Effects of rare earth oxides on stability of Ni/α-Al2O3 catalysts for steam reforming of methane

Abstract

Abstract The stability and the high temperature steam resistance of Ni/α-Al 2 O 3 catalysts doped with rare earth oxides were investigated by means of the accelerated aging tests. Ni metallic particle size and the catalyst phases were examined before and after aging tests by using powder XRD. The effect of rare earth oxide additives on the dispersion of active component, the initial conversion of methane, the formation of undesirable phase such as NiAl 2 O 4 was studied by using XRD, catalytic micro-reactor, and the UV-visible diffuse reflection spectroscopy. The mechanism of rare earth oxide additives in suppressing the catalyst deactivation was also discussed. It was found that the addition of rare earth oxides resulted in great improvement in the stability and high temperature steam resistance of the catalysts through suppressing the growth of Ni particle, the oxidation of active component Ni and the formation of NiAl 2 O 4 . The effect of heavy rare earth oxides was shown to be more distinct than that of light ones. Strong metal-additives interaction exists and it may be the result of interactions that made the performances of catalysts greatly improved. However, it was revealed that although the dispersion of active component was improved due to the presence of rare earth oxides, the initial conversion of methane was slightly affected.