Ozonolysis can produce long-lived greenhouse gases from commercial refrigerants

Max R McGillen*, Zachary T. P. Fried, M. A. H. Khan, Keith T. Kuwata, Connor M. Martin, Simon O'Doherty, Francesco Pecere, Dudley E Shallcross, Kieran M Stanley, Kexin Zhang

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

2 Citations (Scopus)
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Abstract

Hydrofluoroolefins are being adopted as sustainable alternatives to long-lived fluorine- and chlorine-containing gases and are finding current or potential mass-market applications as refrigerants, among a myriad of other uses. Their olefinic bond affords relatively rapid reaction with hydroxyl radicals present in the atmosphere, leading to short lifetimes and proportionally small global warming potentials. However, this type of functionality also allows reaction with ozone, and whilst these reactions are slow, we show that the products of these reactions can be extremely long-lived. Our chamber measurements show that several industrially important hydrofluoroolefins produce CHF3 (fluoroform, HFC-23), a potent, long-lived greenhouse gas. When this process is accounted for in atmospheric chemical and transport modeling simulations, we find that the total radiative effect of certain compounds can be several times that of the direct radiative effect currently recommended by the World Meteorological Organization. Our supporting quantum chemical calculations indicate that a large range of exothermicity is exhibited in the initial stages of ozonolysis, which has a powerful influence on the CHF3 yield. Furthermore, we identify certain molecular configurations that preclude the formation of long-lived greenhouse gases. This demonstrates the importance of product quantification and ozonolysis kinetics in determining the overall environmental impact of hydrofluoroolefin emissions.
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Original languageEnglish
Article numbere2312714120
JournalProceedings of the National Academy of Sciences of the United States of America
Volume120
Issue number51
DOIs
Publication statusPublished - 11 Dec 2023

Bibliographical note

Funding Information: M.R.M. Gratefully acknowledges support by the Marie Skłodowska-Curie Individual Fellowship HOMER (702794). D.E.S. and M.A.H.K. were supported by NERC (NE/K004905/1), the Primary Science Teaching Trust, and Bristol ChemLabS. K.T.K, C.M.M., and F.P. acknowledge support from the Environmental Chemical Sciences program of the National Science Foundation (CHE-2108202). C.M.M. and K.Z. acknowledge support from the Beltmann Chemistry Research Fund of Macalester College. F.P. acknowledges support from the Collaborative Summer Research Fund of Macalester College.

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