A Control over Hydrogenation Selectivity of Furfural\nvia Tuning Exposed Facet of Ni Catalysts

Selective\nhydrogenation of biomass to value-added products plays\na crucial role in the development of renewable energy resources. Herein,\ntwo heterogonous Ni catalysts supported on mixed metal oxides (MMO)\nwere prepared via structural topological transformation from hydrotalcites\n(LDHs) precursors with carbonate or nitrate in interlayer region (denoted\nas Ni/MMO-CO₃ and Ni/MMO-NO₃), which were featured\nby highly exposed Ni(111) facets as well as multifacets with abundant\nsteps/vacancies, respectively. Interestingly, the selectivity of furfural\nhydrogenation can be switched by using these two catalysts: Ni/MMO-NO₃ exhibits a high selectivity (97%) to furfural alcohol (FOL)\n(hydrogenation product of CO bond), whereas Ni/MMO-CO₃ shows an exclusive selectivity (99%) toward tetrahydrofurfuryl\nalcohol (THFOL, hydrogenation product of both CO and furan\nring). A combination study including high-resolution transmission\nelectron microscopy (HRTEM), extended X-ray analysis fine structure\n(EXAFS), and in situ CO-IR confirms a large proportion of steps/edges\nof Ni nanoparticles in Ni/MMO-NO₃ catalyst, which suppresses\nthe adsorption of the furan ring and only facilitates activated adsorption\nof the CO group. In contrast, a high exposure of Ni(111) plane\nin Ni/MMO-CO₃ promotes activated adsorption of both furan\nring and CO group, resulting in the production of THFOL. In\nsitu FT-IR measurements and DFT calculations reveal that the adsorption\nconfiguration of substrate plays a key role in determining the hydrogenation\npathway and selectivity. This work provides a feasible approach for\na control over hydrogenation selectivity of biomass molecules by tuning\nthe surface microstructure of metal catalysts.