The mechanism and kinetics of the atmospheric oxidation of CF(CF)CH&z.dbd;CH (HFC-1447fz) by hydroxyl radicals: investigation

• Published in: Physical chemistry chemical physics : PCCP Vol. 26; no. 14; pp. 1989 - 1997
• Main Authors: Yu, Youqing, Pan, Li, Sun, Qiyao, Wang, Jie
• Format: Journal Article
• Published: 03.04.2024
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d3cp06149c

The oxidation of 3,3,4,4,5,5,5-heptafluoro-1-pentene (HFC-1447fz) by hydroxyl radicals plays a crucial role in atmospheric conditions. By employing the CCSD(T)/cc-pVTZ//M06-2X/6-311++G(d,p) level of theory, the detailed reaction mechanism, kinetics and atmospheric implications of the degradation of HFC-1447fz by hydroxyl radicals were investigated. Compared to H-abstraction channels, the OH addition reaction is determined to be more favorable initial pathways in the degradation processes of HFC-1447fz. The overall rate coefficient of the degradation of HFC-1447fz by OH radicals is estimated to be 1.66 × 10 −12 cm 3 molecule −1 s −1 and the lifetime of HFC-1447fz is found to be 7 days at 298 K, which are in good agreement with the reported experimental results. The global warming potential (GWP) for HFC-1447fz on the 50, 100 and 500-year time horizons is estimated using the calculated rate coefficient. Furthermore, the mechanisms of the subsequent reactions of two OH-addition adducts have also been investigated. By TD-DFT calculations, it was found that eleven species can undergo photodissociation, while ten other species are photolytically stable under sunlight. The reported results of the degradation mechanism of 3,3,4,4,5,5,5-heptafluoro-1-pentene (HFC-1447fz) by hydroxyl indicate HFC-1447fz has insignificant effects on radiative forcing and climate change relative to its analogous compounds.