TiO2 supported non-noble Ni-Fe catalysts for the high yield production of 2,5-dimethylfuran biofuel

Abstract

The establishment of the future biorefinery schemes requires the sustainable conversion and valorisation of renewable bioresources into eco-friendly fuels and chemicals. To this end, 2,5-dimethylfuran (DMF) is a promising biofuel competitive to benchmarks like ethanol due to high-value intrinsic properties. It can be produced by the catalytic hydrogenation of the 5-hydroxymethylfurfural (HMF) platform molecule, one of the biobased intermediate chemicals derived from the abundant lignocellulosic biomass. We evidenced that bimetallic NiFe alloys supported on TiO2 are earth-abundant non-noble metal-based catalysts allowing the high yield production of DMF to be achieved. We showed that the preparation method and the reduction temperature of the catalyst are of prime importance, and are directly influencing the structure of the supported NiFe bimetallic particles and in consequence the catalyst behaviour. The highest yield to DMF is obtained on a catalyst prepared by co-impregnation and reduced at 500 °C, that features an unperfect core/shell structure of the NiFe alloy, with a partial Fe shell surrounding an Fe-enriched Ni core. The key-feature necessary for achieving high performance lies on the surface structure of the NiFe alloy that allows for an optimum availability of highly active Ni domains. The Ni atoms were maintained highly dispersed by the presence of Fe-containing surface phases. The specific surface structure is proposed to promote the HMF adsorption through the carbonyl group, while preventing from the hydrogenation of the aromatic furan ring to maintain high selectivity.