Transition-Metal-Free Catalysts for the Sustainable Epoxidation of Alkenes: From Discovery to Optimisation by Means of High Throughput Experimentation

Warunee      Lueangchaichaweng; Inge      Geukens; Annelies      Peeters; Benjamin      Jarry; Franck      Launay; Jean-Luc      Bonardet; Pierre      A. Jacobs; Paolo      P. Pescarmona

Abstract

Transition-metal-free oxides were studied as heterogeneous catalysts for the sustainable epoxidation of alkenes with aqueous H2O2 by means of high throughput experimentation (HTE) techniques. A full-factorial HTE approach was applied in the various stages of the development of the catalysts: the synthesis of the materials, their screening as heterogeneous catalysts in liquid-phase epoxidation and the optimisation of the reaction conditions. Initially, the chemical composition of transition-metal-free oxides was screened, leading to the discovery of gallium oxide as a novel, active and selective epoxidation catalyst. On the basis of these results, the research line was continued with the study of structured porous aluminosilicates, gallosilicates and silica-gallia composites. In general, the gallium-based materials showed the best catalytic performances. This family of materials represents a promising class of heterogeneous catalysts for the sustainable epoxidation of alkenes and offers a valid alternative to the transition-metal heterogeneous catalysts commonly used in epoxidation. High throughput experimentation played an important role in promoting the development of these catalytic systems.

Keywords: Gallium oxide, Al-SBA-15, Ga-SBA-15, sustainable epoxidation, full-factorial, heterogeneous catalysts, high throughput experimentation, energy, environment, conversion, renewable resources, high turnover, toxic substances, substrates, chemical composition, alkenes, time-consuming, liquid-phase reactions, gas chromatograph, epoxides, precursors, deactivation, isomorphous, microporous