Utilization of Dealkaline Lignin as a Source of Sodium-Promoted MoS2/Mo2C Hybrid Catalysts for Hydrogen Production from Formic Acid

Dealkaline lignin (DAL) was used as a carbon and sulfur source to prepare MoS2/Mo2C-based catalysts (Mo-DAL) with a facile impregnation-pyrolysis two-step process for the hydrogen production from the formic acid decomposition. Comparison of the catalytic performance of the Mo-DAL catalyst with the carbon black-based one (Mo2C-CB) revealed that the Mo-DAL catalyst exhibited superior activity to the Mo2C-CB catalyst. When 20 wt % of Mo was loaded on DAL, the catalyst produced hydrogen quite selectively (99.2%) with almost complete conversion of formic acid (97.4%) at 220 °C. In addition, the catalyst showed stable activity for at least 50 h in these conditions. This catalytic activity and hydrogen selectivity are superior to the other reported nonprecious metal catalysts. Since DAL contains not only carbon but also sodium and sulfur species, multiple kinds of active sites such as Na-intercalated MoS2, MoS2, and β-Mo2C were formed on the Mo-DAL catalysts. Investigation of additional effects of sulfur and sod...