Understanding the role of atomic ordering in the crystal structures of Ni_xSn_y toward efficient vapor phase furfural hydrogenation

Abstract

We have synthesized ordered Ni_xSn_y nanoparticles separated by Al₂O₃ as highly efficient catalysts for the vapor phase hydrogenation of furfural. The Ni_xSn_y-Al₂O₃ composite catalysts with different chemical compositions (Ni₃Sn₄, Ni₃Sn, Ni_1.5Sn, Ni₃Sn₂, Ni) were prepared through the layered double hydroxide (LDH) route by annealing at 800℃ in the presence of H₂. Ni_xSn_y nanoparticles were well dispersed throughout the Al₂O₃ matrix indicating the high thermal stability of these materials. The effect of different concentration of Ni, Sn, and Al in the formation of Ni_xSn_y-Al₂O₃ catalyst was investigated. The X-ray diffraction, transmission electron microscopy, and X-ray absorption fine structure analyses indicate the formation of intermetallic phases with spherical particles having an average size of 30–160 nm. The nanoparticles with different compositions were tested toward the hydrogenation of furfural, and it was found that crystal structure, atomic ordering and composition play crucial roles in the catalytic activity. DFT calculations indicate that the adsorption energy and the geometrical orientation of furfural on the surface of different Ni_xSn_y-Al₂O₃ compounds play crucial role in the hydrogenation of furfural. Ni₃Sn₂–Al₂O₃ was found to be the most efficient catalyst with high furfural conversion (∼65%) and selectivity (57–62%) for furfuryl alcohol.