Global Emissions of Perfluorocyclobutane (PFC-318, c-C4F8) Resulting from the Use of Hydrochlorofluorocarbon-22 (HCFC-22) Feedstock to Produce Polytetrafluoroethylene (PTFE) and related Fluorochemical

Mühle, J., Kuijpers, L. J. M., Stanley, K. M., Rigby, M., Western, L. M., Kim, J., Park, S., Harth, C. M., Krummel, P. B., Fraser, P. J., O’Doherty, S., Salameh, P. K., Schmidt, R., Young, D., Prinn, R. G., Wang, R. H. J., and Weiss, R. F.
Atmos. Chem. Phys. Discuss. [preprint],

Emissions of the potent greenhouse gas perfluorocyclobutane (c-C4F8, PFC-318, octafluorocyclobutane) into the global atmosphere inferred from atmospheric measurements have been increasing sharply since the early 2000s. We find that these inferred emissions are highly correlated with the production of hydrochlorofluorocarbon-22 (HCFC-22, CHClF2) for feedstock (FS) uses, because almost all HCFC-22 FS is pyrolyzed to produce (poly)tetrafluoroethylene ((P)TFE, Teflon) and hexafluoropropylene (HFP), a process in which c-C4F8 is a known by-product, causing a significant fraction of global c-C4F8 emissions. We find a global emission factor of ~0.003 kg c-C4F8 per kg of HCFC-22 FS pyrolyzed. Mitigation of these c-C4F8 emissions, e.g., through process optimization, abatement, or different manufacturing processes, such as electrochemical fluorination, could reduce the climate impact of this industry. While it has been shown that c-C4F8 emissions from developing countries dominate global emissions, more atmospheric measurements and/or detailed process statistics are needed to quantify country to facility level c-C4F8 emissions.