2000 Fiscal Year Final Research Report Summary
Development of Novel Methods for Synthesizing Hydrophobic Metallosilicates
| Project/Area Number |
11555212
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
触媒・化学プロセス
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| Research Institution | Yokohama National University |
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Principal Investigator |
TATSUMI Takashi Faculty of Engineering, Yokohama National University, Professor, 工学部, 教授 (30101108)
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| Co-Investigator(Kenkyū-buntansha) |
TSUNEKI Hideaki Materials & Functions Research Laboratory, Nippon Shokubai Co.Ltd. Manager, No.1 Research Section, 第1研究室長
YOSHITAKE Hideaki Institute of Environmental Science and Technology, Yokohama National University, Associate Professor, 環境科学研究センター, 助教授 (20230716)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Zeolites / Hydrogen peroxide oxidation / Titanosilicate / Hydrophobicity / MFI structure / BEA structure / MWW structure |
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| Research Abstract |
By increasing hydrophobicity, zeolite catalysts showing high activity and selectivity for the oxidation of organic compounds with aqueous hydrogen peroxide were synthesized. The relationship between catalytic performance and either hydrophobicity or acidity was investigated for TS-1, Ti-β and Ti-MWW.Ti-β, which has 3D-12 MR channel, was able to epoxidize bulky cyclic compounds ; however, epoxides were cleaved by water to give diols, which should be due to the acidity of Ti-β. By ion-exchanging calcined Ti-β with quaternary ammonium ions, Ti-β showing high activity and selectivity for epoxidation was successfully prepared. Ammonium ion-exchanged catalyst was not selective for epoxidation because of the oxidation of ammonium ion during the reaction while ion-exchange with alkali metal ions resulted in suppression of oxidation activity. With the coexistence of boric acid, Ti-MWW was successfully crystallized to show pure phase by using either piperidine or hexamethyleneimine as a structure directing agent. Ti-MWW always contained a part of octahedral Ti species which aggregated upon the calcination to form anatase. Nevertheless, these extraframework Ti species together with a part of framework boron was removed readily by treating the as-synthesized samples with acid solutions. Ti-MWW thus pretreated was characterized as containing mainly tetrahedral Ti species in the framework sites by various spectroscopic techniques. Ti-MWW was more active for the epoxidation reactions with hydrogen peroxide than TS-1. Piperidine-directed Ti-MWW was more active than hexamethyleneimine-directed Ti-MWW.The former was hexagonal plate with small crystallite size in shape and the latter consisted of a coagulation of needle-like particles. Thus we have developed a method of obtaining titanosilicate catalysts having small crystallite size, high hydrophobicity and low acidity, which show high activity in liquid-phase oxidations.
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