III International Conference

NOVEL STATISTICAL LATTICE MODEL FOR THE PHYSICOCHEMICALPROCESSES PROCEEDING OVER THE SUPPORTED NANOPARTICLEPP-I-65Kovalyov E., Elokhin V.Boreskov Institute of Catalysis SB RAS, Novosibirsk, RussiaE-mail: kovalev@catalysis.ruThe aim of the study is to reveal the mutual influence the shape and the surfacemorphology of the supported nanoparticles on the reaction kinetics. The analysis has beenprovided by means of the novel statistical lattice model, imitating the physicochemicalprocesses over the supported particles. The influence of monomolecular and dissociativeadsorption on the equilibrium shape and surface morphology has been studied. The modelreaction 2A+B 2 ↔ 2AB has been studied taking into account the roughening of the particlesurface and the spillover phenomena of the adsorbed A ads over the support.The influence of monomolecular and dissociative adsorption on the equilibrium shapeand surface morphology has been studied. To simulate the active metal particle the finiteKossel crystal located on the inert support has been chosen. To simulate the diffusion of themetal atoms over the metal and support surfaces the standard the Metropolis algorithm [1] hasbeen used.It has been shown that at increasing of interaction energies «adsorbate-metal» thereshaping of the initial equilibrium (hemispheric) particle into cone-shaped one occursinduced by adsorption. In the case of bimolecular dissociative adsorption the surface regionsof the metal particle become the pronounced «chessboard» structure (alternate vacancies andpoint defects). The adsorption isotherms simulated with taking into account the interactionbetween atoms of metal and adsorbate differ noticeably from the ideal Langmuir isotherm.The model reaction A+B 2 has been studied (monomolecular adsorption of A, dissociativeadsorption of B 2 and reaction between A ads and B ads ) taking into account the roughening of theparticle surface and the spillover phenomena of the adsorbed A ads species over the support.The kinetic dependencies of A ads and B ads coverages normalized on the number of theactive sites of the catalyst particle versus molar ratio Y A = P A /(P A +P B2 ) (P i are the partialpressures of the reagents in the gas phase) obtained at different variants of the model reactionperformance (with or without A ads species and/or metal atoms diffusion, various ratios ofinteraction energies, etc.) has been compared with ones of the well-known Ziff-Gulari-Barshad model [2]. In our case ZGB-model corresponds to the performance of the reactiononly on the initial flat uniform surface of the catalyst particle without any diffusion of123