Anchoring boron atoms to the specific tetrahedral sites of borosilicate MFI by imidazolium-based molecules

Abstract

Regulating heteroatom-substituted tetrahedral sites (T sites) within a zeolite crystal significantly influences the zeolite properties. Herein, the as-synthesized MFI zeolite with tailored boron locations at various T sites is unveiled by powder X-ray crystallography. The experimental results imply that four similar but structurally different imidazolium-based organic structure-directing agents (OSDAs) adopted in the synthetic system can effectively control the location of final boron-enriched T sites. It is demonstrated that the specific boron location depends on the corresponding OSDA coordinates and their molecular structures. Furthermore, boron-enriched composite building units in the MFI framework are derived as well. Such boron-enriched T sites tailored by zeolite framework (host) and OSDA molecule (guest) interactions afford an effective strategy for the rational design of zeotype catalysts.