In order to improve the preparation process of carbon-based solid acids and expand their application in the synthesis of bio-based chemicals,a multilayer carbon-based solid acid catalyst is prepared through direct milling and blending of L-ascorbic acid and p-toluenesulfonic acid(TsOH)combined with low-temperature carbonization.Influences of catalyst preparation conditions and catalytic reaction conditions on the conversion of fructose and the yield of 5-hydroxymethylfurfural(HMF)are explored.The catalyst is characterized by means of SEM,TG and FTIR.It is indicated that the morphology of carbon-based solid acid changes from multilayer sheet to block with the increase of acid dosage,and there exist a lot of porous structure within carbon-based solid acid.The catalyst's thermal decomposition temperature increases with the increase of acid dosage.The surface of carbon-based solid acid contains sulfonic group,carboxyl group and hydroxyl group.The optimum conditions for the synthesis of HMF from fructose over carbon-based solid acid are obtained as follows:the dosages of TsOH,catalyst and fructose are 1.5 g,50 mg,and 90 mg,respectively,reaction temperature is 120℃,and reaction time is 60 min.Under these conditions,the conversion rate of fructose and the yield of HMF are 100%and 98.5%,respectively.
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