Fischer–Tropsch Product Selectivity Modulation via an FeRh Nanocluster Composition Design

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.