Preferential oxidation of CO (PROX) over CoOx/CeO2 in hydrogen-rich streams: Effect of cobalt loading

PROX reaction over Co catalysts supported on ceria nano-particles was investigated with a special focus on the effect of Co loading. High surface area ceria nano-particles were prepared through a precipitation technique using cerium (III) nitrate hexahydrate and sodium hydroxide. Co incorporation was achieved using a wet impregnation method in aqueous media. Catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction, dispersion measurements, and in situ diffuse reflectance Fourier transform infrared spectroscopy and X-ray absorption spectroscopy. Activity and selectivity of CoOx/CeO2 catalysts with different Co loadings showed higher Co loadings to favor higher CO oxidation at the expense of oxygen selectivity. Higher activation energies for H2 oxidation compared to CO oxidation were observed, regardless of the Co loading, implying a higher temperature sensitivity for the H2 oxidation reaction. The Co phase was identified as Co3O4 and was stable in the reducing environments present in PROX reactions.

XANES studies showed the Co species in the CoOx/CeO2 catalyst to remain as a fully oxidized Co3O4 phase during PROX reaction.Figure optionsDownload as PowerPoint slideHighlights
► Co catalysts supported on nano-particles of ceria are examined for PROX reaction.
► The role of Co loading on the activity and oxygen selectivity has been examined.
► In situ DRIFTS is used to examine surface species during reaction.
► In situ XAFS is used to examine the active phase under reaction conditions.