Metal‐Substituted Zeolites as Heterogeneous Oxidation Catalysts

Tatsumi, Takashi

doi:10.1002/9783527627547.ch4

Cited by 10 publications

(1 citation statement)

References 111 publications

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“…Titanium species supported on silica − or embedded on a silicate framework − are of interest for the heterogeneous catalytic oxidation of several substrates. Usually the active sites are tetrahedral titanium(IV) centers linked to the surface by three siloxy bonds.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Catalytic Activity of Titanium Silsesquioxane Frameworks as Models of Titanium Active Surface Sites of Controlled Nuclearity

et al. 2010

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The synthesis and catalytic activity of some new titanium(IV) complexes with incompletely condensed Cy 6 Si 6 O 7 (OH) 4 and endo-Cy 8 Si 8 O 11 (OH) 2 (Cy = c-C 6 H 11 ) silsesquioxane cages have been carried out with the aim of investigating new Ti silsesquioxane frameworks as molecular models of titanium active sites of catalysts prepared by grafting Ti(IV) precursors on the surface or in a matrix of mesoporous silica. The silsesquioxane Cy 6 Si 6 O 7 (OH) 4 , which bears four potentially reactive OH groups, when reacted with TiCpCl 3 (Cp = η 5 -C 5 H 5 ) affords the new species [Cy 6 Si 6 O 12 Ti 2 (Cp) 2 ], with two titanium atoms connected through one μ-oxygen bridge, as confirmed by a XANES and EXAFS spectroscopic investigation. By reaction of endo-Cy 8 Si 8 O 11 (OH) 2 with [Ti(o-C 6 H 4 O 2 )-(OCH 2 CH 3 ) 2 ] the new complex [Cy 8 Si 8 O 11 O 2 ] 2 Ti was obtained, which exhibits a tetrapodal coordination of Ti, as shown by a X-ray diffraction investigation. The catalytic activity of these two new Ti silsesquioxane complexes was investigated for the catalytic epoxidation of cyclohexene with tert-butyl hydroperoxide and compared with the catalytic activity of the known [Cy 7 Si 7 O 12 TiCp], widely used to model very active tripodal titanium single sites. It appears that a tripodal coordination of Ti sites facilitates the catalytic activity that is in contrast quite low for the two new complexes investigated in this work, probably due to the higher stability toward dissociation to generate a tripodal coordination of the Ti-O-Ti bond and to the steric hindrance of Ti tetrapodal coordination.

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Section: Introductionmentioning

confidence: 99%

Synthesis and Catalytic Activity of Titanium Silsesquioxane Frameworks as Models of Titanium Active Surface Sites of Controlled Nuclearity

et al. 2010

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Environmental Applications of Multifunctional Nanocomposite Catalytic Materials: Issues with Catalyst Combinations

Sullivan¹,

Keane²,

Dulgheru³

et al. 2015

Advanced Catalytic Materials

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Catalytic Epoxidation of Organics from Vegetable Sources

Palumbo¹

2016

Encyclopedia of Inorganic and Bioinorganic Chemistry

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Unsaturated fatty acids, fatty acid esters, and terpenes are alkenic molecules that can be extracted directly from vegetable sources and converted into a broad range of intermediates, commodities, and high value‐added products by means of epoxidation reactions. Conventional stoichiometric epoxidation techniques using environmentally unfriendly oxidants are still performed at the industrial scale. However, several examples, at the laboratory level, show how it is possible to use more sustainable oxidants, such as alkyl hydroperoxides, hydrogen peroxide or, in the best cases, molecular oxygen, in the presence of catalytic systems. Homogeneous, heterogeneous, enzymatic catalysts or, even, metal‐free organocatalysts can help in avoiding the use of hazardous oxidants and noxious solvents and in performing an efficient, selective, and safe epoxidation of C=C bonds in oils, fatty derivatives, and terpenic compounds.

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Metal‐Substituted Zeolites as Heterogeneous Oxidation Catalysts

Cited by 10 publications

References 111 publications

Synthesis and Catalytic Activity of Titanium Silsesquioxane Frameworks as Models of Titanium Active Surface Sites of Controlled Nuclearity

Synthesis and Catalytic Activity of Titanium Silsesquioxane Frameworks as Models of Titanium Active Surface Sites of Controlled Nuclearity

Environmental Applications of Multifunctional Nanocomposite Catalytic Materials: Issues with Catalyst Combinations

Catalytic Epoxidation of Organics from Vegetable Sources

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