Exploring post-treatment-induced transformations of UOV germanosilicate

Abstract

Germanosilicates, renowned for their diverse structure and open porosity, possess superior diffusion properties and promising applicability in heterogeneous catalysis. However, their susceptibility to framework collapse in moist conditions, due to vulnerable Ge-O bond to hydrolysis, presents a significant limitation for practical applications. Thus, enhancing the stability of the germanosilicate framework is essential. Moreover, germanosilicates display significant structural flexibility owing to the instability of their interlayer Ge-enriched double 4-rings (d4r) units. This research outlines the outcomes of UOV germanosilicate subjected to diverse post-synthesis treatments. Notably, under acidic conditions, the synthesized Ge-rich UOV (Si/Ge = 3.2) experienced silicon isomorphous substitution, yielding a high-silica UOV analogue (Si/Ge = 140). In contrast, under neutral and alkaline conditions, the UOV germanosilicate underwent structural reorganization and rearrangement of the constituent units, resulting in interzeolite transformation to ∗MRE-type zeolite. The transformation of UOV germanosilicate in neutral and alkaline environments also provides some supplements for the conditions of mutual transformation between zeolites.