(618e) Selective Hydrodeoxygenation of Furfuryl Alcohol on Doped Metal Oxide Catalysts

Selective hydrodeoxygenation (HDO) is an essential process for biomass valorization to fuels and chemicals. Biomass-derived molecules, such as furanics, often possess multiple reducible groups that in the presence of a hydrogen donor undergo various catalytic transformations such as hydrogenation, decarbonylation, ring opening and HDO.¹ The versatility of those complex molecules poses many challenges for designing selective catalysts targeting specific functional groups.^2,3 Our previous computational study on Ru/RuO_X catalyst demonstrated that cooperative interplay between RuOx and metallic Ru is necessary for high HDO activity: the former catalyzes C-O bond scission and the later activates hydrogen.⁴ However, bifunctional catalysts such as RuO_X can undergo bulk reduction to metallic Ru that is less active for HDO and promotes undesired ring hydrogenation.

An alternative design approach is to incorporate transition metal dopants into moderately reducible metal oxides (MO). In the present work, we prepared a series of doped MO catalysts for the selective HDO of furfuryl alcohol, a biomass model compound. Kinetic studies reveal that small amounts of dopant significantly enhance the HDO rate over moderately reducible metal oxide, whereas the same dopant on irreducible silica shows very low activity. By adjusting the dopant-metal oxide ratio, we successfully prevent undesired ring hydrogenation. Finally, catalytic performance combined with scanning transmission electron microscopy (STEM) and X-ray absorption spectroscopy (XAS) reveals the nature of catalytic active sites.

References:

1. J. Luo, M. Monai, H. Yun, L. Arroyo-Ramirez, C. Wang, C. B. Murry, P. Fornasiero, R. J. Gorte. The H₂ Pressure Dependence of Hydrodeoxygenation Selectivities for Furfural Over Pt/C Catalys. Catal. Lett. 146(4), 711-717 (2016).

2. J. Jae, W. Zheng, R. F. Lobo, and D. G. Vlachos, Production of Dimethylfuran from Hydroxymethylfurfural through Catalytic Transfer Hydrogenation with Ruthenium Supported on Carbon. ChemSusChem 6(7), 1158-1162 (2013).

3. J. Jae, W. Zheng, A. M. Karim, W. Guo, R. F. Lobo, and D. G. Vlachos, The Role of Ru and RuO₂ in the Catalytic Transfer Hydrogenation of 5-Hydroxymethylfurfural for the Production of 2,5-Dimethylfuran. ChemCatChem 6(3), 848-856 (2014).

4. A. V. Mironenko and D. G. Vlachos, Conjugation-Driven "Reverse Mars-van Krevelen"-Type Radical Mechanism for Low-Temperature C-O Bond Activation. J. Am. Chem. Soc. 138(26), 8104-8113 (2016).