Towards improved conversion of wet waste to jet fuel with atomic layer deposition-coated hydrodeoxygenation catalysts

[Display omitted] •Atomic layer-deposited TiO2 onto Pt/Al2O3 enhances production of jet fuel-range alkanes.•Ti cation sites created by reduction of the TiO2 overcoats at highest examined surface coverage.•Conversion of key intermediate in HDO reaction increased upon creation of new Ti cation sites. The conversion of wet waste-derived volatile fatty acids into jet fuel-range hydrocarbons is a promising route for increasing the production of sustainable aviation fuel; however, the cost and moderate alkane selectivity of Pt-based hydrodeoxygenation catalysts present challenges for commercialization. To address this, we used atomic layer deposition to apply TiO2 overcoats to Pt/Al2O3 catalysts and create new interface sites that exhibited 8 times higher site time yield of the desirable n-alkane product than uncoated catalyst. Through TPR/TPD, XPS, CO DRIFTS, and DFT calculations, we found that the increased selectivity of the ALD-coated catalyst was due to the creation of O vacancies at the Pt-TiO2 interface under reducing conditions, resulting in new Ti3+ acid sites near the active metal. Maximum conversion and alkane selectivity during HDO was achieved with an ALD-coated 0.5% wt Pt catalyst, indicating that TiO2 ALD can be used to maximize the utility of precious-metal catalysts.