Pyrolysis of nickel salt@cellulose to prepare Ni/C catalyst with tunable hydrogenation and acid site for the selective hydrogenation of furfuryl alcohol

Ni/C catalysts could be prepared via pyrolysis of biomass impregnated with nickel salts, while varied anions of nickel salt impact not only catalytic behaviors of Ni/C catalyst, but also property/composition of resulting biochar/bio-oil. In this work, pyrolysis of the cellulose with Ni(NO3)2 or NiCl2 was investigated, and the resulting pyrolysis products were analyzed while the Ni/C catalysts were evaluated in hydrogenation of furfuryl alcohol (FA) in water. The results indicated that the nitrate in Ni(NO3)2 catalyzed cracking reactions to form less biochar, less heavy organics with π-conjugated structures but more light ones. It also resulted in the Ni/C with high nickel dispersion and hence superior activity for hydrogenation of FA, producing dominantly tetrahydrofurfuryl alcohol (THFA). In comparison, the chloride in NiCl2 enhanced dehydration of sugars to furans and condensation of heavy organics in the pyrolysis, which also created abundant Brønsted and Lewis acid sites, developed pore structures, but resulted in aggregation of metallic nickel. This decreased its capability for full hydrogenation of FA, but rendered the selective conversion of FA to cyclopentanone (CPO) and cyclopentanol (CPL) (sum yield: 91.0 %) with the aid of the acidic sites.