| Levulinic acid is an important platform compound and has a wide range of applications in the chemical,energy,and pharmaceutical fields.Levulinic acid can be obtained by biomass hydrolysis,but there are still problems such as low production efficiency and poor economic benefits.Therefore,the development of levulinic acid production process to improve the yield of levulinic acid is of great significance.In this paper,one-step and two-step method were used to study the process of biomass hydrolysis to produce levulinic acid and the factors affecting the decomposition of levulinic acid,so as to improve the yield of levulinic acid and process economics.Cellulose hydrolysis can produce levulinic acid.In this paper,furfural residual was used as the raw material to investigate the effect of temperature,acid concentration and liquid-solid ratio on the yield of levulinic acid,and Lewis acid was introduced to cocatalyze the production of levulinic acid with sulfuric acid.The results show that Bronsted acid and Lewis acid can synergistically promote the formation of levulinic acid,and FeCl3·6H2O had the best effect.The maximum levulinic acid yield of 56.16%was obtained at a temperature of 200℃,a sulfuric acid concentration of 0.3mol/L,a FeCl3·6H2O concentration of 0.1mol/L,and a liquid-solid ratio of 6:1.The decomposition of levulinic acid is an important factor affecting the yield of levulinic acid produced by the hydrolysis of biomass.In this paper,the decomposition rate of levulinic acid at different temperatures,acid concentrations and furfural concentrations were studied.It was found that the hydrolysis product of hemicellulose,furfural,can cooperate with sulfuric acid to promote the decomposition of levulinic acid.When furfural or sulfuric acid is catalyzed alone,the total decomposition rate of levulinic acid was 15.44%,while when furfural and sulfuric acid were simultaneously catalyzed,the decomposition rate of levulinic acid was 25.3%.Using four different hemicellulose biomass as raw materials,levulinic acid is prepared by acid hydrolysis.The results show that the higher the hemicellulose content,the lower the levulinic acid production.Considering the influence of sulfuric acid and furfural concentration on the decomposition of levulinic acid,the reaction kinetics of levulinic acid decomposition was established and its parameters were fitted.The activation energy of decomposition of levulinic acid was 34.46kJ/mol.The reaction order of sulfuric acid and furfural concentration were 1.58 and 0.0777,respectively.In order to increase the yield of levulinic acid produced by biomass and increase the economics of the process,hemicellulose and cellulose were hydrolyzed and converted to furfural and levulinic acid,respectively,in order to avoid the influence of furfural on the decomposition of levulinic acid.When the initial concentration of FeCl3·6H2O was 0.25mol/L,the temperature of low temperature reaction was 170℃ and the sulfuric acid concentration of 0.6mol/L,furfural had the maximum yield of 42.39%;In high temperature reaction,under the condition of 200℃,0.3mol/L sulfuric acid,the maximum yield of levulinic acid was 59.88%. |
