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Acidic properties of sulfonic acid-functionalized FSM-16 mesoporous silica and its catalytic efficiency for acetalization of carbonyl compounds
Propyl-sulfonic acid-functionalized FSM-16 mesoporous silica (SO 3H-FSM) is prepared by a conventional post-modification method. For the acetalization of carbonyl compounds with ethylene glycol, SO 3H-FSM shows a higher rate and 1,3-dioxolane yield than conventional heterogeneous solid acids such as...
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Published in: | Journal of catalysis 2005-04, Vol.231 (1), p.131-138 |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that cite this one |
Online Access: | Get full text |
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Summary: | Propyl-sulfonic acid-functionalized FSM-16 mesoporous silica (SO
3H-FSM) is prepared by a conventional post-modification method. For the acetalization of carbonyl compounds with ethylene glycol, SO
3H-FSM shows a higher rate and 1,3-dioxolane yield than conventional heterogeneous solid acids such as zeolites, montmorillonite K10 clay, silica-alumina, and the sulfonic resin. SO
3H-FSM is stable during the reaction, with no leaching and deactivation of sulfonic acid groups, and is reusable without loss of its activity. The acidity and hydrophilicity of SO
3H-FSM are well characterized by the microcalorimetry of NH
3 adsorption, NH
3-TPD, and H
2O-TPD, and the result is compared with those for various aluminosilicate zeolites (HZSM5, HBEA, HY) and K10 clay. It is found that NH
3-TPD is not suitable for characterizing the acidity of SO
3H-FSM, because the decomposition of SO
3H groups on SO
3H-FSM begins above 200 °C. An NH
3 adsorption microcalorimetric experiment at 150 °C shows that, compared with HZSM5, SO
3H-FSM has a smaller number of acid sites but has a similar number of strong acid sites with ammonia adsorption heat above 140 kJ mol
−1. Comparison of the structural properties and catalytic results shows that a large pore diameter and low hydrophilicity are required to obtain high activity. Brønsted acid sites with a relatively strong acid strength are more suitable for this reaction, but the high acid concentration is not indispensable. The high activity of SO
3H-FSM should be caused by the presence of the strong Brønsted acid sites in the mesopore with a relatively low hydrophilicity, where both reactants can smoothly access the acid sites. |
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ISSN: | 0021-9517 1090-2694 |
DOI: | 10.1016/j.jcat.2005.01.017 |