Evaluating the activity and stability of perovskite LaMO₃-based Pt catalysts in the aqueous phase reforming of glycerol

The aqueous phase reforming of glycerol, to hydrogen, alkanes and liquid phase dehydration/dehydrogenation products, was studied over a series of 1 wt% Pt/LaMO₃ (where M = Al, Cr, Mn, Fe, Co, Ni) catalysts and compared to a standard 1 wt% Pt/γ-Al₂O₃ catalyst. The sol–gel combustion synthesis of lanthanum-based perovskites LaMO₃ produced pure phase perovskites with surface areas of 8–18 m²g⁻¹. Glycerol conversions were higher than the Pt/γ-Al₂O₃ (10%) for several perovskite supported catalysts, with the highest being for Pt/LaNiO₃ (19%). Perovskite-based catalysts showed reduced alkane formation and significantly increased lactic acid formation compared to the standard catalyst. However, most of the perovskite materials undergo phase separation to LaCO₃OH and respective M site oxides with Pt particle migration. The exception being the LaCrO₃ support which was found to remain structurally stable. Catalytic performance remained stable over several cycles, for catalysts M = Al, Cr and Ni, despite phase separation of some of these materials. Materials where M site leaching into solution was observed (M = Mn and Co), were found to be catalytically unstable, which was hypothesised to be due to significant loss in support surface area and uncontrolled migration of Pt to the remaining support surface. In the case of Pt/LaNiO₃ alloying between the exsoluted Ni and Pt was observed post reaction.