Hydrogen production by oxidative methanol reforming on Pd/ZnO: Catalyst deactivation

The durability performance of Pd/ZnO for oxidative methanol reforming has been investigated. While Cu/ZnO lost its activity with a constant selectivity of CO formation, Pd/ZnO exhibited a more stable activity, but with increasing CO production throughout the reaction time on stream. Characterization of the catalyst using XRD and XPS revealed the formation of a Pd–Zn alloy, which was thought to be essential for the selective production of hydrogen. Based on the reaction and the catalyst characterization results, two routes were supposed for the deactivation of Pd/ZnO catalyst: surface fouling by deposited carbon and surface oxidation of the Pd–Zn alloy, breaking down the Pd–Zn alloy to produce more elemental Pd on a ZnO support. The catalyst can be regenerated in a H2 reducing atmosphere at higher temperatures and in a diluted O2 atmosphere at lower temperatures.