Preparation Of Ethyl Levulinate From Biomass Sugar Catalyzed By Solid Acid

With the development of economy,the use of fossil fuels is gradually increasing,resulting in a series of problems such as resource depletion and environmental pollution.It is urgent to develop biomass energy to replace fossil fuels.Ethyl levulinate prepared by alcoholysis of biomass cellulose as acid catalyst has been widely used in fuels and fuel additives.In this paper,a series of solid acid catalysts are prepared to efficiently catalyze the alcoholysis of cellulose to prepare ethyl levulinate.Specific studies are as follows:1.Zr-Al/H-Beta-SO₃H solid acid catalyst with Lewis acid(Al³⁺,Zr⁴⁺)and Br（?）nsted acid（-SO₃H）sites was synthesized by HNO₃pretreatment,introduction of metal Zr,and grafting of sulfonic acid group using zeolite Beta as carrier.The structure and surface properties of Zr-Al/H-Beta-SO₃H were characterized by XRD,N₂-BET,XPS,NH₃-TPD and Py-IR.The results showed that Zr-Al/H-Beta-SO₃H still had BEA zeolite structure after modification,and the Lewis acid and Br（?）nsted acid sites increased and the total acid content reached 3.86 mmol/g.In the study of the synthesis of ethyl levulinic acid from cellulose,the yield of ethyl levulinic acid reached 37.3 mol%under the optimum reaction condition（180℃,6 h）.The yield of ethyl levulinate under the optimal reaction conditions obtained by the response surface method model optimization is predicted to reach 36.3mol%,and the actual average yield under the optimal conditions is 36.9 mol%.2.A novel solid catalyst Al-OCS-0.1 with ordered mesoporous structure was synthesized by grafting sulfonic acid groups onto the oxidized ordered mesoporous carbon（OOMC）carrier supported by 10%Al₂（SO₄）₃.Al-OCS-0.1 was characterized by SEM,TEM,XRD,N₂-BET,XPS,NH₃-TPD and Py-IR.The results show that Al-OCS-0.1 has ordered mesoporous structure,and the surface of Al-OCS-0.1 has Lewis acid and Br（?）nsted acid double acid sites,with S content up to 3.8%.In the study of the synthesis of ethyl levulinic acid from cellulose,the yield of ethyl levulinic acid reached 50.8 mol%under the optimum single factor reaction condition（200℃,5 h）.The yield of ethyl levulinate under the optimal reaction conditions obtained by the response surface method model optimization is predicted to reach 51.9 mol%,and the actual average yield under the optimal conditions is 53.1 mol%.