Effects of rare earth oxides on stability of Ni/alpha-Al_2O_3 catalysts for steam reforming of methane

摘要

The stability and the high temperautre steam resistance of Ni/alpha-Al_2O_3 catalysts diped with rare earth oxides were investigated by means of the accelerated aging rests. Ni metallic particle size and the catalyst pahases were dxamined before and after aging tests by using the initial conversion of methane, the formation of undesirable phase such as NIAl_2O_4 was studied by using XRD, catalytic micro-reactor, and the UV-visible diffuse reflection spectroscopy. The mechanism of rate earth oxide additives in suppresisng the catalyst deactivation was also discussed. It was found that the addition of rare earth oxides resulted in great improvementwas in the stability and high temperature steam resistance of the catalysts formation of NiAl_2O_4. The effect of heavy rare earth oxides was shown to be more distinct than that of light ones. Stong metal-additives interaction exists and it amy be the result of interactions that made the p[erformance of catalysts greatly improved. However, it was revealed that although the dispersion of active component was improved due to the presence of tare earth oxides, the initial conversion of methane was slightly affected.