Autothermal Reforming of Methane Over CeO₂-ZrO₂-La₂O₃ Supported Rh Catalyst

Autothermal reforming of methane was studied over La-doped ceria-zirconia-supported Rh catalysts. The CH₄ conversion increased from 49 to 60% on increasing the content of La³⁺ from 5 to 15%, while further increase in the La³⁺ content led to a slight decrease on both CH₄ conversion and H₂ selectivity. H₂-TPR and UV-vis DRS spectrum showed that the interaction between Rh and the support was enhanced by increasing the content of La. We speculated that a so-called “Rh-La interfacial species” was formed on the surface of the support, which played an important role in catalytic activity. The balance between exposed Rh and the “Rh-La interfacial species” was necessary to improve the catalytic activity. Upon increasing the Rh loading on 15% La-doped ceria-zirconia support, the balance was built, i.e., CH₄ conversion increased from ~60 to 69% by increasing Rh loading from 0.1 to 0.5 wt% and only 2% conversion was elevated by doubling the Rh loading from 0.5 to 1.0 wt%.