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Study of the mechanism of microwave heating of zeolite A and the easily heatable composition

A型沸石微波加热机理及易加热组合物的研究

基本信息

批准号：
10650666
负责人：
OHGUSHI Tatsuo
金额：
$ 1.09万
依托单位：
Toyohashi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650666/
关键词：
zeolite microwave heating mechanism absorption efficiency dielectric constant cation site adsorbed water 4-mebmered oxygen ring A型ゼオライトマイクロ波加熱

项目摘要

We studied what factors are important in the microwave heating of zeolite A and how the microwave heating proceeds.It was easy to heat hydrated 4A and 3A zeolites to a glowing (melting) temperature by microwave radiation from room temperature but was different to heated by microwaves. 3A zeolite was not heated by microwaves under the above condition used for 4A zeolite. 5A zeolite could not be heated at all. The easiness of microwaves heating was in the order of 4A>3A>>5A. There are differences in the cation distribution among these zeolites, i. e., 5A zeolite has no cations on the 4-membered oxygen ring sites but the other two have. It was expected from dielectric properties that the cation on 4-ring site can absorb microwave at >450℃ with a higher efficiency but cations in other locations are ineffective for absorption. The following mechanism for the microwave heating was proposed : In the initial period, the hydrated zeolite absorbs the microwaves through its absorbed water and its temperature rises. The absorbed water completes desorption by ca. 400-470℃. In this temperature range the zeolite begins to absorb microwaves and absorption efficiency becomes high with increasing temperature. When zeolite reaches 450-500℃ thermal runaway starts. 5A zeolite cannot reach thermal runaway conditions because of absence of caution on 4-ring site. The absorbed water plays the role of preheating agent in the initial period of microwave heating.The easiness of heating of zeolite with NaィイD1+ィエD1, KィイD1+ィエD1 or AgィイD1+ィエD1 ion on the 4-ring site was studied. It was in the order of NaィイD1+ィエD1>AgィイD1+ィエD1>KィイD1+ィエD1. From this result, it was found that zeolite with the smaller cation on the 4-ring site can be easily heated by microwaves.

研究了影响A沸石微波加热的主要因素及微波加热过程。在室温条件下，微波可将水合4A和3A沸石加热至发光（熔化）温度，而微波加热则不同。3A沸石在上述条件下不经微波加热，用于4A沸石。5A沸石完全不能加热。微波加热的难易程度依次为4A>3A>>5A。这两种分子筛的阳离子分布存在差异，5A分子筛的4元氧环上没有阳离子，而另外两种分子筛的4元氧环上有。从介电性质可以预期，在4环位置的阳离子能以较高的效率吸收bb0 - 450℃的微波，而在其他位置的阳离子则不能吸收。提出了微波加热的机理：在初始阶段，水合沸石通过其吸收的水吸收微波，沸石的温度升高。被吸收的水在400-470℃左右完成解吸。在此温度范围内，沸石开始吸收微波，吸收效率随着温度的升高而提高。沸石温度达到450 ~ 500℃时开始热失控。5A沸石不能达到热失控的条件，因为在4环部位没有谨慎。在微波加热初期，吸收的水起到预热剂的作用。研究了Na γ γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ + γ γ对沸石的加热作用。在Na的顺序ィイD1 +ィエD1 > AgィイD1 +ィエD1 > KィイD1 +ィエD1。结果表明，4环阳离子较小的沸石易于微波加热。