Environmental assessment of CFC alternatives

Tokuhashi, Kazuaki; Chen, Liang; Kutsuna, Shuzo; Uchimaru, Tadafumi; Sugié, Masaaki; Sekiya, Akira

doi:10.1016/j.jfluchem.2004.09.013

Cited by 19 publications

(18 citation statements)

References 16 publications

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“…[5] HFC-227ea (CF 3 CHFCF 3 , 1,1,1,2,3,3,3-heptafluoropropane) is mainly used as a fire retardant, replacing halon-1301 (CF 3 Br), and as a propellant in metered-dose inhalers (MDIs) [UNEP Technology and Economic Assessment Panel, 2010]. Its atmospheric lifetime is estimated to be 38.9 years (Table 1) based on a considerable body of literature [Nelson et al, 1993;Zellner et al, 1994;Zhang et al, 1994;Tokuhashi et al, 2004;Hsu and DeMore, 1995;Wallington et al, 2004]. It has a GWP of 3220 on a 100 year time frame [Forster et al, 2007].…”

Section: Introductionmentioning

confidence: 99%

Atmospheric histories and global emissions of the anthropogenic hydrofluorocarbons HFC-365mfc, HFC-245fa, HFC-227ea, and HFC-236fa

et al. 2011

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-hexafluoropropane). In situ measurements are from the global monitoring sites of the Advanced Global Atmospheric Gases Experiment (AGAGE), the System for Observations of Halogenated Greenhouse Gases in Europe (SOGE), and Gosan (South Korea). We include the first halocarbon flask sample measurements from the Antarctic research stations King Sejong and Troll. We also present measurements of archived air samples from both hemispheres back to the 1970s. We use a two-dimensional atmospheric transport model to simulate global atmospheric abundances and to estimate global emissions. HFC-365mfc and HFC-245fa first appeared in the atmosphere only ∼1 decade ago; they have grown rapidly to globally averaged dry air mole fractions of 0.53 ppt (in parts per trillion, 10 −12 ) and 1.1 ppt, respectively, by the end of 2010. In contrast, HFC-227ea first appeared in the global atmosphere in the 1980s and has since grown to ∼0.58 ppt. We report the first measurements of HFC-236fa in the atmosphere. This long-lived compound was present in the atmosphere at only 0.074 ppt in 2010. All four substances exhibit yearly growth rates of >8% yr −1 at the end of 2010. We find rapidly increasing emissions for the foam-blowing compounds HFC-365mfc and HFC-245fa starting in ∼2002. After peaking in 2006 (HFC-365mfc: 3.2 kt yr −1 , HFC-245fa: 6.5 kt yr −1 ), emissions began to decline. Our results for these two compounds suggest that recent estimates from long-term projections (to the late 21st century) have strongly overestimated emissions for the early years of the projections (∼2005-2010). Global HFC-227ea and HFC-236fa emissions have grown to average values of 2.4 kt yr −1 and 0.18 kt yr −1 over the 2008-2010 period, respectively.

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Section: Introductionmentioning

confidence: 99%

Atmospheric histories and global emissions of the anthropogenic hydrofluorocarbons HFC-365mfc, HFC-245fa, HFC-227ea, and HFC-236fa

et al. 2011

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“…Hence, it is important to study the kinetics and mechanistic degradation pathways of HFEs in troposphere for complete assessment of its atmospheric chemistry as well as its impact on global warming and climate change. Considerable attention has been paid in recent years to perform experimental and theoretical studies on the reactivity of HFEs with OH radicals and Cl atoms . In present work, we have studied the mechanism and kinetics of H‐abstraction reaction from CF 3 CF 2 CF 2 OCH 3 with OH radicals and Cl atoms using density functional theory (DFT) methods.…”

Section: Introductionmentioning

confidence: 99%

“…Considerable attention has been paid in recent years to perform experimental and theoretical studies on the reactivity of HFEs with OH radicals and Cl atoms. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] In present work, we have studied the mechanism and kinetics of H-abstraction reaction from CF 3 CF 2 CF 2 OCH 3 with OH radicals and Cl atoms using density functional theory (DFT) methods. Our calculations suggest that only one reaction channel is feasible for CF 3 CF 2 CF 2 OCH 3 + OH/Cl reactions as given below.…”

Section: Introductionmentioning

confidence: 99%

Theoretical studies on atmospheric chemistry of HFE-347mcc3: reactions with OH radicals and Cl atoms

Mishra

Lily

Chandra

et al. 2014

J. Phys. Org. Chem.

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Detailed theoretical investigation has been performed on the mechanism, kinetics and thermochemistry of the gas phase reactions of CF 3 CF 2 CF 2 OCH 3 (HFE-347mcc3) with OH radicals and Cl atoms using M06-2X/6-31 + G(d,p) level of theory. Reaction profiles are modeled including the formation of pre-reactive and post-reactive complexes at entrance and exit channels, respectively. Using group-balanced isodesmic reactions, the standard enthalpies of formation for species are also reported. The calculated bond dissociation energy for C-H bond is in good agreement with previous data. The rate constants of the two reactions are determined for the first time in a wide temperature range of 250-1000 K. At 298 K, the calculated rate coefficients are in good agreement with the experimental results. The atmospheric life time of HFE-347mcc3 is estimated to be 4.4 years.

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“…As the second generation of CFC alternatives, hydrofluorocarbons (HFCs) were newly introduced, but soon turned out to possess high GWP [5,6]. For this reason, a number of silicone, nitrogen, and oxygen-containing molecules with zero ODP and low GWP were proposed as the third generation CFC alternatives [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Fluoride-catalyzed hydroalkoxylation of hexafluoropropene with 2,2,2-trifluoroethanol

Natalia

Nguyen

et al. 2008

Journal of Fluorine Chemistry

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Environmental assessment of CFC alternatives

Cited by 19 publications

References 16 publications

Atmospheric histories and global emissions of the anthropogenic hydrofluorocarbons HFC-365mfc, HFC-245fa, HFC-227ea, and HFC-236fa

Atmospheric histories and global emissions of the anthropogenic hydrofluorocarbons HFC-365mfc, HFC-245fa, HFC-227ea, and HFC-236fa

Theoretical studies on atmospheric chemistry of HFE-347mcc3: reactions with OH radicals and Cl atoms

Fluoride-catalyzed hydroalkoxylation of hexafluoropropene with 2,2,2-trifluoroethanol

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