Selective oxidation of CO in hydrogen-rich stream over Cu–Ce catalyst promoted with transition metals

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P><P>Cu–Ce/<I>γ</I>-Al<SUB>2</SUB>O<SUB>3</SUB> catalysts promoted with Co were tested for the low temperature selective oxidation of CO in excess hydrogen. The effects of Cu–Ce composition, Co as a dopant, stoichiometric ratio (<I>λ</I>=2O<SUB>2</SUB>/CO), water vapor and CO<SUB>2</SUB> on the selective oxidation of CO to CO<SUB>2</SUB>, O<SUB>2</SUB> consumption and selectivity of O<SUB>2</SUB> to CO oxidation as a function of temperature are presented. Also, the catalytic properties of the catalysts were investigated by using X-ray diffraction, CO-/H<SUB>2</SUB>-temperature programmed reduction, temperature programmed oxidation, CO-/CO<SUB>2</SUB>-/H<SUB>2</SUB>O-temperature programmed desorption (TPD). Small addition (0.2wt) of Co onto the Cu–Ce/<I>γ</I>-Al<SUB>2</SUB>O<SUB>3</SUB> brought large increase in selective CO oxidation activity. In the presence of either CO<SUB>2</SUB> (13 vol%) or H<SUB>2</SUB>O (10 vol%) in the reformed gas feed, both Cu–Ce/<I>γ</I>-Al<SUB>2</SUB>O<SUB>3</SUB> and Cu–Ce-Co/<I>γ</I>-Al<SUB>2</SUB>O<SUB>3</SUB> showed decreased activity in CO oxidation at low temperatures, especially, under 200°C. Compared with the Cu–Ce/<I>γ</I>-Al<SUB>2</SUB>O<SUB>3</SUB>, however, the Cu–Ce-Co/<I>γ</I>-Al<SUB>2</SUB>O<SUB>3</SUB> gives higher resistivity for the CO<SUB>2</SUB> and H<SUB>2</SUB>O. From the CO<SUB>2</SUB>/H<SUB>2</SUB>O-TPD results, it could be explained that the main cause for the decrease in catalytic activity with CO<SUB>2</SUB> and H<SUB>2</SUB>O in the feed may be attributed to the competitive adsorption of CO and CO<SUB>2</SUB> as well as the blockage of the active sites by water vapor at low reaction temperatures.</P>