Encapsulation of Keggin-type phosphotungstic acid into the mesopores of SBA-16 as a reusable heterogeneous catalyst for the epoxidation of oleffns

Abstract

A heterogeneous catalyst for the epoxidation of oleffns was prepared by encapsulating Keggin-type phosphotungstic acid (H3PW12O40) into the mesopores of SBA-16. After the encapsulation, the pore entrance size of SBA-16 was reduced through a silylation method to encompass the catalyst in the mesopores and allow easy diffusion of the reactants and products during the catalytic process. The prepared catalyst was characterized by FTIR and Inductively Coupled Plasma-Optical Emission Spectroscopies(ICP-OES), X-Ray Di fraction (XRD), and Transmission Electron Microscopy (TEM). The analysis results revealed that the mesoporous nature of SBA-16 was conserved after encapsulation of the catalyst following the silylation step. The catalytic activity of the prepared material was assessed in the epoxidation of olens with H2O2. The heterogeneous catalyst was recovered and reused up to ve cycles without considerable decrease in activity.