Thermal decomposition of tetramethyl orthosilicate in the gas phase. An experimental and theoretical study of the initiation process

J. C.S. Chu*, R. Soller, Ming-Chang Lin, C. F. Melius

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

The thermal decomposition of Si(OCH3)4 (TMOS) has been studied by FTIR at temperatures between 858 and 968 K. Additional experiments were performed by using toluene as a radical scavenger. The species monitored included TMOS, CH2), CH4, and CO. According to these measurements, the first-order global rate constants for the disappearance of TMOS without and with toluene can be given by kg = 1.4 × 1016 exp(-81 200/RT) s-1 and kg = 2.0 × 1014 exp(-74 500/RT) s-1, respectively. The noticeable difference between the two sets of Arrhenius parameters suggests that, in the absence of the inhibitor, the reactant was consumed to a significant extent by radical attacks at higher temperatures. The experimental data were kinetically modeled with the aid of a quantum-chemical calculation using the BAC-MP4 method. The results of the kinetic modeling, using the mechanism constructed on the basis of the quantum-chemical data and the known C/H/O chemistry, identified two rate-controlling reactions. In addition to these new kinetic data, the heats of formation of many relevant SiOxCyHz species computed with the BAC-MP4 method are presented herein.

Original languageEnglish
Pages (from-to)663-672
Number of pages10
JournalJournal of physical chemistry
Volume99
Issue number2
DOIs
StatePublished - 1 Jan 1995

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