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

Journal Article · Thu Jan 12 00:00:00 EST 1995 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100002a034· OSTI ID:6605215

Chu, J C.S.; Soller, R; Lin, M C ^[1]; Melius, C F ^[2]

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1. Emory Univ., Atlanta, GA (United States)
2. Sandia National Lab., Livermore, CA (United States)

The thermal decomposition of Si(OCH[sub 3])[sub 4] (TMOS) has been studied by FTIR at temperatures between 858 and 968 K. The experiment was carried out in a static cell at a constant pressure of 700 Torr under highly diluted conditions. Additional experiments were performed by using toluene as a radical scavenger. The species monitored included TMOS, CH[sub 2]O, CH[sub 4], 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 k[sub g] = 1.4 x 10[sup 16] exp(-81 200/RT) s[sup [minus]1] and k[sub g] = 2.0 x 10[sup 14] exp(-74 500/RT) s[sup [minus]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 whose first-order rate constants are given here. 22 refs., 15 figs., 3 tabs.

• OSTI ID: 6605215
• Journal Information: Journal of Physical Chemistry; (United States), Vol. 99:2; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
CHEMICAL REACTION KINETICS
MATHEMATICAL MODELS
ORGANIC SILICON COMPOUNDS
DECOMPOSITION
PYROLYSIS
SILICATES
ACTIVATION ENERGY
EXPERIMENTAL DATA
FORMATION HEAT
FOURIER TRANSFORM SPECTROMETERS
CHEMICAL REACTIONS
DATA
ENERGY
ENTHALPY
INFORMATION
KINETICS
MEASURING INSTRUMENTS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
REACTION HEAT
REACTION KINETICS
SILICON COMPOUNDS
SPECTROMETERS
THERMOCHEMICAL PROCESSES
THERMODYNAMIC PROPERTIES
400201* - Chemical & Physicochemical Properties
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990200 - Mathematics & Computers
400800 - Combustion
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