| Large consumption of energy and chemicals by humans will increase the demand for non-renewable energy sources such as coal and petroleum with the rapid development of the global economy and society.Their excessive comsumption brought heavy pollution to the environment in the past years.Therefore,the depletion of fossil fuel reserves and the increasing environmental have drawn attention to develop an alternative resource which can substitute coal and petroleum.Lignocellulosic materials are composed of large amount of carbon and hydrogen elements.This abundant,low-cost and renewable resource can serve as a source of carbon neutral or carbon-negative feedstock for the production of biofuels and chemicals from petrochemical resources.A so-called biorefinery of platform chemicals,lignocellosic is usually degredated into furfural and levulinic acid and further converted into orther biofuels and chemicals,is considered one of the most promising stretagys about lignocellosic biorefineries.This study focused on the conversion of furffural and levulinic acid from hemicellulose and cellulose,respectively.Lignin was subsequently upgraded to phenolic monomers by hydrogenation.At the same time,the applications of two kinds of platform chemicals in fuel and synthetic lubricant were investigated.The corresponding results are as follows:1.Using a CHF to predict,optimize and control furfural production.A combined hydrolysis factor(CHF),a lumped term that combines the reaction parameters such as.temperature,time,and concentration of catalyst,was developed to predict conversion of furfural production from corn cob.A mathematical reaction model considering further lose reactions of furfural was established successfully.A linear correlation matrix was calculated between experimental and predicted concentration of furfural.The results showed that it correlated strongly with R2 =0.8334.Therefore,the concentration of furfural can be predicted accurately in this study.The maximum of furfural concentration obtained at CHF=1665 with 76.4±2.4%of theoretical yield.Acid was recycled and reused for three times as described in the experimental section for furfural production.The measured furfural yields were 75%above.It could be a very competitive method to produce furfural from lignocellulose materials using a combined hydrolysis factor.2.Integrated conversion of lignocellulosic biomass into furfural and levulinic acid products by the profiling of gradually increasing temperature.Furfural and levulinic acid(LA),two kinds of valuable chemical precursor and important versatile chemical intermediate,have the potential to become major renewable platform chemicals for the production of biochemicals and biofuels.In this study,integrated conversion of corncob to furfural and LA products was developed successfully in a system of batch reactor with distillation by the profiling of gradually increasing temperature.The vapor fraction from the reactor was condensed to produce furfural in excess of 61.6%of the theoretical yield based on total pentose in the first step of temperature.After the isolation of furfural,further increasing temperature for this system will directly result into degradation of hexose to LA.The maximum of LA yield(61.3±7.8)was obtained in the second step of temperature.The distillation of furfural resulted into not only recovery of furfural but also alleviating occurrence of loss reaction between furfural and other intennediates.Therefore,the yield of LA was greatly improved in comparison with usual bath reaction.It allows for exploration of the concept of the integrated biorefinery of lignocellulosic biomass where the hemicellulose composition was converted into furfural product and cellulose composition was degraded into LA product with a high yield.3.Integrated conversion of lignocellulose into furfural,LA and phenolic monomers under a controlled pretreatment severity using CHF.In this study,a new pretreatment strategy for lignocellulosic was developed using a fully recyclable solid acid,Toluenesulfonic acid(p-TsOH).A combined hydrolysis factor(CHF)as a pretreatment severity was used to balance enzymatic saccharification and the structural characteristics of lignin.The results from degradation of carbohydrates,enzymatic hydrolysis of cellulose and characterization of lignin by FT-IR,31P NMR,GPC,2D-HSQC NMR indicated that a CHF of approximately 3.90 was the optimal pretreatment severity to facilitate enzymatic saccharification and the potential serviceability of lignin.Then approximately 90%of the xylan was removed to result in a reasonable sugar yield of 76%.The degredated products of hemicellulose and cellulose were converted into furfural and LA,respectively.Residual lignin which showed low molecular weight(Mw,5783 g/mol),narrow polydispersities(Mw/Mn,1.10)and high content of phenolic hydroxyl groups(3.702 mmol/g)was hydrogened to phenolic monomers.4.A lignocellulosic biorefinery approach towards multi-purpose fractionation:furfural,phenolic monomers and ethanol.In this study,an alternative biorefinery approach towards full use of the lignocellulosic biomass was developed.Hemicellulose was first removed and hydrolyzed into xylose using recyclable acid catalyst under mild condition and further conversion of xylose generated furfural product with a yield of 68.09%.Lignin was extracted from pretreated substrate using GVL solvent.The results from characterization of lignin by FT-IR,31P NMR,GPC,2D-HSQC NMR indicated that 110 ? was the optimal pretreatment temperature,then lignin which showed low molecular weight(13223 g·mol-1),narrow polydispersities(2.26)and high content of phenolic hydroxyl groups(2.7178 mmol·g-1)was subsequently upgraded to phenolic monomers by hydrogenation with a yield of 84.75%.The leftover cellulose was directly degraded to glucose with a high yield after enzymatic saccharification and fermentation of glucose lead to high production of ethanol with 41 g·L-1.5.A 'lignin-first' biorefinery:Integrated conversion of lignocellulose into phenolic monomers and alkane fuels.'lignin-first' biorefinery approach was developed in this study:Firstly,delignification was carried out by a pretreatment method usingp-TsOH.The results from characterization of lignin by FT-IR,31P NMR,GPC,2D-HSQC NMR indicated that a CHF of approximately 112 was the optimal pretreatment severity.Then lignin which showed low molecular weight(9824 g-mol-1),narrow polydispersities(1.45)and high content of phenolic hydroxyl groups(4.688 mmol·g-1)was subsequently upgraded to phenolic monomers by hydrogenation with a yield of 76.9%.The hemicellulose and cellulose were converted into furfural and LA by the profiling of gradually increasing temperature,respectively.The maximum of furfural yield for the delignified sample was 72.56%at CHF 14031.The maximum of LA yield was 69.68%at 170 ? for 80min.The ?,8-FDLA obtained from condensition between furfural and LA was hydrogenated into C14,C15 alkane as a new special biodiseal.6.Synthesis of levulinic acid-based polyol ester and its influence on tribological behavior as potential lubricant.Levulinic acid was used to prepare lubricant base stocks by esterification with three different polyols including neopentyl glycol(NPG),trimethylolpropane(TMP),and pentaerythritol(PE)in the presence of sulfuric acid.The crude product was distilled to obtain target product with a purity above 95%.These products of polyol ester were characterized using 1H NMR and mass spectral techniques.The lubricant properties,such as kinematic viscosity,viscosity index,pour and flash points,were evaluated using standard ASTM methods.Among the base stocks prepared,TMP-tri-LA ester exhibited superior lubricant properties like good kinematic viscosity at 40 ?(87.28)and at 100 ?(8.42),viscosity index(48),low pour point(-25 ?),high flash point(238 ?),cloud point(-4 ?),copper strip corrosion(1a)and Volatility at 120 ?(0.41%).Wear prevention characteristics of this ester was tested and performed low coefficient of friction and small wear scar diameters.It was found that this kind of polyol ester was suitable for lubricant base stocks.7.Preparation of water-based lubricant from lignocellulosic biomass and its'tribological properties.In this study,a new water-based lubricant was prepared using biomass-derived levulinic acid(LA)and polyols such as ethylene glycol(EG)and glycerol(GL).The products were separated by Rotary Film Molecular Distillation and characterized by 1HNMR and mass spectrometry.The lubricant properties,the hydrolytic stability and tribological properties of the products were tested as water-based lubricant.Results indicated that glycerol ester of levulinic acid(LAGLE)exhibited strong resistance to hydrolytic degradation,excellent anti-wear performance and superior lubricant properties such as kinematic viscosity(73.02 mm2/s at 40?,7.31 mm2/s at 100?);pour point(-17 ?),flash points 205 ?)and copper strip corrosion(1a).A low friction coefficient(0.11)and small wear scar diameter(315 ?m)were observered for the aqueous solution consisting of 75%and 100%LAGLE in water(v/v),implying that the biomass-derived LAGLE is a potential water-based lubricant. |
PDF Full Text Request