Promoter effect of potassium in CuO/CeO2 systems supported on carbon nanotubes and graphene for the CO-PROX reaction

Abstract

The effect of K promotion on the CO preferential oxidation (CO-PROX) reaction has been studied over Cu-CeO2 based catalysts supported on carbon nanotubes (CNT) and reduced graphene oxide (G). The catalysts were prepared with 3 wt.% Cu and 20 wt.% CeO2 loadings, and 1 wt.% K when promoted. In the CNT series, K loading was varied between 0.5 and 2 wt%. The catalytic performance and the characterization by powder X-ray diffraction (XRD), TEM-STEM, H2-temperature-programmed reduction (H2-TPR) and X-ray photoelecton spectroscopy (XPS) has been presented. TEM analysis showed that the type of carbon support has an important effect on the dispersion of ceria, this latter being higher for CNT support. Addition of K to the catalysts improved the conversion of CO at lower temperatures. The characterization results reveal that the observed increase in the Cu+ species proportion and in lattice oxygen are related to the better catalytic performance