From natural aluminosilicate minerals to hierarchical ZSM-5 zeolites: A nanoscale depolymerization-reorganization approach

In this article, we describe a novel strategy for synthesizing hierarchical ZSM-5 zeolites via the nanoscale depolymerization-reorganization of natural aluminosilicate minerals. This strategy involves two important steps: the first is the top-down depolymerization of one aluminum-rich aluminosilicate mineral via a novel submolten salt system and one silicon-rich aluminosilicate mineral via conventional thermal treatment into nanoscale building blocks, and the second is the bottom-up rearrangement and reorganization of nanoscale building blocks in the synthesis system into hierarchical ZSM-5 zeolites. When used as a fluid catalytic cracking catalyst additive, the resulting ZSM-5 zeolite with hierarchical micro-mesoporous structure exhibited high activity and selectivity for valuable products in preliminary oil refining tests. The salient features of the strategy lie in that it neither involves any inorganic aluminum and silicon salts as precursors nor uses any secondary mesoscale template and post-treatment to create mesopores, thus demonstrating itself to be a green route to synthesizing hierarchical zeolites.