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Catalyst for reducing nitrogen oxides and process for reducing nitrogen oxides

A technology for purifying catalysts and nitrogen oxides, applied in metal/metal oxide/metal hydroxide catalysts, physical/chemical process catalysts, chemical instruments and methods, etc. Durability iron silicate and other issues

Inactive Publication Date: 2009-06-24
TOSOH CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] However, in the reduction method of nitrogen oxides (NOx) using ammonia as a reducing agent, iron silicate excellent in decomposing performance of nitrogen oxides at low temperature and excellent in hydrothermal durability has not been known so far.

Method used

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  • Catalyst for reducing nitrogen oxides and process for reducing nitrogen oxides
  • Catalyst for reducing nitrogen oxides and process for reducing nitrogen oxides
  • Catalyst for reducing nitrogen oxides and process for reducing nitrogen oxides

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0160] Dissolve aluminum nitrate nonahydrate 18.79g, iron nitrate nonahydrate 4.63g in 257g tetraethylammonium hydroxide 35% aqueous solution (hereinafter referred to as "TEAOH"), then add tetraethyl orthosilicate (TEOS) 209g, Thoroughly stir and mix, carry out hydrolysis at room temperature, and evaporate the ethanol generated. Next, the necessary amount of water is evaporated. 20.88 g of 48% hydrofluoric acid was added thereto, and after mixing with a mortar, the reaction mixture was added to a stainless steel autoclave, and heated at 150° C. for 240 hours to crystallize. The composition of the reaction mixture is 40SiO 2 :Al 2 o 3 :0.23Fe 2 o 3 :20HF:24.4TEAOH:300H 2 O. The crystallized syrupy mixture was white. This mixture was subjected to solid-liquid separation, washed with pure water, and dried at 110°C.

[0161] The dry powder was calcined at 600°C for 2 hours under air circulation. As a result of X-ray diffraction measurement of the obtained β-type iron sil...

Embodiment 2

[0163] In addition to changing the composition ratio of the crystallized reaction mixture to 70SiO 2 :Al 2 o 3 :0.47Fe 2 o 3 :35HF:42TEAOH:490H 2Except for O, a reaction mixture was prepared by the same procedure as in Example 1. This reaction mixture was added to a stainless steel autoclave, and crystallized by heating at 150°C for 160 hours. The crystallized syrupy mixture was white. This mixture was subjected to solid-liquid separation, washed with a sufficient amount of pure water, and dried at 110°C. The dry powder was calcined at 600°C for 2 hours under air circulation.

[0164] From the X-ray diffraction measurement results of the obtained β-type iron silicate, it was found that the X-ray diffraction pattern shown in Table 1 was obtained.

Embodiment 3

[0166] In addition to changing the composition ratio of the crystallized reaction mixture to 70SiO 2 :Al 2 o 3 :Fe 2 o 3 :35HF:42TEAOH:490H 2 Except for O, a reaction mixture was prepared in the same manner as in Example 1. This reaction mixture was added to a stainless steel autoclave, and heated at 150° C. for 240 hours to crystallize. The crystallized syrupy mixture was white. This mixture was subjected to solid-liquid separation, washed with a sufficient amount of pure water, and dried at 110°C. The dry powder was calcined at 600° C. for 2 hours under air circulation.

[0167] As a result of the X-ray diffraction measurement of the obtained β-type iron silicate, the X-ray diffraction pattern shown in Table 1 was obtained.

[0168] figure 1 The ultraviolet-visible absorption spectrum of β-type iron silicate (before durability treatment) is shown. figure 2 An example of electron spin resonance spectra of β-type iron silicate 1 before and after durability treatment...

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Abstract

A first catalyst for reducing nitrogen oxides comprising a crystalline silicate containing an iron in -framework structure wherein a SiO 2 / Fe 2 O 3 mol ratio is 20-300 and at least 80% of the contained iron is an isolated iron ion Fe 3+ . A second catalyst for reducing nitrogen oxides comprising a crystalline silicate containing an iron in -framework structure wherein a SiO 2 / Fe 2 O 3 mol ratio is 20-300 and log(SiO 2 / Al 2 O 3 ) by mol is at least 2. A predominant part of the contained iron is isolated iron ion Fe 3+ and at least a part thereof preferably has a tetrahedral coordination. These catalysts have high hydrothermal stability and exhibit enhanced activity for reducing nitrogen oxides by a reaction with a reducing agent such as ammonia, urea or an organic amine in a broad temperature range between lower temperature and higher temperature.

Description

technical field [0001] The present invention relates to a method for purifying nitrogen oxides discharged from an internal combustion engine, and provides a catalyst for purifying nitrogen oxides containing iron silicate having a β structure, and using the catalyst to make nitrogen oxides and ammonia, urea, and organic amines A purification method for at least one substance reaction. Background technique [0002] A silicate in which a heteroelement is substituted in the framework structure is expected to have characteristics different from general aluminosilicate zeolites, and its use in catalytic reactions has been studied. [0003] For example, a xylene isomerization catalyst using platinum-supported iron silicate (Patent Document 1), a selective methylation catalyst using an iron silicate naphthalene compound (Patent Document 2), and A method for producing polyalkylene glycol using iron silicate as a cyclic ether ring-opening polymerization catalyst (Patent Document 3) a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J23/745B01D53/56B01D53/86B01J21/08
CPCY02C20/30
Inventor 楢木佑介有贺耕青山英和
Owner TOSOH CORP
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