Cracking catalysts inactivation

Catalysts were expensive, however, so the petroleum industry did not solve the problem of cheap, lead-free, knock-free gasoline until the 1970s, after General Motors adopted the catalytic converter. Lead compounds inactivate the catalysts, and sophisticated catalytic cracking techniques had to be developed to replace the fuel additive. Ironically, an even more difficult job was finding a substitute for the protective coating that tetraethyl lead formed on exhaust valve seats not even newly developed, extremely hard materials prevent wear and tear on them as well as tetraethyl lead did. 

The poisoning action of the heavy metals is in accord with their known tendencies to decompose hydrocarbons, at cracking temperatures, to carbon and hydrogen. The mechanism of poisoning is believed not to consist of inactivation of the active centers of the catalyst, but rather a superimposition of heavy-metal-type cracking upon the normal cracking... 

The majority of catalysts are subject to deactivation, e.g. to changes (deterioration) of activity with operation time. The time scale of deactivation depends on the type of process and can vary from a few seconds, as in fluid catalytic cracking (FCC), to several years, as in, for instance, ammonia synthesis. Due to the industrial importance, the modelling of deactivation was mainly developed for heterogeneous catalysis. Although the reasons for deactivation (inactivation) of homogeneous and enzymes could differ from solid catalysts, the mathematical approach can sometimes be very similar. 

A catalyst on which quinoline has been adsorbed at 427° has a pale-green translucent appearance, in marked contrast to the black appearance of a catalyst which has been inactivated by the deposition of a hydrocar-bonaceous residue during cracking. On boiling a quinoline-treated catalyst with aqueous hydrochloric acid solution, an extract was obtained which contained the major portion of the quinoline. These observations... 

Inactivation of a Cracking Catalgst by a Basic Nitrogen Compound Comparison of Quinoline Charged Before or With Cumene over Catalyst Catalyst (200 cc.) Houdry SiOj-AljOj of activity 32 (gasoline) (CAT-A) cracking conditions 427°, 1.5 liquid hourly space velocity, 10-minute test. 

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