Abstract: Magnetic solid acid catalyst S₂O₈^2-/ZrO₂-Al₂O₃-Fe₃O₄ was prepared by coprecipitation and impregnation methods and used to catalyze the liquefaction of Panicum virgatum L.(switchgrass)in ethanol. The physicochemical properties and structure of the catalyst were characterized by X-ray diffraction (XRD), Brunauer-Emmet-Teller method (BET), temperature programmed desorption of NH₃ (NH₃-TPD), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). The influences of Al/Zr molar ratio and calcination temperature on the catalytic performance were investigated. Moreover, the effects of reaction conditions such as reaction temperature, reaction time, as well as mass of catalyst on liquefaction of switchgrass were studied. The experimental results indicated that the catalyst with a Al/Zr molar ratio of 1/1 calcined at 650℃ showed the best activity. An optimum bio-fuel yield of 56% was obtained under the reaction temperature of 260℃, catalyst amount of 4% and 2.5 h of reaction time. The chemical composition of the liquefaction production was identified by GC-MS, in which esters, alcohols and hydrocarbons were the dominate. After 3 times of reuse, the recovery rate of the catalyst still reached 87.5%, and the bio-fuel yield decreased by 12%.

Key words: magnetic solid acid, catalytic liquefaction, acidity, switchgrass