Influence of Morphological, Redox and Surface Acidity Properties on WGS Activity of CuO-CeO2 Catalysts

Abstract

The aim of this work was to study the influence of CuO loading and pretreatment procedure on morphological, redox and acidic properties of CuO-CeO 2 catalysts, and correlate them to their water-gas shift (WGS) activity. Catalysts with a 10, 15 and 20 mol% CuO loading were synthesized with a method of coprecipitation, calcined at temperatures ranging from 400 to 750 • C, and subjected to XRD, N 2 adsorption/desorption, H 2 -TPR/TPD, N 2 O decomposition, NH 3 chemisorption and pulse WGS activity tests in the temperature range of 180-400 • C. Catalyst samples with a higher CuO content exhibited better WGS performance, due to greater oxygen mobility of the CeO 2 phase. Increasing the calcination temperature on the other hand deactivated the catalysts due to sintering and decrease of the CuO-CeO 2 interface area. A strong positive dependence of H 2 selectivity and consequently higher H 2 yield on increased catalyst surface acidity was observed, being more pronounced for catalysts with 10 mol% CuO content. WGS activity trends of the examined solids were successfully correlated with the extent of CeO 2 reduction and surface acidity, while an influence of active surface area on the activity trends was found to be marginal.

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“…The CuO particles [36]. Furthermore, the α peaks indicate the reduction in finely dispersed CuO particles over the surface of the AlFum MOF support [37]. The H 2 -reduction peaks further corroborate the successful loading of Cu and the formation of the desired CuO species after thermal treatment.…”

“…The α peaks indicate the reduction in Cu ions or CuO clusters that are in close contact with the AlFum MOF whereas the β peaks indicate the reduction in "bulk-like" CuO particles [36]. Furthermore, the α peaks indicate the reduction in finely dispersed CuO particles over the surface of the AlFum MOF support [37]. The H2-reduction peaks further corroborate the successful loading of Cu and the formation of the desired CuO species after thermal treatment.…”