Alloyed
Cu−Ni encapsulated in carbon was prepared by loading
Ni and Cu onto biochar (BC) through an initial wetness impregnation
method under mild conditions. The bimetallic catalysts were exploited
to perform selective hydrodeoxygenation (HDO) of 5-hydroxymethylfurfural
(HMF). 2,5-Dimethylfurfural (DMF), a promising liquid fuel/fuel
additive, could be obtained from HMF with the highest yield of 93.5%
under the optimized conditions. During HMF HDO, two key intermediates,
5-methylfurfural (MFF) and 2,5-dihydroxymethylfuran
(DHMF), dominating two distinct conversion pathways were systematically
investigated by Arrhenius kinetics analysis. In addition, the turnover
frequencies (TOFs) of HDO reaction over Cu−Ni/BC corresponding
with Cu amount were thoroughly discussed, finding that the electron
transfer from Cu to Ni in the alloy structure was beneficial to the
HDO reaction and the conversion pathways can be regulated by reaction
temperature variation. Importantly, the synergy of HDO of HMF by alloyed
Cu−Ni metal and Lewis acid sites from oxide NiO
x
were hence clarified by systematic catalyst characterizations.
The Cu−Ni/BC catalyst is stable for at least five consecutive
runs to obtain the stabilized 81.9% of DMF since the third run.