Multi-scale Modelling of Electrochemically Promoted Systems

Abstract

Keywords:NEMCA backspillover multi-scale modelling CFD-kMC coupling Electrochemically Promoted CO oxidation on Pt/YSZ A B S T R A C T The objective of this work is the formulation of a multi-scale framework for electrochemically promoted systems. We have constructed a 3-Dimensional, isothermal, solid oxide single pellet, multi-scale framework, which describes the chemical and electrochemical phenomena taking place in a solid oxide single pellet under closed-circuit conditions, while the electrochemically promoted oxidation of CO over Pt/YSZ is used as an illustrative system. The proposed framework combines a 3-D macroscopic model which employs the finite element method (FEM) for the simulation of the charge transport and the electrochemical phenomena taking place in the pellet, and an in-house developed efficient implementation of a 2-D lattice kinetic Monte Carlo method (kMC) for the simulation of the reaction-diffusion micro-processes taking place on the catalytic surface. Comparison between the multiscale framework and a macroscopic model [1] is carried out for several sets of operating conditions. Differences between the steady-state outputs of the two models are presented and discussed. A subsequent parametric study using the multi-scale framework is performed to investigate the effect of the gaseous species partial pressures and of the temperature on the CO 2 production rate.

A Lattice-Boltzmann scheme for the simulation of diffusion in intracellular crowded systems

“…In order to validate the crowding-adaptation of LBM presented above, the simulation of a diffusion system was carried out by an on-lattice kMC algorithm [ 14 , 15 ], whose results are used as our computational experiments. A brief description of the kMC algorithm is given below.…”

“…See [ 14 , 15 ] for detailed information of the algorithm and the corresponding equations for each step of the process.…”

“…In particular, this paper focuses on 2D simulations of macromolecules’ diffusion which are relevant for the study and analysis of lateral diffusion of proteins in membranes [ 27 – 29 ]. For validation purposes the results are compared with those obtained from kinetic Monte Carlo (kMC) algorithm [ 14 , 15 ].…”

Theoretical study of catalytic activity modifications in CO2 methanation induced by an electric field in solid-oxide cells

“…36 Several theoretical studies on spillover species have been performed for catalytic reactions on metal catalyst surfaces. [39][40][41][42][43][44][45][46][47][48] For example, Vayenas and Pitselis developed a steady-state one-dimensional surface reaction and diffusion model to simulate the NEMCA effect of a porous catalyst on a solid electrolyte. 45 Leiva et al studied the structural and energetic properties of Na/Pt (111) and O/Pt (111) using quantum mechanical calculations and Monte Carlo (MC) grand canonical simulations to understand the NEMCA effect.…”

“…39 Fragkopoulos et al developed a macroscopic multidimensional kinetic model for CO oxidation that considered the oxygen spillover species and evaluated the CO 2 production rate using NEMCA. 40,41,48 In addition, Liu et al performed first-principles calculations of the oxygencoverage effect for hydrogen oxidation on Ni (111) facets and found that the binding energy of H, O, and OH species on the Ni surface decreases as the co-adsorbed oxygen-atom coverage increases owing to the change in the Ni atomic charge by the co-adsorbed oxygen atoms. They reported that the binding energy of H 2 O on the Ni surface increased as the co-adsorbed oxygen-atom coverage increased as a result of the increase in the positive species charge and hydrogen bonds between H 2 O and the co-adsorbed oxygen atoms.…”