Metal-Sulfide Catalysts Derived from Lignosulfonate and their Efficient Use in Hydrogenolysis

Catalytic lignosulfonate valorization is hampered by the in situ liberation of sulfur that ultimately poisons the catalyst. To overcome this limitation, metal sulfide catalysts were developed that are able to cleave the C-O bonds of lignosulfonate and are resistant to sulfur poisoning. The catalysts were prepared by using the lignosulfonate substrate as a precursor to form well-dispersed carbon-supported metal (Co, Ni, Mo, CoMo, NiMo) sulfide catalysts. Following optimization of the reaction conditions employing a model substrate, the catalysts were used to generate guaiacyl monomers from lignosulfonate. The Co catalyst was able to produce 23.7 mg of 4-propylguaiacol per gram of lignosulfonate with a selectivity of 84 %. The catalysts operated in water and could be recycled and reused multiple times. Thus, it was demonstrated that an inexpensive, sulfur-tolerant catalyst based on an earth-abundant metal and lignosulfonate efficiently catalyzed the selective hydrogenolysis of lignosulfonate in water in the absence of additives.