Atmospheric chemistry of perfluorocyclopentene (cyc-CF2CF2CF2CF=CF−): Kinetics, products and mechanism of gas-phase reactions with OH radicals, and atmospheric implications

Abstract

As a high-profile etching gas, perfluorocyclopentene (cyc-CF2CF2CF2CF=CF−) should be assessed for its atmospheric chemistry and environmental impact prior to expanding its industrial applications. However, the corresponding studies have been limited. In this study, the rate constants for the gas-phase reactions of cyc-CF2CF2CF2CF=CF− with OH radicals were determined by a relative rate method, and shown to be consistent with a theoretical computational results: k1-exp.(298 K) = (4.43 ± 0.10) × 10−14, k1-cal.(298 K) = 4.3 × 10−14, and k1-exp.(253–328 K) = (3.39 ± 0.86) × 10−13 exp(–(616 ± 78)/T) cm3 molecule−1 s−1. The atmospheric lifetime of cyc-CF2CF2CF2CF=CF− is 0.715 year, and its photochemical ozone creation potential is 0.48. Furthermore, the products and mechanism of the OH radical-initiated oxidation reactions were studied for the first time. The major products COF2, CO2, CO, and FC(O)OH are considered to have a negligible environmental effect. The radiative efficiency was determined as 0.246 W m−2 ppb−1, and the global warming potentials (GWPs) with 20-, 100-, and 500- year time horizon were estimated as 188, 51, and 15, respectively. The GWP100 value is significantly lower than those of the replacing targets (6630, 11100, 16 100, 23 500, and 9540 for CF4, C2F6, NF3, SF6, and c-C4F8, respectively).