Pretreatment Of Biomass In Proton-type Ionic Liquid And Its Enzymatic Hydrolysis And Saccharification

As a natural organic material,biomass can be transformed into different forms of fuel and different kinds of chemicals through modern multiple production technologies.Sugars such as glucose are important platform compounds that connect biomass and bioenergy,chemicals,and polymer materials.However,due to the characteristics of biomass,the efficiency of direct enzymatic hydrolysis of biomass is low.Therefore,to improve the efficiency of enzymatic hydrolysis of biomass,biomass must be pretreated.As a green solvent,the protic ionic liquid is widely used in biomass pretreatment due to its low synthesis energy and economic cost.In this paper,organic bases and bio-based acids form a proton-type ionic liquid dissolution system and a CO₂ reversible protic ionic liquid electrolyte dissolution system to pretreat biomass,and then enzymatically saccharify the regenerated biomass to achieve high yields of sugars.?1?Bio-based acids and organic bases form protic ionic liquids to dissolve pretreated cellulose and enzymatic saccharification.This subject uses bio-based acids such as levulinic acid and organic bases such as DBN to form protic ionic liquids with different structures.The cellulose is dissolved and regenerated under different pretreatment conditions to obtain regenerated cellulose.Through the characterization of the surface morphology and crystallization index of the regenerated cellulose,the influence of different pretreatment conditions on the structure of regenerated cellulose and the change law between these pretreatment conditions and the enzymatic saccharification yield were explored.The study found that the protic ionic liquid formed by levulinic acid and DBN pretreated cellulose at 100oC for 1 h,which can realize the complete conversion of cellulose I to cellulose II.Enzymatic hydrolysis of 48 h can obtain a glucose yield of 94%.Besides,researches on the recycling of ionic liquids have been carried out,and the research shows that the ionic liquid pretreatment solvent system has good reusability.?2?CO₂-based reversible protic ionic liquid electrolyte pretreatment of corn stover and its enzymatic saccharification.This topic uses the greenhouse gas CO₂ and cheap DMSO,ethylene glycol,and DBU to form a reversible protic ionic liquid electrolyte.Under this solvent system,corn stover is subjected to different pretreatment conditions to obtain regenerated corn stover.Enzymatic saccharification of regenerated corn stover was carried out to explore the effects of different pretreatment conditions on the structure of regenerated corn stalks and the effect on the yield of enzymatically hydrolyzed sugars of regenerated corn stalks.The pretreatment is divided into two stages,the first stage is to pretreat corn stover at 140oC with DBU,ethylene glycol and DMSO,and the second stage is to continue pretreatment of corn stover at 50oC with CO₂.Using FTIR,SEM,AFM,XRD to characterize the crystallization index and surface morphology of the regenerated corn stalks,the study found that the two pretreatment stages are the first stage of lignin removal and the second stage of crystal transformation;after corn stalks were pretreated in these two stages,the yield of glucose and total reducing sugar was 0.85 g/g after 48 h enzymatic hydrolysis.By using GPC,HSQC,³¹P,and FTIR to test the lignin separated from the system,it was found that the lignin separated belonged to GSH type lignin,and it was also found that the lignin was pretreated in the solvent system in the first stage for a large amount of depolymerization,and in the second stage for partial condensation.Besides,the pretreatment solvent system can not only effectively capture CO₂ and alleviate environmental problems,but also can be recycled and has a certain economic effect.