Direct synthesis of hydrogen peroxide over Au–Pd catalyst in a wall-coated microchannel

•Synthesis of hydrogen peroxide from H2 and O2 was studied over Au–Pd catalyst.•A method was developed to wash-coat the catalyst on the microchannel walls.•Capillary microreactor makes it possible to work safely with explosive H2/O2 mixtures.•Explosive regime in microreactor results in a higher selectivity and productivity. Hydrogen peroxide production via direct hydrogenation of molecular oxygen offers many challenges for both catalyst and reactor development to have a high selectivity. An important advantage of using a capillary channel microreactor is the possibility to use H2/O2 concentrations that would be considered explosive in traditional reactors. Au–Pd bimetallic catalysts prepared by impregnation or two-phase synthesis procedure were deposited in a form of thin catalytic film in a capillary microchannel. This coated catalyst performed identical to a comparable slurry catalyst tested in a classical batch autoclave. Operating the microreactor within what would have been the explosive regime in a conventional reactor results in a higher selectivity and productivity.