Molecular interaction-based reaction-diffusion coupling within catalytic nanochannels

The nanoconfinement effect on the inner reaction-diffusion coupling is significant, while the underlying common principle remains ambiguous, which is mainly attributed to the lack of a feasible model. Herein, the dynamic reaction density functional theory (DRxDFT) is extended, by involving the position-dependent local diffusion coefficient, to investigate the reaction-diffusion coupling of an irreversible unimolecular isothermal reaction within catalytic nanochannels. The local diffusion coefficient is jointly determined by the pore size and local density. For demonstration, the reaction-diffusion in a rectangle nanochannel is studied by means of DRxDFT, and the predicted steady-state productivities are in excellent agreement with reactive molecular dynamics simulations. The DRxDFT is further applied to analyze the RD coupling within generic catalytic nanochannels. Towards this end, a microscopic effectiveness factor is introduced to identify the dominant role in the competition between reaction and diffusion, with which it is found that the effect of nanochannel size on productivity exhibits a generic opposite trend under reaction-dominated and diffusion-dominated conditions. This work provides a microscopic insight into the coupling of reaction and diffusion in nanoconfinement.

Automated summary

The study extends the dynamic reaction density functional theory (DRxDFT) to investigate the reaction-diffusion coupling in catalytic nanochannels. By simulating the reaction-diffusion process in a rectangle nanochannel, the predicted steady-state productivities are found to be in excellent agreement with reactive molecular dynamics simulations. The study further analyzes the reaction-diffusion coupling in generic catalytic nanochannels and reveals a generic opposite trend in the effect of nanochannel size on productivity under reaction-dominated and diffusion-dominated conditions. This work provides a microscopic insight into the coupling of reaction and diffusion in nanoconfinement.