- Selective synthesis of ethylene oxide through liquid-phase epoxidation of ethylene with titanosilicate/H2O2 catalytic systems
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Liquid-phase epoxidation of ethylene to ethylene oxide (EO) with H2O2 over various titanosilicate catalysts like Ti-MWW, TS-1, Ti-MOR and Ti-Beta has been investigated. The effects of solvent, catalyst amount, reaction pressure, temperature and time on the catalytic performance of Ti-MWW have been studied in detail. Ti-MWW preferred acetonitrile as a solvent and showed the highest reactivity and EO selectivity among the titanosilicate catalysts investigated. Under optimized reaction conditions, Ti-MWW gave a EO selectivity high as 97.9% as well as a reasonable utilization efficiency of H2O2 of 77.7%. Ti-MWW was gradually deactivated after repeated use in ethylene epoxidation. High-temperature calcination easily recovered the catalytic activity of deactivated Ti-MWW after removing ethylene glycol (EG) and other heavy byproducts with high boiling points that were deposited inside micropores. The issues of molecular dimension and reactivity have also been considered by comparing the epoxidation of linear alkenes with different lengths (C2 to C6) between two representative titanosilicates Ti-MWW and TS-1. Ethylene, with the smallest dynamic diameter but containing electron-deficient C=C double bonds, was more difficult to be epoxidized than other alkenes with higher intrinsic activities.
- Lu, Xinqing,Zhou, Wen-Juan,Wu, Haihong,Liebens, Armin,Wu, Peng
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- Preparation of Ag/α-Al2O3 for ethylene epoxidation through thermal decomposition assisted by extract of Cinnamomum camphora
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An Ag/α-Al2O3 catalyst designed for application in the epoxidation of ethylene was prepared through thermal decomposition assisted by extract of Cinnamomum camphora. The effects of the reaction parameters on the catalytic performance were evaluated, including the extract concentration, calcining temperature and calcining time. The results demonstrated that the thermal decomposition should be conducted at 600 °C in N2 for 60 min, assisted by 0.25 g mL-1Cinnamomum camphora extract. Compared with a simple thermal decomposition method, the sintering and aggregation of Ag particles and Ag loss during the reaction were alleviated by the presence of the catalyst that had been synthesized with the assistance of biomass. The Royal Society of Chemistry 2013.
- Sun, Daohua,Wang, Huixuan,Zhang, Genlei,Huang, Jiale,Li, Qingbiao
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p. 20732 - 20737
(2013/11/06)
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- METHOD OF STARTING-UP A PROCESS OF PRODUCING AN ALKYLENE OXIDE USING A HIGH-EFFICIENCY CATALYST
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A method for starting-up a high efficiency alkylene oxide catalyst is described. A feed gas comprising an alkylene, oxygen, and at least one organic chloride is introduced to the catalyst. The molar ratio of oxygen to alkylene, reaction temperature, and overall chloriding effectiveness are adjusted to specified ranges of values within a specified catalyst aging period.
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Page/Page column 31-32
(2012/06/30)
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