对氨基苯酚的绿色电化学合成及其工业化

GREEN ELECTROCHEMICAL SYNTHESIS OF p-AMINOPHENOL AND INDUSTRIALIZATION

研究了在阴极转动分隔式电解槽中硝基苯电化学还原制备对氨基苯酚 (PAP)时阴极转速、反应温度等工艺参数对电解性能的影响 ,并考察了不同阳极材料的稳定性 .实验结果表明 ,增大阴极转速和升高反应温度有利于反应的进行 ;自制的Pb Sb Sn Ag Cu五元合金作为阳极材料具有比Ti/Ir阳极更长的工作寿命 .当以铅合金为阳极材料、体系温度为 90 ℃、阴极转速为 90 0r·min-1、电解电流为 30 0 0A时 ,硝基苯的平均转化率为99% ,PAP平均收率为 6 9 9% ,电解直流电单耗为 7 2 4kW·h· (kgPAP) -1,产品纯度大于 98% ,熔点为186 1～ 187 3℃ .

The studies on the industrialization of electrochemical synthesis of p-aminophenol (PAP) from nitrobenzene in a divided electrolytic cell with a rotating Cu-Hg cathode were presented. The experimental results showed that the electrolytic properties are greatly depended on the operation parameters, such as cathode rotating speed, current, temperature, as well as anode materials. The reduction of nitrobenzene to PAP was favored by increasing temperature and cathode rotating speed. Compared with Ti/Ir anode, the Pb-Sb-Sn-Ag-Cu alloy was more suitable as anode material when the cost and operating life were concerned. Industrialization tests of electrochemical synthesis of PAP were conducted at the following conditions: Pb alloy anode material, temperature 90°C, cathode rotating speed 900 r &middot min-1, current 3000 A. The average current efficiency and conversion ratio of nitrobenzene were 57% and 99% respectively. The average yield of PAP was up to 69.9% and DC power consumption was 7.24 kW &middot h &middot (kg PAP)-1. The purity of the product was higher than 98%, and its average melting point was 186.1-187.3°C.