Identification of the active site during CF4 hydrolytic decomposition over γ-Al2O3†
Abstract
Aluminum production processes emit carbon tetrafluoride (CF4) directly into the atmosphere, which is a powerful greenhouse gas (with a greenhouse warming potential 6500 times that of CO2) with serious potential to exacerbate global warming. As the most feasible method of eliminating CF4, the hydrolytic decomposition of CF4 at moderate temperatures is still challenging due to the active site remaining elusive. Herein, we demonstrated that three-coordinated Al (AlIII) on the γ-Al2O3 (110) surface is the dominant active site during the hydrolytic decomposition of CF4. DFT calculations present the strong adsorption of CF4 on the AlIII site. γ-Al2O3 nano-slices with exposed (110) crystal planes with different AlIII occupation levels were synthesized. The amounts of AlIII in the catalysts were quantified via27Al MAS NMR and the number of AlIII sites directly affects the catalytic activity. In situ FTIR spectra show that the AlIII sites could be activated and that they had a stable presence under the given reaction conditions.
- This article is part of the themed collections: Environmental Remediation, Environmental Science: Nano Recent HOT Articles and SDG13: Climate Action- chemistry of greenhouse gases, 2022