Catalytic hydrodeoxygenation of lignite-derived model compounds to monomeric hydrocarbons over Co/Al₂O₃

A Co/Al₂O₃ catalyst was synthesized by facile calcination and hydrogen reduction of a cobalt-aluminum hydrotalcite CoAl-LDH, and the X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photon spectroscopy (XPS) were used to characterize the physical and chemical properties of the precursor and catalysts. Using 2-naphthyl ether as the lignite derived model compound, the catalytic performance of Co/Al₂O₃ on the hydrodeoxygenation of 2-naphthyl ether to monomeric hydrocarbons was investigated. The results show that Co/Al₂O₃-700 has the highest hydrodeoxygenation activity. Under the conditions of 250 ℃, 2 MPa of initial H₂ pressure and 90 min of holding time, the 2-naphthyl ether is completely converted to monomeric hydrocarbons (decalin and tetralin), in which the 2-naphthyl ether is first converted to 6,6'-oxybis (1,2,3,4-tetrahydronaphthalene) by hydrogenation and then the tetralin and 5,6,7,8-tetrahydronaphthalene-2-naphthol are formed by the cleavage of C−O bond. In addition, Co/Al₂O₃-700 also shows high activity for the hydrodeoxygenation of lignite-derived benzyl ether and phenyl ether model compounds.