High-performance zeolite for reducing nitrogen oxide emissions, method of preparing same and catalyst using same

Patent metadata

Field	Value
Publication number	US-2021069685-A1
Application number	US-202017009235-A
Country	US
Kind code	A1
Filing date	Sep 1, 2020
Priority date	Sep 9, 2019
Publication date	Mar 11, 2021
Grant date	—

Abstract

Disclosed is a method of preparing a high-performance zeolite catalyst for reducing nitrogen oxide emissions, and more particularly a technique for preparing a zeolite catalyst, suitable for use in effectively removing nitrogen oxide (NOx), among exhaust gases emitted from vehicle internal combustion engines through selective catalytic reduction (SCR), thereby exhibiting high efficiency, high chemical stability and high thermal durability upon SCR using the prepared catalyst.

First claim

What is claimed is:

1 . A copper-impregnated LTA zeolite catalyst for selective catalytic reduction of nitrogen oxide having high hydrothermal stability and base durability, the catalyst comprising
a high-silica-content LTA zeolite in which copper is ion-exchanged, wherein a silicon/aluminum (Si/Al) molar ratio is 8 to 30 and a particle size is 0.5 to 5.0 μm.

2 . The catalyst of claim 1 , wherein the particle size is 0.5 to 2.0 μm, a specific surface area is 700 m2/g or more, the Si/Al molar ratio is 8 to 16, a Cu/Al molar ratio is 0.45 to 0.5, and a residual fluorine (F) content in a skeleton of the catalyst is 0.02% or less.

3 . The catalyst of claim 1 or 2 , wherein the copper-impregnated LTA zeolite has a crystallinity of 50% or more after a hydrothermal treatment at 900° C. and a crystallinity of 30% or more after a base treatment.

4 . The catalyst of claim 3 , wherein a nitrogen oxide conversion efficiency is 70% or more upon reaction with a reaction gas containing nitrogen oxide at 150° C. to 600° C. after the hydrothermal treatment at 900° C.

5 . The catalyst of claim 1 , which is applied to a selective catalytic reduction (SCR) or an SCR-catalyzed diesel particulate filter (SDPF) for an internal combustion engine exhaust system.

6 . A method of preparing a copper-impregnated LTA zeolite catalyst, the method comprising
producing an LTA zeolite and impregnating copper in the LTA zeolite, wherein the producing of the LTA zeolite is performed using a fluorine-substituted structure-directing agent (SDA-F).

7 . The method of claim 6 , wherein the fluorine-substituted structure-directing agent is a fluorine-substituted imidazole-based cation material.

8 . The method of claim 6 , wherein the fluorine-substituted structure-directing agent is produced by substituting a structure-directing agent through linking with a fluorine-containing ion exchange resin or addition of a fluorine source.

9 . The method of claim 8 , wherein the fluorine source is selected from the group consisting of hydrogen fluoride, ammonium fluoride, sodium fluoride, potassium fluoride, and alkylammonium fluoride.

10 . The method of claim 6 , wherein the fluorine-substituted structure-directing agent is subjected to mixing with a silicon material, an aluminum material and a template and then to a hydrothermal synthesis.

11 . The method of claim 10 , wherein a seed crystal introduction is further performed between the mixing and the hydrothermal synthesis.

12 . The method of claim 10 , wherein the hydrothermal synthesis is performed at 80 to 190° C. at a water/silicon (H2O/Si) molar ratio of 2.5 to 20.

13 . The method of claim 10 , wherein the silicon material is selected from the group consisting of ammonia (NH4)-colloidal silica, sodium (Na)-colloidal silica, precipitated silica, fumed silica, sodium silicate, tetraethyl orthosilicate, and aluminosilicate.

14 . The method of claim 13 , wherein the ammonia-colloidal silica is used such that a state of a synthetic mother liquor is maintained in a liquid phase suitable for mass synthesis.

15 . The method of claim 10 , wherein the aluminum material is selected from the group consisting of aluminum sulfate, crystalline aluminum hydroxide, noncrystalline aluminum hydroxide, aluminum chloride, aluminosilicate, and aluminum metal.

16 . The method of claim 6 , wherein a copper source used in the impregnating of the copper is selected from the group consisting of copper nitrate, copper chloride, copper acetate, and an amine-based precursor including tetraammine copper nitrate, tetraammine copper chloride and tetraammine copper sulfate.

17 . The method of claim 16 , wherein the LTA zeolite is impregnated 1 to 3 times using the copper source

18 . The method of claim 10 , wherein the template is selected from the group consisting of tetramethylammonium hydroxide and tetramethylammonium chloride.

19 . The method of claim 10 , wherein the hydrothermal synthesis is performed through a single-temperature synthesis process or a stepwise temperature-elevating synthesis process.

20 . The method of claim 11 , wherein the seed crystal introduction is performed using an LTA-structured zeolite having a Si/Al ratio of 10-20, in which an amount of a seed crystal introduced relative to the silicon material is 1-5 wt %.

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Coporation
• Heesung Catalysts Corp
• Kia Motors Corp

Inventors

• Kim Pyung Soon
• Kim Young Jin
• Kim Chang Hwan
• Na Seung Chul
• Oh Seung Ho
• Yoo Young San
• Kim Ho Dong

Classifications

• B01J37/105

  Hydropyrolysis · CPC title

• B01J35/40

  characterised by dimensions, e.g. grain size (in a colloidal state B01J35/23; crystallite size B01J35/77) · CPC title

• B01J29/7607 Primary

  A-type · CPC title

• B01J2235/15

  X-ray diffraction · CPC title

• B01J2235/30

  Scanning electron microscopy; Transmission electron microscopy · CPC title