Highly efficient unsupported Co-doped nano-MoS2 catalysts for p-cresol hydrodeoxygenation

Unsupported MoS2-Based Catalysts for Bio-Oil Hydrodeoxygenation: Recent Advances and Future Perspectives

In recent years, unsupported MoS₂-based catalysts have been reported as promising candidates in the hydrodeoxygenation (HDO) of bio-oil. However, preparing MoS₂-based catalysts with both high activity and good stability for HDO reaction is still challenging and of great importance. Hence, this mini-review is focused on the recent development of unsupported MoS₂-based HDO catalysts from the understanding of catalyst design. The three aspects including morphology and defect engineering, metal doping, and deactivation mechanism are highlighted in adjusting the HDO performance of MoS₂-based catalysts. Finally, the key challenges and future perspectives about how to design efficient catalysts are also summarized in the conclusions.

Tailoring of Surface Acidic Sites in Co-MoS2 Catalysts for Hydrodeoxygenation Reaction

CoMo sulfides are typical catalysts for selective hydrodeoxygenation (HDO) of phenolics to aromatics which is important in bio-oil upgrading. However, it is still a challenge to promote the intrinsic activity of Co-MoS₂ catalysts. Defect chemistry provides a good option to improve surface reactivity in catalysis. In this work, we report a facile H₂O₂ etching method to tailor the concentration of surface acidic sites. The molar ratio of H₂O₂/MoS₂ can be altered to tune sulfur defects on the MoS₂ surface for stabilizing Co species to form CoMoS active sites. The optimized Co-MoS₂-2 catalyst, with the highest concentration of acidic sites, exhibits 3.4 times higher activity than the Co-MoS₂-0 sample in the HDO of p-cresol to toluene. It is also found the HDO activity shows a linear relationship with the amount of surface acid (both Lewis and Brønsted acid) over the Co-MoS₂-x catalysts. We believe that the understanding of the role of surface acidity would provide new opportunities for the rational design of efficient Co-MoS₂ catalysts.