Study On Electrochemical Directional Control Of Cellulose In Conductive Ionic Liquids

With fossil fuels and other non-renewable energy consuming and increasingly exhausted,research and development of renewable energy has become one of the problems to be solved in twenty-first Century.As a kind of renewable energy,biomass energy is a new focus of global concern,with abundant resources,ecological and environmental friendly and other advantages.Biomass is the only renewable carbon resource,can be transformed into liquid and gaseous fuels and other conventional chemical products through anaerobic digestion,pyrolysis,ethanol fermentation,reduction molding method.Biomass fast pyrolysis technology can effectively convert biomass into liquid products,but the products obtained by conventional pyrolysis are complex,unstable and low calorific value,so it is difficult to achieve market application.In recent years,ionic liquids obtain a lot of attention and research in cellulose dissolution and transformation,and conductive ionic liquids in electrochemical applications is also the research hotspot.As a new green solvent,ionic liquids are not volatile,flammable,good thermal stability and so on,in addition,the unique structure of all ion also leads to good conductivity.However,there are few reports on the use of ionic liquids to promote the catalytic cracking of cellulose.Based on this,the aim of this study is to study the distribution rule of cellulose pyrolysis products,and to explore the mechanism of product control.The effect of ionic liquid structure on its conductivity is analyzed,and the ionic liquid with good conductivity and high thermal stability was screened out.Meanwhile,a homogeneous low temperature pyrolysis system for conducting ionic liquids was constructed.The experiments were carried out at different temperature and voltage gradient,and liquid phase pyrolysis products were analyzed by GC-MS while the solid phase pyrolysis products were characterized by SEM,XRD and FT-IR,so as to find the best way to produce the target products.The main results are as follows:(1)According to the structural characteristics of ionic liquids and cellulose,8 kinds of ionic liquids such as[Emim]Tf2n,[Amim]Cl,[Emim]DCA and so on were synthesized,and FT-IR and NMR were used to characterize the different ionic liquids.The results showed that the target ionic liquids were prepared.Among them,the ionic liquid[Emim]Tf2n has the best thermal stability,its decomposition temperature is about 420?,the ionic liquid[Emim]DCA has the best electrochemical performance,followed by[Emim]Tf2n.(2)Ionic liquids were synthesized with different cations and anions,and the conductivity of different ionic liquids at different temperatures were measured.The results show that the ionic conductivity increases with the increase of temperature.For ionic liquids of the same anion,the order of conductivity is:[Bmim]Br>[Hmim]Br>[Omim]Br,it is indicated that the lower the number of carbon atoms on the side chain of the imidazole ring,the higher the conductivity.In the temperature range of 20-50?,the ionic liquid conductivity order is:[Emim]DCA>[Emim]Tf2n>[Amim]Cl>[Bmim]Cl.(3)Construction of experimental platform for ionic liquid pyrolysis of cellulose and experiments on cellulose pyrolysis at different temperatures,separation of liquid phase and solid phase products.This paper focuses on the regulation mechanism of 5-Hydroxymethylfurfural,furfural,levoglucosenone,ethanol,acetic acid,acetaldehyde,beta.-D-Glucopyranose and so on.The results showed that the cellulose pyrolysis products were significantly different at different temperatures.There are more kinds and contents of pyrolysis products at 220?,among them,the content of levoglucosenone,furfural and 5-Hydroxymethylfurfural was the highest.At 140?,acetaldehyde and ethanol had the highest yield,and the highest concentration of beta.-D-Glucopyranose was found at 260? while acetic acid was highest at 340?.(4)At 220?,the cellulose pyrolysis experiments were carried out at different voltages,This paper mainly discusses the electrochemical directional control mechanism of glyceraldehyde,furfural,levoglucosenone,ethanol,acetaldehyde,fatty acid,beta.-D-Glucopyranose and so on.The results showed that:After adding the voltage,4 kinds of components,such as acetaldehyde,ethanol,glycerol aldehyde and furan,were found in the cellulose pyrolysis liquid products;Aldehydes and furans are the unique products under the condition of voltage,the yield of furan was the highest at 1.5V voltage,and the purity was highest at 3V voltage.The maximum yield and the highest purity of aldehydes are obtained when the voltage is 1.5 V For acetaldehyde,the maximum yield is at 1V voltage,and the highest purity is at 2V voltage,at this time the relative content of acetaldehyde is more than 45%,which indicated that the low voltage condition is more favorable for the formation of aldehydes.There was also a significant change in the yield of levobupivacaine,fatty acid and furfural.When the voltage was 4V,the highest yield and the highest relative content were obtained with both beta.-D-Glucopyranose and levobupivacaine while the maximum ethanol yield and the highest purity fatty acids could be obtained.