Examples of each Catalyst Type

It should be noted that in practical application, the working mechanism of a catalyst cannot be explicitly classified into one specific type, but rather is a combination of two or more of these types and in some cases other mechanisms may also be involved. Consequently, the following classification should be regarded as based only on the predominant working mechanism. In the next section, the reaction mechanisms of each catalyst type will be explained in more detail and promising examples of each catalyst type are given. 

This catalyst may also be referred to as the molten salt catalyst, as referred to by Idles et al, according to the catalyst materials of this type reported to date. It is well known that some of the transition metal oxides, alkaline, and alkaline-earth metal oxides promote carbon oxidation. These oxides are solid and immobile at room temperature but become mobile on the surfaces of soot and support materials on a micrometer scale above certain temperatures, the melting point, or so-called Tamman temperature. In such a mobile state, the catalyst can maintain contact with the soot while the soot surfaces are continually excavated by oxidation. 

However, high mobility at working temperatures is not the only requisite for a material to become a good catalyst of this type. It is also necessary to have high 

Junko Uchisawa, Akira Obuchi and Tetsuya Nanba 

Mixed-metal oxides and eutectic mixtures based on V2O5 or M0O3 have been well investigated from the viewpoint that these materials have relatively low melting points. AgV03 (m.p. = 470°C)/ mixed oxides of V with K or CS2M0O4- 

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