Electrocatalytic Reduction Of Bamboo Lignin To Tert-butylhydroquinone In Alkali Aqueous Solution

This paper has investigated the electrocatalytic reduction of bamboo lignin in alkali solution.The experiment was conducted with an anode of Pb/PbO₂ and a cathode of copper sheet in a solution of bamboo lignin dissolved in alkali water.Degradation products were separated from solution by extraction solvent such as ethyl acetate,anisole,dichloromethane as well as chloroform respectively,and products obtained were purified through TLC and column chromatography.For the target product of tert-butylhydroquinone,GC-MS?¹H NMR and ¹³C NMR were employed for qualitative analysis,and GC was employed for quantitative analysis.Elemental analyzer was employed for revealing the elemental composition of lignin material,FT-IR was employed for analyzing the bamboo lignin residue after reaction.In addition,Pb/PbO₂ anode was characterized by SEM,XRD and CV.The hydrogen evolution at the cathode was also measured at different temperatures and current densities.Conclusions obtained were listed as followed:Owing to the theory that hydrogen evolution reaction occurred on the cathode in electrolytic reaction in alkali solution,in addition to generating hydrogen,absorptive hydrogen on the surface of cathode was also able to react with intermediate products to generate hydrogenation products as a competitive reaction.The tertiary butyl structure in target product of TBHQ was transformed from the intermediates derived from the?-?structure in the lignin by hydrocracking and hydrogenation,which was then synthesized into TBHQ with another intermediate of hydroquinone.Verification test was conducted in this experiment.The influence of raw material lignin concentration,current density,temperature and degradation time on the yield of tert-butylhydroquinone was investigated experimentally.Under optimized reactive conditions,of which the ratio of solid and liquid was 40 g/L,the current density was 20 mA/cm²,temperature 40°C,and reaction time 1 h,the maximal productivity of the target product of TBHQ was 860.4 mg/L.