, the hydrothermal aging resistance is more excellent, the hydrothermal stability of the catalyst is improved, the high temperature resistance stability of the active components such as Cu and Fe is better, dispersion is more uniform, the active temperature window is effectively widened and the SCR catalyst has higher medium-high temperature activity and hydrothermal stability.

Description

Technical field [0001] The invention belongs to the technical field of catalyst preparation, in particular to the technical field of molecular sieve SCR catalyst preparation, and particularly relates to a wide active temperature window and high hydrothermal stability for catalytic conversion of diesel vehicle exhaust NO x Molecular sieve type SCR catalyst for gas and its preparation. Background technique [0002] Diesel engines have been widely used in long-distance and short-distance freight or passenger transportation due to their strong power characteristics. However, due to the high air-fuel ratio of diesel engines and the high temperature and high pressure in the cylinder, a large amount of toxic nitrogen oxides will be produced after diesel combustion. x , Aggravated the deterioration of air quality and seriously endangered the health of residents and animals. Ammonia selective catalytic reduction technology (NH 3 -SCR) is currently processing NO x The most mature and widely...

Claims

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Application Information

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IPC IPC(8): B01J29/85B01D53/94B01D53/56
CPCB01D53/9413B01D2258/012B01J29/85B01J2229/186Y02A50/20Y02T10/12
Inventor 吴干学淡宜王云徐海迪吴春燕王健礼曾东苏晓明张艳华刘征陈耀强李云陈启章
Owner SINOCAT ENVIRONMENTAL TECH
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