Synthesis method for directly preparing h-type molecular sieve having cha framework type and use thereof

Abstract

An H-type molecular sieve having the CHA framework type is directly prepared through hydrothermal synthesis by using the compounds with the chemical formulas (CHNO)PO and/or (CHNO)PO(CHN) as structure-directing agents. The structure-directing agent has a molecular topological structure, which is conducive to quickly and efficiently building a molecular sieve having the CHA framework type, so that the prepared product has a regular morphology and high relative crystallinity. The synthesis method can directly synthesize the H-type molecular sieve having the CHA framework type with a relative crystallinity greater than 95%. The molecular sieve product can be obtained by direct drying and calcination without an ammonium exchange process, so the synthesis method is simple, easy to perform, and suitable for large-scale production. The samarium-based CHA molecular sieve catalyst shows excellent ammonia adsorption capacity, low-temperature activity, active temperature window, Nselectivity, and structural stability in the NH-SCR technology.