Tfa generation and deposition over Europe may currently see a greater influence from hfo-1234yf than hfc-134a

Abstract

Concerns around the prevalence of trifluoroacetic acid (TFA, CF3COOH) in the environment have been ongoing for more than 20 years. One source of TFA to the environment is via the atmospheric degradation of fluorinated gases (F-gases) to TFA and its subsequent deposition. During the past decade, controls on one major class of F-gases, hydrofluorocarbons (HFCs), have resulted in an increase in the production and use of hydrofluoroolefins (HFOs). Here, a tropospheric chemical transport model, STOCHEM-CRI, is used to compare the amount of TFA generated by the breakdown of an abundant HFC, HFC-134a (1,1,1,2-tetrafluoroethane, CF3CH2F), and its typical replacement, HFO-1234yf (2,3,3,3-tetrafluoropropene, CH2═CFCF3). Using derived global emission estimates for 2023, we predict that HFO-1234yf is already dominating atmospheric generation and deposition of TFA over Europe when compared with HFC-134a. This is despite the fact that the derived global emissions of HFC-134a are 22 times higher than those of HFO-1234yf. Globally, our simulations show that TFA production from HFO-1234yf is already equivalent to 26–75% of the TFA production from HFC-134a. As the transition away from HFCs progresses, it is likely that HFO-1234yf will continue to increase in its global contribution to TFA generation and resultant environmental contamination.