The acid-base character of oxide supports is crucial for catalytic reactions. In this work, the acid-base properties of five oxide surfaces common in heterogeneous catalysis were investigated and related to their interaction with monolignol compounds derived from lignin. We have used density functional theory simulations also to understand the role of the surfaces' hydroxylation state. The results show that moderate hydroxyl coverage on the amphoteric γ-Al2 O3 (110) slightly strengthens the oxy-compounds' adsorption due to an increase in Lewis acidity. Similarly, low hydroxyl coverage on the reducible TiO2 (101) enlarges its adsorption capacity by up to 42 % compared with its clean surface. The higher affinity is attributed to the more favourable interaction between the surface-OH groups and the aromatic rings. Overall, the results indicate that hydroxyl coverage enhances the amphoteric and reducible adsorption capacity towards aromatic species.
Keywords: biomass valorisation; density functional calculations; hydrodeoxygenation; hydroxylated surfaces; surface chemistry.
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