Copper-based SCR catalyst and preparation method thereof

An SCR catalyst, copper-based technology, applied in the field of chemistry, can solve the problems of complicated preparation methods and low catalyst activity, and achieve the effects of low cost and simple preparation process

Active Publication Date: 2014-11-05
清华大学苏州汽车研究院(吴江) +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0009] The technical problem to be solved by the present invention is to overcome the defects of complex preparation methods of transition metal zeolite molecular sieves in the prior art and the low activity of the prepared catalysts, and to provide an SCR catalyst for synthetic zeolite carrying copper (II) ions The simple preparation method makes it possible to achieve a conversion efficiency of more than 80% of NOx purification rate when the tail gas temperature is below 200°C

Method used

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  • Copper-based SCR catalyst and preparation method thereof
  • Copper-based SCR catalyst and preparation method thereof
  • Copper-based SCR catalyst and preparation method thereof

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preparation example Construction

[0045]The structurally porous zeolite molecular sieve in the preparation of the SCR catalyst of the present invention, from the single dispersion of copper (II) ions in the framework, the maximum number of oxygen rings is preferably 8 to 12, from the copper (II) ions as The catalyst preferably has a three-dimensional structure in view of retaining a reaction site. In the support of copper (II) ions, hydrogen-type zeolite molecular sieves are usually selected from the viewpoint of durability and heat resistance as a catalyst, and are not particularly limited.

[0046] The zeolite molecular sieves in the preparation of the SCR catalyst of the present invention are exemplified, named according to the structure code of the International Zeolite Association (International Zeolite Association), BEA type structure (such as β as the maximum number of oxygen rings 12), MFI type structure (such as: ZSM-5 with a maximum number of oxygen rings of 10), CHA-type (for example: SSZ-13 with a ...

Embodiment 1

[0088] 1. Synthesis of BEA type zeolite (chemical composition: Na 7 Al 7 Si 57 o 128 ) chemical composition, obtains the BEA type zeolite molecular sieve that ion-exchanges sodium with ammonia. Then calcined at 550°C to obtain the desired BEA-type zeolite molecular sieve.

[0089] 1.1 BEA type synthetic zeolite

[0090] Add aqueous sodium hydroxide solution to colloidal silicon dioxide with a mass fraction of 30%, to obtain a reaction mixture. To this mixture, aluminum nitrate 9 hydrate (Al(NO 3 ) 3 9H 2 O) dissolved in an aqueous solution with a mass fraction of 35% tetraethylammonium hydroxide (TEAOH), obtained after thorough stirring, and the reaction mixture has the following composition.

[0091] 21Na 2 O·10Al 2 o 3 ·300SiO2 2 ·150TEAOH·4000H 2 o

[0092] 1.2 Hydrothermal synthesis

[0093]The above reaction mixture was put into a polytetrafluoroethylene container and heated in an autoclave at a temperature of 155° C. for 3 days. Next, the solid reaction p...

Embodiment 2

[0102] Example 2 is the same as Example 1 except that degassing treatment is not performed, and the Cu-introduced BEA type hydrogenated synthetic zeolite is used as the SCR catalyst.

[0103] The average particle diameter (D50) of the obtained SCR catalyst was 7 μm.

[0104] According to the results of ICP analysis, the copper (II) ion content was 2.3 wt%.

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Abstract

The invention provides a simple method for preparing a copper (II) ion-supported SCR catalyst having a NOx purifying performance at a low temperature. The SCR catalyst is prepared by mixing hydrogenation synthesized zeolite crystals with the largest oxygen ring number of 8-12 and a three dimensional structure with an aqueous solution of copper (II) nitrate ions or copper (II) chloride ions with the pH value of 0.1-3.0 without filtering or washing. The BET specific surface area of the copper-based SCR catalyst is 50-80m<2>/g, the copper-based SCR catalyst has low temperature activity, hydrothermal durability and NOx purifying performance, and the exhaust gas NOx purifying rate of the copper-based SCR catalyst at below 200DEG C reaches above 80%.

Description

technical field [0001] The invention relates to the field of chemical technology, in particular to a method for preparing a catalyst, in particular to the use of nitrogen oxides in automobile exhaust gas in the presence of ammonia and ammonia derivatives (such as cyanic acid) reducing agents obtained by decomposing urea aqueous solution A method for preparing an SCR catalyst composed of synthetic zeolite crystals containing copper (II) ions. Background technique [0002] The SCR catalyst is used to inject urea water after the exhaust gas treatment of diesel vehicles, and use the ammonia obtained by decomposing the urea aqueous solution as a reducing agent. " Abbreviation), the carrier used in it is a known zeolite molecular sieve with a high acidity site. [0003] On the other hand, diesel engine exhaust contains a large number of pollutants, and the key is how to reduce NOx and PM (fine smoke), and great progress has been made in this regard. [0004] In a diesel engine, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J29/76B01J29/46B01J32/00B01D53/56B01D53/94
Inventor 帅石金胡准华伦赵彦光潘金冲乌玉阁松岗宽守屋秀树
Owner 清华大学苏州汽车研究院(吴江)
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