Abstract
We investigated the influence of the reduction method on the preferential oxidation of CO in H2 (CO-PROX) over Au/La2O3/Al2O3 catalysts. An Au/La2O3/Al2O3 sample, prepared using deposition–precipitation with urea, was reduced by chemical reduction with NaBH4 or glycerol. Several techniques, such as diffuse-reflectance infrared Fourier-transform spectroscopy after CO adsorption (CO-DRIFTS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) were used to characterize the catalysts. Additionally, the catalysts were examined by in situ DRIFTS during methanol decomposition. The results reveal that the reduction method affects the average particle size and electronic state of gold, as well as the characteristics of the CO–Au0 interactions. The best CO-PROX performance was observed for the catalyst chemically reduced using NaBH4 with a NaBH4/Au molar ratio of 35. This catalyst contained gold particles with size of ~4 nm, for which the XPS binding energy was lower than that of metallic gold.
Highlights
The catalytic removal of CO by preferential CO oxidation in H2 (CO-PROX) is considered as a promising approach to prepare high-purity H2 for polymer electrolyte membrane fuel cells [1]
In order to improve the catalytic performance of gold centers in the CO-PROX process, much attention has been focused on the effects of the support and size of the gold particles
The variation of the CO conversion with the reaction temperature reveals that the temperature of maximum CO conversion (Tmax ) is considerably affected by the reduction method
Summary
The catalytic removal of CO by preferential CO oxidation in H2 (CO-PROX) is considered as a promising approach to prepare high-purity H2 for polymer electrolyte membrane fuel cells [1]. Recent studies have revealed that gold can be an attractive alternative to platinum group metal (PGM)-based catalysts for this process [2], in view of its proven CO oxidation ability at low temperatures and lower catalytic performance in H2 -mediated reactions [3,4,5,6,7]. The latter property derives from the lower capacity of gold to dissociate hydrogen compared with the PGM catalysts [8,9,10].
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