Preparation of NiS2//MoS2 catalysts by two-step hydrothermal method and their enhanced activity for hydrodeoxygenation of p-cresol

•Two-step hydrothermal method was developed for the synthesis of NiS2//MoS2 catalysts.•NiS2 and MoS2 existed separately in the resultant catalysts.•NiS2//MoS2 catalyst presented a higher surface area and exposed more active sites.•Both methylcyclohexane selectivity and deoxygenation degree on NiS2//MoS2 catalysts were enhanced.•The hydrodeoxygenation mechanism was well explained by the Remote Control model via spillover hydrogen.

NiS2//MoS2 catalysts with different Ni/Mo molar ratios were prepared by two-step hydrothermal method, i.e., MoS2 was firstly synthesized and then NiS2 was prepared and deposited on the surface of MoS2. The resultant catalysts were characterized by XRD, XPS, TEM, SEM, N2 physisorption and their activities were tested using the hydrodeoxygenation of p-cresol as a probe. The results showed that separated NiS2 and MoS2 phases rather than Ni–Mo–S phase existed in NiS2//MoS2 catalysts. In the HDO of p-cresol, NiS2 acted as a donor phase to provide spillover hydrogen, which migrated to MoS2 for reaction. Because of the particular synthesis procedure, NiS2//MoS2 had higher surface area to expose more active sites. When Ni/Mo molar ratio was adjusted to 0.3, p-cresol conversion and the deoxygenation degree reached to 98.5% and 95.4% at 275 °C for 4 h, respectively. The hydrogenation activity was enhanced in the presence of NiS2, leading to the increases on both methylcyclohexane selectivity and deoxygenation degree. NiS2//MoS2 catalysts prepared by this two-step synthesis method exhibited higher hydrodeoxygenation activity than that by other methods, presenting a good potential of this method for the synthesis of other bi-component sulfides with high catalytic activity.

Graphical abstractNiS2//MoS2 catalysts were prepared by two-step hydrothermal method and separated NiS2 and MoS2 phases were presented in the resultant catalysts. In the HDO of p-cresol, because of the large surface area to expose more active sites, these catalysts exhibited higher activity than that synthesized by other methods. Both methylcyclohexane selectivity and deoxygenation degree were enhanced.Figure optionsDownload full-size imageDownload as PowerPoint slide