### Global Warming Potential

Perfluorotributyl Amine (PTBA) (CAS Number: 1064698 -37-8)

Summary: This document describes analysis conducted by 3M to determine a Global Warming Potential (GWP) for Perfluorotributyl Amine (PTBA). The form at of this report is consistent with submittals to EPA for the use of Provisional GWP’s. The Mandatory Reporting Rule 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 t he F-GHG mass emissions by the Global Warming Potential (GWP) for the indiv idual fluorinated gases that comprise the flow. EPA has provided a table of 100-year time horizon GWP values for about 70 individual F-GHG, and specifies that these values a re to be used for the purpose of computing CO 2 -equivalent emissions. [2] Default GWP’s can be use d for any fluorinatedGHG not listed in Table A-1. The regulation allows a facility to request a lower provisional GWP when clear scientific evidence exists to suppor t such a lower value.

Table A–1 does not list a GWP for PTBA. As describ ed in greater detail in a subsequent section, the atmospheric lifetime of PTBA has been estimated as 400 years [3]; the radiative forcing of PTBA has been estimated as 1.05 W/m2/ppb v [3] and the GWP of PTBA has been estimated as 9020 relative to CO 2 with a 100-year integration time horizon. Evidence Supporting Request: F-GHG Identity: perfluorotributyl amine (PTBA)

Chemical Formula: C 12 F 27 N

CAS Number: 1064698-37-8

Estimated GWP: 9020 relative to CO 2 with a 100-year integration time horizon Data and analysis: Atmospheric and Environmental Re search (AER) measured the kinetic rate constants for the vapor phase reaction of PTBA with • OH and O( 1 D) [3], significant degradation was not observed. Given the configurat ion of the experimental apparatus and the performance of the analytical equipment, the longes t atmospheric lifetime that could be observed in their experimental system was >390 year s. Based on this observation the atmospheric lifetime was estimated as 400 years. T he authors did note some degradation of PTBA in control experiments and hypothesized that d irect photolysis may have occurred at a wavelengths near 222 nm. Thus the actual atmospher ic lifetime of PTBA may be further limited by direct photolysis mechanism. Radiative forcing: Band by band absorption cross-se ctions were obtained from averaged IR spectra. Radiative forcing was calculated by a con sultant using an internal model (AER 1-D RC) [3] and used to calculate a direct, equilibrium surface temperature response ( ∆ T) assuming a 1 ppbV introduction. The IR spectrum for PTBA from that report is provided in Figure 1. The corresponding value relative to CFC- 11 on a per-molecule basis was reported as 4.20. This value converted to a radiative forci ng using the known value for CFC-11 (0.25 W/m2/ppbv) reported in [4]. Radiative forcing for PTBA is 1.05 W/m2/ppbV.Using these data in the equation referenced by the IPCC [4] to determine the GWP of a given

substance, a GWP of 9020 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. Ko, M.K.W. and D.T. Chang, Estimates of the Global Warming Potential of Propos ed Chemical Compounds. 1992, Atmospheric and Environmental Research, Inc. : Cambridge, MA 5. IPCC, 2007: Climate Change 2007: Impacts, Adapta tion 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



### Figure 1. FTIR Reference Spectrum for perfluorotributylamine (PTBA)