Multi-component Biorefinery Strategies Based On The Production Of Furan-derived Platform Chemicals

Due to the saturation of carbon emission,the access to carbon neutral is eager worldwide for the self-help of human beings.However,modern society will not stop to develop for the carbon-neutral future.Biorefinery is the key to balance carbon emissions and social development.Based on the research on the production of furan-derived platform compounds from lignocellulose,this study expanded from the furfural production to the valorizations of the three main components of lignocellulose.After optimizing stepwise,an integrated biorefinery strategy with high efficiency and feasibility was finally achieved.A bifunctional solid organocatalyst,sulfamic acid,was evaluated to produce furfural from xylose and different biomass in an environmentally friendly system comprising Gamma-Valerolactone（GVL）and water.The highest yield（70.19%）of furfural was achieved in a 90%solution of GVL in water containing 10 mol%of sulfamic acid at 190°C for 15 min from xylose.The potential mechanism of sulfamic acid efficiently catalyzing xylose isomerization and dehydration is presented for the first time.It is hypothesized that another sulfamic acid form,the zwitterionic unit（H₃N⁺SO₃^-）is crucial in efficiently catalyzing isomerization reaction due to its electron-rich sulfonate being superior in attacking the hydrogen atom on C₁ leading to the xylose tautomerization to xylulose,a shorter route to furfural.And finally,the NH₂SO₃H with strong acidity also promotes the xylulose dehydration to furfural.The above system was evaluated using various biomass species.Almost all the biomass showed excellent furfural yields（over 70%）,with tung shell providing the best yield of 92.19%at 200°C and reaction time of 30 min.For a better utilization of lignocellulose,a sustainable and integrated biorefinery strategy was achieved by a facile biphasic system,ferric trichloride（Fe Cl₃）solution assisted by methyl isobutyl ketone（MIBK）,yielding multiple products:furfural,sugars,and lignin nano-particles simultaneously.For the highest yield of furfural,the conditions were optimized resulting in 75.55%and over 69.38%of the yields from xylose and some typical biomasses respectively.Both the catalyst and MIBK can be recycled.Eucalyptus was lucubrated on the valorizations of three major-components with 75.18%of furfural yield,97.54%of cellulase digestibility from the residue and 40.13%of lignin nano-particles.Meanwhile,the regularities of biomass degradation under this biphasic system were summarized as well as high digestibility which was resulted by hemicellulose and lignin removal in cooperation.Lignin can be obtained as nano-sale from the MIBK phase,with a high purity of 100%,a low molecular weight of 767（Mn）and the average diameter was131.8 nm.Based on the proposed biorefinery strategy,65.82%of the initial mass can be valorized into high-value end-products.Seeking a new pathway to valorize the cellulose,the conversion of cellulose to the platform chemical,5-hydroxymethylfurfural（HMF）was taken into account.The possibility of furfural and HMF production from lignocellulose simultaneously was first confirmed.Then,a functional biphasic system composed by 2-methyltetrahydrofuran（2-Me THF）and DES was designed for the separation of the two products.Under this biphasic system,the furfural and HMF yields from xylose and glucose can be reached to 72.29%and 53.26%respectively.When involved into the lignocellulose,Eucalyptus specifically,a“one pot”process was applied.The reaction was heated to 160°C then cooled down to 120°C with a10-minute retention time,the furfural yield in the 2-Me THF phase was 78.71%and the HMF yield in DES phase was 42.93%.At this time,the polysaccharide in Eucalyptus was maximally valorized based on the yields of the two products,50.38%of the polysaccharide particularly.Besides,partial lignin with high purity and low molecular weight can be obtained from DES phase after the“one pot”process.The theory of furfural and HMF separation by this biphasic system was illustrated.Due to the hydrogen bond between HMF and the choline chloride（Ch Cl）in the DES phase,HMF was remained in the DES phase and only furfural can be extracted by 2-Me THF.Focus on the low yield of HMF from lignocellulose during biorefinery,the HMF was furtherly converted into 5-chloromethyl furfural（CMF）as another cellulose valorization.A functional biphasic system was also used in this study for three-main components of Eucalyptus valorized into furfural,CMF and nano-lignin.The biphasic system contained dichloroethane（DCE）phase and DES phase,and therein,the DES phase was composed of Ch Cl（75 wt%）and water（25 wt%）.The glucose and xylose were primarily used to optimized the reaction conditions.Then the Eucalyptus was valorized by two steps with81.89%of the furfural yield and 61.72%of the CMF yield with the purities of 73%and 87%respectively.And 64.18%of lignin was obtained in nano-scale by centrifuging the rest DES phase without other process,with the purity of 91.12%and average diameter of 143.1nm.After the biorefinery,56.64 wt%of the lignocellulose was valorized into three main end-products.After optimizing stepwise,an integrated biorefinery strategy with high efficiency and feasibility was finally achieved.This functional biphasic system provides a new idea for not only bio-based chemicals by biorefinery but also other similar chemicals production and separation.