Influence of the secondary pore system on methyl oleate epoxidation using TS-1 with hierarchical pore system

Abstract

In order to understand the influence of a secondary pore system introduced into TS-1 as well as its method of introduction, the epoxidation of methyl oleate with H₂O₂ was investigated at 323 K in the liquid phase over microporous TS-1 as well as micro-/mesoporous TS-1 and micro-/macroporous TS-1. Micro/macroporous TS-1 outperforms conventional microporous TS-1 in catalytic activity, producing 4.2 epoxy methyl oleate molecules per Ti-atom versus 2.3 for conventional microporous TS-1. Micro-/macroporous TS-1 was successfully synthesized by steam-assisted crystallization (bottom-up approach) with macropores up to 350 nm. Mesoporosity was successfully introduced in the range between 2.7 and 4.2 nm by two top-down approaches, i.e., alkali treatment and surfactant templating. The latter results in an up to 4 times lower material loss while keeping a comparable catalytic activity. Most importantly, an increase in the pore size of the secondary pore system correlates with increased catalytic activity for pore sizes up to 350 nm was found.