Study On The Preparation Of Fine Chemicals By Electrochemical Redox Degradation Of Lignin In Fluidized Bed

In this paper,we study the by-product lignin raw material in the paper industry to achieve the purpose of preparing high value-added biomass-based fine chemicals through the use of electrochemical degradation methods.This paper uses a method of electrocatalytic redox degradation of lignin to prepare biomass-based chemicals in a fluidized bed reactor.The electrodeposited Ti/SnO₂-Sb₂O₃/?-PbO₂/?-PbO₂ electrode was used as the anode,Cu grid electrode was used as the cathode,and activated carbon particles were used as the particle electrode.The cyclic voltammetry was used to study the electrochemical oxidation performance of the Ti/SnO₂-Sb₂O₃/?-PbO₂/?-PbO₂ anode and the reduction performance of the Cu grid cathode under different conditions.X-ray diffraction(XRD)and scanning electron microscope(SEM)methods were used to study the crystal form,microstructure,and electrochemical performance of the Ti/SnO₂-Sb₂O₃/?-PbO₂/?-PbO₂ anode.After the corn stover alkali lignin is electrochemically degraded in the fluidized bed reactor,three kinds of organic solvents(n-butanol,ethyl acetate,xylene)are used to simultaneously extract the lignin degradation products while degrading;and after the degradation is finished,the degradation products are extracted,and the undegraded lignin residues are separated by centrifugation.The main products of electrocatalytic degradation of corn stalk lignin are phenols,aromatics,aromatic alcohols,aromatic ketones,aromatic acids,and aromatic aldehydes.Analysis of organic phase:Qualitative analysis of degradation products by gas chromatography-mass spectrometry(GC-MS)and gas chromatography(GC)internal standard method,a total of 21 compounds were detected,8 kinds of aromatic compounds with relatively high yield and economic value were selected as the target products.Analysis of lignin raw materials and lignin residues after degradation:analysis of the oxygen-carbon ratio(O/C)and hydrogen-carbon ratio(H/C)of lignin and lignin residues before and after degradation by elemental analyzer;GPC analysis of the molecular weight and molecular weight distribution of lignin and lignin residues during electrocatalytic degradation.Optimize the reaction conditions of extraction solvent,current density,particle electrode filling amount,reaction temperature,lignin concentration to target product yield.When the degradation time is prolonged until the lignin is completely degraded,the lignin degradation is complete within 10 h when the lignin concentration is less than 50 g/L.The yields of the two oxidation products syringaldehyde and syringic acid are 15.34 g/kg-lignin and 6.33 g/kg-lignin,respectively.Six reduction products,4-ethylphenol,4-ethyl-2-methoxyphenol,The yields of 2,6-dimethoxyphenol,vanillin,syringone,and ferulic acid were 13.01 g/kg-lignin,2.12 g/kg-lignin,4.11 g/kg-lignin,and 11.76 g/kg-lignin,10.36 g/kg-lignin,9.54 g/kg-lignin.