Hydrogenolysis of wheat straw for bio-oil production over a novel Ni-Fe microemulsion catalyst

Developing cost-effective dispersed catalysts is a crucial approach for the hydro-upgrading of biomass to produce high-value biofuels and chemicals. Herein, we designed a novel Ni-Fe microemulsion catalyst, with nickel and iron sources dispersed in polyethylene glycol-thiourea and wax oil respectively, facilitating the convenient formation of ternary sulfide without relying heavily on expensive organic ligands. Among the catalysts tested, the Ni10Fe1 catalyst exhibited the highest performance in the hydrogenolysis of wheat straw and heavy residue, outperforming the Ni catalyst. Incorporating of a slight amount of organic irons successfully enhanced the stability and dispersibility of the microemulsion system, and restructured the in-situ sulfidation of nickel components, producing a high-efficiency nanostructure with (Fe,Ni)9S8 phases surrounding the nickel sulfides, which maximized the synergism between nickel and iron. Analysis of the solid residues further revealed the promoted hydrogenolysis effect and anti-coking role of the Ni10Fe1 catalyst in the hydroconversion process of biomass.