Study Of Hydrothermal Conversion Of Biomass Derived Saccharides Over Carbon-based Solid Acid Catalyst

The technical route of producing high-value platform compounds from isomerization-dehydration cascade transformation of biomass-derived saccharides is one of the key ways of biomass resource utilization.The reaction process shows specific complexity and presents technical challenges for its efficient transformation.Reasonable design of new multifunctional solid acids is the key to improve the catalytic performance of the cascade conversion.In this paper,a dual functional carbon-based solid acid（DFCSA）catalyst with adjustable Br?nsted/Lewis acid sites was developed for the cascade conversion of biomass saccharides.The combined modification of H₃PO₄and HNO₃on the carbon substrate with reasonably porous structures facilitates the direct grafting of acidic fractional species.Combined with the novel developed Al PO₄with an orthorhombic crystal structure as Lewis acid and subsequent sulfonation process,the catalyst has high catalytic properties for isomerization and subsequent dehydration processes.Under the optimal conditions,the maximum yields of products from glucose and xylose were 38.2%LA and 69.7%FF,respectively.The high activity of the catalyst was further demonstrated by a 1:10 mass ratio of catalysts to xylose with 86.2%conversion and FF yield of 57.9 mol%.In addition,the catalyst has good hydrothermal stability with only a slight decrease in activity after 10 cycles,mainly due to the high thermal stability of Al PO₄and strong grafting of surface functional groups.At the same time,the catalyst also has excellent feedstock adaptability.For the hydrothermal conversion of common disaccharides such as cellulose,maltose,and sucrose,the catalyst can promote LA production up to 36.2%,38.2%,and 44.1%,respectively.The product distribution of disaccharides is related to its monosaccharide unit and glycoside bond type.Kinetic analysis showed that DFSCA has higher activity during xylose conversion than glucose because of lower activation energy,resulting in higher FF yield.