Heteroatom-doping regulated Mg6MnO8 for improving C2+ hydrocarbons during chemical looping oxidative coupling of methane

• Published in: Fuel processing technology Vol. 235; p. 107352
• Main Authors: Huang, Ju, Zhao, Kun, Jiang, Shican, Kang, Shunshun, Lin, Yan, Huang, Zhen, Zheng, Anqing, Zhao, Zengli
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2022
• Subjects: C2+ hydrocarbons; Chemical looping oxidative coupling; Methane; Oxygen carrier; Oxygen species; Methane; Chemical looping oxidative coupling; Oxygen carrier; Oxygen species; C2+ hydrocarbons
• ISSN: 0378-3820; 1873-7188
• DOI: 10.1016/j.fuproc.2022.107352

Chemical looping oxidative coupling of methane (CLOCM) is a novel process for the selective oxidization of methane to produce C2+ hydrocarbons. However, the high activity of oxygen carriers usually promotes the undesired complete or partial oxidation of methane to form large amounts of COx. Herein, a series of novel composite oxide carriers of Mg6MnO8 doped by heteroatoms (Na, W, and P) are developed to achieve selective and stable production of C2+ hydrocarbons from CLOCM of methane. The redox performance of heteroatom-doped Mg6MnO8 was evaluated in a U-tube reactor coupling with various analytical methods. It is found that Na doping can improve the content of surface O− and Mn2+/Mn3+ species of Mg6MnO8, thus improving the C2+ selectivity and yield. The highest C2+ selectivity of 82.9% and the highest C2+ yield of 23.2% are obtained on 4Na-Mg6MnO8 and 10Na-Mg6MnO8, respectively. The co-doping of W can stabilize the surface Na species via the formation of Na-O-W and Na-O-Mn bonds, thus resulting in the stable performance of NaW-Mg6MnO8 in 20 redox cycles. It is thus concluded that the key to achieving CLOCM with high C2+ selectivity and yield is the stable formation of surface O− and Mn2+/Mn3+ species of oxygen carriers regulated by doping of heteroatoms. •Na doping improves the content of surface O− and Mn2+/Mn3+ species of Mg6MnO8.•The highest C2+ selectivity of 82.9% is obtained by 4Na-Mg6MnO8.•The highest C2+ yield of 23.2% is obtained by 10Na-Mg6MnO8.•The stable performance of NaW-Mg6MnO8 in 20 redox cycles is achieved.