Effect of NaCl precipitation on vapour–liquid dechlorination of CHClF2

Abstract

AbstractA dechlorination process for chlorinated compounds such as the chlorinated fluorocarbons (CFCs) is proposed. In this process, CFCs are dissolved in alcohols and irradiation with UV promotes their decomposition at room temperature and atmospheric pressure. Remarkably, irradiation is unnecessary to decompose chlorodifluoromethane, CHClF2 (HCFC22 or R22), which gives NaCl and 1,1‐difluorodimethyl ether CH3OCHF2 as products. In this work, experiments were carried out on the vapour–liquid reaction to produce the fluoroether CH3OCHF2 from HCFC22. The reaction was found to have no side reactions. The initial decomposition rate obtained from experimental results indicated that the reaction rate was proportional to the concentration of both NaOH and dissolved HCFC22. However, as the reaction proceeded, the reaction rate decreased more than expected from the initial reaction rate. Assuming that the produced NaCl precipitation created poor mixing of the methanol solutions, the volumetric coefficient KLa was measured and a model developed based on mass transfer relations. Calculated results showed that the model qualitatively agreed with the reaction rate data.© 2003 Society of Chemical Industry