Control of location and distribution of heteroatoms substituted isomorphously in framework of zeolites and zeotype materials

Abstract

Zeolites and zeotype materials, which are porous and crystalline metallosilicates, are key functional materials widely used as adsorbents and catalysts in the chemical industry. The function and performance of these materials are significantly dependent on heteroatoms that substitute isomorphously the tetrahedral sites, so-called the T-sites, of the frameworks. In addition to the types of substituting heteroatoms, their location and distribution in frameworks also dominate the performance of zeolites and zeotype materials as adsorbents and catalysts; for example, the acid sites generated on substituting Al³⁺ for Si⁴⁺ in the channels and at the channel intersections of MFI-type zeolites exhibit different catalytic activities for some reactions. In this context, the development of a synthetic procedure to control isomorphous substitution by heteroatoms with precision is highly desired. This highlight introduces recent achievements related to such precise tuning of the location and distribution of substituting heteroatoms, mainly Al³⁺, by a variety of synthetic approaches along with the effects of such well-controlled heteroatom siting on catalytic performance.