Green and selective oxidation reactions catalyzed by kaolinite covalently grafted with Fe(III) pyridine-carboxylate complexes

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• 作者：Emerson H. de Faria^a ; ^{eh.defaria@unifran.br} ; Gustavo P. Ricci^a ; Liziane Març ; al^a ; Eduardo J. Nassar^a ; Miguel A. Vicente^b ; Raquel Trujillano^b ; Antonio Gil^c ; Sophia A. Korili^c ; Katia J. Ciuffi^a ; ^{ciuffi@unifran.br} ; Paulo S. Calefi^a
• 关键词：Kaolinite ; Heterogeneous catalysis ; Fe(III)&ndash ; picolinates and dipicolinates ; Oxidation reactions ; Baeyer&ndash ; Villiger
• 刊名：Catalysis Today
• 出版年：2012
• 期刊代码：13_09205861
• 类别：ce
• 出版时间：30 June, 2012
• 卷：187
• 期：1
• 页码：135-149
• 文件大小：1523 K

摘要

The immobilization of Fe(III) picolinate and Fe(III) dipicolinate complexes on kaolinite furnished heterogeneous catalysts, whose catalytic activity was evaluated. The precursor materials were kaolinite grafted with picolinic (Ka-pa) and dipicolinic (Ka-dpa) acids obtained by melting of the pyridine carboxylic acids. To obtain the catalysts Fe(Ka-pa)-n and Fe(Ka-dpa)-n (n = 1, 2, or 3 is the ligand/Fe ratio), the precursors were suspended in Fe³⁺ solutions with cation/ligand ratios of 1:1, 1:2, or 1:3. The resulting materials were characterized by thermal analyses (simultaneous TG/DTA), X-ray diffraction, UV/vis and infrared spectroscopies, and transmission electron microscopy. The grafted complexes were employed as heterogeneous catalysts in the epoxidation of cis-cyclooctene to cis-cyclooctenoxide and in the oxidation of cyclohexane to cyclohexanol and cyclohexanone at ambient temperature and pressure. Hydrogen peroxide was used as oxygen donor at a catalyst/oxidant/substrate molar ratio of 1:300:100. Fe(Ka-pa)-n catalysts were very efficient for cis-cyclooctene epoxidation (38%conversion). For cyclohexane oxidation, Fe(Ka-dpa)-n was 100%selective for cyclohexanone formation, with substrate conversion of 14%. This last series of catalysts was also very effective in the Baeyer-Villiger reaction, with 60%substrate conversion and 100%selectivity for 尉-caprolactone. After reuse (5 times), the catalysts still led to high substrate conversion.