H2-TPR, XPS and TEM Study of the Reduction of Ru and Re promoted Co/γ-Al2O3, Co/TiO2 and Co/SiC Catalysts

Abstract

Effects of Ru and Re promoters on Co-CoOx catalysts supported on γ-Al2O3, TiO2 and SiC were investigated to improve the understanding of the role of promoters of the active phase of Co-CoOx-Ru and Co-CoOx-Re. The influence of promoter addition on the composition and activity of the catalysts was characterized by several methods, such as H2-TPR, XPS, chemisorption and TEM. Furthermore, the role of support and metal-support interaction was especially studied and different support materials were compared. Based on the results, addition of promoter metals (Ru or Re) will most likely improve catalytic activity of Co/γ- Al2O3, Co/TiO2 and Co/SiC catalysts by increasing the active metal surface available for chemical reaction and by decreasing the size of the metallic nanoparticles. These changes in the catalytic activity were also associated with the changes in the ratio of metal and metal oxide phases in the surface composition as observed by XPS. Promoter metals also decreased the reduction temperatures needed for the reduction of Co3O4 to CoO and further to metallic cobalt. Significant decrease in reduction temperature was observed especially when ruthenium was used as the promoter.