Hydrogenation of benzoic acid in the liquid phase over Pt/SnO2 has afforded excellent selectivity to benzyl alcohol under mild reaction conditions (97% at 98% conversion of benzoic acid). DFT calculations have shown that the favoured mode of adsorption of benzoic acid switched from the aromatic ring to the acid carbonyl group with partial reduction of the SnO2 support. The switch in adsorption mode corroborates the experimentally observed selectivity with acid carbonyl group adsorption and hydrogenation occurring over Pt/SnO2. Reduction of Pt/SnO2 was observed by in-situ XPS forming a degree of metallic tin and complete reduction of Pt which could lead to Pt-Sn alloy phases and/or migration of SnOx onto Pt blocking sites for ring hydrogenation. No hydrogenation of benzene or the benzene ring of benzoic acid was observed over Pt/SnO2 with oxidic tin species at the interface of Pt particles proposed to activate the acid carbonyl group for hydrogenation.
Manyar, H., Chen, X., Wang, Z., Daly, H., Morgan, R., Byrne, C., ... Hardacre, C. (2020). Hydrogenation of benzoic acid to benzyl alcohol over Pt/SnO2. Applied Catalysis A: General, . https://doi.org/10.1016/j.apcata.2020.117420