【Paper】
A Study on Catalyst Preparation of Dioxin Decomposition
Katsuhiro Tokura*, Kazuyuki Oshita**, Tetsuya Yanase* and Masakatsu Hiraoka***
* Engineering Business Group, NGK Insulators Ltd.
** Department of Enviromental Engineering, Graduate School of Engineering, Kyoto University
*** Research Center for Eco-Technology, Ritsumeikan University
† Correspondence should be addressed to Katsuhiro Tokura:
Engineering Business Group, NGK Insulators Ltd.
（2-56 Suda-cho, Mizuho-ku, Nagoya-shi, Aichi, 467-8530 Japan）

Abstract
The base-catalyzed decomposition process is superior to the activated carbon absorption process because a secondary waste product is not created when dioxin is broken down. However, some problems remain. Trace constituents in the exhaust gas cause the catalyst to deteriorate, which decreases breakdown performance. Also, there is a possibility that the catalyst may help to form the dioxin.
The authors studied the behavior of precious metal catalysts, which are considered to have a low possibility of dioxin formation, and discovered that the dioxin is composed of the carbon that is included in the catalyst. This carbon adheres while the catalyst is being made. Therefore, this process has been improved so that a catalyst could be made that does not synthesize dioxin.

Key words: dioxins, formation, decomposition, catalyst