摘要
通过Monel合金电极上硝基苯(NB)直接电还原合成对氨基苯酚(PAP)。实验发现,反应初期PAP 产率接近Cu-Hg电极;随反应进行,PAP产率缓慢降低,500 h以内可稳定在70％以上;随反应的继续进行, PAP产率下降较快,800 h时降为63．1％,接近Cu电极。用XRD、SEM、EDS和电化学的测试和分析手段对电极进行了表征。结果表明,使用800 h的Monel合金电极与初始相比,表面组成显著改变,电还原过程中,Monel 合金电极表面Cu富集引起的表面组成及状态改变是导致电极电催化特性劣化的主要原因。稳态极化曲线测定结果进一步从电化学角度证明了这种影响。
In the investigations of electrochemical reduction of nitrobenzene to p-aminophenol at the Monel alloy electrode, it was found that the yield gradually decreased with the increase of the service time of the Monel alloy electrode. At the initial stage of reaction, the yield of p-aminophenol at the Monel electrode was 75.2%, which was close to that at the Cu-Hg electrode. Within 500 h service time, the yield could be maintained above 70%. However, the yield decreased greatly to 63.1% after 800 h service, which was close to that at the Cu electrode. In order to figure out the reasons of the decrease, the Monel alloy electrodes before and after service were characterized by means of X-ray diffraction （XRD）, scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy（EDS） and the electrochemical method. The results from the XRD indicate that the surface unit cell composition of the Monel ahoy electrode had significant variations after 800 h service, compared with that of the electrode before service. The results from the SEM and EDS show that the changes of the surface composition and state of the Monel alloy electrode were caused by the surface element enrichment of Cu, they were the main reasons for the deterioration of electrocatalytic properties of the electrode in the electrochemical reduction of nitrobenzene. The results from steady-state polarization confirm the conclusion further.
出处
《应用化学》
CAS
CSCD
北大核心
2006年第1期48-53,共6页
Chinese Journal of Applied Chemistry
基金
河南省重点科技攻关资助项目(03223023800)
关键词
Monel合金电极
表面状态
硝基苯
对氨基苯酚
电还原
Monel alloy electrode, surface state, nitrobenzene,p-aminophenol （ PAP）, electroreduction
