Preparation of Bifunctional Carbon-based Solid Acid and Its Catalytic Alcoholysis of Cellobiose
Chitosan was used as a carbon source to prepare iron-loaded nitrogen-containing activated carbon(ACN-Fe)through metal impregnation and high-temperature carbonization.A series of metal-loaded dual-functional carbon-based solid acid(ACN-Fe-SO3H)catalysts were further prepared by hydrothermal sulfonation.The catalysts were applied to catalyze the alcoholysis of cellobiose.The catalysts were characterized in detail using X-ray diffraction(XRD),Raman spectroscopy,Fourier-transform infrared spectroscopy(FT-IR),N2 adsorption/desorption,X-ray photoelectron spectroscopy(XPS),inductively coupled plasma optical emission spectrometry(ICP-OES),and acid-base titration.The results showed that the unsaturated trivalent iron ions in the catalyst had Lewis acidity,while the sulfonic acid groups exhibited Brønsted acidity.The catalyst prepared at a carbonization temperatureof800℃(800-ACN-Fe-SO3H)possessed the strongest acidity(acidity of 0.81 mmol/g)and the best structural characteristics(specific surface area of 85.7 m2/g),showing the best catalytic performance.With a catalyst dosage of 0.20 g,a reaction temperature of 200℃,and a reaction time of 5 h,the cellobiose conversion rate reached99.6%,with yields of levulinic acid(LA)and methyl levulinate(ML)of 15.6%and 62.1%,respectively.After 5 cycles,the cellobiose conversion rate remained 93.1%,with a product yield of 51.1%,indicating good catalyst reusability.Additionally,a preliminary exploration of the reaction mechanism of cellobiose alcoholysis was conducted.
catalytic conversion of biomasscarbon-based solid acidcellobioselevulinic acidmethyl levulinate
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