The reaction mechanism of *CHx formation in Fischer-Tropsch synthesis on various FeRh nanoclusters is studied using DFT calculations. We find that the energy barrier of *CH2 formation from hydrogen-assisted *CH2O dissociation can be directly modulated using the Fe/Rh composition ratio. Thermodynamic investigations and the natural bond orbital (NBO) analysis indicate that the barrier dropping of C-O bond scission in *CH2O can be ascribed to the interaction between the Fe and the O atoms. In particular, the *CH2 formation can be selectively stabilized with respect to the *CH3O formation using a local tri-Fe configuration on the FeRh nanocluster when the Fe ratio exceeds 50%. An optimal barrier may be achieved by carefully balancing the number of Rh and Fe atoms in the local configuration of the active site to stabilize both ends of the intermediates.
關聯:
JOURNAL OF PHYSICAL CHEMISTRY C 卷冊: 124 期: 28 頁數: 15225-15230
