Oxidation Catalyzed by Polyoxometalate-Anion-Intercalated Layred Compounds

多金属氧酸盐阴离子插层层状化合物催化的氧化

基本信息

批准号：
05453106
负责人：
TATSUMI Takashi
金额：
$ 4.03万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

Layred double hydroxides (LDH) consisting of Mg-Al, Zn-Al, and Ni-Al with the atomic ratios varied were prepared, and intercalated with heteropolyoxometalate anions including Mo or W as the addenda atom. It has been found rather difficult to insert SiW_<12>O_<40>^<4-> into the layr space of Zn-Al LDH with the Zn/Al ratio of 2. However, the insertion was promoted with decreasing Al/Zn ratio, To avoid decomposition of polyoxometalate, the pH during the insertion was kept at lower than 4, where the Zn-Al LDH was more stable than the Mg-Al LDH.Zn-Al LDHs intercalated with silicotungstates SiW_<12>O_<40>^<4->, SiW_<11>O_<39>^<8->, and SiW_9O_<34>^<10-> were prepared and the structure of the anions in the gallery space was examined by infrared spectroscopy. The SiW_<11>O_<39>^<8-> intercalate proved to be a good catalyst for olefin epoxidation with H_2O_2 as oxidant. In contrast, the SiW_<12>O_<40>^<4-> intercalate was effective in epoxidizing olefins with O_2-aldehyde, although it showed poor activity in the epoxidation with H_2O_2 Substitution of V for W of the addenda atom resulted in enhancement of activity for epoxidation with O_2-aldehyde. The Ni-Al LDH with no polyoxometalate included exhibited considerable activity in olefin epoxidation with O_2-aldehyde. Thus it has been suggested that the introduction of active metals into both the LDH itself and the gallery space may lead to emergence of bifunctional catalysis, which would be applied to novel catalytic reactions.

制备了由Mg-Al，Zn-Al和Ni-al组成的叶氢氧化物（LDH），并与原子比不同，并与包括MO或W（包括MO或W）的杂多氧含量阴离子相结合，作为附加原子。发现很难将Siw_ <12> O_ <40>^<4->插入Zn-Al LDH的Layr空间，而Zn/Al比率为2。为了避免多氧胺的分解，比例将插入过程中的pH值保持在低于4的位置，其中Zn-Al LDH比Mg-al ldh.zn-al ldhs更稳定>^<4->，siw_ <11> o_ <39>^<8->，并制备了Siw_9o_ <34>^<10->，并通过红外光谱法检查了画廊空间中阴离子的结构。 Siw_ <11> O_ <39>^<8->插入率被证明是用H_2O_2作为氧化剂的烯烃环氧化的良好催化剂。相比之下，siW_ <12> O_ <40>^<4->间含量有效地用o_2-醛来的烯烃化烯烃，尽管它在h_2o_2替换为v的h_2o_2替换为w的h_2o_2替代w的活性较差，从而增强了附加原子的w。用O_2-醛来进行环氧化的活性。 NI-AL LDH具有无多氧碱的Ni-Al LDH在烯烃环氧化中用O_2-醛来表现出相当大的活性。因此，已经提出，将活性金属引入LDH本身和画廊空间可能会导致双功能催化的出现，这将应用于新型的催化反应。