The High-Performance Hollow Silicalite-1@Titanium Silicalite-1 Core-Shell Catalyst for Propene Epoxidation

Hollow silicalite-1@titanium silicalite-1 (H−S-1@TS-1) core-shell catalyst was synthesized in hydrothermal system with hollow silicalite-1 serving as core. In this novel method, tetrapropylammonium hydroxide (TPAOH) served as the single template in the whole synthesis process so as to avoid secondary structure directing agents (SDAs) that traditional methods applied to give core-shell TS-1. Since inner hollow structure was given by S-1, H−S-1@TS-1 avoided framework Ti leaching in coventional dissolution-recrystallization process that gave hollow TS-1 and thus it was in absence of extra-framework Ti. H−S-1@TS-1 showed better propene epoxidation activity (TOF=13.61 mol (mol h)−1) than microporous TS-1 (TOF=8.08 mol (mol h)−1) and micro-TS-1 post-treated with TPAOH solution (TOF=9.75 mol (mol h)−1) due to the synergy function of pure framework Ti species, higher surface Ti content and enhanced diffusion property.