Isomerization cracking inhibitors

Neither isomerization initiators nor cracking inhibitors need to be present when isomerization occurs in the presence of these acidic catalysts. Disproportionation does not accompany the isomerization. 

These catalysts are sflica-aluminas whose cradcing and dispropordonatioq power has been altered by steam treatment, the use of an inhibitor, or of alui as containing a halogenated compound or fluorine. They are very rugged, are empfoyed without hydrogen and hence cannot isomerize ethylbenzene, which is therefore cracked or transformed by a disproportionation reacdon into benzene and Cio aromatics. Consequently, they can only be used with feeds poor in ethylbenzene. However, no naphthenic hydrocarbons are formed. 

The mechanism given above is merely a suggestion, based on presently available data, as to the function of the decomposition inhibitors in the isomerization of n-pentane. It is hoped that a systematic study of the kinetics of isomerization of saturated liquid hydrocarbons in the presence and absence of cracking suppressors, may furnish additional information about the mechanism of isomerization. 

In isomerizing butane with aluminum chloride, only a small amount of catalyst-hydrocarbon complex is formed, but pentane and especially hexane produce more complex. Both pentane and hexane tend to crack during treatment and this is the cause of the extensive side reactions. The formation of sludge is inhibited in pentane isomerization by the use of 0.3 to 1.3 weight per cent benzene, and in hexane isomerization, hydrogen is used as an inhibitor. 

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