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Comparative study of Keggin-type polyoxometalate pillared layered double hydroxides via two synthetic routes: Characterization and catalytic behavior in green epoxidation of cyclohexene
AbstractMgAl LDH pillared by Keggin-type polyoxometalate [PW12O40]3− (PW12) have been fabricated by the ion-exchange and exfoliation/restacking methods respectively (denoted as PW12/LDHEx and PW12/LDHRe). X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR) spectroscopy and N2 adsorption-desorption were used to characterize the structure and morphology of the intercalated compounds. PW12/LDHRe can be obtained without the formation of the impurity phase, which is unavoidable for the ion-exchange product PW12/LDHEx. XRD results showed that the C3 axis of the PW12 anions is perpendicularly oriented to the surface of LDH layers. The catalytic properties of these hybrid materials were investigated in the green epoxidation of cyclohexene with oxygen as oxidant and isobutyraldehyde as co-reagent. Both hybrids were demonstrated to be efficient heterogeneous catalysts and can be recycled five times without obvious loss of catalytic activity. By comparison, PW12/LDHRe shows relatively higher catalytic activity and the conversion can reach 100% after 1.5h at 60°C.
Graphical abstract
HighlightsPOM pillared LDHs were prepared by ion-exchange and exfoliation/restacking methods.The exfoliation/restacking product PW12/LDHRe shows no impurity phase.Both PW12/LDH nanohybrids can catalyze cyclohexene epoxidation efficiently.PW12/LDH can be reused for at least 5 times without obvious decrease of activity.
Comparative study of Keggin-type polyoxometalate pillared layered double hydroxides via two synthetic routes: Characterization and catalytic behavior in green epoxidation of cyclohexene
AbstractMgAl LDH pillared by Keggin-type polyoxometalate [PW12O40]3− (PW12) have been fabricated by the ion-exchange and exfoliation/restacking methods respectively (denoted as PW12/LDHEx and PW12/LDHRe). X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR) spectroscopy and N2 adsorption-desorption were used to characterize the structure and morphology of the intercalated compounds. PW12/LDHRe can be obtained without the formation of the impurity phase, which is unavoidable for the ion-exchange product PW12/LDHEx. XRD results showed that the C3 axis of the PW12 anions is perpendicularly oriented to the surface of LDH layers. The catalytic properties of these hybrid materials were investigated in the green epoxidation of cyclohexene with oxygen as oxidant and isobutyraldehyde as co-reagent. Both hybrids were demonstrated to be efficient heterogeneous catalysts and can be recycled five times without obvious loss of catalytic activity. By comparison, PW12/LDHRe shows relatively higher catalytic activity and the conversion can reach 100% after 1.5h at 60°C.
Graphical abstract
HighlightsPOM pillared LDHs were prepared by ion-exchange and exfoliation/restacking methods.The exfoliation/restacking product PW12/LDHRe shows no impurity phase.Both PW12/LDH nanohybrids can catalyze cyclohexene epoxidation efficiently.PW12/LDH can be reused for at least 5 times without obvious decrease of activity.
Comparative study of Keggin-type polyoxometalate pillared layered double hydroxides via two synthetic routes: Characterization and catalytic behavior in green epoxidation of cyclohexene
Ma, Juanjuan (author) / Yang, Min (author) / Chen, Qian (author) / Zhang, Shusu (author) / Cheng, Han (author) / Wang, Shiyue (author) / Liu, Lin (author) / Zhang, Chengyan (author) / Tong, Zhiwei (author) / Chen, Zhong (author)
Applied Clay Science ; 150 ; 210-216
2017-09-26
7 pages
Article (Journal)
Electronic Resource
English
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