Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 61: Heterogeneous Catalysis
O 61.1: Poster
Dienstag, 21. März 2017, 18:30–20:30, P2-OG2
Simulation of gas-phase mediated sintering — •Elisabeth Dietze1,2 and Philipp Plessow1,2 — 1Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany — 2Institute of Catalysis Research and Technology (IKFT), Karlsruhe, Germany Institute of Catalysis Research and Technology (IKFT), Karlsruhe, Germany
It is a longstanding question whether sintering of Pt under oxidizing conditions is mediated by surface migration of Pt species or through the gas phase, by PtO2. Simulations have shown that ripening through the gas phase is relevant [1]. In addition, experiments have shown how sintering depends on the gas flow and the geometrical setup of the reactor for the sintering of Pt particles in an oxidizing atmosphere [2]. Accurate prediction of gas-phase mediated sintering requires to go beyond continuum approximations and to model mass transport in the gas phase. The transport is modeled through an explicit simulation of single-particle scattering events in the gas phase, using a kinetic Monte Carlo (kMC) model that describes the collision of an explicit molecule within an uniform background of ideal gas that is characterized by its temperature as well as its mass distribution, collision cross section and collective gas-flow. Since Argon is often used as a gas in experiments it is an appropriate model system. First results are promising. The diffusion constant of an Ar40 molecule in Ar40 could be reproduced.
[1] P. Plessow, F. Abild-Pedersen, ACS Catal. 2016, 6 (10), 7098-7108. [2] T.W. Hansen, A.T. Delariva, S.R. Challa, A.K. Datye, Acc. Chem. Res. 2013, 46 (8), 1720-30.