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Synthesis of Some Kinds of Metallosilicates by Atom-Planting Method and Their Catalytic Properties

原子植入法合成几种金属硅酸盐及其催化性能

基本信息

批准号：
03453083
负责人：
YASHIMA Tatsuaki
金额：
$ 4.48万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1993
项目状态：
已结题

项目摘要

Some kinds of metallosilicate could be prepared by Atom-Planting method using highly silicious MFI type zeolite and dealuminated mordenite, and metal chlorides. When vapor of metal chloride contacts with highly silicious zeolites at the higher temperatures, the metal cation can occupy the defect sites in zeolite framework.The acidity of metallosilicates ion-exchanged by proton deferred to the kind of trivalent metal cation inserted into the framework. The order of acid strength of some metallosilicates was measured as follows ;As-> Ga-> Fe-> In-> Sb-> As-When these metallosilicates were used as a catalyst for the alkylation of monoalkylbenzene, the fraction of para isomer in dialkylbenzene produced reached 80-100%. It can be concluded from the results obtained by using metallosilicate catalysts with same pore window size but different acid strength that para isomer is shape-selectively produced through the transition state restriction.The transition-metal cation inserted into the zeolite framework was a tetrahedral state and was not easily reduced nor oxidized. Therefore, it is expected that the catalytic properties of transition-metal cations in zeolite framework would be different from those in oxides and coplex compounds. Iron cation with tri-valent state in zeolite framework showed the high activity for the oxidative dehydrogenation and the low activity for the complete oxidation of lower paraffins, while iron oxide showed the high activity for the complete oxidation of lower paraffins. On the other hand, titanosilicate with mordenite type structure could be prepared by Atom-Planting method, and showed high catalytic activity for the liquid phase hydroxylation of benzene ring with hydrogen peroxide.From these results it is concluded that Atom-Planting is a good method for the preparation of metallosilicates and these metallosilicates will show the unique catalytic properties for some reactions.

以高硅MFI型沸石和脱铝丝光沸石为原料，加入金属氯化物，采用原子植晶法可制备出多种金属硅酸盐。当金属氯化物蒸气在较高温度下与高硅沸石接触时，金属阳离子可占据沸石骨架中的缺陷位，质子交换金属硅酸盐的酸性取决于插入骨架中的三价金属阳离子的种类。测定了几种金属硅酸盐的酸强度顺序为：As-> Ga-> Fe-> In-> Sb-> As。用这些金属硅酸盐作单烷基苯烷基化催化剂时，生成的二烷基苯中帕拉异构体的含量可达80- 100%。结果表明，在相同孔窗口大小、不同酸强度的金属硅酸盐催化剂上，帕拉异构体的生成是通过过渡态限制的择形性进行的，插入沸石骨架的过渡金属阳离子是四面体状态，不易被还原或氧化。因此，可以预见，过渡金属阳离子在沸石骨架中的催化性能将不同于氧化物和络合物中的催化性能。沸石骨架中三价态的铁阳离子表现出高的氧化脱氢活性，而低的低级烷烃完全氧化活性，而氧化铁则表现出高的低级烷烃完全氧化活性。原子植入法可以制备出具有丝光沸石型结构的钛硅酸盐，并对过氧化氢与苯环的液相羟基化反应表现出很高的催化活性，说明原子植入法是一种很好的制备金属硅酸盐的方法，而且这些金属硅酸盐对某些反应将表现出独特的催化性能。