Preparation Of 5-HMF From Cellulose Catalyzed By SnCl₄ Under Microwave In ZnCl₂ New System

Biomass,which is one of the richest renewable energy on Earth,has a wide range of sources.Biomass has very important research value.If it can be developed and utilized effectively,biomass will replace petroleum chemicals and improve the ecological environment.In recent years ca rbohydrate compounds,including cellulose,sucrose,maltose,fructose and glucose,are considered to be the most representative research objects in biomass energy because it can be converted to 5-hydroxymethylfurfural（5-HMF）.5-HMF is an extremely important platform compound,because its molecules contain hydroxymethyl and aldehyde structure.5-HMF can be used to synthesis of pharmaceuticals,polymer monomer materials and fuel additives and other high commercial value of the compound.It is a research focus in the field to find a catalytic system that can efficiently convert biomass into 5-HMF.In this thesis,the mainly tests were to explores the new catalytic system for the conversion of cellulose to 5-HMF under microwave.In the experiment,5-HMF was prepared by catalytic degradation of cellulose using metal chloride（SnCl₄,MnCl₂,FeCl₃,CrCl₃,NiCl₂,CuCl₂）as catalyst in ZnCl₂ solution under microwave irradiation.The effects of various process conditions on the yield of 5-HMF were investigated.the results of test showed that under the reaction conditions: 1.0 g of cellulose was dissolved in 100 mL of 70% ZnCl₂ solution,the microwave power was 420 W and the reaction time was 9 min,the order of catalytic acitivity was SnCl₄> MnCl₂> MnCl₂> FeCl₃> CuCl₂.Under the optimal conditions,the catalytic amount of SnCl₄ was 2: 1（the molar ratio of catalyst to cellulose）,the maximum yield of 5-HMF is 39.4%,and correspond to the yield of 5-HMF is 22.3% without catalyst.The effects of HC l,HNO₃ and H₂SO₄ as promoters on the yield of 5-HMF were investigated.It was found that when 1.0 g of cellulose was dissolved in 100 mL of 70% ZnCl₂ solution,the main catalyst was SnCl₄（the molar ratio of catalyst to cellulose was 2:1）and co-catalyst was HC l（the molar ratio of catalyst to cellulose was 0.25:1）,microwave power of 420 W,reaction time of 9 min,the yield of 5-HMF reached the maximum value of 41.9%.The results of tests indicated that the addition of HC l in the system can increase the yield of 5-HMF.The effects of organic solution on the yield of 5-HMF were also investigated in the experiments.The results showed that the order of effects of the three organic solvents was DMAc> DMSO> DMF,when the volume ratio of the solution to the organic solvent was 100: 10,and when the DMAc was added,1.0 g of the cellulose was dissolved in the solution（100 mL of 72% ZnCl₂ solution）,the microwave power was 420 W,reaction time was 10 min.Under the optimal conditions the highest yield of 5-HMF were 44.3% using SnCl₄（the molar ratio of catalyst to cellulose was 2:1）and HC l（the molar ratio of catalyst to cellulose was 0.25:1）as catalysts.Finally,the effects of disaccharide（sucrose,maltose）or monosaccharide（glucose,fructose）on the yield of 5-HMF were investigated.The results of tests showed that when the mass of fructose,glucose,sucrose and maltose was 1.0 g in 100 mL of 68% ZnCl₂ solution,SnCl₄（the molar ratio of catalyst to raw materials was 2:1）and HC l（the molar ratio of catalyst to raw materials was 0.25:1）was used as catalysts,the microwave power was 420 W,and the reaction time was 7 min,the yield of 5-HMF from fructose was up to 52.1%,the yield of glucose,sucrose and maltose converted to 5-HMF were 50.2%,46.8% and 45.6%,respectively.The yield of these four simple carbohydrates to produce 5-HMF is higher than that of cellulose as raw material.