Ethylene Polymerization over Homogeneous Bis(imino)pyridine Vanadium Catalysts: Data on the Number and Reactivity of Active Sites Научная публикация
| Журнал |
Journal of Polymer Research
ISSN: 1022-9760 , E-ISSN: 1572-8935 |
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| Вых. Данные | Год: 2012, Том: 19, Номер: 11, Страницы: 9998 Страниц : 9 DOI: 10.1007/s10965-012-9998-y | ||
| Ключевые слова | Activation energy, Ethylene polymerization catalysts, Kinetics, Number of active centers, Propagation rate constants, Vanadiumcomplexes | ||
| Авторы |
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| Организации |
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Информация о финансировании (1)
| 1 | Российский фонд фундаментальных исследований | 07-03-00311 |
Реферат:
Method of polymerization quenching with radioactive carbon monoxide (14СО) has been used to determine the number of active centers (С P ) and propagation rate constants (k P ) for ethylene polymerization over the homogeneous catalysts 2,6-R2LVCl3+MAO (L: 2,6-(C6H3N=CMe)2C5H3N, R=Me, Et). For both catalysts the maximum number of active centers at 60 °C was found to be 0.42–0.50 mol molV −1 and the k P values—(16.4–20.0) × 103 L mol−1 s−1. It has been shown that noticeable decrease in the catalysts activity with polymerization time results from the decrease in the active centers number and simultaneous transformation of some part of the initial centers into a new ones with lower reactivity. Analysis of the С P and k P values, measured at different polymerization times, together with the values of the polyethylene molecular-weight distribution, allowed to calculate the content of the active centers of both types and the k P values of these centers. For the 2,6-Et2LVCl3+МАО catalyst, the effect of polymerization temperature on the С P and k P values has been studied. It has been found that with polymerization temperature growth from 25 to 60 °С, the С P value substantially increases. As a result, the value of the effective activation energy (E eff = 22.6 kcal mol−1) noticeably exceeded that of the activation energy of propagation reaction (E P = 14.2 kcal mol−1). It is proposed that the reason for the unusually high E P value is formation of “dormant” sites with vanadium-polymer bond at lower polymerization temperature.
Библиографическая ссылка:
Barabanov A.
, Semikolenova N.V.
, Bukatov G.D.
, Matsko M.A.
, Zakharov V.A.
Ethylene Polymerization over Homogeneous Bis(imino)pyridine Vanadium Catalysts: Data on the Number and Reactivity of Active Sites
Journal of Polymer Research. 2012. V.19. N11. P.9998. DOI: 10.1007/s10965-012-9998-y WOS Scopus РИНЦ CAPlusCA OpenAlex
Ethylene Polymerization over Homogeneous Bis(imino)pyridine Vanadium Catalysts: Data on the Number and Reactivity of Active Sites
Journal of Polymer Research. 2012. V.19. N11. P.9998. DOI: 10.1007/s10965-012-9998-y WOS Scopus РИНЦ CAPlusCA OpenAlex
Даты:
| Поступила в редакцию: | 22 мая 2012 г. |
| Принята к публикации: | 8 окт. 2012 г. |
| Опубликована online: | 16 окт. 2012 г. |
| Опубликована в печати: | 1 нояб. 2012 г. |
Идентификаторы БД:
| Web of science: | WOS:000311672600021 |
| Scopus: | 2-s2.0-84867300889 |
| РИНЦ: | 20491383 |
| Chemical Abstracts: | 2012:1659186 |
| Chemical Abstracts (print): | 158:216366 |
| OpenAlex: | W2042129976 |