Preparation Of 5-Hydroxy Me Thy Lfurfural From Cellulose Catalyzed By NiCl₂ Under Microwave In ZnCl₂ Solution

As a kind of new energy,Biomass energy is considered to be the most dominant replacement of fossil fuels such as coal and oil.Rational utilization of biomass,can effectively reduce the pollution of the environment,adjust the energy structure.For china,which contains abundant resources but with less per capita share,The development and use of biomass energy has significant importance.This paper takes advantage of four kind of renewable green cellulose such as the rice hull cellulose fiber,wood fiber,cotton,paper scraps cellulose as raw materials,then choose NiCl₂ as catalyst and high concentration ZnCl₂ as solvent in microwave reaction to transformed the cellulose into 5-HMF.To investigated the effecting factors of 5-HMF yield,the experiment investigated technological conditions including the concentration of ZnCl₂ solution,microwave reaction time,microwave power,mole ratio of Ni Cl2 catalyst to cellulose,amount of cellulose.The results shows that all raw materials including cotton,rice husk,sawdust,wastepaper fiber can be effectively transformed into 5-HMF in ZnCl₂ solution.And in this reaction system microwave function plays an positive improvement comparing with normal heating reaction method.Besides,viscosity of the reaction system was regarded to be key factors affecting the yield of 5-HMF when changing the concentration of ZnCl₂ solution and dissolve quality of cellulose.Catalytic conversion of cellulose in ZnCl₂ solution is a cascade reaction process,The obtained 5-HMF can aggregate into humin or further decompose into side reaction products such as formic acid and levulinic acid.In addition,factors like excessive reaction time,too large microwave power and mole ratio of catalyst to cellulose can all leads to further reaction of 5-HMF,So the yield of 5-HMF tends to increase at first and decrease later according to the change of corresponding variables.In the process condition experiment,the results reveals that using absorbent cotton as raw materials,the yield of 5-HMF reached 22.0 % under the optimized conditions when the microwave power was 350 W,the microwave reaction time was 4 min,ZnCl₂ concentration was 69 %,the mole ratio of NiCl₂ and cellulose was 6.4:1,the quality of cellulose was 0.25 g.For rice husk material,5-HMF yield reached 15.8 % under the optimized conditions when the microwave power was 420 W,the microwave reaction time was 5 min,ZnCl₂ concentration was 70 %,the mole ratio of NiCl₂ and cellulose was 4.5:1,the quality of cellulose was 0.53 g.For wood raw material,5-HMF yield reached 10.1 % under the optimized conditions when the microwave power was 420 W,the microwave reaction time was 6 min,ZnCl₂ concentration was 70 %,the mole ratio of NiCl₂ and cellulose was 6:1,the quality of cellulose was 0.6 g.For paper scraps material,5-HMF yield reached 12.4 % under the optimized conditions when the microwave power was 420 W,the microwave reaction time was 5 min,ZnCl₂ concentration was 70 %,the mole ratio of NiCl₂ and cellulose was 6:1,the quality of cellulose was 0.4 g.