Structure-Activity Relationship of Ceria Based Catalyst for Hydrogen Production

T he role of Sm addition on water gas shift performance of Re/ceria was studied. A redox cycle between Ce4+ and Ce3+ of ceria support by oxygen vacancies generation is one of the elementary step in water gas shift mechanism. In this work, we have attempted to enrich the Ce3+ content at the ceria surface of Re/doped ceria to enhance the water gas shift performance. The water gas shift reaction was carried out over Re/Sm-doped ceria catalysts with different contents of Sm (0, 5, 10, 15 wt%). The H2-TPR explained the activity enhancement of these catalysts due to Sm addition which have lowered the reduction temperature of rhenium oxide species and promoted the surface of ceria. The results of water gas shift activity investigation presented that the activity of 1%Re/Ce10%SmO was higher than that of other catalysts. The influence of Sm on increasing the catalytic activity of Re catalysts is concluded to be from enhancing the Ce3+ content which then facilitate the redox process at the surface.