A Kinetic View on Proximity-Dependent Selectivity of Carbon Dioxide Reduction on Bifunctional Catalysts
Huijun Jiang, Zhonghuai Hou, Yi Luo
Abstract
Multifunctional catalysts with distinct functional components are known to have much improved selectivity. However, the well-known proximity-dependent selectivity observed in several high-profile experiments is yet to be understood. Here, we reveal that such dependence is closely associated with the kinetics involved. Based on reaction–diffusion dynamics together with kinetic Monte Carlo simulation on a coarse-grained model, one famous example, namely, the proximity-dependent selectivity from carbon dioxide to liquid fuels on a bifunctional catalyst composed of HZSM-5 and In2O3, has been systematically examined. It is found that the diffusion kinetics of the intermediate methanol generated on In2O3 plays a decisive role for the selectivity. For different In2O3/HZSM-5 proximities, the local methanol concentration induces a shift of the dominant process for subsequent methanol-to-hydrocarbon reactions inside HZSM-5, resulting in a preferred reaction window to generate favorable liquid fuels with profound high selectivity. Our findings emphasize the importance of kinetic effects in the design of multifunctional catalysts.