Resource Utilization Of Levulinic Acid And Lignin Based On DES Pretreatment

Lignocellulosic resources are renewable and abundant.Due to its complex structure,it is necessary to separate components through pretreatment,so as to achieve comprehensive utilization of all components.In recent years,the resource utilization of levulinic acid(LA)and lignin,which are important platform compounds derived from biomass,have attracted extensive attention.In this study,the components of lignocellulose were separated by efficient pretreatment method,polyol ester was synthesized by levulinic acid and applied in the field of energy storage,and micro-nano capsule materials were prepared by lignin,so as to realize full resource utilization.The specific research contents and results are as follows:Firstly,lignocellulose was pretreated with deep eutectic solvent(DES)to explore the separation effect of lignocellulose under different pretreatment conditions,and enzymatic hydrolysis of the pretreated solids.At the same time,the molecular weight and chemical structure of lignin obtained were characterized.Under the optimal pretreatment conditions,the cellulose retention rate of the recovered solids was 81.42%,and the sugar conversion rate reached 73.31% after enzymatic hydrolysis.The extraction yield of lignin was 78.02% and the purity was 88.35%.Most of the lignin obtained was GS type lignin with narrow molecular weight distribution(PDI 1.82),low molecular weight(Mw,3453 g/mol)and high phenolic hydroxyl content(3.68mmol/g).Secondly,using lignocellulosic levulinic acid and 1,4-butanediol as raw materials,1,4-butanediol levulinic acid poloy ester(LBE)was prepared by enzyme-catalyzed method,and its thermal properties were characterized.In solvent-free system,LBE was successfully prepared by esterification reaction of LA and 1,4-butanediol catalyzed by Novozym435.After optimized enzymatic reaction conditions,the yield of LBE can reach 91.89%,the melting temperature is 50.51 ℃,the latent heat of melting can reach 156.1 J/g,and the thermal conductivity is better than that of traditional paraffin and the thermal stability is better.As a new phase change energy storage material,LBE has great application potential.Finally,using lignin pretreated by DES and the new phase change energy storage material LBE synthesized by enzymatic method as raw materials,a new type of lignin composite micronano capsule was successfully prepared by self-assembly method,and the particle size,morphology and latent heat performance of the capsule were studied.The results show that the lignin composite microcapsules have good core-shell structure morphology,and the particle size is about 700 nm,the best performance,melting temperature of64.76 ℃,melting latent heat up to 108.65 J/g,excellent thermal stability and storage stability,play a key role in the easy storage of phase change materials,anti-leakage and other aspects.