Synthesis Of Acid-base Bifunctional UiO-66-type Metal-organic Frameworks Catalysts And Their Catalytic Effects On The Transformation Of Glucose To 5-hydroxymethylfurfural

The preparation of high value-added chemicals using sugar as raw material is currently considered one of the effective ways to replace traditional fossil energy,alleviateenergyshortagesandsolveenvironmentalpollution.5-Hydroxymethylfurfural?5-HMF?is a versatile biomass-based platform compound that can be used to derive numerous chemicals through subsequent conversion.These chemicals are widely used in fuels,biopharmaceuticals,pesticides,active agents,plastics and other fields.The construction of catalytic reaction system is the key to realize the preparation of 5-HMF using sugar as raw material.The design of new-type and high-efficiency catalyst is the core of the catalytic reaction system.In recent years,metal-organic frameworks?MOFs?have been widely favored because of developed pore structures,large specific surface areas,tailored structures and unsaturated metal sites.Simultaneously,they have the advantages of easy recycling and less corrosion of equipments,which were belong of solid catalysts.This paper aims to prepare a series of acid-base bifunctional MOFs-based solid catalysts for the preparation of glucose to 5-HMF.The yield of 5-HMF is improved by adjusting the acid-base active sites of the materials and optimizing the catalytic reaction system.The morphology,pore structure,chemical composition,thermal stability,acidity and bascity of the catalysts were determined and analyzed by systematic characterization.The effects of catalyst dosage,catalytic reaction temperature,reaction time on the catalytic system and the yield of 5-HMF were investigated.The catalytic rules were explored,and the results of the study were analyzed and summarized.The main research contents are as follows:?1?Preparation of acid-base bifunctional UiO-66 MOFs catalysts and their catalytic effect on the preparation of 5-HMF from glucoseUiO-66-NH₂ was synthesized by Modulated Hydrothermal approach?MHT?,which using Zr⁴⁺as metal ion and 2-aminoterephthalic acid as organic ligand,and then modified by 1,3-propanesultone to synthesis acid-base bifunctional UiO-66-NH₂-SO₃H-X series catalysts.Catalyst catalytic performance was evaluated by catalyzing glucose to 5-HMF in DMSO solvent system.The results showed that the acidic and basic active sites in the catalysts had a synergistic effect on the glucose conversion process,and the highest 5-HMF yield was 48.2%.?2?Synthesis of UiO-66-NH₂-SO₃H catalysts with one-step MHT method and their catalytic activity for the preparation of 5-HMF from glucoseA one-step synthesis of MOFs catalyst with acid-base bifunctional by MHT method,which using Zr⁴⁺as metal ion,2-sulfonic acid monosodium terephthalate as acidic organic ligands and 2-aminoterephthalic acid as basic organic ligands,and the acidity and bascity were controlled by changing the amount of acid-base organic ligands.The influencing factors of catalytic reaction system and 5-HMF yield were systematically discussed.The results show that the basic active site inside the catalyst mainly acts on the glucose isomerization process,while the acid site mainly participates in the dehydration reaction of fructose.And under the optimized reaction conditions,the yield of 5-HMF reached 49.7%.?3?Preparation of acid-base bifunctionalized UiO-66-NH₂-SO₃H composite catalysts supported on nitrid carbon and their catalytic performance for the synthesis of 5-HMFIn order to solve the particle agglomeration and low catalytic activity of catalysts,the acid-base bifunctional UiO-66-NH₂-SO₃H/C₃N₄@PDA was synthesized on the surface of grafted dopamine-modified C₃N₄@PDA with MHT method.The physical and chemical properties of the composite catalyst were characterized and analyzed by various characterization methods.The acid-base bifunctional composite catalyst was used to catalyze the glucose conversion to produce 5-HMF.The catalytic performance of the catalyst was excellent and the yield of 5-HMF obtained was as high as 64.9%.