Silica magnesia catalyst regeneration

The composition of acid-treated natural clay catalysts was more or less duplicated in the synthetic catalyst formulations. TTie main advantage of synthetic catalysts was a reproducible composition with few impurities known to cause deactivation. Both silica/alumina and silica/magnesia formulations were nsed in early tests but, despite good activity, silica/magnesia catalysts were nnstable and difficult to regenerate. 

Silica-magnesia matrices have not yet been properly evaluated as an RCC catalyst matrix. However, such a matrix in conjunction with stabilized zeolite might provide an attractive matrix with a Kaolin-enhanced dual pore structure. Silica-magnesia matrices are notorious for their poor regeneration characteristics. When prepared by the dual pore Kaolin-enhanced method, they might be easier to regenerate and, thereby, open up a new family of residuum catalysts. Such catalysts have not yet been explored. 

Typical ratios of carbon dioxide to carbon monoxide in the regenerator flue gas produced with uncontaminated silica-alumina, silica-magnesia, and activated-clav catalysts are shown in the following tabulation (274) ... 

The common catalysts lose most of their activity at the following temperatures Super Filtrol natural, 1400°F silica-alumina synthetic, 2000 F silica-magnesia, 1400°F and silica-boria, 1400°F. However, in practice, regeneration temperatures are kept below 1000 to 1100 or 1150°F except bauxite which may be regenerated at even 1300°F without appreciable loss in activity. All catalysts lose some activity upon long use. The decline is. particularly noticeable with natural catalyst processing sour stocks and even the excellent catalyst cases of the Houdry process allow some decline in activity over a period of a... 

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