Study On Preparation Of Carbon-based Solid Acid From Lignin And Using As A Catalyst On Synthesis Of ?-terpineol From ?-pinene

A carbon-based solid acid was synthesized via carbonization and sulfonation of dry lignin gel derived from lignin and epichlorohydrin by gel method.Synthesis of?-terpineol via hydration of?-pinene by using carbon-based solid acid derived from lignin as a catalyst was studied.The main research contents and results were as follows:1.Lignin-based hydrogel was prepared by cross-linking of lignin with epoxychloropropane.Carbon-based solid acid derived from lignin was obtained from lignin-based hydrogel which was dried by vacuum,then followed by carbonization at 400?and sulfonation using concentrated sulfuric acid as sulfonating agent.The carbon-based solid acids were used as catalyst to synthesize?-terpineol through the hydration of?-pinene.The conditions of synthesis of lignin-based hydrogel,preparation of carbon-based solid acid derived from lignin and catalytic reaction were studied,and the optimum synthesis of conditions of lignin-based hydrogel were obtained as follows:the dosage of lignin was 5.00 g,the dosage of NaOH was 1.20 g,the dosage of water was 4.00 g,the dosage of epoxychloropropane was 2.50 g,gelation temperature was 60?,and gelation time was 6h.The appropriate conditions of preparation of carbon-based solid acid from dry lignin-based gel were as follows:the carbonization temperature was 400?,carbonization time was 3h,the sulfonated temperature was 180?,sulfonated time was 3h.The synthesis conditions of?-terpineol via hydration of?-pinene by using carbon-based solid acid as a catalyst were as follows:the dosage of?-pinene was4.00 g,the dosage of water was 4.00 g,the dosage of catalyst was 0.40 g,the volume of isopropyl alcohol was 20.00 mL,and the reaction temperature was 80?.Under optimum conditions,the conversion of?-pinene was 93.07%,the yield of?-terpineol was 40.36%,and the selectivity of?-terpineol was 43.37%.The catalyst had a good reusability.After five reuses,the conversion of?-pinene decreased from 93.07% to 86.67%,the yield of?-terpinol decreased from 40.36% to 32.56%,and the selectivity of?-terpinol decreased from 43.37% to 37.57%.2.Lignin-based aerogel was prepared by supercritical CO₂ drying.The effects of drying temperature,drying stress and aging time on the microstructure of lignin aerogel and the catalytic properties of carbon-based solid acids derived from lignin were studied,and the appropriate of drying conditions were acquired:aging temperature was 40?,aging time was 3 days,the drying temperature was 40?,drying stress was 10 MPa.Carbon-based solid acids were synthesized from lignin-based aerogels carbonizated and sulfonated,and be used to catalyze the hydration of?-pinene to synthesize?-terpineol.Under the optimum conditions,the conversion of?-pinene was 98.27%,the yield of?-terpineol was 48.71%,and the selectivity of?-terpineol was 49.57%.After five reuses of the carbon-based solid acid,the conversion of?-pinene decreased from 98.27%to 89.91%,the yield of?-terpinol decreased from 48.71% to 39.67%,and the selectivity of?-terpinol decreased from 49.57% to 44.12%.3.The carbon-based solid acid was characterized by FT-IR,XRD,N₂ adsorption-desorption experiment,adsorption capacity of?-pinene,adsorption of methylene blue,and contact angle test.The results showed that sulfonic acid groups were successfully introduced onto carbon-based solid acid with oxygen-containing groups such as carboxyl and hydroxyl.Carbon-based solid acids were mainly composed of amorphous carbon.The specific surface area of the carbon-based solid acid prepared by vacuum drying was 281.3 m²/g,and the average pore diameter was 4.87nm.The adsorption capacity of?-pinene and methylene blue on carbon-based solid acid prepared by supercritical drying were 425.16 mg/g and 97.97 mg/g,respectively.Carbon-based solid acid had good hydrophilic properties and the water contact angle was 38.36°.4.Kinetic experiments were carried out on the hydration reaction of pinene using carbon-based solid acid as a catalyst at different temperatures,and it conforms to the first-order dynamics model.The rate constant of the reaction was determined to be 0.2020 h^-1,and the activation energy was 67.501 KJ/mol.