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The C2 chlorinated solvents that have major commercial significance are perchloroethylene (PCE), trichloroethylene (TCE), and 1,1,1-trichloroethane or methyl chloroform (TCA). Consumption of these solvents has been negatively impacted by declines in emissive applications as a result of regulations related to the 1987 Montreal Protocol on ozone depleting chemicals and the 1997 Kyoto Protocol on global warming and climate change. Use of TCA has been phased out in most countries because of its ozone depletion potential (ODP) in the upper atmosphere. Consequently, global consumption of all three solvents is primarily for use as a feedstock in the production of fluorocarbons.
Over the past two decades, the global fluorocarbons market has undergone a number of major transitions toward a greater use of non-ozone-depleting HFCs and non-global-warming, nonfluorocarbon alternatives in emissive applications. Consumption in the largest market segment, refrigeration and air-conditioning, was negatively impacted by both Montreal and Kyoto Protocol amendments and legislation and there are current and proposed regulations limiting the future production, consumption and trade of CFCs, HCFCs and HFCs.
The following chart shows world production and consumption of the three major C2 chlorinated solvents as a percentage of the world total:
Global consumption of C2 chlorinated solvents has decreased significantly for emissive uses (e.g., dry cleaning and metal cleaning) in the last twenty years. Governments in all major industrialized regions have set strict standards limiting the exposure of workers and the environment to these potentially hazardous compounds. The presence of chlorinated solvents in groundwater remains problematic. Furthermore, 1,1,1-TCA is considered an ozone depleter and its use for emissive applications has been almost totally banned around the world. It is still being used as an intermediate in the production of fluorocarbons, pharmaceuticals and other small applications.
Currently, the largest use for all three C2 chlorinated solvents is as feedstocks for fluorocarbons. PCE has historically been used to make the chlorofluorocarbons CFC-113, CFC-114 and CFC-115. This end use has almost totally disappeared, as emissive uses of these materials have been banned in most countries because of their contribution to ozone depletion. In the United States both PCE and TCE are used to make hydrofluorocarbon-134a (HFC-134a), which is the most popular alternative to CFC-12 refrigerant in car air-conditioning systems. Lesser quantities of PCE and TCE are used for production of HCFC-123, HCFC-124 and HFC-125. PCE is used in Japan to produce HFC-134a, while TCE is used in Western Europe. HFC-125 consumption is growing as a replacement for HFC-134a, which will be banned in Europe after 2017.
1,1,1-TCA is used principally to make HCFC-141b and HCFC-142b, and HFC-143a. Countries like China and India have agreed to cease use of 1,1,1-TCA and CFCs no later than 2010. China phased out CFCs in 2008, and remains ahead of schedule. The use of 1,1,1-TCA was banned in the United States in 2003 for emissive uses.
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