Auto-catalytic Hydrothermal Pretreatment Process Of Corn Stover Based On Full Components Use

Fuel ethanol as an important part of the renewable energy is the most successfulalternative liquid transportation fuel by far which belongs to renewable biomassenergy and can not be replaced by other renewable energy sources such as solar andwind energy. Fuel ethanol plays an important role in improving the environment,easing the energy crisis and protecting national energy security. So, fuel ethanol hasbeen paid widespread attention by related enterprises and research institutions ofmany countries such as US, Brazil, Europe and China. Lignocellulosic biomass is themost abundant renewable resources on earth. Crop stalks are produced over700million tons per year in China and600million tons for corn stover. The potentialeconomic benefits of full use of cellulose, hemicelluloses and lignin of corn stoverwill provide a huge impetus to the development of cellulosic ethanol industry.Pretreatment technologies as one of important technologies of cellulosic ethanolproduction process have significant effect on the clean and economical production ofenzymatic, fermentation and wastewater treatment.Firstly, the liquid hot water (LHW) pretreatment of corn stover was conducted.The formation of xylose, glucose, acetic acid, furfural, HMF and phenolics and theefficiency of enzymatic hydrolysis were studied. Furthermore, a two-step LHWpretreatment was proposed. The results showed that the optimal conditions for thefirst step LHW pretreatment was180?,30min and those for the second step LHWpretreatment was200?,20min. High xylose in pretreatment liquid and high glucoseglucose in enzymatic hydrolysis liquid were obtained and the content of furfural,HMF and phenolics in pretreatment liquid can be controlled in corn stover LHWpretreatment, which can provide appropriate substrates for enzymatic, fermentationand wastewater treatment.On the basis of the corn stover LHW pretreatment experiments, the effects ofacetic acid on pretreatment were further investigated. Direct recycle of spent liquorrich with acetic acid to enhance cellulose digestibility of corn stover. The optimalconditions were180?,30min,7.98g/L acetic acid, and75%spent liquor forrecycling in continuous operation. The glucose yield increased from80.82%to85.44%in enzymatic hydrolysis. The effect of surfactant Tween80on enhancing cellulosedigestibility was also studied. The glucose yield increased from80.82%to84.64%in enzymatic hydrolysis.Finally, on the basis of the above research and previous studies of our researchteam, the cellulosic ethanol production process based on full use of corn stovercomponents was proposed. This process was composed of auto-catalytic two stepLHW pretreatment unit, simultaneous saccharification and fermentation unit,distillation unit, molecular sieve adsorption unit and waste mash biological treatmentunit, which was an important attempt to reduce pretreatment cost and maximize theuse of lignocelluloses.