Patent ID: 7579513

Claim:
A process for direct conversion, by catalytic cracking, of a light olefinic hydrocarbon feed comprising at least 80% by weight of hydrocarbons containing at most 12 carbon atoms for the production of propylene, said process comprising direct cracking of the feed on a supported catalyst comprising at least one zeolite comprising silicon and aluminum and having form selectivity, from the group constituted by zeolites with one of the following structure types: MEL, MFI, NES, EUO, FER, CHA, MFS, MWW, and from the following zeolites: NU-85, NU-86, NU-88 and IM-5, comprising circulating the feed at a temperature in the range about 480° C. to 620° C. in at least one reactor on a granular moving bed of said catalyst, extracting from the lower portion of the reactor, continuously or discontinuously, a flow of catalyst comprising a carbonaceous deposit, transferring said catalyst to a regeneration zone where it undergoes at least one controlled oxidation step, then downstream of the regeneration zone, re-introducing the catalyst comprising a reduced amount of carbonaceous deposit directly or indirectly into the upper portion of said reactor, the catalyst used being such that the zeolites from said group have a Si/Al ratio in the range 40 to 130 and in which the residence time for the catalyst in the reaction zone is in the range of 1 to 40 hours.