Importance of oxyphilic FeNi alloy in NiFeAl catalysts for selective conversion of biomass-derived 5-hydroxymethylfurfural to 2,5-dimethylfuran

Abstract

2,5-Dimethylfuran (DMF) is a promising fuel additive. Its selective production from 5-hydroxymethylfurfural (HMF) requires effective hydrodeoxygenation and simultaneous retainment of CC in furan ring, which is challenging over nickel-based catalysts. In this work, an alloying method was explored for selective conversion of HMF to DMF by introducing Fe species into Ni–Al catalysts to form oxyphilic FeNi alloy. The results showed that the formation of alloy in Ni–Fe–Al lowered the capability for adsorption and activation of hydrogen, reducing the activity for hydrogenation of the furan ring in HMF, forming mainly 2,5-dihydroxymethyl furan (DHMF) and 5-methylfurfuryl alcohol (5-MFA). In addition, the oxyphilic FeNi alloy had the high affinity for the adsorption/activation of C–OH in DHMF and 5-MFA, enhancing their hydrogenolysis to DMF. The kinetic study indicated that the hydrogenolysis of 2,5-dihydroxymethyl furan was the rate-determining step, showing a higher Ea (89.2 kJ mol−1) than that in hydrogenation of CO in HMF (59.7 kJ mol−1). Under optimized condition, DMF with yield of 93.4% from HMF was achieved over 1.5Ni-1.5Fe-1.0Al catalyst. In comparison with Ni–Al, 1.5Ni-1.5Fe-1.0Al also showed much higher resistivity towards sintering of metallic species, rendering the catalyst with superior catalytic stability.