Development of Novel Methods for Synthesizing Hydrophobic Metallosilicates

疏水性金属硅酸盐合成新方法的开发

基本信息

批准号：
11555212
负责人：
TATSUMI Takashi
金额：
$ 7.94万
依托单位：
Yokohama National University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

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.

通过增加疏水性，合成了沸石催化剂，表现出对有机化合物氧化物具有过氧化水的氧化物的高活性和选择性。研究了具有3D-12 MR通道的TS-1，TI-β和Ti-Mww.ti-β的催化性能与疏水性或酸度之间的关系，能够使笨重的循环化合物化合物；但是，环氧化物被水裂解以产生二醇，这应该是由于TI-β的酸度。通过离子交换的TI-β，与四元铵离子，TI-β成功制备了高活性和选择性。铵离子离子交换的催化剂对环氧化不是选择性的，因为在反应过程中氧化了铵离子，而与碱金属离子的离子交换导致氧化活性抑制。随着硼酸共存，通过使用哌啶或己酰胺作为结构指导剂，Ti-MWW成功地结晶为纯相。 Ti-MWW始终包含八面体Ti物种的一部分，这些物种是在计算形成催化酶时汇总的。然而，这些外部炸药Ti物种以及一部分框架硼通过酸溶液轻松处理了合成的样品，从而轻松去除硼硼。因此，预处理的Ti-MWW被描述为通过各种光谱技术在框架位置中主要包含四面体Ti物种。与TS-1相比，Ti-MWW对于与过氧化氢的环氧反应更为活跃。哌啶指导的Ti-MWW比己酰胺指导的Ti-Mww更活跃。前者是六边形板，形状较小，后者由针状颗粒凝结。我们已经开发了一种获得具有较小的结晶石大小，高疏水性和低酸度的钛硅酸盐催化剂的方法，这些催化剂在液相氧化中表现出很高的活性。