ABSTRACT

It is urgent to develop a high-efficient process for recycling the spent mercuric chlorides catalyst (SMC) from vinyl chloride monomer (VCM) production with the implementation of the ‘Minamata Convention on mercury’. A ultrasound and microwave-assisted technology were developed to treat SMC in this study. Firstly, organic carbon deposition was separated from SMC by pretreatment (ultrasonic-assisted ethanol extraction). The optimized extraction conditions were: ultrasonic time 2 h, ultrasonic power 700 W, extraction temperature 65°C, and liquid–solid ratio 7:1. Under these conditions, 90% of hazardous Cl-containing organics were separated from SMC. Then the pretreated SMC was treated by microwave heating for mercury removal. Residual mercury concentration of SMC decreased from original 1.33% to only 11.92 mg/kg at the preferred conditions of 500°C for 60 min and the treated SMC passed the Toxicity Characteristics Leaching Procedure (TCLP) test. Simultaneously, catalyst support activated carbon (AC) was regenerated with specific surface area increasing from original 263.85 to 627.5 m²/g. The organics from macropores and surface of AC was removed by pretreatment, intensifying the subsequent Hg removal and regeneration of AC as revealed by the comparative studies. Finally, SMC was subjected to water leaching for recovering metal values. 88.7% of Ba and 95.3% of Ce were leached with ultrasonic power 500 W and ultrasonic time 120 min. SMC was detoxified and valuable components Hg, AC, Ba, Ce were recovered by this new process, which may provide a new idea for industrial treatment of SMC.

摘要

随着《关于汞的水俣公约》的实施，迫切需要开发一种高效回收氯乙烯单体 (VCM) 生产中的废氯化汞催化剂 (SMC) 的工艺。本研究开发了一种超声和微波辅助技术来治疗 SMC。首先，通过预处理（超声波辅助乙醇提取）从 SMC 中分离出有机碳沉积物。优化的提取条件为：超声时间2 h，超声功率700 W，提取温度65 ℃，液固比7:1。在这些条件下，90% 的有害含氯有机物从 SMC 中分离出来。然后通过微波加热处理预处理的SMC以去除汞。SMC 的残留汞浓度从原来的 1.33% 下降到只有 11。92 mg/kg 在 500°C 的优选条件下持续 60 分钟，并且处理过的 SMC 通过了毒性特征浸出程序 (TCLP) 测试。同时，催化剂载体活性炭（AC）得到再生，比表面积从原来的 263.85 增加到 627.5 m² /克。对比研究表明，预处理去除了活性炭大孔和表面的有机物，加强了活性炭的后续除汞和再生。最后，SMC 进行水浸出以回收金属价值。超声功率500 W，超声时间120 min，浸出88.7%的Ba和95.3%的Ce。该新工艺对SMC进行了脱毒处理，并回收了有价值的组分Hg、AC、Ba、Ce，为SMC的工业化处理提供了新思路。