Facile synthesis of hydrophobic MoS2 and its activity and stability in the hydrodeoxygenation reaction

In this study, MoS2 with different hydrophobicity was prepared by adding silicomolybdic acid and their catalytic activity and stability were tested by using the HDO of p-cresol as a probe. The addition of silicomolybdic acid enhanced the hydrophobicity and surface area, and changed the morphology and S/Mo atomic ratio. The air-water contact angle reached up to 132.3 degrees, suggesting a high hydrophobicity. During the HDO reaction, with increasing hydrophobicity of MoS2, p-cresol conversion was slightly decreased but the product distribution was almost unchanged, which was attributed to the fact that the hydrophobicity weakened the adsorption of reactant molecules due to the hydrophilic phenolic hydroxyl group. Most importantly, the hydrophobicity prevented water from contacting the MoS2 surface and then protected its structure from sulfur loss, leading to a low decrement of conversion (0.4%) and low increment of toluene selectivity (5.3%) after three cycles of reactions at 300 degrees C. Hence, enhancing the hydrophobicity was a good strategy to improve the stability of sulphide catalysts for HDO reactions.