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

[Display omitted] • Atomic layer-deposited TiO 2 onto Pt/Al 2 O 3 enhances production of jet fuel-range alkanes. • Ti cation sites created by reduction of the TiO 2 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 TiO 2 overcoats to Pt/Al 2 O 3 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-TiO 2 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 TiO 2 ALD can be used to maximize the utility of precious-metal catalysts. [ABSTRACT FROM AUTHOR]