Direct synthesis of hydrogen peroxide in a catalytic membrane contactor

Asymmetric porous alumina membranes with palladium nanoparticles deposited into the thin surface layer are used as a structured catalyst to perform the direct synthesis of hydrogen peroxide with separate supply of the reactants in a catalytic membrane contactor. Parameters such as mode of supply of the gaseous species, type of liquid medium used, as well as differential and liquid side pressure, have been investigated and their influence on the productivity and selectivity of the reaction is discussed. The presented concept, which targets local hydrogen peroxide production, offers improved safety of the process compared to conventional methods for direct synthesis described in the literature. By optimization of the reactant supply, high productivity (up to 16.8 mol h(-1) m(-2) in methanol) and high selectivity (between 80% and 90%) to hydrogen peroxide could be demonstrated in this reaction for the first time with catalytic membranes. (C) 2007 Elsevier B.V. All rights reserved.