Valorization of renewable cellulose into initial platform chemicals(IPCs)generally suffers from low process efficiency owing to difficult depolymerization of recalcitrant cellulose and troublesome repolymerization of ...Valorization of renewable cellulose into initial platform chemicals(IPCs)generally suffers from low process efficiency owing to difficult depolymerization of recalcitrant cellulose and troublesome repolymerization of high-reactive intermediates to undesired humins.Herein,we report a double-protective strategy for cellulose depolymerization and orientated conversion to levulinic acid(LA),one of the important IPCs,by in-situ adding protective formaldehyde(HCHO).This approach initiates from the(hemi)acetalation of hydroxyl groups in cellulose with HCHO,causing controllable depolymerization to(hemi)acetalized glucose with increased rate kinetically and a new mechanism of its catalytic conversion to LA via(hemi)acetal-driven direct C1-C2 cleavage.As such,the cellulose-to-LA conversion is protectively proceeded with the repolymerization of reactive intermediates prevented remarkably,leading to an excellent LA yield of 87.3 mol% from high-loading microcrystalline cellulose(15.0 wt% in aqueous phase)in a biphasic solvent containing 2-methyltetrahydrofuran and water.The process efficiency,expressed as space-time yield,is improved by 3.6 fold when compared with a non-protective approach.This work highlights an advance in maximizing the utilization of biomass-derived carbons for high-efficiency production of important IPCs directly from cellulose for future biorefinery.展开更多
基金financially supported by the National Natural Science Foundation of China(No.22378277)111 Center(B17030)+1 种基金the Basal Research Fund of the Central University(2016SCU04B06)the technical support from the Analysis and Test Center of Sichuan University。
文摘Valorization of renewable cellulose into initial platform chemicals(IPCs)generally suffers from low process efficiency owing to difficult depolymerization of recalcitrant cellulose and troublesome repolymerization of high-reactive intermediates to undesired humins.Herein,we report a double-protective strategy for cellulose depolymerization and orientated conversion to levulinic acid(LA),one of the important IPCs,by in-situ adding protective formaldehyde(HCHO).This approach initiates from the(hemi)acetalation of hydroxyl groups in cellulose with HCHO,causing controllable depolymerization to(hemi)acetalized glucose with increased rate kinetically and a new mechanism of its catalytic conversion to LA via(hemi)acetal-driven direct C1-C2 cleavage.As such,the cellulose-to-LA conversion is protectively proceeded with the repolymerization of reactive intermediates prevented remarkably,leading to an excellent LA yield of 87.3 mol% from high-loading microcrystalline cellulose(15.0 wt% in aqueous phase)in a biphasic solvent containing 2-methyltetrahydrofuran and water.The process efficiency,expressed as space-time yield,is improved by 3.6 fold when compared with a non-protective approach.This work highlights an advance in maximizing the utilization of biomass-derived carbons for high-efficiency production of important IPCs directly from cellulose for future biorefinery.
