| Summary: | <jats:p>Abstract. 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) 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 kilogram of HCFC-22 FS
pyrolyzed. Mitigation of these c-C4F8 emissions, e.g., through
process optimization, abatement, or different manufacturing processes, such
as refined methods of electrochemical fluorination and waste recycling,
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 c-C4F8 emissions at country to facility
levels.
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