Study On The Transformation Of Cornstalk Lignin To Aromatic Compounds By Electrocatalytic Hydrogenation Over Ni Cathode In Alkaline Liquor

This paper presented a new process to degrade cornstalk lignin in alkaline liquor by using an electrolytic cell,which consisted a Ni plate?2*6cm?cathode and a Pb/PbO₂ anode.The crystal structure of the two electrodes was characterized by XRD.Meanwhile,the redox ability and the hydrogen evolution potential of the nickel electrode in the lignin alkaline solution were characterized by cyclic voltammetry and cathodic polarization curves,respectively.The degradation products was carried out using GC-MS.Then,the yields of aromatic hydrocarbons were determined by means of external standard method on GC.The influence factors of temperature,current density,substrate concentration and degradation time on the products concentration of aromatic hydrocarbon were optimized.The molecular weight distribution of lignin residue was analyzed by GPC on HPLC,and the functional groups of lignin before and after degradation were analyzed by FT-IR.The results shown that the nickel electrode has good redox ability and stability in the lignin alkaline solution,and the hydrogen evolution potential in the lignin alkaline solution was-1.317 V,which can ensure that the chemical adsorption of hydrogen in alkaline solution(H_adsM_eled)with lignin intermediates(RM_eled)to complete the electrocatalytic hydrogenation reaction.The main products obtained by electrocatalytic degradation of cornstalk lignin were toluene,xylene,anisole and three guaiacol products.With optimized operation parameters,40 g lignin dissolved into 1 L 1.0 M NaOH solution,employed 30mA/cm² current density,30°C temperature,given 78.1g/kg-lignin total yield.When the reaction time was 10 h,the molecular weight of lignin was decreased and the yield of toluene was 36.1 g/kg-lignin,the yield was 12.1 g/kg-lignin,the yield of m-xylene was10.3 g/kg-lignin,and the yield of anisole was 9.5 g/kg-lignin.