Cooperative Catalysis by Multiple Active Centers in Nonoxidative Conversion of Methane
Teng‐Hao Li, Ming Yan, Yuan Liu, Zheng‐Qing Huang, Chun-Ran Chang, Jun Li
Abstract
A breakthrough in direct, nonoxidative conversion of methane was accomplished on a silica-confined single-atom iron catalyst (Fe©SiO 2 ) in 2014. However, the formation mechanism of the identified active center (FeSiC 2 ©SiO 2 ) remains mysterious and the catalytic reaction mechanism is still under debate. Here, we report a dynamic formation mechanism of FeSiC 2 ©SiO 2 starting from FeO 3 ©SiO 2 by combining density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. It is found that FeSiC 2 ©SiO 2 is formed under the reaction atmosphere of methane, which undergoes two periods: the removal of oxygen and the insertion of carbon species. The removal of oxygen by generating CO/CO 2 is the dominant way, and the insertion of carbon species can be facilely achieved once oxygen is removed. Importantly, during the formation of FeSiC 2 ©SiO 2, six other active centers, FeSiO 2 ©SiO 2, FeCO 2 ©SiO 2, FeSiCO©SiO 2, FeC 2 O©SiO 2, FeSi(CH 2 ) 2 ©SiO 2 and FeSi(CH) 2 ©SiO 2, are revealed, which deliver different and cooperative catalytic behaviors on methane conversion and thus demonstrate a combined gas-phase and surface reaction mechanism.