A Comparative Study of Nanosized Gold and Copper Catalysts on Y-doped Ceria for the Water-Gas Shift Reaction

Abstract

The increasing demands for high-purity hydrogen for fuel-cell processing systems caused a renewed interest in the watergas shift reaction. This work aims to analyse the suitability of gold-and copper-based catalysts for efficient upgrading the purity of hydrogen for small-scale applications. New catalytic materials were developed by deposition of nanosized gold or copper oxide particles on ceria doped by various amount of Y2O3 (1.0, 2.5 and 5.0 wt.%). A favourable effect of the ceria modification on the WGS activity of gold/ceria catalysts was observed. Superior CO conversion degrees (> 95 %) were achieved in the range 180-220 °C. The similarity in the catalytic activity was explained with the insignificant differences in the gold particle size among all gold-based samples. Surprisingly, copper-based catalysts exhibited decreased activity at increasing amount of Y2O3 in the composition of ceria supports. A characterization of the catalysts by N2 physisorption, XRD, HRTEM/HAADF, XPS, EPR and H2-TPR was carried out to reveal the effect of dopant amount on the WGS activity. The differences in the WGS performance were related to the catalysts reducibility, e.g. the availability of oxygen species with enhanced mobility. The analysis of structure-property-WGS activity relations proved to be a reliable tool for the improvement of catalyst performance by rational changes in the catalyst composition and structure.