Catalyst activation components, physically mixed

Two or more soHd catalyst components can be mixed to produce a composite that functions as a supported catalyst. The ingredients may be mixed as wet or dry powders and pressed into tablets, roUed into spheres, or pelletized, and then activated. The promoted potassium ferrite catalysts used to dehydrogenate ethylbenzene in the manufacture of styrene or to dehydrogenate butanes in the manufacture of butenes are examples of catalysts manufactured by pelletization and calcination of physically mixed soHd components. In this case a potassium salt, iron oxide, and other ingredients are mixed, extmded, and calcined to produce the iron oxide-supported potassium ferrite catalyst. 

Experimental methods and techniques for catalyst manufacture are particularly important because chemical composition is not enough by itself to determine activity. The physical properties of surface area, pore size, particle size, and particle structure also have an influence. These properties are determined to a large extent by the preparation procedure. To begin with, a distinction should be drawn between preparations in which the entire material constitutes the catalyst and those in which the active ingredient is dispersed on a support or carrier having a large surface area. The first kind of catalyst is usually made by precipitation, gel formation, or simple mixing of the components. 

B. A mechanical (physical) mixture of the FT synthesis catalyst and zeolite [87], The size and shape of the mixed particles affects the performance of the resulting mixture [88]. a-Olefins formed as primary FT synthesis products are isomerized or cracked on acid sites of the zeohte, which prevents the participation of these a-olefins in the further chain growth via readsorption. When the powdered components are mixed, the activity enhancement is most pronounced [89]. 

In the search for stable catalysts, the influence of the support has been one of the issues most investigated. The need to support the active metal is evident when supported catalysts are compared with physical mixtures of components.76 Merely by mixing NiO and very low activity is... 

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