fulltext.study @t Gmail

Manganese(III) porphyrin-encapsulated Ti,Si-mesoporous molecular sieves as heterogeneous catalysts for the epoxidation of alkenes

Paper ID Volume ID Publish Year Pages File Format Full-Text
44474 46033 2006 10 PDF Available
Title
Manganese(III) porphyrin-encapsulated Ti,Si-mesoporous molecular sieves as heterogeneous catalysts for the epoxidation of alkenes
Abstract

The mesoporous molecular sieves containing different amounts of titanium were synthesized using cetyltrimethylammonium bromide (CTAB) as the structure-directing agent and tetraethyl orthotitanate (TEOT) as the source of titanium. The heterogeneous catalysts were obtained by encapsulating cationic manganese-porphyrin, [meso-tetrakis(4-trimethylammoniophenyl)porphyrinato]manganese(III) pentachloride (MnTAPP) into the titanium-substituted mesoporous molecular sieves. Both the type of catalysts, i.e., supported and unsupported were characterized by FTIR, TGA, low-angle X-ray diffraction, nitrogen adsorption isotherm, scanning electron microscopy and DRUV–vis spectroscopy. A combined study on the characterization and catalytic performance of MnTAPP supported systems suggests the successful encapsulation of MnTAPP inside the mesoporous molecular sieves. The catalytic activity of the manganese(III) porphyrin-encapsulated materials was tested in the epoxidation of cyclohexene and styrene using iodosylbenzene (PhIO) as oxygen source. When compared to the homogeneous system, the manganese(III) porphyrin-encapsulated materials show higher activity for the epoxidation reactions. The activity and selectivity of these heterogeneous catalysts were also compared with a heterogeneous catalyst containing no titanium and with unsupported molecular sieves. The former shows lower activity than the heterogeneous catalyst prepared by encapsulating MnTAPP onto titanium-substituted molecular sieves, whereas the latter was inactive in the oxidation of both cyclohexene and styrene. The selectivity of these heterogeneous catalysts does not change appreciably after three times of reusing, but their catalytic activity decreases marginally. The decrease in the activity may be due to some leaching and/or decomposition of MnTAPP complex under the reaction conditions.

Graphical abstractThe cationic manganese-porphyrin, [meso-tetrakis(4-trimethylammoniophenyl)porphyrinato]manganese(III) pentachloride (MnTAPP) was encapsulated on well-defined pores of titanium substituted mesoporous materials; the synthesized composites provided good catalytic activity and epoxide selectivity. These heterogeneous catalysts were re-used successively under the same reaction conditions. Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Ti-MCM-41; Manganese(III) porphyrin; Heterogeneous catalysts; Cyclohexene; Styrene; Epoxidation
First Page Preview
Manganese(III) porphyrin-encapsulated Ti,Si-mesoporous molecular sieves as heterogeneous catalysts for the epoxidation of alkenes
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 314, Issue 2, 9 November 2006, Pages 216–225
Authors
, , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us