Carbon-supported, Pt and PtCo nanocrystals (NCs) with controlled size and composition were synthesized and examined for hydrodeoxygenation (HDO) of 5-hydroxymethylfurfural (HMF). Experiments in a continuous flow reactor with 1-propanol solvent, at 120 to 160 °C and 33 bar H2, demonstrated that reaction is sequential on both Pt and PtCo alloys, with 2,5-dimethylfuran (DMF) formed as an intermediate product. However, the reaction of DMF is greatly suppressed on the alloys, such that a Pt3Co2 catalyst achieved DMF yields as high as 98%. XRD and XAS data indicate that the Pt3Co2 catalyst consists of a Pt-rich core and a Co oxide surface monolayer whose structure differs substantially from that of bulk Co oxide. Density functional theory (DFT) calculations reveal that the oxide monolayer interacts weakly with the furan ring to prevent side reactions, including overhydrogenation and ring opening, while providing sites for effective HDO to the desired product, DMF. We demonstrate that control over metal nanoparticle size and composition, along with operating conditions, is crucial to achieving good performance and stability. Implications of this mechanism for other reactions and catalysts are discussed

The liquid-phase (69 bar) reaction of 5-hydroxymethylfurfural (HMF) with 2-propanol for production of furanyl ethers was studied at 413 and 453 K over a series of oxide catalysts, including γ-Al 2 O 3 , ZrO 2 , TiO 2 , Al 2 O 3 /SBA-15, ZrO 2 /SBA-15, TiO 2 /SBA-15, H-BEA, and Sn-BEA. The acidity of each of the catalysts was first characterized for Brønsted sites using TPD-TGA of 2-propanamine and for Lewis sites using TPD-TGA of 1-propanol. Catalysts with strong Brønsted acidity (H-BEA and Al 2 O 3 /SBA-15) formed 5-[(1-methylethoxy) methyl]furfural with high selectivities, while materials with Lewis acidity (γ-Al 2 O 3 , ZrO 2 , TiO 2 , and Sn-BEA)or weak Brønsted acidity (ZrO 2 /SBA-15 and TiO 2 /SBA-15) were active for transfer hydrogenation from the alcohol to HMF to produce 2,5-bis(hydroxymethyl)furan, with subsequent reactions to the mono-or diethers. Each of the catalysts was stable under the flow-reactor conditions but the selectivities varied with the particular oxide being investigated.

The three-phase hydrodeoxygenation reaction of 5-hydroxymethylfurfural (HMF) with H 2 was studied over a 10 wt % Pt/C catalyst using both batch and flow reactors, with ethanol, 1-propanol, and toluene solvents. The reaction is shown to be sequential, with HMF reacting first to furfuryl ethers and other partially hydrogenated products. These intermediate products then form dimethyl furan (DMF), which in turn reacts further to undesired products. Furfuryl ethers were found to react to DMF much faster than HMF, explaining the higher reactivity of HMF when alcohol solvents were used. With the optimal residence time, it was possible to achieve yields approaching 70% in the flow reactor with the Pt/C catalyst. Much higher selectivities and yields were obtained in the flow reactor than in the batch reactor because side products are formed sequentially, rather than in parallel, demonstrating the importance of choosing the correct type of reactor in catalyst screening.