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Prodical Application of Environmental Catalysis through the Chemical Vapor Deposition of Silica

二氧化硅化学气相沉积环境催化的实际应用

基本信息

批准号：
10555278
负责人：
NIWA Miki
金额：
$ 7.49万
依托单位：
Tottori University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10555278/
关键词：
Environmental Catalyst Hydrohobicity Silica CVD pallodium Zeolite Alumina NO Removal Catalytic Combastion

项目摘要

The improvement of the catalytic activity and durability of Pd/zeolite catalyst for the NO-CH_4-O_2 reaction in the presence of water vapor is an important subject. We found that the much improvement in the durability was attained by the modification of the external surface of zeolite with SiO_2 monolayer through the chemical vapor deposition (CVD) due to the generation of the hydrophobic character in the external surface of zeolite. The initial activity for NO reduction was increased by the addition of the Ag, Mn into the Pd/zeolite. The combination of the addition effect of and CVD of SiO_2 layer over ZSM-5 external surface resulted in the improvement in both activity and durability of Pd for NO-CH_4-O_2 reaction.A continuous-flow method of chemical vapor deposition of tetramethoxysilane on γ-alumina was developed for industrial utilization of silica monolayer solid-acid catalyst. The flow method caused relatively heterogeneous coverage of silicon compared to static reactor especially in the low silicon concentration region. However, the difference in the structure was small in the high silicon concentration region where the coverage arrived at almost 100%. The catalytic activity for double-bond isomerization of 1-butene and thermal stability obtained by the two methods were similar, showing that the continuous flow method was sufficient to prepare the silica monolayer catalyst industrially.Chemical vapor deposition of Si(OCH_3)_4 was carried out on silicalite crystals in order to control the pore-opening size. Adsorption of alkanes on silicalite an CVD-silicalite was performed gravimetrically and chromatographically. It was found that the linear and branched paraffins could be separated by choosing the extent of silica deposition on silicalite.

提高水蒸气存在下Pd/沸石催化剂对NO-CH_4-O_2反应的催化活性和耐久性是一个重要的课题。我们发现，通过化学气相沉积（CVD）方法用SiO_2单层修饰沸石外表面，由于沸石外表面产生了疏水性，从而大大提高了耐久性。在Pd/沸石中加入Ag、Mn后，催化剂的初始NO还原活性提高。通过在ZSM-5外表面化学气相沉积SiO_2层，提高了Pd的NO-CH_4-O_2反应活性和稳定性。与静态反应器相比，流动法导致硅的相对不均匀覆盖，特别是在低硅浓度区域。然而，在覆盖率几乎达到100%的高硅浓度区域中，结构的差异很小。两种方法制备的SiO2单分子层催化剂对1-丁烯双键异构化反应的催化活性和热稳定性相近，表明连续流动法制备的SiO2单分子层催化剂完全可以用于工业化制备。采用重量法和色谱法研究了烷烃在硅质岩和CVD-硅质岩上的吸附。结果表明，通过选择硅质岩上硅的沉积程度，可以实现直链和支链烷烃的分离。