Ethylene epoxidation on Ag catalysts supported on non-porous, microporous and mesoporous silicates |
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Authors: | Apostolos P Fotopoulos Kostas S Triantafyllidis |
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Affiliation: | aDepartment of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece |
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Abstract: | The ethylene epoxidation activity of Ag catalysts supported on non-porous SiO2, microporous silicalite zeolite and mesoporous MCM-41 and HMS silicates was investigated in the present study in comparison to conventional low surface area -Al2O3 based catalysts. The MCM-41 and HMS based catalysts exhibited similar ethylene conversion activity and ethylene oxide (EO) selectivity with the SiO2 and -Al2O3 based catalysts at relatively lower temperatures (up to 230 °C), whereas their activity and selectivity decreased significantly at higher temperatures (≥300 °C). The silicalite based catalyst was highly active for a wide temperature range, similar to the SiO2 and -Al2O3 based catalysts, but it was the less selective amongst all catalysts tested. High loadings of Ag particles (up to ca. 40 wt.%) with medium crystallites size (20–55 nm) could be achieved on the mesoporous materials resulting in very active epoxidation catalysts. The HMS-type silicate with the 3D network of wormhole-like framework mesopores (with average diameter of 3.5 nm), in combination with a high-textural (interparticle) porosity, appeared to be the most promising mesoporous support. |
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Keywords: | Ethylene epoxidation Silver catalysts Mesoporous MCM-41 HMS Silicalite zeolite |
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