Skeletal chemical mechanism of high-temperature TEOS oxidation in hydrogen–oxygen environment

Abstract

This paper improves the tetraethoxysilane (TEOS) oxidation mechanism proposed by Nurkowski et al. (Proc. Comb. Inst., 35:2291-2298, 2015) by refining the rate parameters of the key reaction channels in the mechanism. A skeletal version of the mechanism is proposed for hydrogen-oxygen environment. The rates of ethylene-loss from (tetra-, tri-, di-and dimethyldi-) ethoxysilane are computed using transition state theory. The energetics of the main pathways are refined by performing detailed ab initio calculations using the CBS-Q technique. An analysis of ethanol formation via silicates is also performed resulting in the addition of 27 new silica species to the model. Thermodynamic properties for these species are calculated via the balanced reactions method. Reasonably good agreement between the improved model and available experimental data is observed. The subsequent elimination of unimportant species and reactions is achieved via a three-stage reduction procedure. The first and second stages involve the Direct Relation Graph with Error Propagation (DRGEP) method, whereas the third stage analyses rate of progress of each reaction. The investigated conditions are taken from the experimental studies of TEOS oxidation in oxygen-hydrogen flames. The final skeletal mechanism comprises 70 species and 457 reactions and retains good reproduction of the key model properties across

A group additivity methodology for predicting the thermochemistry of oxygen‐containing organosilanes

“…(CH 3 ) 2 Si=O was hypothesized to be an important intermediate for SiO production in TMS oxidation 3, 5 . Species with Si=O double bonds, such as O=Si(OC 2 H 5 ) 2 , O=Si(OH)(OC 2 H 5 ), and (OH) 2 Si=O were also considered in the TEOS oxidation mechanism of Nurkowski et al 7 . We considered the possibilities of SiH 3 , CH 3 , H, and OH as ligands to the Si=O moiety and used the combinatorial approach (see Figure S1 in the Supporting Information) to generate species relevant to the subsequent GAV estimation.…”

“…Organic silicon-containing compounds like siloxanes are frequently used precursors for the synthesis of silica (SiO 2 ) nanoparticles, coatings, and SiO 2 -containing nanocomposites. The combustion chemistry of specific precursor compounds such as silane (SiH 4 ), 1,2 tetramethylsilane (Si(CH 3 ) 4 ; TMS), [3][4][5] and tetraethoxysilane (Si(OC 2 H 5 ) 4 ; TEOS) [6][7][8] was studied in detail. In these studies, the related thermochemical data were developed and usually estimated for the specific reaction systems, and a generalized, self-consistent thermochemical database for the precursor compounds and reaction intermediates is unavailable.…”

Production of new type insulation material: Expanded Perlite-Silica aerogel composite

“…This is due to the fact that perlite inside the structure does not allow the formation of nano stalactites. Because, in our study where nano stalactite structures were seen, the reason for the formation of these structures was that TEOS converted to SiO2 and Diethyl Ether at temperatures above 600 o C (Nurkowski et al 2016), when this aerogel was placed in the oven the reaction occurred firstly and the resulting Diethyl Ether burned with the impact of the air and boosted the temperature of the particles in micron size caused by the formation of melting particles together with each other grew and formed a network-shaped structure. Gases from ignition of diethyl ether and air trapped in SiO2 particles by cause of rapid melting.…”

Controllable Preparation of Monodisperse Mesoporous Silica from Microspheres to Microcapsules and Catalytic Loading of Au Nanoparticles

“…The corresponding elemental compositions of products are summarized in Table S1. After calcination, the final M-MSMs materials still contained a trace amount of carbon (Figure b), which is hardly burned off because of the silanol groups on M-MSMs. , …”

“…After calcination, the final M-MSMs materials still contained a trace amount of carbon (Figure 2b), which is hardly burned off because of the silanol groups on M-MSMs. 38,39 Moreover, it is worth noting that a series of M-MSMs from microspheres to microcapsules can be prepared by only varying the CLDs of S-CLPS templates. The SEM and the corresponding cross-sectional SEM images of these M-MSMs are summarized in Figure 3.…”