CHA type molecular sieve for purifying diesel vehicle tail gas, catalyst, preparation method and application

Abstract

The invention discloses a CHA type molecular sieve for purifying diesel vehicle tail gas, a catalyst, a preparation method and application, and belongs to the field of chemical synthesis technology and application thereof. The CHA-type aluminosilicate zeolite molecular sieve is synthesized by adopting an N,N,N-trimethyl-3,3,5-trimethylcyclohexyl quaternary ammonium onium compound as an organic template agent, wherein the molar ratio of silicon dioxide to aluminum oxide is 6-80, the average grain diameter is less than or equal to 500nm, the total specific surface area is more than or equal to 400m2 / g, the total pore volume is more than or equal to 0.20 ml / g, the micropore volume is more than 0.10 ml / g, and thecrystal grain diameter in the crystal face (-210) direction is 50-160 nm. After the molecular sieve is subjected to hydro-thermal treatment at 600-850 DEG C, the tetra-coordinated aluminum accounts for more than or equal to 90% of the total aluminum amount, and the hexa-coordinatedaluminum accounts for less than or equal to 10% of the total aluminum amount. The molecular sieve provided by the invention has high hydrothermal stability under the condition of no large crystal grains, and shows high nitrogen oxide reduction characteristics after being exposed at high temperature and high humidity, especially shows high nitrogen oxide reduction characteristics in a temperaturerange of 200-550 DEG C.

Description

technical field [0001] The invention relates to a CHA-type molecular sieve used for purifying diesel vehicle tail gas, a catalyst, a preparation method and application, and belongs to the field of chemical synthesis technology and its application. Background technique [0002] The silica-alumina zeolite molecular sieve is a CHA-type topological structure with a three-dimensional pore structure and orthogonal symmetry. The one-dimensional main channel is composed of double eight-membered rings, the pore size is 0.38nm×0.38nm, and the skeleton density is 14.5. The topological structure of CHA molecular sieve is composed of double 6 rings (d6r) connected by 4-membered rings to form a large cha cage. The d6r crystal plane faces the cha large cage. Cu ions can be stabilized in d6r at high temperature, allowing Cu ions to migrate. It is also the unique physical and chemical characteristics of small-pore molecular sieves with SCR reaction potential. In the literature (J.Phys.Chem....

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Problems solved by technology

[0006] The technical problem to be solved by the present invention is to overcome the SCR catalyst using synthetic molecular sieves loaded with iron and copper in the prior art to be active at low temperatures through the hydrothermal durability test. Lower defects, providing a copper-based SCR catalyst with high activity at low temperature after hydrothermal durability test and its preparation method

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