Oxidation resistance of Ni/La_0.7Sr_0.3AlO _3-δ catalyst for steam reforming of model aromatic hydrocarbon

Oxidative resistance of Ni catalysts supported on various oxides La _0.7Sr_0.3AlO_3-δ, LaAlO₃, and α-Al₂O₃ were investigated for hydrogen production by steam reforming of model aromatic hydrocarbons. Ni/α-Al₂O ₃ lost its steam reforming activity by oxidation treatment. In contrast, Ni/La_0.7Sr_0.3AlO_3-δ and Ni/LaAlO₃ catalysts showed steam reforming activity even after the oxidation treatment. The XANES (X-ray absorption near-edge structure) spectra at Ni K-edge for Ni/La_0.7Sr_0.3AlO_3-δ and Ni/α-Al₂O₃ after oxidation treatment revealed that the supported Ni on La_0.7Sr_0.3AlO_3-δ and α-Al₂O₃ were oxidized completely. Although the mean particle size of Ni on Ni/α-Al₂O₃ increased by oxidation treatment or reduction treatment, Ni particles on Ni/La _0.7Sr_0.3AlO_3-δ retained the fine structure after oxidation treatment or reduction treatment. Moreover, TPR (temperature programmed reduction) and XPS (X-ray photoelectron spectroscopy) measurements for elucidating the reducibility of Ni/La_0.7Sr _0.3AlO_3-δ showed that the supported Ni on La _0.7Sr_0.3AlO_3-δ was easily reduced even after the oxidation treatment.