- High selectivity of MCM-22 for cyclopentanol formation in liquid-phase cyclopentene hydration
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Highly effective formation of cyclopentanol through the liquid-phase hydration of cyclopentene has been attempted on various zeolites catalysts. MCM-22 zeolite was the most selective catalyst, which actively converted cyclopentene to cyclopentanol with a selectivity up to 99%. The effects on the hydration of catalyst preparation method, reaction atmosphere and temperature have been investigated for the MCM-22 catalysts. On the basis of the effect of reaction atmosphere, the mechanism of liquid-phase cyclopentene hydration was proposed. The thermodynamic equilibrium between cyclopentene and cyclopentanol was suggested to control greatly the cyclopentene conversion. The cyclopentene conversion was increased to 10% by increasing the water/cyclopentene ratio. Poisoning using organic amines with different molecular sizes revealed that the hydration occurred mainly in the 10-membered ring channels of MWW structure, which had an elliptic aperture smaller than that of MFI structure, exhibiting a significant shape selectivity by suppressing the etherification cyclopentanol.
- Nuntasri, Duangamol,Wu, Peng,Tatsumi, Takashi
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- Rhodium and iridium nanoparticles entrapped in aluminum oxyhydroxide nanofibers: Catalysts for hydrogenations of arenes and ketones at room temperature with hydrogen balloon
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The recyclable metal nanoparticle catalysts, rhodium in aluminum oxyhydroxide [Rh/ AlO(OH)] and iridium in aluminum oxyhydroxide [Ir/A1O(OH)], were simply prepared from readily available reagents. The catalysts showed high activities in the hydrogenation of various arenes and ketones under mild conditions. Selective hydrogenation was possible for bicyclic and tricyclic arenes in high yields. The catalysts were active at room temperature even with a hydrogen balloon. Also, the catalysts showed high turnover frequency (TOF) values under solventless conditions at 75 °C under 4 atm hydrogen pressure: ca. 1700h 1 in the hydrogenation of benzene. Furthermore, Rh/A1O(OH) can be reused forat least 10 times without activity loss. The catalysts were characterized by the transmission electron microscopy (TEM), powder X-ray diffraction (XRD), inductively coupled plasma (ICP), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption and hydrogen chemisorption experiments. The sizes of rhodium and iridium particles were estimated to be 3-4 nm and 2-3 nm, respectively. Aluminum oxyhydroxide nanofibers of these catalysts have surface areas of 500-600 m2 g -1.
- Park, In Soo,Kwon, Min Serk,Kang, Kyung Yeon,Lee, Jae Sung,Park, Jaiwook
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- Synthesis of Benzyl Alkyl Ethers by Intermolecular Dehydration of Benzyl Alcohol with Aliphatic Alcohols under the Effect of Copper Containing Catalysts
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Synthesis of benzyl alkyl ethers was performed in high yields by intermolecular dehydration of benzyl and primary, secondary, tertiary alcohols under the effect of copper containing catalysts. The formation of benzyl alkyl ethers occurs with participation of benzyl cation.
- Bayguzina,Gimaletdinova,Khusnutdinov
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- Highly selective formation of cyclopentanol through liquid-phase cyclopentene hydration over MCM-22 catalysts
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MCM-22 catalyst exhibits an extremely high shape selectivity not observed on other zeolites of MFI, MOR and BEA structures, in that it effectively catalyzes the liquid-phase hydration of cyclopentene at a conversion up to 10% and a cyclopentanol selectivi
- Nuntasri, Duangamol,Wu, Peng,Tatsumi, Takashi
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- Process for the production of symmetrical ethers from secondary alcohols
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Secondary alcohols are converted to symmetrical secondary alkyl ethers in high selectivity. The method employs acidic solid metallosilicate catalyst particles to accomplish the etherification by selective intermolecular dehydration of secondary alcohol to form di-secondary alkyl ethers. Preferably, the catalysts are solid shape selective aluminosilicate particles, especially zeolite such as ZSM-5, zeolite HY and zeolite Beta. Continuous separation of by-product olefin and ether during the etherification reaction improves selectivity.
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