Atmospheric Chemistry of (CF3)2CF–CN: A Replacement Compound for the Most Potent Industrial Greenhouse Gas, SF6

• Published in: Environmental science & technology 2017-02, Vol.51 (3), p.1321-1329
• Main Authors: Sulbaek Andersen, Mads P, Kyte, Mildrid, Andersen, Simone Thirstrup, Nielsen, Claus J, Nielsen, Ole John
• Format: Article
• Language: English
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.6b03758

FTIR/smog chamber experiments and ab initio quantum calculations were performed to investigate the atmospheric chemistry of (CF3)2CFCN, a proposed replacement compound for the industrially important sulfur hexafluoride, SF6. The present study determined k(Cl + (CF3)2CFCN) = (2.33 ± 0.87) × 10–17, k(OH + (CF3)2CFCN) = (1.45 ± 0.25) × 10–15, and k(O3 + (CF3)2CFCN) ≤ 6 × 10–24 cm3 molecule–1 s–1, respectively, in 700 Torr of N2 or air diluent at 296 ± 2 K. The main atmospheric sink for (CF3)2CFCN was determined to be reaction with OH radicals. Quantum chemistry calculations, supported by experimental evidence, shows that the (CF3)2CFCN + OH reaction proceeds via OH addition to −C­(N), followed by O2 addition to −C­(OH)N·, internal H-shift, and OH regeneration. The sole atmospheric degradation products of (CF3)2CFCN appear to be NO, COF2, and CF3C­(O)­F. The atmospheric lifetime of (CF3)2CFCN is approximately 22 years. The integrated cross section (650–1500 cm–1) for (CF3)2CFCN is (2.22 ± 0.11) × 10–16 cm2 molecule–1 cm–1 which results in a radiative efficiency of 0.217 W m–2 ppb–1. The 100-year Global Warming Potential (GWP) for (CF3)2CFCN was calculated as 1490, a factor of 15 less than that of SF6.