Hydrogen production via methane partial oxidation over ceria-nickel and ceria-zirconia-nickel mixed-oxide catalysts

Abstract

Hydrogen production via the partial oxidation of light hydrocarbons has received much attention in recent years due to the high demand for clean energy sources alleviating environmental problems. An alternative means of producing hydrogen from methane partial oxidation (MPO) over different types of catalysts has been investigated by a number of research groups. However, carbon deposition on a catalyst bed, resulting in deteriorating its kinetics, is observed as a major cause of catalyst deactivation. In order to find alternative catalyst that can be more tolerant to carbon deposition, (Ce₀.₇₅Zr₀.₂₅)₂.₁₄Ni₀.₈₆o₃ and Ce₂.₁₄Ni₀.₈₆o₃ mixed oxide catalysts were investigated for MPO over the temperature range of 400-800°C at atmospheric pressure. The catalysts were prepared by the co-impregnation method and characterized by X-ray diffraction (XRD) analysis, BET surface area measurement, H₂ chemisorption, temperature programmed reduction (TPR) and oxidation (TPO), and transmission electron microscopy (TEM). The XRD results showed that the reduction of the oxides proceeds through the formation of intermediate species to obtain Ni⁰ and CeC₂. Under the reaction conditions, both (Ce₀.₇₅Zr₀.₂₅) ₂.₁₄Ni₀.₈₆O₃ and Ce₂.₁₄Ni₀.₈₆O₃ catalysts were active at temperatures above 650°C. Among the catalysts tested, the (Ce₀.₇₅Zr₀.₂₅) ₂.₁₄Ni₀.₈₆O₃ catalyst calcined at 700°C exhibited better catalytic activity and stability for methane partial oxidation.