Hydrofluorocarbons zero ozone depletion potential

The CFC replacements need to be nontoxic, nonflammable and have significantly lower, or zero ozone depletion potentials. Many organic- and aqueous-based systems, that do not contain chlorine or fluorine, have been developed for some applications while others use hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). Unlike hydrocarbon catalysis, the presence of hydrogen, chlorine and fluorine in the same molecule creates a very large number of... 

Industry is seeking high yield, zero waste processes. Companies are evaluating the replacement of some base metal catalysts by more selective precious metal catalysts to eliminate troublesome by-product formation and/or contaminated waste waters. In the case of Chlorofluorocarbons (CFC s) industry is trying to develop cost effective processes to manufacture non-toxic Hydrofluorocarbons (HFC s) of zero ozone depleting potential to replace existing CFC s. 

Hydrofluorocarbons ("HFCs") consist of molecules containing only atoms of hydrogen, fluorine and carbon and were known at the time of the Montreal Protocol to have effectively zero ozone depletion potential (ODP). Following the Montreal Protocol, many participants in the refrigerant manufacturing and end-user industries therefore looked towards HFCs as replacements for CFCs across a range of applications. R-134a is one such HFC. 

Vertrel KCD-9547 is a proprietary azeotrope-like blend of Vertrel XF hydrofluorocarbon with trans-1,2-dichioro-ethylene and cyclopentane. It is ideally suited for use in vapor degreasing equipment to remove light oils, fingerprints, and particulate contaminants. Vertrel KCD-9547 is specially formulated to provide a high degree of compatibility with plastics, elastomers, and other nonferrous metals, such eis in aerospace parts. Vertrel KCD-9547 is nonflammable, has "zero" ozone depletion potential, and heis low global warming potential. It can replace CFC-113,1,1,1 -trichloroethane (1,1,1 -TCA), hydrochlorofluorocarbons (HCFC), and perfluorocarbons (RFC) in many applications. 

An important outcome of this work has been the formulation of the ozone depletion potentials (ODPs) for chlorine-containing fluids. Arbitrarily. CFC-11 is assigned an ODP of unity the ODPs of other fluids are normalized to that of CFC-11 on a mass-for-mass basis. Important factors in determining the ODP of a fluid include its atmospheric lifetime and the quantity of chlorine it contains. Hydrochlorofluorocarbons (HCFCs) have much lower ODPs than CFCs—a consequence mainly of the former s lower atmospheric lifetimes. Hydrofluorocarbons (HFCs), which by definition contain no chlorine, have zero ODPs. 

One technical approach to solve this environmental problem is to eliminate the chlorine content of CFCs, primarily by replacing any chlorine atoms with fluorine atoms in these molecules. Hydrochlorofluorocarbons (HCFC s) do not have inqtact zero on the ozone layer and although they have been used in this period, they are already currently subject to restrictions and will be proscribed fi-om 2025. Hydrofluorocarbons (HFC s) have ODP (Ozone Depletion Potential) equal to zero and low GWP (Global Warming Potential) and they are therefore designated as substitutes to CFCs in the field of refijgeration [3]. 

For the last two decades, attention has been focused on redressing the ozone depletion in the earth s protective layer. It is believed that chlorine radicals dissociated from chlorofluorocarbons (CFCs), upon irradiation of sun s UV in the stratosphere, promotes the ozone depletion. Hence, in addition to development of CFC alternatives there is an urgent need for the safe disposal of CFCs. Several processes such as pyrolysis, incineration, photocatalysis, oxidative destruction over metal oxide or zeolite catalysts and destruction at very high temperatures ( by plasma technique ) are reported in the literature for the disposal of CFCs[ 1-5]. But all these processes yield harmful products like CO, HF/F2 etc. Catalytic conversion of chlorinated organics in presence of hydrogen seems to be a better technique as it yields either hydrofluorocarbons(HFCs) or hydrochlorofluorocarbons(HCFCs) whose ozone depletion potential is either zero or very low and yet most of these products act as CFC alternatives. 

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