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In situ synthesis of molybdenum oxide@N-doped carbon from biomass for selective vapor phase hydrodeoxygenation of lignin-derived phenols under H₂ atmosphere

Xu, Lujiang, Han, Zheng, Zhang, Ying, Fu, Yao
RSC advances 2016 v.6 no.110 pp. 108217-108228
X-ray diffraction, X-ray photoelectron spectroscopy, benzene, biomass, carbon, catalysts, catalytic activity, cellulose, energy-dispersive X-ray analysis, fuels, guaiacol, hydrogen, molybdenum, pyrolysis, synergism, temperature, toluene, transmission electron microscopy, vapors
The vapor phase hydrodeoxygenation (HDO) of lignin-derived phenols under H₂ atmosphere has great significance for producing high-quality fuels and commodity chemicals. Herein, we reported a simple, green method to prepare molybdenum oxide@N-doped carbon (MoOₓ@NC) via in situ pyrolysis of molybdenum precursor preloaded cellulose and demonstrated its catalytic performance for vapor phase HDO of lignin-derived phenols. When the pyrolysis temperature was at 600 °C, the catalyst (MoOₓ@NC-600) exhibited the best catalytic performance in vapor phase HDO of guaiacol. Through systematically investigating the parameters, such as: reaction temperature, WHSV, residence time, and concentration, the optimal reaction conditions for vapor phase HDO of guaiacol were 450 °C and 1 h⁻¹ with atmospheric H₂. The concentration of the feed was 20% in mesitylene, and the residence time was about 3.3 s. The carbon yield of aromatic hydrocarbons was 83.3%, with 65.7% benzene, 15.5% toluene and 2.1% alkylbenzenes. In addition, other lignin-derived phenols were also investigated and desired results were achieved with the MoOₓ@NC-600 catalyst. Furthermore, MoOₓ@NC-600 showed good stability due to the N-doped carbon formed on the surface of the MoOₓ particles. The catalysts were characterized using elemental analysis, AAS, BET, XRD, XPS, TEM, and EDS mapping. The high catalytic performance of MoOₓ@NC-600 toward lignin-derived phenols HDO can be attributed to the synergistic effect of the carbon supports and Mo⁵⁺ (molybdenum oxynitrides), Moᵟ⁺ (Mo₂N) and Mo⁴⁺ on the surface of the MoOₓ particles.