Chlorofluorocarbons Montreal Protocol

Recently several patents have been issued (16—18) describing the use of 1,2-dichloroethylene for use in blends of chlorofluorocarbons for solvent vapor cleaning. This art is primarily driven by the need to replace part of the chlorofluorocarbons because of the restriction on their production under the Montreal Protocol of 1987. Test data from the manufacturer show that the cleaning abiUty of these blends exceeds that of the pure chlorofluorocarbons or their azeotropic blends (19). 

The Montreal Protocol of July 1987 resulted in an international treaty in which the industrialized nations agreed to halt the production of most ozone-destroying chlorofluorocarbons by the year 2000. This deadline was hastily changed to 1996, in February 1992, after a U.S. National Aeronautics and Space Administration (NASA) satellite and high-altitude sampling aircraft found levels of chlorine monoxide over North America that were 5i % greater than that measured over Antarctica. 

Recognition of the threat of stratospheric ozone depletion posed by chlorofluorocarbons and chloro-fltiorohydrocarbons led 131 countries to sign the Montreal Protocol in 1987. Production of chlorofluorocarbons was banned as of January 1, 1996, because of their potential to further deplete stratospheric ozone. Chlorofluorohydrocarboiis will be... 

Until recently, chlorofluorocarbons (CFCs) for refrigeration were major end products of HF chemistry, but these compounds are being phased out in accord with the Montreal Protocols because of their effect on the ozone layer (see Chapter 15). 

The Montreal Protocol was initiated in 1987 which required the reduction of production and consumption of chlorofluorocarbons. 

Methane is removed continually from the atmosphere by reaction with OH radicals (Section 8.3). In contrast, chlorofluorocarbons and related volatile compounds are inert under the conditions of the lower atmosphere (troposphere), so atmospheric concentrations of these refrigerants and solvents will tend to increase as long as releases continue. The chief concern over chlorofluorocarbons is that they are a major factor in destruction of the stratospheric ozone layer (Section 8.3). They have been banned under the Montreal Protocol of 1988, but it is important that whatever substitutes (inevitably greenhouse active) are introduced to replace them degrade relatively quickly in the troposphere to minimize any contribution they may be capable of making to greenhouse warming. 

Prior to their current phase-out, chlorofluorocarbons (CFCs) were widely used as processing solvents for various materials. CFCs were well suited for many medical applications owing to their high solvency, nonflammability, good materials compatibility, and low toxicity. The uses for CFCs include a silicone deposition solvent, a fluoropolymer dispersion liquid, and processing solvents. However, the Montreal Protocol phase-out of ozone-depleting substances has required that alternative dispersants and solvents be found. Limitations of most available alternatives include flammability, low volatility, poor solvency, and poor materials compatibility. 

Levels of chlorofluorocarbons in the atmosphere have declined measurably since the implementation of the Montreal Protocol. In light of this success, should further restrictions be placed on the use of chlorofluorocarbons or should we stay the course of the protocol Should certain restrictions, such as those that most dramatically impact the economy, be lifted ... 

All of the chlorofluorocarbons and halons discussed above have been implicated in the halogen atom-catalyzed destruction of atmospheric ozone. As a result of U.S. Environmental Protection Agency regulations imposed in accordance with the 1986 Montreal Protocol on Substances that... 

CFCs CC12F2, CCI3F, CCIF3 chlorofluorocarbons (freons, Freon-12) colourless, odourless gas CFCs are now banned by the Montreal Protocol in the past, were used as refrigerants and aerosols... 

States would spend 160 billion per year on pollution control. In 1996 Ben Lieberman, an environmental research associate with the Competitive Enterprise Institute, estimated that in the United States the cost of the phaseout of chlorofluorocarbons (CFCs) in accordance with the 1987 Montreal Protocol on Substances That Deplete the Ozone Layer could reach 100 billion over the next ten years. Indeed chemical manufacturers had to develop eco-friendly substitutes such as hydrochlorofluorocarbon (HCFC) and hydro-fluorocarbon (HFC), which are more costly to make, and hundreds of millions of pieces of air-conditioning and refrigeration equipment using CFCs had to be discarded. 

The currently marketed MDIs may look similar to the devices that were first developed by Riker in 1950. However, due to the replacement of the ozone-depleting chlorofluorocarbon (CFC) propellants with HFA propellants, virtually all of the components of the MDI have been altered. In 1987, the Montreal Protocol was drawn up, leading to the eventual phase-out of CFC propellants. MDIs contain-... 

Under the agreements of the Montreal Protocol on Substances that Deplete the Ozone Layer, the production of chlorofluorocarbons (CFCs), halons and several other halocarbons has been prohibited [1,2]. Consequently, there is an interest in replacing these compounds [3]. As part of the development of such replacing compounds, it is necessary to consider and evaluate the potential environmental effects of their use, especially on stratospheric ozone [2],... 

For many years chlorofluorocarbons (CFCs) were manufactured in huge quantities by Swarts-type processes but, after the introduction of the Montreal Protocol legislation, these compounds were superseded by non-ozone depleting HFCs (see Chapter 1). Fortunately, much of the chemistry developed for the manufacture of the CFCs can be adapted for the production of HFCs [7, 12-15]. 

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