Efficient depolymerization of sodium lignosulfonate assisted by sulfur migration

Lignosulfonate (LS), as the most abundant technical lignin, is hard to depolymerize due to highly condensed structure. To overcome the limitation, in this work, NiMoO4/Al2O3 catalyst with regulated acidity/hydrogenation activity was developed for highly efficient LS depolymerization. Results show that the performance of NiMoO4/Al2O3 was improved by sulfur migration. Meanwhile NiMo alloy contributed to the good stability during LS depolymerization. The NiMoO4/Al2O3 was favor for the intermediate compounds production by the cleavage of CO and CC bonds, which intermediate compounds were eventually hydrogenated to monomers by highly active MoS2. Also, NiMoO4/Al2O3 and sulfonic groups play a synergistic role in the sulfur migration (only 39.1% bio-oil yield obtained by MoS2/Al2O3). After reacting at 300 °C for 4 h, 81.7% of bio-oil yield with 95% desulfurization rate were obtained. Thus, it was demonstrated that an inexpensive catalyst was developed which can efficiently catalyze the depolymerization of lignosulfonate. [Display omitted] •Strong acidic NiMoO4 and highly active MoS2 shows high performance of LS conversion.•Formation of NiMo alloy enhanced stability of catalysts during LS depolymerization.•The performance of catalysts was greatly improved by sulfur migration.•81.7% of bio-oil and 95% desulfurization from LS depolymerization were obtained.