Thermochemical stability of alumina-supported Rh-LaCoO3 catalysts for tar conversion

The thermal and chemical stability of alumina-supported catalysts (Rh/Al2O3, LaCoO3/Al2O3, Rh-LaCoO3/Al2O3) have been investigated by performing cycles of tar conversion at 700 C followed by regeneration of the catalyst by oxidation of coke deposited on the surface up to 800 C. Structural and chemical modifications underwent by the catalysts upon conversion/ regeneration cycles have been studied by BET, TPR/TPO, and DRIFT analyses. The catalysts containing rhodium are highly stable maintaining the original performance and chemical properties of the fresh sample also after several cycles, dispersion of rhodium on Al2O3 surface being sufficiently preserved also at 800 C. On the contrary, LaCoO3/Al2O3 catalyst undergoes a partial deactivation after the first cycles related to the irreversible migration of cobalt into the alumina lattice.