Hydrodeoxygenation of guaiacol via in situ H2 generated through a water gas shift reaction over dispersed NiMoS catalysts from oil-soluble precursors: Tuning the selectivity towards cyclohexene

Abstract

We report efficient hydrodeoxygenation of guaiacol via in situ hydrogen generated through Water Gas Shift (WGS) reaction over nanosized unsupported NiMoS catalysts with tunable selectivity toward cyclohexene. This strategy possesses a direct reaction route of oxygen-containing compounds from bio-oils depending on catalysts precursors and reaction conditions. The active catalytic species were formed in situ through the high-temperature decomposition of oil-soluble metal precursors followed by sulfidation in water-in-oil sulfur-containing emulsions. Unsupported NiMoS catalysts were found to provide 100% guaiacol conversion at 320–380 ℃ and 5 MPa CO pressure. Reaction routes and mechanisms for hydrodeoxygenation of guaiacol were proposed. Ni:Mo= 1:3 and sulfur content of 1.2–1.5 wt% favor higher cyclohexene selectivity decreases at low temperature and short reaction time (30–40 wt% water content, CO pressure of 5 MPa). The catalysts were found to be reusable at least 6 cycles in the sulfur-assisted hydrodeoxygenation of guaiacol with maintaining conversion, and active component evolution was studied.