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Selective Hydrodeoxygenation of Lignin-Derived Phenols to Cyclohexanols over Co-Based Catalysts
- Liu, Xiaohao, Jia, Wenda, Xu, Guangyue, Zhang, Ying, Fu, Yao
- ACS sustainable chemistry 2017 v.5 no.10 pp. 8594-8601
- X-ray diffraction, X-ray photoelectron spectroscopy, catalysts, catalytic activity, cobalt, desorption, eugenol, feedstocks, hydrogen, hydrogenation, industry, particle size, phenols, polymers, spices, surface area, temperature, transmission electron microscopy
- Cyclohexanols are important feedstock for polymers, spices, and medicines production in industry. In this work, a series of cobalt-based catalysts with different supports were prepared and used to catalyze lignin-derived phenols to cyclohexanols. Among the catalysts, Co/TiO₂ showed the best hydrodeoxygenation (HDO) activity. An equivalent of propylcyclohexanol (>99.9%) was achieved under 1 MPa H₂, 200 °C for 2 h. According to the characterization results of transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area analysis, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H₂-TPR), hydrogen temperature-programmed desorption (H₂-TPD) and NH₃-TPD, the particle size and dispersion of Co could have important influence on catalytic activity. For Co/TiO₂, the SMSI effect may significantly affect the catalytic activity. The influences of different temperature, H₂ pressure and reaction time on the eugenol conversion by Co/TiO₂ were explored. 99% yield of propylcyclohexanol could even be obtained under 0.4 MPa H₂, 180 °C for 8 h. This should be the mildest condition that has been reported for HDO of eugenol to propylcyclohexanol catalyzed by non-noble metal catalyst. On the basis the mechanism and substrates extension studies, all the Co-based catalysts selected in this study showed high activity to cleave the Cₐᵣyₗ–OCH₃ bond before the hydrogenation of the aromatic ring when the −OCH₃ group substituted at ortho-position.