The development of environmentally acceptable fluorocarbons

Abstract

Chlorofluorocarbons (CFCs) were introduced in the 1930s as the safe replacements for the toxic and flammable refrigerants being used at that time. Subsequently, hydrochlorofluorocarbons (HCFCs) were also developed. In addition to refrigerant applications, they were used as foam blowing agents, as solvents and as propellants for many aerosols. In the 1970s and 1980s, concern developed about their environmental impact, specifically on stratospheric ozone depletion. Industry began to consider acceptable replacements. In 1987, many of the governments of the world came together and drafted the Montreal Protocol, calling upon Industry to initially phase out production of the CFCs and later HCFCs. Within 4 months of the signing of the Montreal Protocol, the 15 global major producers joined together to form the Alternative Fluorocarbons Environmental Acceptability Study (AFEAS), which sponsored research into environmental effects and the Program for Alternative Fluorocarbons toxicity Testing, PAFT), which examined the toxicology of potential replacements for the CFCs and HCFCs. Nine replacements were identified by companies and, through this international cooperation; toxicology programs were designed, conducted, and evaluated without duplication of effort and testing; consequently these new products were introduced within less than 10 years. Indeed the Montreal Protocol has been recognized as the most appropriate international treaty to phase-down HFCs. In 2016 the Kigali Amendment to the Montreal Protocol set out a phase-down schedule for the consumption and production of HFCs. In order to reduce the consumption and emissions of high GWP HFCs. Recently lower GWP HFCs and very low GWP HFOs (hydrofluoroolefins and HCFOs (hydrochlorofluoroolefins) have been introduced into a range of applications. Summaries of the toxicology profiles of some of the original CFCs and HCFCs, the replacements and the new post-PAFT replacements are described.

United Nations Sustainable Development Goals as a Thematic Framework for an Introductory Chemistry Curriculum

“…When the ability of CFCs to catalytically destroy the ozone layer was first suggested by Molina and Rowland and later confirmed, CFCs were initially replaced by gases with lower ODPs, then by gases with negligible ODPs but high GWPs, and most recently by gases with zero ODPs and negligible GWPs by virtue of their short resident atmospheric lifetimes. These are all properties that can be rationalized in terms of the chemical structures and relative bond strengths of these compounds. − The activity therefore offers a rich demonstration of Holme’s “chemicals have benefits and hazards” central learning outcome, a concept upon which students are asked to reflect at the end of the activity. This case study demonstrates how even relatively simple introductory chemistry concepts permit a sophisticated understanding of an interdisciplinary topic with relevance to multiple UN SDGs: (3) Good Health and Well-Being, (9) Industry, Innovation and Infrastructure, (11) Sustainable Cities and Communities, (12) Responsible Consumption and Production, (13) Climate Action, and (15) Life on Land.…”

Difluoromethane (HFC-32) and Pentafluoroethane (HFC-125) Sorption on Linde Type A (LTA) Zeolites for the Separation of Azeotropic Hydrofluorocarbon Refrigerant Mixtures

“…Recent legislation restricting the use of HFCs includes the Kyoto Protocol in 2005, 7 European Union in 2014, 7 and the Kigali Amendment to the Montreal Protocol in 2016. 8 The most recent legislation, the U.S. American Innovation and Manufacturing (AIM) Act passed by Congress and signed by the President in December 2020, requires the phase down of HFC production and consumption by 85% in the next 15 years. 9 There is currently an estimated 2800 ktonnes of refrigerant in use globally.…”

“…For example, HFC-134a is frequently used in mobile air conditioning and as a foam blowing agent with a GWP of 1430. , HFCs are currently being regulated because of high GWPs. Recent legislation restricting the use of HFCs includes the Kyoto Protocol in 2005, F-gas regulations by the European Union in 2014, and the Kigali Amendment to the Montreal Protocol in 2016 . The most recent legislation, the U.S. American Innovation and Manufacturing (AIM) Act passed by Congress and signed by the President in December 2020, requires the phase down of HFC production and consumption by 85% in the next 15 years…”

Self-foaming polymers: Opportunities for the next generation of personal protective equipment

“…[34] These ozone depleting substances are however responsible for the major environmental crises of the last century: the ozone hole. [35] The Montreal protocol (1987) has banned the use of CFCs [36] and the latter have been replaced by hydrofluorocarbons (HFCs) that do not harm the ozone layer as much as CFCs. With thousands of times the global warming potential of CO2, they will be gradually phased-out over the next 20 years by amendment of the Montreal protocol.…”