Manipulation of surface reaction dynamics by global pressure and local temperature control: A model study

Abstract

Specific catalyst design and external manipulation of surface reactions by controlling accessible physical or chemical parameters may be of great benefit for improving catalytic efficiencies and energetics, product yield, and selectivities in the field of heterogeneous catalysis. Studying a realistic spatiotemporal one-dimensional model for CO oxidation on Pt(110) we demonstrate the value and necessity of mathematical modeling and advanced numerical methods for directed external multiparameter control of surface reaction dynamics. At the model stage we show by means of optimal control techniques that species coverages can be adjusted to desired values, aperiodic oscillatory behavior for distinct coupled reaction sites can be synchronized, and overall reaction rates can be optimized by varying the surface temperature in space and time and the CO and O2 gas phase partial pressure with time. The control aims are formulated as objective functionals to be minimized which contain a suitable mathematical formulation for the deviation from the desired system behavior. The control functions pCO(t) (CO partial pressure), pO2(t) (O2 partial pressure), and T(x,t) (surface temperature distribution) are numerically computed by a specially tailored optimal control method based on a direct multiple shooting approach which is suitable to cope with the highly nonlinear unstable mode character of the CO oxidation model.

On one dimensional chemical diode and frequency generator constructed with an excitable surface reaction

“…The numerical values for activation energies and the pre-exponential factors are taken from the ref. 16 (see also ref. 17) and they are equal: ).…”

“…We use the numerical values of reaction parameters and diffusion given in the recent paper 16 (the only difference is the value of A 5 which is larger by an order of magnitude). It is assumed that the reaction rates k 1 and k 4 for the adsorption of CO and O on the surface do not depend on small variations of the local surface temperature and they are equal to:…”

Nanoassembled Interface for Dynamics Tailoring

“…Over the past few centuries, humans have ardently sought the design and manipulation of reaction dynamics. 5 Research in these sectors has increasingly focused on ways to tailor the reaction dynamics at nanoscale interface; 6 a shared boundary across two or more separate components (comprising of solid−liquid and solid−gas reaction in this study) has always involved an exchange of mass and energy. 7 The interface plays a pivotal role in determining the performance and properties of nanomaterials because the elementary reaction processes during molecular conversion are intricately determined by the interfacial dynamics.…”

“…Over the past few centuries, humans have ardently sought the design and manipulation of reaction dynamics . Research in these sectors has increasingly focused on ways to tailor the reaction dynamics at nanoscale interface; a shared boundary across two or more separate components (comprising of solid–liquid and solid–gas reaction in this study) has always involved an exchange of mass and energy .…”

Canard Explosion and Coherent Biresonance in the Rate Oscillation of CO Oxidation on Platinum Surface

“…To understand these interesting phenomena which are also of practical importance, on the basis of mechanisms that had been verified by experiments, various dynamical models, successfully reproducing those experimentally observed phenomena, have been put forward. These models have been employed in testing hypotheses for reaction mechanisms and motivating and selecting further experimental investigations to clarify vague mechanistic issues . Then, progress has been made in controlling spatiotemporal pattern formation in heterogeneous catalytic reactions by prepatterned surface and in improving the reaction performance such as selectivity and reaction rates by, for example, periodic perturbations of reactant concentrations, temperature, or flow reversal …”