對苯二甲酸生產工廠，使用液態鈷錳溴化物為觸媒，廢觸媒隨廢氣燃燒後累積於飛灰中。此種飛灰在經硫酸溶液酸洗浸漬後，萃取溶液含有豐富的鈷離子、錳離子等，及其他石油原料而來的少量雜質。本硏究使用電化學還原法，將廢觸媒飛灰酸洗液中回收產製高純度鈷金屬，酸性浸漬液中成份複雜，此外電解還原鈷離子於酸性硫酸溶液中進行，主要副反應為氫離子還原，為了抑制此反應之發生，電解時間、電流密度、電解液酸鹼值與電解槽設計等，皆關鍵影響整體電流效率，本研究將評估實用化之操作條件及未來建廠之可行性。

The terephthalic acid production plant uses liquid cobalt manganese bromide as a catalyst. The waste catalyst is burned with the exhaust gas and accumulated in the fly ash. After the fly ash is pickled and impregnated with sulfuric acid solution, the extraction solution is rich in cobalt ions, manganese ions, etc., and a small amount of impurities from other petroleum raw materials. In this study, the electrochemical reduction method was used to purify and recover cobalt metal from the waste catalyst fly ash pickling solution. The composition of the acid impregnation solution is complicated. In addition, the electrolytic reduction of cobalt ions is carried out in sulfuric acid solution, and the main side reaction is hydrogen ion reduction. In order to suppress the occurrence of this reaction, the key conditions that affect current efficiency are electrolysis time, current density, electrolyte pH and electrolytic cell design. This study can evaluate the practical operating conditions and the feasibility of building a factory in the future.