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Solid-phase Synthesis of [4.4] Spirocyclic Oximes
Published on: February 6, 2019
Decomposition of hexamethylcyclotrisiloxane over solid oxides
Elisabetta Finocchio1, Gilberto Garuti, Marco Baldi
1Dipartimento di Ingegneria Chimica e di Processo, Facoltà di Ingegneria, Università di Genova, Pl.e Kennedy 1, 16126 Genova, Italy. elisabetta.finocchio@unige.it
Chemosphere
|July 8, 2008
Summary
Alumina effectively removes hexamethylcyclotrisiloxane (HMCTS) from synthetic biogas at high temperatures via reactive adsorption and methane release. This process achieves a silication monolayer capacity on the alumina surface.
Area of Science:
- Materials Science
- Chemical Engineering
- Environmental Science
Background:
- Siloxanes, like hexamethylcyclotrisiloxane (HMCTS), are volatile compounds found in synthetic biogas.
- Effective removal of HMCTS is crucial for biogas utilization and preventing equipment damage.
- Understanding the decomposition pathways of HMCTS on various oxide surfaces is essential for developing efficient removal technologies.
Purpose of the Study:
- To investigate the decomposition of hexamethylcyclotrisiloxane (HMCTS) over different oxide surfaces.
- To evaluate the effectiveness of acidic and basic oxides as adsorbents for HMCTS removal at elevated temperatures.
- To determine the adsorption capacity and mechanism of HMCTS decomposition on alumina.
Main Methods:
- Experimental study of HMCTS decomposition at room temperature and 473-673 K.
- Utilized basic oxides (CaO, MgO) and acidic oxides (Al2O3, SiO2) as adsorbents.
- Characterized adsorption capacity and reaction products, including methane release and surface silication.
Main Results:
- Alumina (Al2O3) demonstrated complete removal of HMCTS at 673 K through reactive adsorption, forming a silication monolayer with a capacity of 0.31 g(HMCTS)/g(Al2O3).
- Silica (SiO2) showed reduced adsorption ability at high temperatures, indicating molecular adsorption behavior.
- Basic oxides (MgO, CaO) effectively decomposed siloxanes without CO2 but lost reactivity upon carbonation.
Conclusions:
- Alumina is a highly effective adsorbent for HMCTS removal from synthetic biogas at 673 K, offering a stable silication monolayer.
- Silica's adsorption performance for HMCTS is temperature-dependent, decreasing significantly at higher temperatures.
- The presence of CO2 negatively impacts the performance of basic oxides for siloxane decomposition due to surface carbonation.
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