Harnessing synergism between Ni particles and Ni-ceria interface for efficient biomass reductive amination

Abstract

Catalytic reductive amination of 5-hydroxymethylfurfural (HMF) into primary amine has become a very promising upgrading route for cellulosic biomass. Ingenious integration of distinct catalytic centers on a single catalyst can synergistically drive transformations of organic reactants and H2 molecules, addressing selectivity maneuvering toward this complex amination process. Herein, this work reported a ceria-support Ni nanocatalyst with bifunctional Ni sites from Ni particle surface and Ni-CeO2 interface. Regulating Ni size can gradually tune interaction between Ni and ceria. Hence, the exposed amount of Ni0 active sites and the catalytic function of Ni at distinct locations can be finely modulated. This type of Ni catalyst achieved 100% yield of 5-aminomethyl-2-furanyl alcohol (AMF) and a high formation rate (10.6 gAMF-1 gNi-1 h-1) at 100 ℃ under hypobaric H2 at only 2 bar. Ni size effect and reaction parameter investigation gave rise to significant differences in product distribution, enabling elaboration on the complicated reaction path. It was disclosed that further selective transformations of reaction intermediates (i.e., imine, Schiff base) can be greatly important for inhibiting byproducts (i.e., trimer and furfurine) and accruing AMF yield. Physical characterizations and advanced chemisorption techniques unraveled that adsorption and activation of Schiff base and H2 occurred at Ni-CeO2 interface and Ni surface, respectively. Ammonolysis process involved with NH3 activation underwent on Ni2+ sites. The so-designed Ni/CeO2 catalyst showed good substrate scope toward various bio-amine synthesis and exhibited stable reusability after suitable regeneration.