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Beta-type zeolite for scr catalyst and method for converting nitrogen oxide using the zeolite

一种SCR催化剂、氮氧化物的技术,应用在催化剂活化/制备、分子筛催化剂、化学仪器和方法等方向,能够解决还原性能降低、不能使用、不十分清楚等问题,达到低温NOX还原性优良的效果

Active Publication Date: 2009-08-26
TOSOH CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] NO X The reduction performance is reduced, especially at low temperatures below 300°C, the performance reduction is significant, and it cannot be used
The reason why the performance of the SCR catalyst using β-type zeolite deteriorates after hydrothermal durability treatment is mainly due to insufficient heat resistance of β-type zeolite, especially at low temperatures, has not yet been fully understood.
Performance of existing literature reports and commercially available SCR catalysts using zeolite beta at 200°C after hydrothermal durability treatment X Reduction rate is less than 30%
(Patent Document 5) But even by this method, NO at 200°C X The reduction rate is still less than 30%, and expensive rare earths must be used
(Refer to Patent Documents 5 to 9) However, for the β-type zeolite used as an SCR catalyst, no NO after hydrothermal durability treatment has been proposed. X Beta zeolite with high reduction rate, especially NO at low temperature X β-type zeolite with high reduction rate

Method used

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  • Beta-type zeolite for scr catalyst and method for converting nitrogen oxide using the zeolite
  • Beta-type zeolite for scr catalyst and method for converting nitrogen oxide using the zeolite
  • Beta-type zeolite for scr catalyst and method for converting nitrogen oxide using the zeolite

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0106] Use sodium silicate aqueous solution, aluminum sulfate aqueous solution and the composition of the slurry product is SiO 2 : 0.05Al 2 o 3 The ratio is reacted under stirring to obtain a slurry product, which is washed after dehydration to make granular amorphous aluminosilicate.

[0107] Next, with the composition of the reaction mixture as SiO 2 : 0.05Al 2 o 3 :0.67TEAF:11.0H 2 The ratio of O was mixed, and 0.36 parts of seed crystal (HSZ940NHA manufactured by TOSOH CORPORATION) was added to 100 parts of the composition, and hydrothermal synthesis was carried out at 155° C. in a reactor for 72 hours to crystallize. The crystallized slurry was washed and dried at 110°C. (TEAF: Tetraethyl fluoride hydrate 50%) This dried powder was sintered at 600°C to obtain SiO 2 / Al 2 o 3 Beta zeolite with a molar ratio of 25.

[0108] SiO of the obtained zeolite beta 2 / Al 2 o 3 Table 1 shows the molar ratio, SEM particle size, half-width of the main diffraction peak (2θ...

Embodiment 2

[0110] The composition of the raw material slurry obtained by using an aqueous solution of sodium silicate and an aqueous solution of aluminum sulfate is SiO 2 : 0.034Al 2 o 3 , the composition of the reaction mixture is SiO 2 : 0.034Al 2 o 3 : 0.16TEAOH : 9.9H 2 O, the hydrothermal synthesis conditions are 66 hours at 150°C, and the sintering temperature is 600°C. In addition, the same treatment is carried out as in Example 1 to synthesize SiO 2 / Al 2 o 3 Beta zeolite with a molar ratio of 29. (TEAOH: 35% aqueous solution of tetraethylammonium hydroxide)

[0111] SiO of the obtained zeolite beta 2 / Al 2 o 3 Table 1 shows the molar ratio, SEM particle size, half-width of the main diffraction peak (2θ=22.4°) of X-ray crystal diffraction, and the amount of ammonia adsorption after hydrothermal treatment.

Embodiment 3

[0113] The composition of the raw material slurry obtained by using an aqueous solution of sodium silicate and an aqueous solution of aluminum sulfate is SiO 2 : 0.07Al(OH) 3 , the composition of the reaction mixture is SiO 2 : 0.07Al(OH) 3 : 0.10KOH: 0.30TEAOH: 9.9H 2 O, the seed crystal uses HSZ930NHA manufactured by TOSOHCORPORATION, the hydrothermal synthesis condition is 150°C for 88 hours, and the sintering temperature is 600°C, except that, the same treatment as Example 1 is carried out to synthesize SiO 2 / Al 2 o 3 Beta zeolite with a molar ratio of 24.

[0114] SiO of the obtained zeolite beta 2 / Al 2 o 3 Table 1 shows the molar ratio, SEM particle size, half-width of the main diffraction peak (2θ=22.4°) of X-ray crystal diffraction, and the amount of ammonia adsorption after hydrothermal treatment.

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Abstract

The NOx reducibility of an SCR catalyst using beta-zeolite is low after the hydrothermal aging, especially at a temperature below 300 DEG C. Besides, the SCR catalyst using ammonia has a problem of large irritant and toxic ammonia gas emission. An SCR catalyst using beta-zeolite in which the molar ratio of SiO 2 / Al 2 O 3 is from 20 to less than 40, the particle diameter determined by SEM is 0.35 [mu]m or more, the full width at half maximum (FWHM) of the X-ray diffraction peak for (302) is less than 0.30 DEG , and the amount of adsorbed NH 3 is 1 mmol / g or more, or has an amount of adsorbed NH 3 following hydrothermal aging of 0.4 mmol / g or more, demonstrates high catalytic activity for NOx reduction at low temperatures following hydrothermal aging while also demonstrating a low level of discharge of irritating ammonia in exhaust gas.

Description

technical field [0001] The invention relates to a high-performance SCR catalyst and β-type zeolite used in the catalyst. This application claims the priority of Japanese Patent Application No. 2006-262303 for which it applied to Japan on September 27, 2006, and uses the content here. Background technique [0002] Beta zeolite is known to be used for NO X Reduction catalysts, especially NO using ammonia as reductant X A reduction catalyst (typically a zeolite called "Selective catalytic reduction" called an SCR catalyst). (refer to patent document 1) [0003] NO X The reduction performance is reduced, especially at low temperatures below 300°C, the performance reduction is significant, and it cannot be used. The reason why the performance of the SCR catalyst using β-type zeolite deteriorates after hydrothermal durability treatment is mainly due to insufficient heat resistance of β-type zeolite, especially at low temperatures, has not yet been fully understood. . Perfor...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B39/04B01D53/94B01J29/70B01J35/00
CPCC01B39/46B01J35/002B01J29/7615C01B39/48B01J29/7007B01J37/10B01J35/023B01J37/0246B01D53/8628B01D2255/502B01J29/7215Y10T428/2982B01J35/30B01J35/40B01J2235/30B01J2235/15B01J35/70C01B39/04B01J29/76B01D53/94F01N3/10
Inventor 德永敬助小川宏有贺耕青山英和
Owner TOSOH CORP
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