Salen-Co(II) complex incorporated into amino-functionalized MIL-101(Cr) through postsynthetic modification as a cooperative catalyst for cyclohexane selective oxidation

Authors:  Zhiguo Sun, Gang Li, Hai-ou Liu, Liping Liu

Abstract:
A series of MOF-based catalysts, metal-salen complexes incorporated into amino-functionalized MIL101 matrices by salicylaldehyde condensing to amino group and coordinating metal ion through one pot method, have been prepared and characterized. The successful preparation of catalysts demonstrates that postsynthetic modification (PSM) is a practical and powerful route to generate MOF-based catalyst with multiple active sites. The catalytic performances of prepared catalysts were investigated via selective oxidation of cyclohexane to cyclohexanone and cyclohexanol (KA-oil) by molecular oxygen in the absence of solvent. It was found that NH₂-MIL-101(Cr)-Sal-Co, as a typical case, behaves as cooperative catalyst for cyclohexane selective oxidation. That is, salen-Co(II) attached to framework of MOF is able to assist in the generation of new radicals from peroxides via a Haber–Weiss catalytic cycle to promote conversion of cyclohexane while framework Cr ion is able to catalyze the dehydration of intermediate product cyclohexyl hydroperoxide (CHHP) to improve KA-oil selectivity. Furthermore, this catalyst exhibits good recyclability and behaves as truely heterogeneous catalyst. 

Keywords:
Metal-organic framework
Postsynthetic modification
Metal-salen
Cooperative catalyst
Cyclohexane selective oxidation

Published in: Applied catalysis A: General  (Volume 466, Pages 1-314, 10 September 2013)

Publisher: Elsevier  

ISSN Information: 0926-860X

Salen-Co(II) complex incorporated into amino-functionalized MIL-101(Cr) through postsynthetic modification as a cooperative catalyst for cyclohexane selective oxidation

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