Study On The Preparation Of 5-hydroxymethylfurfural From Biomass-derived Sugar By Hf-based Zsm-5 Catalysts

The excessive exploitation and use of fossil fuels cause serious pollution to the environment.Therefore,the exploitation and utilization of green biomass energy is conducive to the transformation of energy structure and conforms to the main direction of energy development.5-Hydroxymethyl furfural（HMF）,as an important platform compound,is one of the important products of high value biomass,and can be applied to various high-value terminal chemicals such as synthetic fuel additives,pharmaceutical intermediates and polyesters.Based on the formation mechanism of cellulose to HMF,a series of low-cost catalysts for the preparation of bifunctional solid acid were designed and prepared in this paper.The conclusions of this paper are as follows:（1）Direct catalysis of cellulose is usually difficult.Therefore,the structural monomer of cellulose（glucose）is used as the reaction substrate,and the commercial H-ZSM-5 is used as the catalyst to verify the optimal catalysis conditions of H-ZSM-5molecular sieves in the HMF formation reaction.In H₂O/THF biphasic system,H-ZSM-5 catalyzed dehydration of glucose yielded up to 61%HMF yield,which was the best reaction system selected in this paper.In addition,H-ZSM-5 zeolite maintained good stability in the reaction system and maintained its catalytic activity and structure after four consecutive cycles,indicating that H-ZSM-5 could catalyze the formation of HMF.（2）The H-ZSM-5 was modified inside and outside the framework with Hf element and applied to the production of HMF with cellulose as the substrate.A series of（x）Hf/ZSM-5 catalysts were successfully synthesized by simple impregnation method,in which（5）Hf/ZSM-5 exhibited the best catalytic performance and the yield of HMF was 67.5%under the optimal reaction conditions of H₂O/THF（1/4m L）,190℃and 120min.Under the same conditions,the（x）HF-ZSM-5 catalyst synthesized by the isomorphous substitution method was not effective,and the yield of HMF was only kept between 40%and 45%.（3）With the improvement of the research on the main catalyst system,additives are introduced into the optimal reaction system to further achieve higher HMF yield.The effects of reaction temperature,reaction time and concentration of additives on the yield of HMF were investigated.Under the optimal reaction conditions,when the mass ratio of Al Cl₃ and（5）Hf/ZMS-5 was 1:25,the yield of HMF was 70.95%,which was higher than that when（5）Hf/ZSM-5 was used alone as catalyst system.