Assessing the atmospheric fate of trifluoroacetaldehyde (CF₃CHO) and its potential as a new source of fluoroform (HFC-23) using the AtChem2 box model

Abstract

The use of human-made refrigerants and blowing agents have a long record of restrictions because of the impacts their emissions have had on the atmospheric composition and climate. One of...

Working Fluid Selection for High-Temperature Heat Pumps: A Comprehensive Evaluation

“…As part of the PFAS family, the European Union, through the European Chemicals Agency (ECHA), is moving towards gradually phasing out these substances. Apart from the TFA issue, another drawback arises with HFOs like R1234ze, where secondary products with GWPs of up to 14,800 can be formed, indicating a potentially variable GWP value for such HFOs [33].…”

Perspective on Theoretical and Experimental Advances in Atmospheric Photochemistry

“…A topical case study is the posited production of HFC-23 (fluoroform, CF 3 H) from UV photolysis of CF 3 CHO which is an intermediate in the OH-initiated oxidation of hydrofluoroolefins (HFOs) being introduced as new refrigerant gases. 55,56 Although existing databases have compiled quantum yield data of atmospheric photochemical significance from available laboratory measurements, 10,11 these data sets are sparse. 27 2.3.…”

“…Even quantum yields of only a few percent for minor photochemical channels can be significant in an atmospheric context, for example, if the precursor compounds are growing in use (and hence emissions to the atmosphere) and the products are long-lived greenhouse gases. A topical case study is the posited production of HFC-23 (fluoroform, CF 3 H) from UV photolysis of CF 3 CHO which is an intermediate in the OH-initiated oxidation of hydrofluoroolefins (HFOs) being introduced as new refrigerant gases. , Although existing databases have compiled quantum yield data of atmospheric photochemical significance from available laboratory measurements, , these data sets are sparse …”

“…Moreover, the internally excited ground-state molecules can react with O 2 to make HO 2 in so-called “photophysical oxidation” reactions that are energetically inaccessible from thermalized molecules in their vibrational ground-state energy levels . Yet this photochemistry matters in the atmosphere because carbonyl compounds such as formaldehyde are key intermediates in OH and O 3 initiated oxidation of VOCs including isoprene, their photochemistry is a source of HO x radicals, and in some cases this photochemistry might be a step in unintended pathways to the production of long-lived greenhouse gases such as HFC-23 (CF 3 H) from the oxidation of hydrofluoroolefins. , …”

“…202 Yet this photochemistry matters in the atmosphere because carbonyl compounds such as formaldehyde are key intermediates in OH and O 3 initiated oxidation of VOCs including isoprene, their photochemistry is a source of HO x radicals, and in some cases this photochemistry might be a step in unintended pathways to the production of long-lived greenhouse gases such as HFC-23 (CF 3 H) from the oxidation of hydrofluoroolefins. 56,203 Notwithstanding the complexities of carbonyl photochemistry outlined above, calculation of the nuclear dynamics in photoexcited molecules (as described in Section 3.2) can simulate changes in electronic state and spin and the competition between bond breaking, isomerization, and relaxation to the ground electronic state. In principle, these calculations can therefore predict branching between different photochemical pathways, and hence quantum yields.…”