Efficient catalytic epoxidation of olefins with silylated Ti-TUD-1 catalysts

M. Ramakrishna Prasad, Mohamed S. Hamdy, Guido Mul, E. Bouwman, E. Drent

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Various silylated Ti-TUD-1 samples were synthesized by treating Ti-TUD-1 samples of differing Ti loadings with hexamethyldisilazane (HMDS). The silylation of silanol (Sisingle bondOH) and titanol groups (Tisingle bondOH) on the mesoporous silica was confirmed by FTIR spectroscopy, hydrophobicity (TGA), and NH3-TPD measurements. The relatively unreactive olefins, such as 1-octene and p-tert-butylphenylallyl ether, were epoxidized using both silylated and unsilylated Ti-TUD-1 samples with different Ti loadings in the range of 1–10 wt% Ti. The catalytic epoxidation reactions were performed with commercial solutions of organic hydroperoxides as oxidants without the addition of any other organic solvent. The selectivities in peroxide utilization were found to depend on the type of olefin, oxidant, and catalyst. Using unsilylated Ti-TUD-1, low selectivity to epoxide was achieved for cumyl hydroperoxide (CHP), which is attributed to its facile acid-catalyzed decomposition to phenol and acetone under the reaction conditions. However, both t-butyl hydroperoxide (TBHP) and cumyl hydroperoxide yielded high selectivity to epoxide (based on converted hydroperoxide) with silylated Ti-TUD-1 samples. The selectivity to epoxide was lower for the electron-poor olefin p-tert-butylphenylallyl ether than for simple 1-octene. The experiments with CHP as the oxidant were used as a diagnostic tool to demonstrate that the enhanced epoxidation activity and selectivity of the silylated samples with TBHP can be credited to two effects of silylation. The elimination of protic Tisingle bondOH sites of the Ti-TUD-1 catalyst resulted in a significant reduction of the competing acid-catalyzed decomposition of the peroxide, whereas the enhanced hydrophobicity of the catalyst surface enhanced the accommodation of the apolar olefinic substrate.
Original languageUndefined
Pages (from-to)288-294
JournalJournal of catalysis
Volume260
Issue number2
DOIs
Publication statusPublished - 2008

Keywords

  • METIS-306557

Cite this

Ramakrishna Prasad, M. ; Hamdy, Mohamed S. ; Mul, Guido ; Bouwman, E. ; Drent, E. / Efficient catalytic epoxidation of olefins with silylated Ti-TUD-1 catalysts. In: Journal of catalysis. 2008 ; Vol. 260, No. 2. pp. 288-294.
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title = "Efficient catalytic epoxidation of olefins with silylated Ti-TUD-1 catalysts",
abstract = "Various silylated Ti-TUD-1 samples were synthesized by treating Ti-TUD-1 samples of differing Ti loadings with hexamethyldisilazane (HMDS). The silylation of silanol (Sisingle bondOH) and titanol groups (Tisingle bondOH) on the mesoporous silica was confirmed by FTIR spectroscopy, hydrophobicity (TGA), and NH3-TPD measurements. The relatively unreactive olefins, such as 1-octene and p-tert-butylphenylallyl ether, were epoxidized using both silylated and unsilylated Ti-TUD-1 samples with different Ti loadings in the range of 1–10 wt{\%} Ti. The catalytic epoxidation reactions were performed with commercial solutions of organic hydroperoxides as oxidants without the addition of any other organic solvent. The selectivities in peroxide utilization were found to depend on the type of olefin, oxidant, and catalyst. Using unsilylated Ti-TUD-1, low selectivity to epoxide was achieved for cumyl hydroperoxide (CHP), which is attributed to its facile acid-catalyzed decomposition to phenol and acetone under the reaction conditions. However, both t-butyl hydroperoxide (TBHP) and cumyl hydroperoxide yielded high selectivity to epoxide (based on converted hydroperoxide) with silylated Ti-TUD-1 samples. The selectivity to epoxide was lower for the electron-poor olefin p-tert-butylphenylallyl ether than for simple 1-octene. The experiments with CHP as the oxidant were used as a diagnostic tool to demonstrate that the enhanced epoxidation activity and selectivity of the silylated samples with TBHP can be credited to two effects of silylation. The elimination of protic Tisingle bondOH sites of the Ti-TUD-1 catalyst resulted in a significant reduction of the competing acid-catalyzed decomposition of the peroxide, whereas the enhanced hydrophobicity of the catalyst surface enhanced the accommodation of the apolar olefinic substrate.",
keywords = "METIS-306557",
author = "{Ramakrishna Prasad}, M. and Hamdy, {Mohamed S.} and Guido Mul and E. Bouwman and E. Drent",
year = "2008",
doi = "10.1016/j.jcat.2008.09.021",
language = "Undefined",
volume = "260",
pages = "288--294",
journal = "Journal of catalysis",
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Ramakrishna Prasad, M, Hamdy, MS, Mul, G, Bouwman, E & Drent, E 2008, 'Efficient catalytic epoxidation of olefins with silylated Ti-TUD-1 catalysts', Journal of catalysis, vol. 260, no. 2, pp. 288-294. https://doi.org/10.1016/j.jcat.2008.09.021

Efficient catalytic epoxidation of olefins with silylated Ti-TUD-1 catalysts. / Ramakrishna Prasad, M.; Hamdy, Mohamed S.; Mul, Guido; Bouwman, E.; Drent, E.

In: Journal of catalysis, Vol. 260, No. 2, 2008, p. 288-294.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Efficient catalytic epoxidation of olefins with silylated Ti-TUD-1 catalysts

AU - Ramakrishna Prasad, M.

AU - Hamdy, Mohamed S.

AU - Mul, Guido

AU - Bouwman, E.

AU - Drent, E.

PY - 2008

Y1 - 2008

N2 - Various silylated Ti-TUD-1 samples were synthesized by treating Ti-TUD-1 samples of differing Ti loadings with hexamethyldisilazane (HMDS). The silylation of silanol (Sisingle bondOH) and titanol groups (Tisingle bondOH) on the mesoporous silica was confirmed by FTIR spectroscopy, hydrophobicity (TGA), and NH3-TPD measurements. The relatively unreactive olefins, such as 1-octene and p-tert-butylphenylallyl ether, were epoxidized using both silylated and unsilylated Ti-TUD-1 samples with different Ti loadings in the range of 1–10 wt% Ti. The catalytic epoxidation reactions were performed with commercial solutions of organic hydroperoxides as oxidants without the addition of any other organic solvent. The selectivities in peroxide utilization were found to depend on the type of olefin, oxidant, and catalyst. Using unsilylated Ti-TUD-1, low selectivity to epoxide was achieved for cumyl hydroperoxide (CHP), which is attributed to its facile acid-catalyzed decomposition to phenol and acetone under the reaction conditions. However, both t-butyl hydroperoxide (TBHP) and cumyl hydroperoxide yielded high selectivity to epoxide (based on converted hydroperoxide) with silylated Ti-TUD-1 samples. The selectivity to epoxide was lower for the electron-poor olefin p-tert-butylphenylallyl ether than for simple 1-octene. The experiments with CHP as the oxidant were used as a diagnostic tool to demonstrate that the enhanced epoxidation activity and selectivity of the silylated samples with TBHP can be credited to two effects of silylation. The elimination of protic Tisingle bondOH sites of the Ti-TUD-1 catalyst resulted in a significant reduction of the competing acid-catalyzed decomposition of the peroxide, whereas the enhanced hydrophobicity of the catalyst surface enhanced the accommodation of the apolar olefinic substrate.

AB - Various silylated Ti-TUD-1 samples were synthesized by treating Ti-TUD-1 samples of differing Ti loadings with hexamethyldisilazane (HMDS). The silylation of silanol (Sisingle bondOH) and titanol groups (Tisingle bondOH) on the mesoporous silica was confirmed by FTIR spectroscopy, hydrophobicity (TGA), and NH3-TPD measurements. The relatively unreactive olefins, such as 1-octene and p-tert-butylphenylallyl ether, were epoxidized using both silylated and unsilylated Ti-TUD-1 samples with different Ti loadings in the range of 1–10 wt% Ti. The catalytic epoxidation reactions were performed with commercial solutions of organic hydroperoxides as oxidants without the addition of any other organic solvent. The selectivities in peroxide utilization were found to depend on the type of olefin, oxidant, and catalyst. Using unsilylated Ti-TUD-1, low selectivity to epoxide was achieved for cumyl hydroperoxide (CHP), which is attributed to its facile acid-catalyzed decomposition to phenol and acetone under the reaction conditions. However, both t-butyl hydroperoxide (TBHP) and cumyl hydroperoxide yielded high selectivity to epoxide (based on converted hydroperoxide) with silylated Ti-TUD-1 samples. The selectivity to epoxide was lower for the electron-poor olefin p-tert-butylphenylallyl ether than for simple 1-octene. The experiments with CHP as the oxidant were used as a diagnostic tool to demonstrate that the enhanced epoxidation activity and selectivity of the silylated samples with TBHP can be credited to two effects of silylation. The elimination of protic Tisingle bondOH sites of the Ti-TUD-1 catalyst resulted in a significant reduction of the competing acid-catalyzed decomposition of the peroxide, whereas the enhanced hydrophobicity of the catalyst surface enhanced the accommodation of the apolar olefinic substrate.

KW - METIS-306557

U2 - 10.1016/j.jcat.2008.09.021

DO - 10.1016/j.jcat.2008.09.021

M3 - Article

VL - 260

SP - 288

EP - 294

JO - Journal of catalysis

JF - Journal of catalysis

SN - 0021-9517

IS - 2

ER -