Recovery of platinum-group metals from recycled automotive catalytic converters by carbochlorination

Abstract

The carbochlorination behavior of scrapped honeycomb-type automobile catalysts was investigated using a chlorine and carbon monoxide gas mixture to fully extract platinum and rhodium in the catalysts. The recoveries of platinum, rhodium, and base metals are monitored by ICP-AES analyses. Upflow type of fixed-bed carbochlorination experiments were performed between 250 and 700 degrees C. The effects of flow rate, time, and partial pressures of chlorine and carbon monoxide were also determined. After optimization of these parameters, the recoveries of about 95.9% of platinum and 92.9% of rhodium were obtained at 550 degrees C. The recovered condensate was contaminated by various base metal chlorides; The chlorides generated from the base metals could be minimized by decreasing the flow rate of the gas mixture without any deterioration of PGM recoveries, but at the expense of the volatility. The carbochlorination of scrapped automobile catalysts could be an efficient way for the profitable recovery of platinum and rhodium chlorinated compounds at comparatively low temperatures.