Effect of Doped Metals on Hydrodeoxygenation of Phenol over Pt-Based Bimetallic Alloys: Caryl–OH Versus CaliphaticH–OH Bond Scission

Herein, using density functional theory calculations complemented by microkinetic modeling, we systematically investigated hydrodeoxygenation (HDO) of phenol, a model compound for phenolic oxygenates, over two Pt-based bimetallic alloys, namely, M@Pt(111) single-atom surface alloys and M/Pt(111) complete surface alloys, where M = Mo, Fe, Co, and Ni. Our results show that M@Pt(111) is more readily to be formed than M/Pt(111) in the HDO reaction environment. Benzene formation on Mo@Pt(111) is produced almost entirely from partial HDO (PHDO) via C aliphatic H–OH bond scission below 700 K, above which, the contribution from direct deoxygenation (DDO) via C aryl –OH bond scission grows exponentially with increased temperature. A host metal should have moderate hydrogenation (HY) capability for PHDO meanwhile avoids deep HY of the phenyl ring. To achieve an optimal phenolic-HDO activity for hydrocarbon products, a trade-off of oxophilicity of doped M must be carefully considered so that DDO, PHDO, and H 2 O formation activity can be promoted simultaneously. For M@Pt(111), the desired oxophilicity of doped M is predicted to be −3.00 to −3.85 eV in terms of OH* binding energy, which in turn can be used as a good descriptor for deoxygenation activity.