Single-stage water gas shift reaction over structural modified Cu–Ce catalysts at medium temperatures: Synthesis and catalyst performance

Abstract

Cu–Ce catalysts were synthesized by simple impregnation and coprecipitation-impregnation methods. The water gas shift reaction was investigated at medium temperatures. The impregnated 5Cu/CeO2 was regarded as optimum and resulted in 87% CO conversion, but showed 10% loss in activity over the 20 h of time-on-stream. To increase stability, the coprecipitation-impregnation method was used and 5Cu/Ce10Cu recorded 89.2% CO conversion. Activity loss for all cases in this category was ≤2.7%. The activity and the stability results were validated by FESM, XRD, BET and H2-TPR analyses. The smallest crystalline size was found to produce the highest CO conversion. It was also found that catalyst stability strongly depended on Cu–Ce interaction and the cases with more stability had less BET change after the reaction. H2-TPR analysis showed that the Cu species were reduced to three phases (α, β and γ). It was determined that the interaction, activity and Cu–Ce stability relied on the surface area and β phase intensity. No methanation occurred in any case for either method.