| Nowadays,fossil resources such as coal,oil and natural gas as the core hydrocarbon resources,which are used in the fields of chemical industry,energy and materials etc.As a non-renewable hydrocarbon resource,fossil resources are increasingly exhausted and bring huge environmental pollution problem.Howe'ver,people's lives are inseparable from coal chemical and petrochemical industries,so it is extremely urgent to choose suitable renewable resources to replace the fossil fuels.Biomass is the most abundant organic hydrocarbon resource on the planet,with renewable and "carbon neutrality".The development of renewable biomass resources and the realization of high-capacity utilization of lignocellulose materials are of great strategic significance for the sustainable development of chemical,resource,energy and environmental fields.Lignin represents the most abundant source of renewable aromatic resources,which is biosynthesized through oxidative radical polymerization from primary monolignols in plant growth.The search for efficient and selective catalysts for the production of monolignols and corresponding unsaturated derivatives from direct depolymerization of lignin is of great interest and importance as they are evaluated as important platform chemicals for synthesis of natural products,pharmaceuticals,and functional materials.This paper reported a molybdenum-based metal supported catalyst as an efficient and selective catalyst for fragmentation of woody lignocelluloses,leading to monolignols and ethers in high yields with high selectivity for the first time.The hydrogenation of lignin products' side-chain and monomer recondensation were not observed,this indicated that the end etherification is a new mechanism for the stabilization of lignin monomers in the current Mo catalytic system.The holo-cellulose components were preserved well and amenable to valorization via enzymatic hydrolysis and chemo-catalytic conversion.This method constituted an economically responsible pathway for lignin valorization,as well as fractionation and sequent utilization of biomass components.Mo-based metal catalyst(MoOx/SBA-15)catalyzed the hardwood and softwood biomass and showed good selectivity and catalytic activity(MoOx/AC).We also studied the degradation of herbaceous biomass by molybdenum-based metal catalyst.The monomers with methyl ferulate and methyl p-coumarate as main products were obtained,and these two products are important intermediate products of organic polymer materials.At the same time,the high selectivity of lignin products(76%),the high delignification rate of sawdust(90%)and the good retention rate of carbohydrate(87%)were found,which established the good catalytic activity of molybdenum-based metal catalysts.The good retention rate of carbohydrate provided conditions for subsequent utilization.The search for efficient routes for the production of fructose from biomass-derived glucose is of great interest and importance as fructose is a highly attractive substrate in the conversion of cellulosic biomass to biofuels and chemicals.We herein report a one-pot,multi-step procedure involving enzyme-catalyzed oxidation of glucose at C2 position and Ni/C-catalyzed hydrogenation of D-glucosone at C1 position selectively,thus giving a remarkable 77%yield of fructose.Starting from upstream substrates such as a-cellulose and starch,were also generated with similar efficiency and selectivity by the combination of enzymatic and heterogeneous catalysis.This method constituteed a new protocol for preparation fructose from biomass-derived substrates in an efficient fashion.For good carbohydrate retention in molybdenum-based catalytic systems,after separation of cellulose and hemicellulose with alkali treatment,after using sulfamic acid to catalyze the degradation of cellulose to form 5-hydroxymethylfurfural under microwave-assisted heating in a two-phase system.Finally,the theoretical yield of 5-HMF:52.2%;the isolated yield:35.5%.The catalytic separation and transformation of lignocellulose was realized. |
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