Mechanism of dehydration and intumescence of soluble silicates

Langille, K. B.; Nguyen, Duc Trung; Bernt, J. O.; Veinot, D. E.; Murthy, M. Krishna

doi:10.1007/bf00588307

Cited by 19 publications

(33 citation statements)

References 7 publications

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“…Sample A exhibited broad bands in the range of 1110–1000 cm −1 that are attributed to the Si–O–Si stretching vibrations . The zoomed part of the spectrum (Fig.…”

Section: Resultsmentioning

confidence: 98%

“…. There is a linear weight drop between the start of the run and the point marked ‘A’, which corresponds to evaporation of free water, and water physically adsorbed by hydrogen bonding to silanol groups . According to Hyde water contained in the reaction mixture could crystallize with a portion of potassium siloxanolate salts as the hydrate, since the water evaporation was continuing at relatively high temperature about 150 °C.…”

Section: Resultsmentioning

confidence: 99%

“…The solid product exhibited several TCD signals at decomposition temperatures of 77, 126, 145, 195 and 255 °C. The first two signals can be related with the presence of free water and ionically bonded water molecules, whereas the other two signals can be related to the release of cyclic siloxanes. Mass spectrometry was used to analyze the presence of water, carbon monoxide and dioxide in the oxidation products resulting from TPO.…”

Section: Resultsmentioning

confidence: 99%

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The base-catalyzed transformation of tetramethyldisiloxane: influence of reaction media

Kupareva

Mäki‐Arvela

Grénman

et al. 2014

J. Chem. Technol. Biotechnol.

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BACKGROUND: Nowadays, different automotive sources generate globally large amounts of used oils. To achieve maximum energy conservation and environmental benefits, re-refining of used oil is preferable. Since removal of silicon and its chemical species is of great interest in the oil recycling industry, the aim of this study was to improve understanding of the behaviour of silicon-containing compounds at industrially relevant alkali treatment conditions. RESULTS: At industrially relevant alkali treatment conditions transformations of the model hydrogen-terminated tetramethyldisiloxane (TMDS)resulted in the formation of solid siloxanolate salts. The activation energy for TMDS transformation in the presence of 33 wt% aqueous KOH was found to be 37 kJ mol −1 , which is almost two-fold lower than that for NaOH. The experimental data demonstrated that the formation of solid products undesired from an industrial point of view can be diminished by an addition of either an alcoholic solvent or dimethyl carbonate. CONCLUSIONS:The experimental results obtained can be utilized for optimization of silicon-containing used oil recycling. In particular KOH as an alkali agent is more efficient than NaOH; addition of methanol dramatically increases the reaction rate, while dimethyl carbonate introduced into the reaction mixture enhances selectivity to the liquid products. Industry 7 145 ml Dodecane, 3.72 mmol TMDS, 12.5 mmol NaOH, 55.5 mmol H 2 O, 3.72 mmol DMC 8 145 ml Dodecane, 3.72 mmol TMDS, 12.5 mmol NaOH, 55.5 mmol H 2 O, 3.72 mmol DMC, 11 mmol CH 3 OH J Chem Technol Biotechnol 2015; 90: 34-43

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“…Sample A exhibited broad bands in the range of 1110–1000 cm −1 that are attributed to the Si–O–Si stretching vibrations . The zoomed part of the spectrum (Fig.…”

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

The base-catalyzed transformation of tetramethyldisiloxane: influence of reaction media

Kupareva

Mäki‐Arvela

Grénman

et al. 2014

J. Chem. Technol. Biotechnol.

View full text Add to dashboard Cite

show abstract

“…This result could be explained by the presence of potassium silicates, which are known to be highly hygroscopic and to expand signicantly with water incorporation. 16,17 Therefore, to prevent any moisture interfering with the nominally dry experiments, samples were kept in desiccators and were heated to high temperatures, typically 750-800 C, for several hours in situ prior to all measurements. Electrodes were initially prepared by painting Ag paste on to the pellet surfaces followed by sintering at 700 C for 1 hour.…”

Section: Resultsmentioning

confidence: 99%

On the oxide ion conductivity of potassium doped strontium silicates

Bayliss

Cook

Fearn

et al. 2014

Energy Environ. Sci.

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“…Sample A (before TPO), exhibited bands at 1260 and 800 cm −1 corresponding to the presence of the Si–CH 3 groups, in contrast to the sample B (after TPO). Moreover, only sample A exhibited broad bands in the ranges 1100–1000 cm −1 and 1000–900 cm −1 which are attributed to the Si–O–Si and Si–O–metal stretching vibrations . The solid subjected to TPO did not show any presence of Si–O–Si structures.…”

Section: Resultsmentioning

confidence: 99%

The transformation of silicon species contained in used oils under industrially relevant alkali treatment conditions

Kupareva

Mäki‐Arvela

Grénman

et al. 2014

J of Chemical Tech & Biotech

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BACKGROUND: In the lube oil re-refining industry silicon, coming mainly from antifoaming agents, is recognized to be a contaminant generating undesired solid deposits. The behavior of the hydrogen-terminated model compound, tetramethyldisiloxane, under base-catalyzed conditions was investigated at 100 ∘ C in dodecane as the solvent with sodium siloxanolate as an alkali agent. RESULTS:The use of sodium siloxanolates led to high reaction rates and selectivity to the liquid products. Experiments with an industrially relevant silicon-containing substrate, namely silicone-based antifoam agent showed that its transformation in the presence of 33 wt% aqueous solution of sodium hydroxide resulted in 80% yield of solid sodium siloxanolates, whereas, when sodium siloxanolate was used as an initial alkali agent, no solid products were formed. CONCLUSIONS: Experimental results demonstrated that under alkali treatment conditions silicon-containing species existingin real industrial feedstock undergo transformation reactions, with formation of solid sodium siloxanolates. It was found that the use of sodium siloxanolate as an alkali agent could significantly increase the rate of polydimethylsiloxane depolymerization reaction and completely eliminate formation of the undesired solids under industrially relevant conditions.

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Mechanism of dehydration and intumescence of soluble silicates

Cited by 19 publications

References 7 publications

The base-catalyzed transformation of tetramethyldisiloxane: influence of reaction media

The base-catalyzed transformation of tetramethyldisiloxane: influence of reaction media

On the oxide ion conductivity of potassium doped strontium silicates

The transformation of silicon species contained in used oils under industrially relevant alkali treatment conditions

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