Experimental Study On Preparation Of Methyl Levulinate By Alcoholysis Of Biomass

Agricultural waste is a prolific biomass resource.Its main components are cellulose,hemicellulose and lignin.Through catalytic conversion of these biomass resources,high value-added chemicals such as methyl levulinate can be obtained.Methyl levulinate is an important platform compound and has important applications in the fields of energy,fragrance and medicine.At present,there are some related studies on the preparation of methyl levulinate from biomass,but they all have certain shortcomings.Therefore,further research can be carried out in terms of the diversity of raw materials,improvement of the catalytic system,and optimization of process conditions.Peanut shells and wheat straw are common agricultural wastes,and the annual output is very large,but they are not fully utilized.With the advancement and development of science and technology,people increasingly pay attention to environmental protection and economic benefits.Agricultural wastes such as peanut shells and wheat straws can be used in more abundant ways.In this paper,peanut shells and wheat straws were used as raw materials,and sulfuric acid and aluminum sulfate were used as catalysts to prepare methyl levulinate.First,the transformation of peanut shells was studied in methanol system,its catalytic system,process conditions and catalyst recovery were studied,and its kinetic analysis was performed.Then the conversion of wheat straw was studied in the alcohol-water mixed system,the catalyst system,process conditions and solvent system were studied,and the kinetic analysis was performed.Finally,a comparative analysis and economic evaluation of the two conversion methods are conducted.The main conclusions are as follows:1.The catalytic system for the alcoholysis of peanut shells to prepare methyl levulinate was studied.In the screening of the catalyst,a mixed acid catalyst with a combination of ultra-low acid sulfuric acid and metal salt aluminum sulfate had better catalytic activity.The response surface optimization method was used to optimize the process conditions.When the reaction temperature was 169 °C,the aluminum sulfate loading was 0.09 M,the peanut shells to methanol S / L ratio was 0.06 g/m L,and the reaction time was 2.7 h.The maximum yield of methyl levulinate was 16.49%.The peanut shells before and after the reaction and the reaction solution with different reaction times were characterized and analyzed.The kinetics of the reaction process was studied.The transformation process of peanut shells was mainly the alcoholysis reaction path.The reaction catalyst was recovered,and it was found that the aluminum sulfate catalyst could be recovered and recycled.When it was used 5 times,it still had high catalytic activity.2.The further optimization of the process parameters for the alcoholysis of peanut shell to methyl levulinate was studied.The neural network genetic algorithm was used to optimize the four variables: reaction temperature,reaction time,solid-liquid ratio of peanut shell to methanol,and metal sulfate loading during the alcoholysis of peanut shell.The optimal process conditions were reaction temperature 160 ?,reaction time 3.6 h,solid-liquid ratio of peanut shell and methanol 0.06 g/m L,and metal sulfate loading 0.09 M.The optimization results of the neural network genetic algorithm were experimentally verified.Under the optimized process conditions,a yield of 17.61% of methyl levulinate could be obtained.Comparing the neural network model with the response surface method model,it is found that the neural network model predicts more accurately,the neural network genetic algorithm has better optimization ability,and can obtain a higher yield of methyl levulinate.3.The preparation of levulinic acid and methyl levulinate from wheat straw in an alcohol-water mixed system was studied.Comparing the catalytic effect of a single sulfuric acid catalyst and a mixed acid catalyst of sulfuric acid and aluminum sulfate,the mixed acid catalyst has a better catalytic effect.Investigate the amount of sulfuric acid and aluminum sulfate catalyst,using 1% sulfuric acid and 0.015 M aluminum sulfate can obtain a higher yield of methyl levulinate.Optimizing the process condition of solid-liquid ratio,0.1 g/m L is a suitable solid-liquid ratio while maintaining high yield and large yield.The effects of different ratios of alcohol-water mixed systems on the yield of levulinic acid and methyl levulinate were studied,and the appropriate alcohol-water ratio was 3: 1.The effect of adding water on the reaction system was studied.Compared with the single alcoholysis process,the reaction process obtained a greater yield.The total yield of levulinic acid and methyl levulinate was 23.01%,and the reaction pressure Reduced,the reaction by-products decreased.The kinetic study in the alcohol-water system was carried out at a constant temperature,and it was concluded that in this reaction system,alcoholysis and hydrolysis reaction paths coexisted,and the addition of water changed the reaction path.4.The two reaction processes of the direct hydrolysis of peanut shells to produce methyl levulinate and wheat straw in alcohol-water system to produce levulinic acid and methyl levulinate were compared with the related research results of biomass to methyl ester.Material conversion and economic evaluation of the conversion process of the two biomass raw materials.The conversion process of peanut shells and wheat straw is a utilization method with greater economic benefits and has broad application prospects.