Effect of Ce and Zr Addition to Ni/SiO2 Catalysts for Hydrogen Production through Ethanol Steam Reforming

A series of Ni/CexZr1-xO2/SiO2 catalysts with different Zr/Ce mass ratios were prepared by incipient wetness impregnation. Ni/SiO2, Ni/CeO2 and Ni/ZrO2 were also prepared as reference materials to compare. Catalysts' performances were tested in ethanol steam reforming for hydrogen production and characterized by XRD, H-2-temperature programmed reduction (TPR), NH3-temperature programmed desorption (TPD), TEM, ICP-AES and N-2-sorption measurements. The Ni/SiO2 catalyst led to a higher hydrogen selectivity than Ni/CeO2 and Ni/ZrO2, but it could not maintain complete ethanol conversion due to deactivation. The incorporation of Ce or Zr prior to Ni on the silica support resulted in catalysts with better performance for steam reforming, keeping complete ethanol conversion over time. When both Zr and Ce were incorporated into the catalyst, CexZr1-xO2 solid solution was formed, as confirmed by XRD analyses. TPR results revealed stronger Ni-support interaction in the CexZr1-xO2-modified catalysts than in Ni/SiO2 one, which can be attributed to an increase of the dispersion of Ni species. All of the Ni/CexZr1-xO2/SiO2 catalysts exhibited good catalytic activity and stability after 8 h of time on stream at 600 degrees C . The best catalytic performance in terms of hydrogen selectivity was achieved when the Zr/Ce mass ratio was three.