Electrpchemical Conversion Of Lignin To Bioss-based Chemicals Between Cu/Ni-Mo-Co Cathode And Pb/PbO₂ Anode In Alkali Solution

In this paper,a novel method for preparing biomass-based chemicals through electrocatalytic oxidation and reduction of corn stover lignin in alkaline solution was explored,in which the Pb/PbO₂ electrode prepared by anodic polarization was used as the anode and the Cu/Ni-Mo-Co electrode prepared by electrodeposition was used as the cathode.Cyclic voltammetry and polarization curves were employed to study the electrochemical oxidation performance of Pb/PbO₂ anode and reduction performance of Cu/Ni-Mo-Co cathode under different operation conditions.After degradation of corn stover lignin,the products in the electrolyte liquor were extracted by organic solvent,and the lignin residue was precipitated and separated by centrifugation.Firstly,the components in organic phase were analysized by gas chromatography-mass spectrometer?GC-MS?and gas chromatograph?GC?analysis,24 kinds of compounds were detected and thereinto 8 kinds of commercial compounds were selected as target products.And then,the following analysis of the residue in water phase was also carried out according to the same way,as they didn't be extracted by organic solvent.Finally,the analysis of solid residue was carried out as following,the changes of functional groups before and after degradation of lignin were recorded by fourier transform infrared spectroscopy?FT-IR?;the element changes of H/C and O/C before and after degradation of lignin were analyzed by elemental analysis;and the changes of average molecular weight and polymer dispersity index?PDI?during the degradation of lignin were monitored by gel permeation chromatography?GPC?.The effect of operation conditions,such as cobalt ion concentration,extraction solvent,current density,degradation time,lignin concentration and reaction temperature on the yield of degradation products were investigated,and the optimum reaction conditions for each product were determined.Lignin was degraded repeatedly under the optimal degradation conditions for each product until the residual lignin could never be degraded after 6^th run experiment.The cumulative yields of five oxidation products,including trans-ferulic acid,vanillin,3-hydroxy-4-methoxyphenyl-ethanone,syringaldehyde and acetosyringone were up to 22.40 g/kg-lignin,11.09 g/kg-lignin,2.37 g/kg-lignin,10.04 g/kg-lignin and 6.95g/kg-lignin,respectively.The cumulative yields of three reduction products,including 4-methoxy-3-methyl-phenol,2,4-bis?1,1-dimethylethyl?-phenol and 2,2'-methylenebis[6-?1,1-dimethylethyl?-4-methyl-phenol reached to 38.83 g/kg-lignin,1.68 g/kg-lignin and 1.73 g/kg-lignin,respectively.