Zeolite is an important class of inorganic crystalline material and widely employed in catalytic processes such as fludized catalytic cracking (FCC) and methanol to olefins (MTO). However, the intrinsic channels of molecular dimensions unavoidably limited the mass transportation of reacant/product inside the zeolite, leading to coke deposition and consequently catalyst deactivation. To develop zeolite with hierachical porosity, is an effective solution to amoreliate the diffusion limitaions of zeolite.

Recently, our laboratory successfully post-synthesized the hierarchical SAPO-18 molecular sieves in the alkaline tetraethyl ammonium hydroxide (TEAOH) solution and hydrochloride (HCl) acid solution. The preferential dissolution occurs surrounding the defect sites in a controlled manner is critical for the successful preparation.The defects are predominantly located at the intergrowth interface and vulnerable to acid/alkaline attacks. This work also proves that the crystallization of SAPO-18 proceeds via an oriented nanoparticle attachment mechanism in the early stage (non-classical crystallization mechanism).

The relevant study was published in Microporous and Mesoporous Materials. This work was supported by National Natural Science Foundation of China and KeyResearch Program of Frontier Sciences, Chinese Academy of Sciences.

Preparation of Hierarchical SAPO-18 via alkaline/acid etching. Dong Fan, Yuyan Qiao, Kaipeng Cao, Lijing Sun, Shutao Xu, Peng Tian, ZhongminLiu*, Microporous and Mesoporous Materials, 300:97-102, 2020.