Microreactors technology for hydrogen purification: Effect of the catalytic layer thickness on CuOx/CeO2-coated microchannel reactors for the PROX reaction

Abstract

Two blocks of microreactors composed by 100 microchannels and coated, respectively, with 150 and 300 mg of a CuOx/CeO2 catalyst, were prepared and tested in the preferential oxidation of CO in presence of H2 (PROX). The deposition of different amount of catalyst resulted in different catalytic layer thicknesses thus modifying the catalytic performances of the microreactor. The evaluation of the main reaction variables (the space velocity, the O2-to-CO ratio and the presence of H2O and/or CO2 in the stream) was performed over both microreactors and compared to that of the parent powder catalyst. The least loaded microreactor, with a coating thickness around 10 μm, presented the highest CO conversion and selectivity levels at temperatures below 160 ºC. This result evidences i) the improvement of the catalytic performances got by the structuration of the powder catalyst and ii) the importance of the selection of the adequate thickness of the catalytic layer on the microreactor, which have not to exceed and optimal value. An adequate coating thickness allows minimizing the mass and heat transport limitations, thus resulting in the enhancement of the catalytic performance during the PROX reaction