钛基二氧化铅电极的制备及在电合成4-吡啶甲酸中的应用

Preparation and Application of Ti-Supported Lead Dioxide Electrode in the Electrochemical Synthesis of 4-Picolinic Acid

钛基二氧化铅电极 (Ti/PbO2 )具有较好的耐腐蚀性和导电性 ,析氧过电位高且硬度大 ,是一种理想的不溶性阳极材料。该电极由半导体中间层和电沉积的二氧化铅组成 ,经过实验获得了最佳的电极制备参数。中间层Sb2 O3 的质量分数为 15 %～ 2 5 % ,电沉积液中的添加剂NaF可使PbO2 镀层致密 ,浓度为 0 .4mg/L ,pH值为 1～2 ,电流密度为 5 0mA/cm2 。将该钛基二氧化铅电极应用到电解氧化 4-甲基吡啶合成 4-吡啶甲酸的实验中 ,以反应的转化率、电流效率和电极的腐蚀速度为依据 ,考察了电极的活性、镀层的质量和电极寿命 ,并通过极化曲线评价了电极的导电性及X -衍射光谱表征了二氧化铅的晶型为

Ti-supported lead dioxide electrode (Ti/PbO 2) is of strong corrosion resistance, good electric conductivity and high overpotential to oxygen evolution. Therefore Ti/PbO 2 is a considerable insoluble anode material at present. The electrode consists of a semiconductor interlayer and electrodeposited PbO 2 films, and its optimal preparative processes were obtained. The influences of antimony amount in the semiconductor interlayer were investigated and the better ratio of Sb 2O 3 to SnO 2 is between 15% to 25%, the additive NaF(0.40 g/L) in electroplating solution can decrease the rate of PbO 2 deposition, resulting in small crystal particles and compact PbO 2 films, the combination of current density 50 mA/cm 2 and 25 mA/cm 2 for the electrochemical deposition is appropriate, the solution pH value should be controlled between 1 to 2 by using PbCO 3. In the end the application of above Ti/PbO 2 electrode in the electrochemical synthesis of 4-picoline acid was discussed. The reaction conversion, current efficiency and electrode corrosion rate could be used to measure some properties of the electrode such as activity, life time and stability. The conductivity was studied by the electrochemical polarity curves in 4-picoline solution of sulfate acid, and the PbO 2 surface crystal is mainly beta-forms showed by the X-ray diffraction.