Hydrofluoroolefins

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Structural formula of 1,3,3,3-tetrafluoropropene (HFO-1234ze)

Hydrofluoroolefins (HFO) are unsaturated organic compounds made from hydrogen , fluorine and carbon . These organofluorine compounds are of interest as refrigerants . In contrast to the traditional saturated fluorocarbons (HFCs) and chlorofluorocarbons (CFCs), HFOs are alkenes ( olefins ).

HFO refrigerants into the categories with no ozone depletion potential and low global warming potential classified and thus offer a more environmentally friendly alternative to HFCs and CFCs.

HFO are being developed as a “fourth generation” refrigerant with a share of 0.1% of the global warming potential of PFCs. HFOs currently in use include 2,3,3,3-tetrafluoropropene (HFO-1234yf) and 1,3,3,3-tetrafluoropropene (HFO-1234ze).

The production of HFO takes place almost exclusively using classic, halogenated hydrocarbons , the direct use of which as volatile substances is mostly prohibited by the Montreal Protocol . However, since they are only used for synthesis, this mode of production is possible. It is assumed that 0.5% of the material flows are released, so that although HFO directly have only a slight negative effect on the environment, there may be an indirect ozone or climate damaging effect due to losses during the production process.

Relevant primary degradation products of HFO such as HFO-1234yf or HFO-1336mzz (z) are trifluoroacetic acid (TFA) and carbonyl fluoride . So far, TFA is briefly washed out by precipitation. In this case, TFA has a phytotoxic effect in the environment and an extremely long lifespan in surface waters . But it is also possible that it lingers longer in the atmosphere due to chemical interaction processes with so-called Criegee intermediates , which is currently the subject of current research. Carbonyl fluoride further breaks down into CO 2 and HF .

See also

Individual evidence

  1. ↑ a b HETEROGENEOUS CATALYSIS UNDER MICROWAVE HEATING . In: Società Chimica Italiana (ed.): La Chimica & L'Industria . No. 4, May 2012, p. 22.
  2. ↑ HFO, i nuovi gas refirgerant
  3. ↑ Hydrofluoroolefins (HFOs) , European Fluorocarbons Technical Committee
  4. ↑ Honeywell Sells Novel Low-Global-Warming Blowing Agent To European Customers , Honeywell press release, Oct. 7, 2008.
  5. ↑ Martyn P. Chipperfield, Ryan Hossaini, Stephen A. Montzka, Stefan Reimann, David Sherry, Susann Tegtmeier: Renewed and emerging concerns over the production and emission of ozone-depleting substances . In: Nature Reviews Earth & Environment . tape 1 , no. 5 , May 2020, p. 251-263 , doi : 10.1038 / s43017-020-0048-8 .
  6. ↑ Freja F. Østerstrøm, Simone Thirstrup Andersen, Theis I. Sølling, Ole John Nielsen, Mads P. Sulbaek Andersen: Z- and E-CF 3 CH = CHCF 3 . In: Physical Chemistry Chemical Physics . tape 19 , no. 1 , 2017, p. 735-750 , doi : 10.1039 / C6CP07234H .
  7. ^ Federal Office for the Environment FOEN: Vienna Convention and Montreal Protocol. Retrieved May 6, 2019 .
  8. ↑ Rayne Holland, M. Anwar H. Khan, Rabi Chhantyal-Pun, Andrew J. Orr-Ewing, Carl J. Percival, Craig A. Taatjes, Dudley E. Shallcross: Investigating the Atmospheric Sources and Sinks of Perfluorooctanoic Acid Using a Global Chemistry Transport Model . In: Atmosphere . tape 11 , no. 4 , April 19, 2020, p. 407 , doi : 10.3390 / atmos11040407 .