A finite-rate model for oxygen-silica catalysis through computational chemistry simulation

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

The goal of this work is to model the heterogeneous recombination of atomic oxygen on silica surfaces, which is of interest for accurately predicting the heating on vehicles traveling at hypersonic velocities. This is accomplished by creating a finite rate catalytic model, which describes recombination from an atomistic perspective with a set of elementary gas-surface reactions. Fundamental to surface catalytic reactions are the chemical structures on the surface where recombination can occur. Using molecular dynamics simulations with the ReaxFF potential, we find that the chemical sites active in oxygen atom recombination on silica surfaces consist of a small number of specific defects. The individual reactions in our finite rate catalytic model are based on the possible outcomes of oxygen interaction with these defects. The parameters of the functional forms of the rates, including activation energies and pre-exponential factors, are found by carrying out molecular dynamics simulations of individual events. We find that the recombination coefficients predicted by the finite rate catalytic model display an exponential dependence with temperature, in qualitative agreement with experiment at between 1000 K-1500 K. However, the ReaxFF potential requires reparametrization with new quantum chemical calculations specific to the reaction pathways presented in this work.

Original languageEnglish (US)
Title of host publication28th International Symposium on Rarefied Gas Dynamics 2012
Pages1137-1144
Number of pages8
Edition1
DOIs
StatePublished - 2012
Event28th International Symposium on Rarefied Gas Dynamics 2012, RGD 2012 - Zaragoza, Spain
Duration: Jul 9 2012Jul 13 2012

Publication series

NameAIP Conference Proceedings
Number1
Volume1501
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

Other28th International Symposium on Rarefied Gas Dynamics 2012, RGD 2012
CountrySpain
CityZaragoza
Period7/9/127/13/12

Keywords

  • Gas Surface Interactions
  • Heterogeneous Catalysis

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