Study On The Paired Electrosynthesis Using Furfural As Raw Material

Furfural,derived from abundant and renewable biomass,has a wide range of applications and is one of the major platform chemicals.At present,with the increasing of furfural derivatives in the field of fine chemical industry,the deep processing of furfural has been paid attention to.Furfural is at an intermadiate oxidation state between the corresponding alcohol and acid.Therefore it can be reduced into furfuryl alcohol or oxidized into furoic acid.Furfuryl alcohol and furoic acid are very valuable intermediates,occupying an important position in pesticide,medicine,dye,leather and other fields.The thesis studied kinetics of cathodic reduction of furfural to furfuryl alcohol,and put forward the paired electrosynthesis techniques which furfural reducted to furfuryl alcohol,and oxided to furoic acid at the same time.In this way,it can greatly reduce the consumption of the energy and time.The total yield has been increased and also avoid the pollution of the catalyst chromium in the traditional method.It is the technology of green,environmental protection,energy saving and high efficiency.1.The electrocatalytic hydrogenation of furfural to furfuryl alcohol has a great relationship with the type of catalyst.This paper reports the mechanism including the reaction process and rate determining step of the hydrogen evolution reaction(HER)at seven kinds of electrodes(Cu,Pb,Ni,Fe,Pt,Ti,C)in 0.1 mol/L Na2CO3-NaHCO3 buffer solution(pH=10).The sequences of exchange current density and overpotential for the HER at different electrodes were determined.The sequence of hydrogen evolution reaction at seven kinds of electrodes is : Pt > C > Ti > Fe > Ni > Cu > Pb.In particular,the mechanism and kinetics of the electrocatalytic hydrogenation of furfural at those electrodes were analyzed by cathodic linear sweep voltammetry in the presence of furfural.Current efficiency and selectivity were obtained bypotentiostatic electrolysis method.It is showed that the optimal electrode for the reduction of furfural is Cu electrode.2.The effects of current density,the concentration of furfural,the concentration of electrolyte and reaction temperature on the selectivity and the current efficiency were studied by the cathode orthogonal experiment.The optimal conditions for the electrochemical reduction of furfural to furfuryl alcohol was as follows: current density 3 m A/cm~2,0.1 mol/L furfural,0.2 mol/L?pH=10 Na2CO3-NaHCO3 buffer solution,temperature 25?.3.The possible mechanism by anodic linear sweep voltammetry and oxygen evolution at the electrode of C,Ti/Ru-Ti-Sn,Ni,Ti/PbO2,Pt,Ti/BDD in 0.1 mol/L sodium hydroxide solution were studied.It is obtained that the optimal electrode for the electrochemical oxidation of furfural to furoic acid is Ni electrode.4.Based on previous experiments,the parallel experiment for the electrochemical oxidation of furfural to furoic acid was conducted at Ni anode at the experimental condition of current density 1.0 mA/cm~2,0.1 mol/L furfural,0.1 mol/L sodium hydroxide solution,temperature 25?.The current efficiency was 69.95% and the selectivity was 63.09%.5.The effects of pH of the solution,current density,the concentration of furfural,temperature,electrolysis time on the paired electrosynthesis techniques,the electrochemical reduction of furfural to furfuryl alcohol and the electrochemical oxidation of furfural to furoic acid.The optimum experimental condition was : pH 11,the cathodic current density 2 mA/cm~2,the anodic current density 1 mA/cm~2,temperature 25 ?,cathodic electrolytic time 4 h,anodic lectrolytic time 6 h.The total current efficiency is 130% and the selectivity is 140%.It provided the reference and basis for the paired electrosynthesis of furfural industry.