Enhanced water-gas shift reaction performance of MOF-derived Cu/CeO2 catalysts for hydrogen purification

Abstract

The water-gas shift (WGS) reaction has received renewed interest because it is one of the key reactions for producing hydrogen and renewable energy in contemporary technologies like fuel cells and bio-refineries. Catalysts play an important role in WGS reaction for achieving high CO conversion and hydrogen generation activity. Thus, the performance and stability of catalysts are vital for the WGS reaction. In the present work, the CuCe metal-organic framework (MOF) is used as a template to derive the nanostructured Cu/CeO2 catalyst. The influence of CuCe-MOF templated approach on the WGS activity of Cu/CeO2 has been established. Different Cu doping levels had a significant impact on WGS activity. Amongst, the Ce0.8Cu0.2O2 (Cu2Ce) catalyst had a highest CO conversion (96%). The long-term stability tests further prove that the Cu2Ce catalyst had maintained high CO conversion over 100 h reaction time. XRD and TEM results suggest that different loadings of Cu content have a distinct impact on the dispersion of Cu and the catalytic properties. N2O chemisorption results suggest that 20 wt.% of Cu loading resulted in high Cu dispersion (52%) compared to other loadings. The H2-temperature programmed reduction (TPR) revealed that the superior catalytic activity of Cu2Ce catalyst could be attributed to the strong reducibility (i.e. lower redox temperature) derived from CuCe-MOF template. It further suggests well-dispersed copper oxide species at low Cu loadings and crystalline copper oxide species at high Cu loadings. This work emphasizes the significance of Cu/CeO2 catalysts with exceptional catalytic activity and stability for the WGS process with MOF-precursor.