权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Study on Novel Method of Catalyst Preparation Using Molecule Assembly and Control of Catalyst Microstructure

分子组装制备催化剂新方法及催化剂微观结构控制研究

基本信息

批准号：
06453102
负责人：
WAKABAYASHI Katsuhiko
金额：
$ 4.67万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06453102/
关键词：
microemulsion novel method of catalyst preparation supported noble metal catalyst metal particle size control CO hydrogenation CO_2 hydrogenation シリカ担持Rh触媒

项目摘要

The purpose of this work is a microstructure control of supported catalysts for improving the catalytic activity and the product selectivities. Thus, we proposed a novel preparation method of the supported catalysts using microemulsions, and studied the control of metal micropartticle size, regardless of metal content, and the improvement of the radio of metal particle surface exposed on surface to total metal particle surface. The results are as follows. [1] The silica- or zirconia-supported noble metal catalysts prepared by the microemulsion method exhibited an extremely higher activity than those prepared by the impregnation method for the CO and CO_2 hydrogenation. [2] The control of Rh particle size irrespective of Rh content has been studied on the Rh/SiO_2 catalysts. It was found that the Rh particle size in the range between 3 and 6 nm was controlled by the water core size inside the invert micelle and the concentration of RhCl_3. Furthermore, the Rh particle size in the wide range of 1.5 to 9 nm could be controlled by the synthesis temperature of the Rh particles in the microemulsion, the chain length of the hydrophilic group of the surfactant and the chain length of the organic solvent. For the Pd/ZrO_2 catalysts, the Pd particle size could also be controlled in the same manner. [3] The Rh/SiO_2 catalyst with the Rh particle size of about 5 nm had the highest turnover frequency for the CO hydrogenation. [4] It was suggested that some of the Rh particles prepared by the microemulsion method were partly or wholly buried in the silica support. Thus we investigated the effect of the catalyst preparation conditions on the ratio of the Rh surface area exposed to the gas phase to the total Rh surface area. The Rh exposure ratio of about 80% was obtained by the shortening of hydrolysis time of alkoxide and the increase of the water content during hydrolysis period. The increase of the Rh exposure ratio enhanced the catalytic activity for the CO hydrogenation.

本研究的目的是控制负载型催化剂的微观结构，以提高催化剂的催化活性和产物选择性。因此，我们提出了一种利用微乳液制备负载型催化剂的新方法，并研究了在不考虑金属含量的情况下控制金属微粒的大小，以及提高暴露在表面的金属微粒表面与总金属微粒表面的比值。结果如下：微乳液法制备的二氧化硅或氧化锆负载贵金属催化剂的CO和CO_2加氢活性显著高于浸渍法制备的催化剂。在Rh/SiO_2催化剂上，研究了与Rh含量无关的Rh粒度控制。结果表明，在3 ~ 6 nm范围内的Rh粒径受反胶束内水芯粒径和RhCl_3浓度的控制。在1.5 ~ 9 nm范围内，Rh颗粒的粒径可由微乳液中Rh颗粒的合成温度、表面活性剂亲水性基团的链长和有机溶剂的链长控制。对于Pd/ZrO_2催化剂，同样可以控制Pd的粒径。Rh粒径约为5 nm的Rh/SiO_2催化剂的CO加氢翻转频率最高。结果表明，微乳液法制备的Rh颗粒部分或全部埋在二氧化硅载体中。因此，我们研究了催化剂制备条件对暴露于气相的Rh表面积与总Rh表面积之比的影响。通过缩短醇盐水解时间和增加水解过程中的含水量，获得了80%左右的Rh暴露比。Rh暴露比的增加增强了CO加氢的催化活性。