Hydrothermal Synthesis of Carbon-Coated CoS2-MoS2 Catalysts with Enhanced Hydrophobicity and Hydrodeoxygenation Activity

Carbon-coated CoS2-MoS2 catalysts were prepared by a hydrothermal method via the addition of polyvinylpyrrolidone (PVP). The effects of PVP amount on their structure properties and hydrodeoxygenation (HDO) activity were studied. The characterization results showed that carbon coated on the surface of CoS2-MoS2 and that its hydrophobicity was enhanced. During the HDO of 4-ethylphenol, these catalysts presented high direct deoxygenation activity, even at high hydrogen pressure. High reaction temperature and hydrogen pressure were beneficial to increase the conversion, but had little effect on the product distribution. After reaction at 250 degrees C and 4.0 MPa hydrogen pressure for 5 h, the deoxygenation degree reached 96.1% with a selectivity of 99.3% ethylbenzene. The high HDO activity of carbon -coated CoS2-MoS2 catalysts mainly resulted from its enhanced hydrophobicity. Moreover, the reusability tests also showed that these catalysts had a good stability during the HDO reaction because of the inhibition of hydrophobic coated carbon to sulfur loss. Therefore, improving the hydrophobicity of the sulfide catalyst was favored for increasing its HDO activity and inhibiting the deactivation.