Enhancement of Hydrogen Production Using Ni Catalysts Supported by Gd-Doped Ceria

Abstract

A redox cycle between Ce4+ and Ce3+ is the elementary step in water gas shift (WGS) mechanism. Facilitating a redox cycle between +4 and +3 of cerium enhanced the formation of oxygen vacancy which is considered as a dominate factor for developing the WGS performance and stability of ceria material. Therefore, in this work, we have tried to facilitate the redox cycle in CeO 2 to enrich the WGS activity. The WGS reaction was carried out on Ni catalyst supported by Gd-doped ceria (GDC). Gd-doped ceria material from Daiichi was employed as support for water gas shift reaction. Ni and Re were added onto GDC by impregnation method to examine the role of Re addition on surface, structural and reducibility which was altered to their catalytic activities. An influence of rhenium on increasing the water gas shift performance of Ni/GDC catalysts since Re facilitating the redox process at the ceria surface, dispersing Ni particles and oxygen vacancy formation. The results of water gas shift activity tests presented that the activity of 1%Re4%Ni/GDC was higher than that of 5%Ni/GDC. The role of Re on improving the WGS activity was promoting the dispersion of active metal site on catalyst surface which result in increases CO molecules adsorption and accelerating a redox cycle between Ce4+ and Ce3+ of ceria support by oxygen vacancies generation. Therefore, the WGS performance can be enhanced by the combination of these two effects.