Highly Efficient Selective Hydrodeoxygenation of Guaiacol to Cyclohexanol over Co/ZrSi-<i>x</i> Catalysts

Hydrodeoxygenation of guaiacol (GUA) to cyclohexanol (CHL) using nonnoble-metal catalysts is a valuable area of research. This work involved the preparation and application of a series of 20Co/ZrSi-x (x = 0.1, 0.2, 1) with various Zr/Si molar ratios for the selective hydrodeoxygenation of GUA to CHL. It was discovered that adding Zr species promotes the dispersion of Co and facilitates the reduction of Co species, thereby improving the hydrogenation activity of the catalyst. Furthermore, the high electron transfer between Zr and Co increases the content of Co–O–Zr3+–Vo sites, which enhances the ability to remove methoxyl selectively. More importantly, kinetic studies and in situ diffused reflectance infrared fourier transform spectroscopy (DRIFTS) results show that 20Co/ZrSi-0.2 preferentially adsorbs and activates methyl groups and the reaction is more favorable to the intermediate phenol pathway. Under optimized conditions, 20Co/ZrSi-0.2 gives >97.3% yield of CHL and exhibits excellent cycling stability.