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Iron-based SCR (Selective Catalytic Reduction) catalyst and preparation method thereof

An SCR catalyst and catalyst technology, applied in the chemical field, can solve the problems of short hot water resistance time, achieve simple procedures, excellent NOx purification performance, and reduce costs

Active Publication Date: 2014-12-24
清华大学苏州汽车研究院(吴江) +1
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  • Summary
  • 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 shortcomings of the iron SCR catalyst in the prior art that it can withstand hot water for a short time, and after being subjected to the action of sulfur oxides for a long time, it has low activity at low temperatures, and provides a catalyst with good durability. Iron-based SCR catalyst with high activity in hot water and low temperature and preparation method thereof

Method used

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  • Iron-based SCR (Selective Catalytic Reduction) catalyst and preparation method thereof
  • Iron-based SCR (Selective Catalytic Reduction) catalyst and preparation method thereof
  • Iron-based SCR (Selective Catalytic Reduction) catalyst and preparation method thereof

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preparation example Construction

[0043] The present invention is used for the synthetic zeolite of porous structure of the preparation of SCR catalyst, considers that iron (Ⅲ) ion is monodisperse in framework, and the maximum number of oxygen rings is advisable to be 8~12, from iron (Ⅲ) ion as catalyst In consideration of having a reaction site, it is preferable to have a three-dimensional structure. In carrying iron (III) ions, there are no particular limitations as long as the above-mentioned hydrogenated synthetic zeolite is used as an oxide having long-lasting hydrothermal resistance and long-lasting sulfur resistance as a catalyst.

[0044]The synthetic zeolite in the preparation of the SCR catalyst of the present invention can be distinguished by the structure code of the International Zeolite Association (International Zeolite Association), such as BEA type structure (for example, β as the maximum oxygen ring number 12), MFI type structure (such as ZSM-5 with a maximum number of oxygen rings of 10), CH...

Embodiment 1

[0082] Embodiment 1 synthesizes BEA type zeolite (chemical composition: Na 7 Al 7 Si 57 o 128 ) to obtain a BEA-type synthetic zeolite that ion-exchanges sodium with ammonia. Then, heat treatment was performed at 550° C. to prepare a BEA type hydrogenated synthetic zeolite.

[0083] BEA type synthetic zeolite

[0084] Aqueous sodium hydroxide solution was added to colloidal silicon dioxide (30 wt%) to obtain a reaction mixture. To this mixture, aluminum nitrate nonahydrate (Al(NO 3 ) 3 9H 2 O) Mix the obtained solution in 35 wt% tetraethylammonium hydroxide (TEAOH) aqueous solution, stir evenly, and the obtained reaction mixture has the following composition.

[0085] 21Na 2 O·10Al 2 o 3 ·300SiO2 2 ·150TEAOH·4000H 2 o

[0086] hydrothermal synthesis

[0087]The above reaction mixture was placed in a Teflon vessel and heated in an autoclave at a temperature of 155° C. for 3 days under autogenous pressure. Then, the solid reaction product was separated with a cen...

Embodiment 2

[0096] Example 2 is the same as Example 1 except that degassing treatment is not performed, and the BEA type hydrogenated synthetic zeolite carrying iron ions is used as the SCR catalyst. The ratio (mass / volume percentage concentration) of the mass of hydrogenated synthetic zeolite crystals to the volume of the nitric acid aqueous solution containing iron (III) ions is 166%. The average particle diameter (D50) of the obtained SCR catalyst was 7 μm. According to the results of ICP analysis, the iron (III) ion content was 2.3 wt%.

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Abstract

The invention discloses an SCR (Selective Catalytic Reduction) catalyst containing synthetic zeolite and iron, and particularly relates to an SCR catalyst which always has an NOx purifying property in a low-temperature region after being subjected to relatively long-term action of hot water and relatively long-term action of sulfur oxides. A preparation method of the SCR catalyst, disclosed by the invention, comprises the following steps: crystallizing a hydrogenised synthetic zeolite with maximal oxygen cycle number of 8-12 and a three-dimensional structure by using a mixing procedure, and blending with a ferric nitrate (III) water solution or ferric chloride (III) water solution with a pH value of 0.1-0.7 to obtain the SCR catalyst without a filtering procedure and a cleaning procedure.

Description

technical field [0001] The invention relates to the technical field of chemistry, in particular to an SCR catalyst, in particular to a preparation method for an Fe-based SCR catalyst composed of synthetic zeolite crystals containing iron (III) ions. In the presence of ammonia and ammonia derivatives (such as cyanic acid, etc.) obtained by thermal hydrolysis of urea, it is used to purify NOx in automobile exhaust. Background technique [0002] Utilize the diesel engine vehicle exhaust gas treatment device to inject urea water, and use the ammonia obtained by hydrolyzing the urea water as a reducing agent. The SCR catalyst is used as a NOx selective reduction catalyst (usually called "selective catalytic reduction" of the SCR catalyst. Abbreviation) The carrier used is a known synthetic zeolite with high ammonia adsorption capacity at solid acid sites. [0003] Patent document WO2011 / 024847 discloses an SCR catalyst with good NOx reduction performance, especially NOx reductio...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J29/76B01J29/46B01D53/94B01D53/56
Inventor 帅石金胡准华伦朱君君赵彦光潘金冲松冈宽
Owner 清华大学苏州汽车研究院(吴江)
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