Fluoroform (CHF3) Production from CF3CHO Photolysis and Implications for the Decomposition of Hydrofluoroolefins and Hydrochlorofluoroolefins in the Atmosphere

Joshua D Thomson; Jyoti S Campbell; Ethan B Edwards; Christopher Medcraft; Klaas Nauta; Maria Paula Pérez-Peña; Jenny A Fisher; David L Osborn; Scott H Kable; Christopher S Hansen

doi:10.1021/jacs.4c11776

Fluoroform (CHF₃) Production from CF₃CHO Photolysis and Implications for the Decomposition of Hydrofluoroolefins and Hydrochlorofluoroolefins in the Atmosphere

J Am Chem Soc. 2024 Dec 23. doi: 10.1021/jacs.4c11776. Online ahead of print.

Affiliations

¹ School of Chemistry, University of New South Wales, Kensington, NSW 2052, Australia.
² National Marine Science Centre, Southern Cross University, Coffs Harbour, NSW 2450, Australia.
³ Centre for Atmospheric Chemistry, School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW 2522, Australia.
⁴ Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States.
⁵ Department of Chemical Engineering, University of California, Davis, California 95616, United States.

PMID: 39714911
DOI: 10.1021/jacs.4c11776

Abstract

Hydrofluoroolefins (HFOs) and hydrochlorofluoroolefins (HCFOs) are the leading synthetic replacements for compounds successively banned by the Montreal Protocol and amendments. HFOs and HCFOs readily decompose in the atmosphere to form fluorinated carbonyls, including CF₃CHO in yields of up to 100%, which are then photolyzed. A long-standing issue, critical for the transition to safe industrial gases, is whether atmospheric decomposition of CF₃CHO yields any quantity of CHF₃ (HFC-23), which is one of the most environmentally hazardous greenhouse gases. This comprehensive experimental investigation employs purpose-built photoionization mass spectrometry, Fourier-transform infrared, and microwave spectroscopy techniques and confirms production of CHF₃ following excitation at a tropospherically relevant wavelength (λ = 308 nm) and under atmospheric pressure conditions. Pressure-dependent CHF₃ quantum (Φ) and molar (Y) yields are reported from Φ = Y = 0.16 ± 0.03 under collision-free conditions to Φ = (2.3 ± 0.3) × 10^-4, Y = (1.17 ± 0.27) × 10^-3 at 1 bar N₂.