Low temperature hydrodeoxygenation of guaiacol into cyclohexane over Ni/SiO2 catalyst combined with Hβ zeolite

Hydrodeoxygenation (HDO) of guaiacol to cyclohexane, important for bio-oil upgrading, is usually performed at high reaction temperature (>= 200 degrees C). In this work, low temperature transformation of guaiacol to cyclohexane was achieved at 140 degrees C over non-noble metal Ni/SiO2 and various zeolites. Among zeolites tested (HUSY, HMOR, H beta, HZSM-5, SAPO-34), H beta zeolite exhibited superior catalytic activity due to its appropriate pore structure and acid strength. The open pore with three-dimensional structure of Hb facilitates the diffusion of guaiacol and intermediates. Meanwhile, weak acid strength of Hb efficiently reduces the competitive adsorption of guaiacol, and then promotes the dehydration of intermediate 2-methoxycyclohexanol. Moreover, the catalytic performance in guaiacol HDO to cyclohexane is also closely related to Si/Al ratio of Hb. Owing to its moderate acid density, the maximum yield of cyclohexane reaches 91.7% on Hb(Si/Al = 50) combined with Ni/SiO2 at 140 degrees C, which is the lowest temperature ever reported over non-noble metal catalysts.