Abstract: The packed bed cell was used in the preparation of p-aminophenol from the electrochemical reduction of nitrobenzene.The effects of current density, flow rate of catholyte, reactor thickness and temperature on electrolysis were studied.The results showed that under the conditions of 10 mm thickness of copper mesh as cathode, DSA as anode, current density 1000 A·m^-2, flow rate of catholyte 4.28 cm·s^-1 and temperature 85℃, current efficiency for nitrobenzene reduction was almost 100%, and selectivity of p-aminophenol could reach 83%.The catholyte could be reused five times for electrolysis, which resulted in that the lowered consumptions of sulfuric acid and ammonia approximately to 25% of the original value, and reduced discharge amounts of ammonia sulfate and effluent by 75%.Diffusion dialysis was used to recycle sulfuric acid from the spent catholyte.The results showed that under the conditions of APS as anion exchange membrane, flow rate of simulated solution 0.01 ml·min^-1 and temperature 20℃, recovery of sulfuric acid was up to 61%, and transmissivities for p-aminophenol and aniline were only 1.4% and 1.6%, respectively.

Key words: nitrobenzene, p-aminophenol, electrochemical reduction, electrolyte circulation, sulfuric acid recovery

摘要： 采用固定床电解槽还原硝基苯制备对氨基苯酚,并对其工艺条件进行了优化。以铜网组成固定床电解槽阴极,镀铱钛网(DSA)作为阳极,在电流密度为1000 A·m^-2,阴极电解槽内流速为4.28 cm·s^-1,铜网厚度为10 mm,温度为85℃条件下,硝基苯还原的电流效率接近100%,对氨基苯酚的选择性可达到83%。电解液可循环套用5次,硫酸和氨水的消耗量降至原来的25%,硫酸铵和废水的排放量也减少了75%。采用扩散渗析法回收废弃电解液中的硫酸,以APS为阴离子交换膜,模拟液的流量为0.01 ml·min^-1、温度为20℃时,酸回收率达到61%,且对氨基苯酚和苯胺的透过率分别仅为1.4%和1.6%。

关键词: 硝基苯, 对氨基苯酚, 电化学还原, 电解液循环, 酸回收