ECNU‐36: A Quasi‐Pure Polymorph CH Beta Silicate Composed of Hierarchical Nanosheet Crystals for Effective VOCs Adsorption

Abstract

A quasi‐pure C H polymorph of microporous zeolite beta, named ECNU‐36, was obtained as a highly crystalline silicate using 1,5‐bis(tetramethylimidazolium) hydroxide as organic structure‐directing agent (OSDA) in fluoride media. An appropriate concentration of free fluoride in the synthetic mother liquor was crucial to purify the C H ‐phase. The framework structure of ECNU‐36 consists of polymorph C H (> 95%) and polymorph B, elucidated by a combination of PXRD data, DIFFaX simulation, EDT, and HRTEM techniques. For the first time, the framework structure of beta C H polymorph was directly confirmed and solved using electron diffraction data. The pure‐silica ECNU‐36 showed an unusual crystal morphology, composed of stacked nanosheets, with typical 17 nm thickness and exposed {100} facets, which exhibited attractive adsorption performance for hydrocarbons and aromatics.