Preparation of hydrophobic MoS2, NiS2-MoS2 and CoS2-MoS2 for catalytic hydrodeoxygenation of lignin-derived phenols

The water produced during the hydrodeoxygenation (HDO) processes has a negative effect on sulfide catalysts, which lowers the activity and stability. To solve this problem, hydrophobic MoS2, NiS2-MoS2 and CoS2-MoS2 catalysts are prepared and then applied into the HDO of 4-ethylphenol and 4-propylguaiacol. The obtained MoS2 had strong hydrophobicity and its air-water contact angle reached up to 147.5°, which might be attributed to that modification of the surface morphology due to the addition of silicomolybdic acid. During the HDO reaction on MoS2, the specific surface area played an important effect on the HDO activity. After the deposition of NiS2 or CoS2, the hydrophobicity of NiS2-MoS2 and CoS2-MoS2 reduced slightly, but the HDO activities of these two catalysts were enhanced, especially for CoS2. 99.9% Conversion was achieved with a selectivity of 99.6% ethylbenzene after the HDO of 4-ethylphenol at 225 °C for 3 h. These hydrophobic catalysts also had good activity for the HDO of 4-propylguaiacol. Moreover, because the hydrophobicity could prevent water from contacting with active sites and then protect the sulphide structure, hydrophobic sulphide catalysts exhibited high stability.