Direct gas-phase photocatalytic epoxidation of propylene with molecular oxygen by photocatalysts

Chan, Hsiang Yu; Wu, Jeffrey C.S.; Bai, Hsun-Ling

doi:10.1016/j.cej.2011.11.003

Cited by 29 publications

(17 citation statements)

References 28 publications

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“…In the last years, the group of Bai has developed a V-Ti/MCM-41 catalyst, which has proved to be the most favorable, producing PO with a selectivity of 47% at a formation rate of 114 μmol g cat −1 h −1 under very mild reaction conditions of 323 K and atmospheric pressure, with an irradiation of UV-A of λ = 320-500 nm 140). This catalyst was functional using artificial sunlight, with a PO formation rate of 112 μmol g cat −1 h −1 and PO selectivity of 54% (10).…”

Section: Photocatalystsmentioning

confidence: 99%

Direct Oxidation of Propylene to Propylene Oxide with Molecular Oxygen: A Review

2015

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The direct oxidation of propylene to propylene oxide (PO) using molecular oxygen has many advantages over existing chlorohydrin and hydroperoxide process, which produce side products and require complex purification schemes. Recent advances in liquid-phase and gas-phase catalytic oxidation of propylene in the presence of only molecular oxygen as oxidant and in absence of reducing agents are summarized. Liquid-phase PO processes involving soluble or insoluble Mo, W, or V catalysts have been reported which provide moderate conversions and selectivities, but these likely involve autoxidation by homogeneous chain reactions. Gas-phase PO catalysts have been mostly Ag-, Cu-, or TiO 2 -based substances, although other compositions such as Au-, MoO 3 -, Bi-based catalysts and photocatalysts have also been suggested as possibilities. The Ag catalysts differ from those used for ethylene oxide production in having high Ag contents and numerous additives. The additives are solid-phase alkali metals, alkaline earth metals, and halogens, with the most common substances being NaCl and CaCO 3 . Nitrogen oxides in the form of gas-phase species or nitrates have also been found to be effective in enhancing PO production. Direct epoxidation by surface nitrates is a possibility. Titania catalysts supported on silicates have also been reported. These have higher PO selectivities at high conversion than silver catalysts.

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Section: Photocatalystsmentioning

confidence: 99%

Direct Oxidation of Propylene to Propylene Oxide with Molecular Oxygen: A Review

2015

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“…We previously proposed that the titanium in V-Ti/MCM-41 should be Ti 4+ with a tetrahedral coordination [17]. The K-edge XANES of vanadium (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Much effort has been devoted to develop green PO production processes and photo-epoxidation utilizing light energy and O 2 oxidant under mild conditions attracts much attention. Differently designed photocatalysts were examined [17–24], and the reaction conditions such as reaction temperature [18], light irradiation [25–26] and oxygen/propylene ratio [23,27] were also tested. Yoshida and co-workers reported the first systematic investigation of the photo-epoxidation of propylene over more than 50 silica-supported metal oxides, in which TiO x /SiO 2 was the most effective photocatalyst [20].…”

Section: Introductionmentioning

confidence: 99%

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Artificial sunlight and ultraviolet light induced photo-epoxidation of propylene over V-Ti/MCM-41 photocatalyst

Lin¹,

Wu²,

Bai³

2014

Beilstein J. Nanotechnol.

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SummaryThe light irradiation parameters, including the wavelength spectrum and intensity of light source, can significantly influence a photocatalytic reaction. This study examines the propylene photo-epoxidation over V-Ti/MCM-41 photocatalyst by using artificial sunlight (Xe lamp with/without an Air Mass 1.5 Global Filter at 1.6/18.5 mW·cm−2) and ultraviolet light (Mercury Arc lamp with different filters in the range of 0.1–0.8 mW·cm−2). This is the first report of using artificial sunlight to drive the photo-epoxidation of propylene. Over V-Ti/MCM-41 photocatalyst, the propylene oxide (PO) formation rate is 193.0 and 112.1 µmol·gcat −1·h−1 with a PO selectivity of 35.0 and 53.7% under UV light and artificial sunlight, respectively. A normalized light utilization (NLU) index is defined and found to correlate well with the rate of both PO formation and C3H6 consumption in log–log scale. The light utilization with a mercury arc lamp is better than with a xenon lamp. The selectivity to PO remains practically unchanged with respect to NLU, suggesting that the photo-epoxidation occurs through the same mechanism under the conditions tested in this study.

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“…Nowadays, major epoxide chemicals, which are produced by epoxidation of olefins such as ethylene, propylene and cyclohexene, etc., have become considerably more important, valuable and versatile intermediates in industrial organic synthesis [1][2][3][4][5][6]. Among epoxides, 1,2-epoxycyclohexane is an attractive chemical intermediates with multiple applications although it has been produced on the small scale only.…”

Section: Introductionmentioning

confidence: 99%

Real-Time Raman Monitoring during Photocatalytic Epoxidation of Cyclohexene over V-Ti/MCM-41 Catalysts

Chan

Casilda

et al. 2015

Catalysts

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A series of V-and/or Ti-loading MCM-41 catalysts are successfully synthesized with a hydrothermal method. The photocatalytic and thermal epoxidations of cyclohexene in the presence of tert-butyl hydroperoxide (t-BuOOH) were investigated with real-time monitored by NIR-Raman spectroscopy. It suggests that both V-and Ti-loading can be responsible for the cyclohexene epoxidation. Moreover, the complementary behavior of V-and Ti-loading may be related to a similar role of activation. Interestingly, the progress of the photo-epoxidation on V0.25Ti2/MCM-41 photocatalyst was monitored by changes in intensity of the characteristic Raman bands without interference from the UV-light irradiation. The result, for the first time, reveals that cyclohexene was directly photo-epoxidized to 1,2-epoxycyclohexane by t-BuOOH during the reaction. A possible mechanism of cyclohexene photo-epoxidation is also proposed for this study.

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Direct gas-phase photocatalytic epoxidation of propylene with molecular oxygen by photocatalysts

Cited by 29 publications

References 28 publications

Direct Oxidation of Propylene to Propylene Oxide with Molecular Oxygen: A Review

Direct Oxidation of Propylene to Propylene Oxide with Molecular Oxygen: A Review

Artificial sunlight and ultraviolet light induced photo-epoxidation of propylene over V-Ti/MCM-41 photocatalyst

Real-Time Raman Monitoring during Photocatalytic Epoxidation of Cyclohexene over V-Ti/MCM-41 Catalysts

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