A highly selective and efficient Pd/Ni/Ni(OH)2/C catalyst for furfural hydrogenation at low temperatures

Abstract

Hydrogenation of furfural (FF) produces a train of products such as furfuryl alcohol (FFA), tetrahydrofurfuryl alcohol (THFFA) and 2-methylfuran (2-MF). The Pd/Ni/Ni(OH)2/C nanocatalyst was successfully prepared under mild conditions by hydrazine hydrate reduction and galvanic replacement methods. Pd/Ni/Ni(OH)2/C had much higher conversion of furfural and selectivity toward furfuryl alcohol for the selective hydrogenation of furfural than the monometallic catalysts (eg. Pd/C or Ni/C) due to its unique nanostructure of palladium island-on-Ni/Ni(OH)2 nanoparticles and thus the synergy effect between Pd, Ni and Ni(OH)2 related species. The proposed mechanism of the synergistic effect was also provided. Pd/Ni/Ni(OH)2/C showed high selectivity (90.0% or 92.4%) to furfuryl alcohol at quite low reaction temperatures (5 °C or 10 °C), and had good stability. We used various characterization techniques (XRD, HRTEM, STEM-EDS elemental mapping and line-scanning, XPS, HS-LEIS) to compare the nanostructural differences between the monometallic and bimetallic catalysts as well as to explain the possible reasons for the superior performance of Pd/Ni/Ni(OH)2/C to corresponding monometallic catalysts.