A process for the production of olefins by catalytic cracking, the process comprising
feeding a hydrocarbon feedstock containing at least one olefin of C4
or greater over a MFI-type crystalline silicate catalyst to produce an effluent
containing at least one olefin of C2 or greater by catalytic cracking
which is selective towards light olefins in the effluent, whereby for increasing
the catalyst stability by limiting formation of coke thereon during the cracking
process the catalyst has a silicon/aluminum atomic ratio of at least about 180,
the olefin partial pressure is from 0.1 to 2 bars, and the feedstock contacts the
catalyst at an inlet temperature of from 500 to 600 C. A process for increasing
the stability of a MFI-type crystalline silicate catalyst, by limiting formation
of coke on the catalyst, for catalytically cracking a hydrocarbon feedstock containing
at least one olefin of C4 or greater to produce an effluent containing
at least one olefin of C2 or greater, the process comprising pre-treating
the catalyst so as to increase the silicon/aluminum atomic ratio thereof to a value
of at least about 180 by heating the catalyst in steam and de-aluminating the catalyst
by treating the catalyst with a complexing agent for aluminum.