Effect of reducing gas on the hydrogen production by thermo-oxidation of water over 1%Rh/Ce0.6Zr0.4O2

Abstract

We have studied the effect of the reducing gas (H2, CO and CH4) on the hydrogen production by thermo-oxidation of water over the 1%Rh/Ce0.6Zr0.4O2 catalyst prepared by impregnation. The catalyst is characterized by hydrogen chemisorption (Hc), before and after catalytic decomposition of water, temperature-programmed desorption, temperature-programmed reduction, X-ray diffraction and scanning electron microscopy. The catalyst is reduced in situ at 500 °C (4 h) under H2, CO or CH4 flows and flushed with Ar gas. Then, pulses of water (1 μL/pulse) are injected at 500 °C under Ar flow (30 mL/min). The results show clearly that the reducing gas has a strong effect on the H2 production which follows the order: H2 > CH4 > > CO. H2 chemisorption measurements at room temperature highlight a strong metal–support interaction over fresh reduced catalysts which decreases after water decomposition (reduced centers + H2O → oxidized centers + H2).