English  |  正體中文  |  简体中文  |  Items with full text/Total items : 54367/62174 (87%)
Visitors : 14933484      Online Users : 66
RC Version 6.0 © Powered By DSPACE, MIT. Enhanced by NTHU Library IR team.
Scope Tips:
  • please add "double quotation mark" for query phrases to get precise results
  • please goto advance search for comprehansive author search
  • Adv. Search
    HomeLoginUploadHelpAboutAdminister Goto mobile version
    National Tsing Hua University Institutional Repository > 理學院 > 化學系 > 會議論文 >  Chemistry of CoAPO-11 and VAPO-5: ESR studies of molecular oxygen adducts.


    Please use this identifier to cite or link to this item: http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/57899


    Title: Chemistry of CoAPO-11 and VAPO-5: ESR studies of molecular oxygen adducts.
    Authors: Naccache C;Vishnetskaya M;Chao KJ
    教師: 趙桂蓉
    Date: 1997
    Publisher: Elsevier
    Relation: PROGRESS IN ZEOLITE AND MICROPOROUS MATERIALS,PTS A-C Book Series: STUDIES IN SURFACE SCIENCE AND CATALYSIS,Volume: 105,Pages: 795-800,Part: Part A-C,Published: 1997
    Keywords: peroxo cobalt
    Tetravalent V
    oxygen
    Abstract: CoAPO-11 and VAPO-5 were synthesized in the presence of diisopropylamine. XRD indicates high crystalline materials with the isotopic structure of respectively ALPO-11 and ALPO-5. CoAPO-11 UV-spectra and the existence of acidic OH revealed by infrared, indicate isomorphous substitution of divalent cobalt for aluminium Removal of the template by O-2- treatment at 773 K produced a diamagnetic ore-type cobalt Co = O. This species activates molecular oxygen only after H-2-treatment at high temperature. The esr spectra of the oxygen adduct formed upon O-2 adsorption on H-2-reduced CoAPO-11 correspond to the paramagnetic species Co(2+)-O-O-.. The amount of this peroxo cobalt adduct increases with the severity of the H-2-treatment. One concludes that Co = O is converted into an active Co(2+) species by H-2-treatment. Co(2+)-O-O-. is very reactive toward H-2, hydrocarbons, and is regenerated by cyclic O-2 adsorption. At high temperature about 573-773 K Co(2+)-O-O-. is converted into Co = O oxo species non active to activate molecular oxygen.
    VAPO-5 was studied by esr. The esr spectra revealed the presence of V4+ both in the sample as synthesized and in the 773 K O-2-treated sample to remove the template. Tetravalent V is rather stable in O-2 at high temperature which indicates that V4+ ion substitutional framework position is resistant towards oxidation. Like CoAPO-11, oxygen adducts V-O-O-. are formed, as revealed by esr, only after H-2-treatment at high temperature. The esr results are interpreted similarly to those on CoAPO-11.
    URI: http://www.elsevier.com/
    http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/57899
    Appears in Collections:[化學系] 會議論文

    Files in This Item:

    File Description SizeFormat
    index.html0KbHTML939View/Open


    在NTHUR中所有的資料項目都受到原著作權保護,僅提供學術研究及教育使用,敬請尊重著作權人之權益。若須利用於商業或營利,請先取得著作權人授權。
    若發現本網站收錄之內容有侵害著作權人權益之情事,請權利人通知本網站管理者(smluo@lib.nthu.edu.tw),管理者將立即採取移除該內容等補救措施。

    SFX Query

    與系統管理員聯絡

    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - Feedback