Bi2O3@mSiO2 as an Environmentally Benign and Sustainable Solid Acid Catalyst for Benzoylation of Aromatics: Impact of Silica Encapsulation on Catalyst Leaching and Reaction Synergy

摘要

Leaching of active species is one of the major causes of catalyst deactivation. The accumulation of this leached species as chemical waste can be detrimental to the environment. In this study, a series of environmentally benign core-shell catalysts of type Bi2O3@mSiO2 were synthesized to address these issues. The catalysts, varying in silica content and shell thickness, were characterized and evaluated for Friedel-Crafts benzoylation. Amongst them, Bi-4 (containing 71.8% Bi2O3), having shell thickness of ~42nm, showed the best response under optimized conditions. Textural analysis of Bi-4 confirmed the mesoporous nature of shell, with average pore diameter of ~40 A and surface area of 62 m2/g. During the reaction, the Bi2O3 core was converted to BiOCl, which was easily recycled back to its original form. No leaching or any loss in catalytic activity was observed for the recycled catalyst during reuse. Thus, an inexpensive, reusable and environmentally benign catalyst is proposed.