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Catalyst decay in the presence of chain processes in catalytic cracking
Author(s) -
Rice N. M.,
Wojciechowski B. W.
Publication year - 1991
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450690509
Subject(s) - catalysis , cracking , chemistry , decay chain , desorption , photochemistry , chemical physics , physics , organic chemistry , nuclear physics , adsorption
The Chemical events involved in cracking and catalyst decay are examined in order to ascertain the possible course of catalyst decay. We find that, regardless of whether site activity is lost by “sudden death” or by gradual “inhibition”, the time course of catalyst decay under a wide variety of assumptions is described by the function ā(t ) = (1 + Gt)– N′ . Under certain conditions, however, sites on their way to complete deactivation may undergo reactivation by the desorption of an inhibiting species. In such cases, our models predict the existence of a lower activity condition which can be time invariant or, after being established by an initial rapid decay, the intermediate less‐active condition evolves to a final, inactive state. Furthermore, if some of the intermediate steps on the way to complete deactivation lead to site activities higher than those of the pristine sites, a sigmoidal curve of conversion versus time on stream can result.