Enhancement of toluene oxidation performance over LaCoO perovskite by lanthanum non-stoichiometry.

LaCoO catalysts with different non-stoichiometry of lanthanum ions were synthesized by using the sol-gel method, and their catalytic performance in toluene combustion was investigated. The results showed that the catalytic activity and stability of A-site nonstoichiometric LaCoO were improved to a certain extent compared with pure LaCoO perovskite. Among them, the LaCoO catalyst gave the best catalytic performance for toluene oxidation. It achieved 90% toluene conversion at 205°C under the conditions of a WHSV (weight hourly space velocity) of 22,500 mL/(g·hr) and a 500 ppmV-toluene concentration. Various characterization techniques were used to investigate the relationship between the structure of these catalysts and their catalytic performance. It was found that the non-stoichiometric modification of the lanthanum ion at position A in LaCoO changed the surface element state of the catalyst and increased the oxygen vacancy content, thus, combined with improved reducibility, improving toluene degradation on the catalyst.