中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 32 No. 5 May 2022 |
（1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. National Engineering Research Center for Low-carbon Nonferrous Metallurgy, Central South University, Changsha 410083, China）
Abstract:In view of the unclear cause of perfluorocarbons (PFCs) emission in the anode effect stage of aluminum electrolysis, the microscopic formation mechanism of PFCs was studied by density functional theory calculation and X-ray photoelectron spectroscopy (XPS). It is found that the discharge of fluorine containing anions ([F]-) on carbon anode first causes the substitution of C—H by C—F and further results in the saturation of aromatic C—C bonds, leading to the appearance of —CF3 or —C2F5 group through six-carbon-ring opening. Elimination of —CF3 and —C2F5 with F atom could be a likely mechanism of CF4 and C2F6 formation. XPS results confirm that different types of —CFx group can be formed on anode surface during electrolysis, and the possibility that [F]- discharges continuously at the C edge and finally forms different C—F bonds in quantum mechanical calculation was verified.
Key words: microscopic formation mechanism; aluminum electrolysis; perfluorocarbon gas; density functional theory calculation
