Hierarchical Ti-Beta zeolites with uniform intracrystalline mesopores hydrothermally synthesized via interzeolite transformation for oxidative desulfurization

Abstract

Precisely designing and constructing metallosilicate zeolite with abundant and uniform intracrystalline mesopore is urgently desired, bearing the merits of boosting accessibility of active sites and of improving diffusion properties for organics in the process of catalytic reactions. Herein, hierarchical Ti-Beta zeolite with uniform intracrystalline mesopore (ca. 3.4 nm) is hydrothermally synthesized via interzeolite transformation of siliceous FAU zeolite, which is not capable to be achieved using amorphous silica sources. The crystallization process is thoroughly explored via series of characterization methods, obeying liquid crystallization mechanism. Additionally, the assembly of hierarchical Ti-Beta zeolite is nourished by the primary structural units (mainly 4-membered ring) resulting from the degraded silicate species of FAU zeolite. This burgeoning hierarchical Ti-Beta zeolite shows extraordinary catalytic performances in terms of both active site-based turnover frequency and weight-based space-time-yield for oxidative desulfurization of model oil, far beyond than conventional fluoride-mediated Ti-Beta and microporous Ti-Beta prepared by this developed strategy without addition of CTAB, which is attributed to its excellent diffusion properties and undemanding contact of active sites with reaction substrates. This work provides a span-new guidance for designing hierarchical metallosilicates with uniform mesopore from the standpoint of employing exotic primary structural units derived from the degradation of crystallized siliceous zeolites.