Electrocatalytic Degradation Of Alkali Lignin To Refine Chemicals On The Ti/SnO₂-Sb₂O₃/α-PbO₂/β-PbO₂anode

This paper presents a method for electrocatalytic degradation of alkali lignin basedthree-dimensional electrodes(TDE). The Ti/SnO2-Sb2O3/-PbO2/β-PbO2electrode wasprepared by coating and electrodeposition based Titanium net as work electrode. Thecathode was copper net. The granular activated carbon (GAC) was taken as particleelectrode. Electrocatalytic degradation of alkali lignin was carried out in the homogeneousaqueous solution in combination with the extraction technology to get small molecularchemicals. The morphology of Ti/SnO2-Sb2O3/-PbO2/β-PbO2electrode was examined byscanning electron microscopy(SEM). Surface layer structure and quantitative phaseanalysis of the Ti/SnO2-Sb2O3/-PbO2/β-PbO2electrode about before and after electrolysiswere confirmed by the X-ray diffraction (XRD) pattern. The electrochemical performanceof the Ti/SnO2-Sb2O3/-PbO2/β-PbO2electrode was characterized using cyclic voltammetry(CV). After separation and purification with silica gel column chromatography, the productsof lignin degradation were analyzed by NMR spectra and GC-MS. And the separatedproducts were quantified by internal standard method on the gas chromatographyinstrument. The operation conditions for electrocatalytic degradation of alkali lignin, suchas current density, solid-liquid ratio and pH value, were optimized simultaneously. Thechemical structure variation of lignin before and after reaction was compared by FT-IR.The experimental results show that the main constituent on surface of theTi/SnO2-Sb2O3/-PbO2/β-PbO2electrode was β-PbO2. And β-PbO2had made theTi/SnO2-Sb2O3/-PbO2/β-PbO2electrode much better stable and higher catalytic activity.The main products of lignin by electrochemical degradation in alkaline solution were thearomatic derivatives, i.e. BHT, vanillin, DIBP and DBP. The DIBP yield was up to0.98g/Laccording to optimum condition for electrocatalytic degradation of alkali lignin asfollowing: room temperature, current density25mA/cm2, pH value12and the solid-liquidratio40g/L. The maximum concentration of DIBP and DBP could up to0.427g/L,0.434g/Lby doping Co2+ion into the particle electrode. The concentration of Vanillin without addingmetal ion was0.29g/L. It indicated that the particle electrode adding metal ion influencedthe selectivity of different products. Some metal ions could promote the formation ofcertain products.