Unravelling CO oxidation reaction kinetics on single Pd nanoparticles in nanoconfinement using a nanofluidic reactor and DSMC simulations

Abstract

Steady state catalytic oxidation of CO in nanofluidic channels decorated with Pd nano particles was studied using the Direct Simulation Monte Carlo (DSMC) method. Diffusion, collision, adsorption, desorption and reaction processes are simulated simultaneously. The influence of various adsorption (sticking coefficient, saturation coverage), desorption (activation energy, pre-exponential factor) and reaction (activation barrier) parameters on the final CO2 turnover are determined. These effects are considered to tune DSMC surface reaction model with respect to the experimental results. With DSMC, it was possible to get insights on reactivity of the individual Pd particles and the resulting varying reaction conditions along the channel due to local conversion effects. From the local coverages, the limit of CO:O2 inlet ratio to get maximum CO2 turnover without poisoning the catalyst with CO were determined. The approach paves the way to accurately represent micro- and nanoscale flows at the same system size as that of experiments.