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
气凝胶凭借其独特的三维网络结构,作为目前已知世界上密度最低且微观尺度极小的固体材料,在材料科学及相关领域引发了广泛关注。纤维素气凝胶无疑是与可持续发展理念相契合的新型材料,它不仅具备高孔隙率和大比表面积等优异特性,还具有...气凝胶凭借其独特的三维网络结构,作为目前已知世界上密度最低且微观尺度极小的固体材料,在材料科学及相关领域引发了广泛关注。纤维素气凝胶无疑是与可持续发展理念相契合的新型材料,它不仅具备高孔隙率和大比表面积等优异特性,还具有可被微生物降解以及与多种物质良好兼容等优势。文章介绍了制作纤体素凝胶的方法,常压干燥,冷冻干燥,超临界干燥等特征论述。在应用上,对纤素气凝胶所展现的广阔前景进行了探索,并展望了它的发展前景。Aerogels, with their unique three-dimensional network structure, have attracted widespread attention in materials science and related fields as the lowest density solid materials known in the world with extremely small microscopic scales. Cellulose aerogels are undoubtedly a new type of material that aligns with the concept of sustainable development;they not only possess excellent characteristics such as high porosity and large specific surface area but also have advantages such as biodegradability and good compatibility with various substances. This article introduces methods for producing cellulose aerogels, discussing features such as ambient pressure drying, freeze-drying, and supercritical drying. In terms of applications, it explores the broad prospects demonstrated by cellulose aerogels and anticipates their future development.to the Hans standard, which illustrates all the formats.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.
文摘气凝胶凭借其独特的三维网络结构,作为目前已知世界上密度最低且微观尺度极小的固体材料,在材料科学及相关领域引发了广泛关注。纤维素气凝胶无疑是与可持续发展理念相契合的新型材料,它不仅具备高孔隙率和大比表面积等优异特性,还具有可被微生物降解以及与多种物质良好兼容等优势。文章介绍了制作纤体素凝胶的方法,常压干燥,冷冻干燥,超临界干燥等特征论述。在应用上,对纤素气凝胶所展现的广阔前景进行了探索,并展望了它的发展前景。Aerogels, with their unique three-dimensional network structure, have attracted widespread attention in materials science and related fields as the lowest density solid materials known in the world with extremely small microscopic scales. Cellulose aerogels are undoubtedly a new type of material that aligns with the concept of sustainable development;they not only possess excellent characteristics such as high porosity and large specific surface area but also have advantages such as biodegradability and good compatibility with various substances. This article introduces methods for producing cellulose aerogels, discussing features such as ambient pressure drying, freeze-drying, and supercritical drying. In terms of applications, it explores the broad prospects demonstrated by cellulose aerogels and anticipates their future development.to the Hans standard, which illustrates all the formats.
基金国家高技术研究发展计划(863 计划)(No. 2006AA10Z422)资助项目Alcoa Foundation’s Conservation and Sustainability Fellowship Program-Sustainable Development of Rural Area in China
