IN BRIEF: TRENDS IN HFC-23 BY-PRODUCT EMISSIONS FROM HCFC-22 PRODUCTION

HFC-23 is a by-product from the production of HCFC-22. According to a 2020 paper [1], global HFC-23 emissions derived from atmospheric measurements were historically at their highest level in 2018, in contrast to the expected emissions of HFC-23 by-product, primarily from reported HCFC-22 production, that were much lower. The paper noted that in 2017 it is likely that China had not been successful in meeting its target of abating 98% of HFC-23 emissions. This conclusion is consistent with the HFC-23 emissions data for China in a 2020 TEAP Report [2], that showed only 49% of reported HFC-23 by-product production was abated (incinerated) in 2018.

Another paper [3] had previously concluded that between 2009 and 2016 atmospheric abundance of HFC-23 had increased faster than the atmospheric abundance of HCFC-22, with the divergence in annual average growth rates consistent with increasing HFC-23 emissions as a consequence of incomplete mitigation of HCFC-22 production. However, the paper also notes that this slowing atmospheric growth of HCFC-22 is consistent with HCFC-22 moving from dispersive (high fractional emissions) to feedstock (low fractional emissions) uses.

It was only from 1 January 2020 that the Montreal Protocol Article 2J (the Kigali Amendment) requires HFC-23 from HCFC-22 production to be destroyed to the extent practicable. In advance of the Kigali Amendment, F-gas Regulation 517/2014 in Article 7 states that the placing on the market of HFCs and HFOs shall be prohibited unless, where relevant, that trifluoromethane, produced as a by-product during the manufacturing process, including during the manufacturing of feedstocks for their production, has been destroyed or recovered for subsequent use, in line with best available techniques.

References
[1] K. M. Stanley, D. Say, J. Mühle, C. M. Harth, P. B. Krummel, D. Young, S. J. O’Doherty, P. K. Salameh, P. G. Simmonds, R. F. Weiss, R. G. Prinn, P. J. Fraser, M. Rigby, Increase in global emissions of HFC-23 despite near-total expected reductions, Nature Communications, 11, Article number: 397 (2020), https://doi.org/10.1038/s41467-019-13899-4
[2] May 2020 TEAP Decision XXXI/1 Replenishment Task Force Report, Table 4.3 Amounts of HCFC-22 and HFC-23 produced in various plants in China, as well as the HFC-23 reduction amounts in 2018.
[3] Simmonds, P. G. et al., Recent increases in the atmospheric growth rate and emissions of HFC-23 (CHF3) and the link to HCFC-22 (CHClF3) production, Atmos. Chem. Phys., 2018, 18, 4153–4169. https://www.atmos-chem-phys.net/18/4153/2018/.