### Request to Use an Alternate GWP for

Perfluorotriamyl Amine (PTAA) (CAS Number: 338-84-1 )

Summary:

This document describes analysis conducted by 3M to determine a Global Warming Potential (GWP) for HFE-7500. The format of this report is c onsistent with submittals to EPA for the use of Provisional GWPs. The Mandatory Reporting R ule requires facilities to monitor and report CO 2 -equivalent F-GHG process vent emissions, if those emissions exceed a threshold of 10,000 metric tons CO 2 -equivalent per year. [1] Estimated CO 2 -equivalent emissions are obtained by multiplying the F-GHG mass emissions by the Global Warming Potential (GWP) for the individual fluorinated gases that comprise the flow. EPA has provided a table of 100- year time horizon GWP values for about 70 individua l F-GHG, and specifies that these values are to be used for the purpose of computing CO 2 -equivalent emissions. [2] Default GWPs can be used for any fluorinated-GHG not listed in Table A-1. The regulation allows a facility to request a lower provisional GWP when cl ear scientific evidence exists to support
such a lower value.

Table A–1 does not list a GWP for perfluorotriamyl amine (PTAA). As described in greater detail in a subsequent section, the atmospheric lif etime of perfluorotriamyl amine has been estimated as 2000 years; the radiative forcing has been estimated using a QSAR and the GWP of perfluorotriamyl amine has been estimated as 8900 relative to CO 2 with a 100-year integration time horizon.

Evidence Supporting Request:

F-GHG Identity: perfluorotriamyl amine (PTAA)

Chemical Formula: C 15 F 33 N

CAS Number: 338-84-1

Estimated GWP: 8900 relative to CO 2 with a 100-year integration time horizon

Data and analysis: Molina et al. have measured kinetic rate constants for the vapor phase reaction of perfluorotriethyl amine with OH and O( 1 D) [3], and have estimated the atmospheric lifetime as >2000 years. The atmospher ic lifetime of perfluorotriamyl amine was estimated as 2000 years based on the physical/c hemical similarity with respect to the mode of atmospheric degradation between of perfluor otriethyl amine and perfluortriamyl amine. Both compounds are in the same class of com pounds, namely perfluorinated amines and differ only in perfluorinated alkyl chain lengt h.

Radiative forcing was estimated using a QSAR model developed by 3M specifically for perfluorinated amines using measured data for perfl uorinated amines as a QSAR model input. In one QSAR the estimated forcing of PTAA ( (C 5 F 11 ) 3 N) was estimated from the radiative forcing of PTPA (0.71 Wm -2 ppbV -1 ) plus the forcing of 12 perfluoropropane C-F bonds (12 × 0.03 = 0.36 Wm -2 ppbV -1 ) to yield a radiative forcing 1.1 Wm -2 ppbV -1 . In the second QSAR the radiative forcing was estimated fro m radiative forcing of PTBA (1.05 Wm

2 ppbV -1 ) plus the forcing of 6 perfluoropropane C-F bonds (6 × 0.03 = 0.18 Wm -2 ppbV -1 ) toyield a radiative forcing of 1.2 Wm -2 ppbV -1 . The average of these two radiative forcing

estimates and rounding to two significant figures g ives a radiative forcing of 1.2 Wm -2 ppbV -1

for PTAA.

Using these data in the equation referenced by the IPCC [4] to determine the GWP of a given substance, a GWP of 8900 relative to CO 2 with a 100-year integration time horizon was
established.

1. "Mandatory Reporting of Greenhouse Gases: Additiona l Sources of Fluorinated GHGs;
Final Rule" , Federal Register 75:230 (December 1, 2010) p.7477 4.

2. "Table A-1 to Subpart A of Part 98—Global Warming P otentials" : Table A-1 in 40 CFR part 98, subpart A.

3. Tang, Yi, Atmospheric Fate of Various Fluorocarbons . Master’s Thesis, Massachusetts Institute of Technology, Cambridge, MA



### . 4. IPCC, 2007: Climate Change 2007: Impacts, Adapt ation and Vulnerability. Contribution of Working Group II to the Fourth Assessment. Repor t of the Intergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Pal utikof, P.J. van der Linden and C.E. Hanson, Eds., Cambridge University Press, Cambridge , UK, 976pp