Chlorine gas recovery from polyvinyl chloride

Hydrogen chloride, evolved from polyvinyl chloride by heating at 533 K, was fixed by metal oxides at 533-673 K to form the corresponding metal chlorid es. The metal chlorides thus formed were calcined at 623-723 K under an oxy gen flow in order to recover chlorine gas and to regenerate the metal oxide s. Among the metal oxides employed, cobalt oxide was the most effective bot h for the fixation and release of chloride ions. With the iterative use of cobalt oxide for HCl fixation at 573 K and subsequent Cl-2 release at 673 K , the amount of chloride ions fixed by cobalt oxide powder decreased to one -fifth of those fixed by the fresh cobalt oxide. This is due to the decreas e in the BET surface area of cobalt oxide caused by the iterative use. (C) 1999 Elsevier Science B.V. All rights reserved.