Silica-magnesia catalysts sintering

In Fig. 5 the striking similarity of the isotherms for a virgin DA-5 and a steam-treated DA-5 is apparent. The pore volume and area of the steam-sintered sample are far below those of the virgin, but the isotherm contours are almost identical. A small increase in pore radius is observed. Thus the presence of steam during sintering does not alter significantly the pore structure of the silica-magnesia catalysts studied. It should also be noted here that the isotherms for the DA-5 catalyst... 

A preliminary overall picture of cracking catalyst structures is available in the first three horizontal rows of the composite plot of Fig. 2 and the corresponding data of Table I. Isotherms presented in the lowest row are discussed in Sec. IV. Only the general features of these representative types of cracking catalysts are indicated here, since the detailed plots of individual isotherms will be considered in subsequent sections on sintering. Cracking catalysts of principal interest are represented by three types silica-magnesia silica-alumina and activated clay. 

The main functions of a carrier or support are usually to lend mechanical strength, increase stability to sintering and provide a larger active surface area than would otherwise be available. There is evidence that, in many instances, compound or complex formation takes place between the catalyst and the support, with a consequent effect on the catalytic properties. The most commonly used support materials are silica, alumina, silica-alumina, titania, silicon carbide, diatomaceous earths, magnesia, zinc oxide, iron oxide and activated carbon. 

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