Response of a catalytic reaction to periodic variation of the CO pressure: Increased CO_2 production and dynamic phase transition

TL;DR

This study uses kinetic Monte Carlo simulations to investigate how periodic CO pressure variations influence catalytic CO oxidation, revealing a dynamic phase transition that enhances CO_2 production and aligns with the 2D Ising universality class.

Contribution

It demonstrates a dynamic phase transition in a catalytic reaction under periodic forcing, with critical exponents matching the 2D Ising model, providing new insights into nonequilibrium phase behavior.

Findings

Enhanced CO_2 production at the phase transition

Identification of a dynamic phase transition with power-law singularities

Critical exponents consistent with the 2D Ising universality class

Abstract

We present a kinetic Monte Carlo study of the dynamical response of a Ziff-Gulari-Barshad model for CO oxidation with CO desorption to periodic variation of the CO presure. We use a square-wave periodic pressure variation with parameters that can be tuned to enhance the catalytic activity. We produce evidence that, below a critical value of the desorption rate, the driven system undergoes a dynamic phase transition between a CO_2 productive phase and a nonproductive one at a critical value of the period of the pressure oscillation. At the dynamic phase transition the period-averged CO_2 production rate is significantly increased and can be used as a dynamic order parameter. We perform a finite-size scaling analysis that indicates the existence of power-law singularities for the order parameter and its fluctuations, yielding estimated critical exponent ratios $\beta/\nu \approx 0.12$ and $\gamma/\nu \approx 1.77$. These exponent ratios, together with theoretical symmetry arguments and numerical data for the fourth-order cumulant associated with the transition, give reasonable support for the hypothesis that the observed nonequilibrium dynamic phase transition is in the same universality class as the two-dimensional equilibrium Ising model.