Response of a Model of CO Oxidation with CO Desorption and Diffusion to a Periodic External CO Pressure

TL;DR

This study investigates a CO oxidation model with desorption and diffusion, showing how these factors influence phase transitions and catalytic activity under periodic CO pressure variations.

Contribution

It introduces a detailed analysis of how CO desorption and diffusion affect phase behavior and catalytic efficiency in a CO oxidation model under periodic pressure.

Findings

Diffusion increases CO₂ production rate.

Discontinuous phase transition observed between low and high CO coverage.

Periodic pressure variation does not enhance activity beyond diffusion effects.

Abstract

We present a study of the dynamical behavior of a Ziff-Gulari-Barshad model with CO desorption and lateral diffusion. Depending on the values of the desorption and diffusion parameters, the system presents a discontinuous phase transition between low and high CO coverage phases. We calculate several points on the coexistence curve between these phases. Inclusion of the diffusion term produces a significant increase in the CO_2 production rate. We further applied a square-wave periodic pressure variation of the partial CO pressure with parameters that can be tuned to modify the catalytic activity. Contrary to the diffusion-free case, this driven system does not present a further enhancement of the catalytic activity, beyond the increase induced by the diffusion under constant CO pressure.