Patent ID: 7566811
Filing Date: 2009-07-28
Classification: C10G

Abstract:
1. A moving bed process for catalytic oligocracking of a light olefinic hydrocarbon feed comprising hydrocarbons containing 2 to 12 carbon atoms, for the production of propylene, said process comprising contacting said feed with a supported catalyst having a particle size of 0.5 to 5 mm comprising at least one zeolite having form selectivity and with a Si/Al ratio in the range 50 to 1200, said zeolite being selected from one of the two following groups: one is the group formed by MEL, MFI, NES, EUO, FER, CHA, MFS and MWW and the other is the group formed by NU-85, NU-86, NU-88 and IM-5, or a mixture of zeolites from the two groups, the process being characterized in that the feed is circulated as a cross flow with respect to the catalyst in at least one vertically disposed radial reactor having a head portion and a lower portion functioning in moving bed mode, a flow of used catalyst is withdrawn continuously or discontinuously from the lower portion of the reactor, a first fraction of the withdrawn used catalyst is recycled to the reactor head portion, the complementary fraction of the used catalyst is transferred into a regeneration zone where it undergoes at least one controlled oxidation step, and the regenerated catalyst fraction is reintroduced into the head portion of said reactor in admixture with the first fraction of used catalyst, wherein the recycling of the used catalyst to the reactor head portion results in reducing the catalytic activity gradient between the head and lower portion of the reactor.