Unraveling the surface state and composition of highly selective nanocrystalline Ni-Cu alloy catalysts for hydrodeoxygenation of HMFElectronic supplementary information (ESI) available. See DOI: 10.1039/c6cy02647h

• Main Authors: Luo, Jing, Monai, Matteo, Wang, Cong, Lee, Jennifer D, Ducho, Tomáš, Dvo ák, Filip, Matolín, Vladimír, Murray, Christopher B, Fornasiero, Paolo, Gorte, Raymond J
• Format: Article
• Language: English
• ISSN: 2044-4753; 2044-4761
• DOI: 10.1039/c6cy02647h

The selective hydrodeoxygenation (HDO) of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF) is an important step in cellulosic biomass upgrading to biofuels, where bimetallic oxophilic catalysts have shown promising performance. Well controlled bimetallic NiCu and NiCu 3 nanocrystals supported on carbon are shown to give high yields and selectivities to DMF. To shed light on the active phase, near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) was used to characterize the surface composition of these highly selective base-metal catalysts under reducing conditions relevant to the HDO reaction. Reactions were performed in a continuous flow reactor under reasonable conditions of 33 bar and 180 °C. The Ni alloys were significantly more selective for DMF compared to monometallic Ni or Cu catalysts. With a well-controlled surface composition, the nanocrystal NiCu 3 /C catalyst exhibited a maximum DMF yield of 98.7%. NAP-XPS characterization showed that the Ni-Cu nanocrystals were completely reduced below 250 °C in H 2 ; this, together with bulk thermodynamic calculations, implies that the catalysts were completely reduced under the reaction conditions. NAP-XPS also indicated that the NiCu 3 nanocrystal structure consisted of a Cu-rich core and a 1 : 1 molar Ni : Cu shell. Surface composition of the highly selective Ni-Cu catalysts was characterized by NAP-XPS under the conditions relevant to the HDO reaction.