The role of lattice oxygen on the activity and selectivity of the OMS-2 catalyst for the total oxidation of toluene

• OMS-2 exhibited excellent activity for catalytic oxidation of toluene.
• The active species and the adsorption sites on OMS-2 are lattice oxygen.
• The selectivity to CO2 is influenced by the nature of replenished lattice oxygen.

The role of lattice oxygen on the activity and selectivity of the OMS-2 catalyst synthesized by the hydrothermal method was investigated for the catalytic oxidation of toluene. The OMS-2 catalyst exhibited excellent activity for the catalytic oxidation of toluene, but the by-product benzaldehyde was detected at low temperatures. A DRIFT study showed that the lattice oxygen was both the adsorption site and active catalytic site. The nature of the replenished surface lattice oxygen was found to influence the selectivity, and toluene that was adsorbed on the lattice oxygen replenished by gaseous oxygen could be oxidized easily into benzaldehyde. A possible reaction mechanism has been proposed that could elucidate the toluene oxidation activity over OMS-2 involving two reaction routes, either with or without gaseous oxygen.

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