Trifluoromethane is one of the most potent and stable greenhouse gases with global warming potential of 14,800 times higher than CO 2 (100-year time horizon). At present, it is destroyed by incineration or plasma at temperatures above 1200 K. For the first time, this work report that CHF 3 can be reverted to HCFC-22 via the intermolecular Cl/F exchange reaction of CHF 3 with CHCl 3 over AlF 3 catalyst under moderate conditions. As CHF 3 is produced during the manufacture of HCFC-22 via the fluorination of CHCl 3 in liquid phase, no additional feedstock and products are involved for the treatment of CHF 3 in this proposed process. At 593 K and atmospheric pressure, CHF 3 conversion levels of about 18%–20% are achieved and no significant deactivation is observed following time on stream of 100 h. In addition, the catalytic reaction mechanism is proposed. According to the experiments and DFT calculation, the intermolecular Cl/F exchange reaction of CHF 3 with CHCl 3 is mainly initiated by the breakage of C Cl. The present work provides a potential resource utilization route for the treatment of CHF 3 and other hydrofluorocarbons (HFCs).
Electrochemical ammonia synthesis (EAS) has emerged as a promising alternative to the traditional Haber–Bosch process. Indeed, N2 activation in room-temperature EAS systems remains a formidable challenge due to the strong NN bond. Solid oxide proton conductor EAS (PCEAS) electrolysis cells operating at intermediate temperatures offer a promising solution by utilizing both temperature and potential. In this process, the design of the cathode is crucial, requiring abundant proton and electron conduction channels, along with highly active catalysts. Herein, we design a cathode composed of ruthenium–La0.6Sr0.4Co0.2Fe0.8O3−δ–BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (Ru–LSCF–BZCYYb) to meet the aforementioned requirements for PCEAS. LSCF and BZCYYb form a porous skeleton at the cathode, with Ru nanoparticles dispersed on the surface of this structure. This configuration features numerous triple-phase boundaries (TPBs), facilitating the contact between activated N2, H+, and e−, thereby promoting electrochemical ammonia synthesis. The impregnated Ru–LSCF–BZCYYb|BZCYYb|Ni–BZCYYb PCEAS electrolysis cell exhibited a maximum NH3 formation rate of 5.14 × 10−11 mol s−1 cm−2 and a maximum Faraday efficiency (FE) of 0.128% at 400 °C and −0.2 V with H2 and N2 as feedstock gases. Its yield surpassed those of the mixed Ru–LSCF–BZCYYb|BZCYYb|Ni–BZCYYb and the impregnated Ru–BZCYYb|BZCYYb|Ni–BZCYYb by a factor of 3.9 and 11.5, respectively. The authenticity of ammonia synthesis is confirmed using the 15N2 isotope combined with NMR detection. This study also achieved EAS using water as the hydrogen source. This approach would better meet the future demand for EAS by directly using N2 and H2O.
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