Patent ID: 6093867
Filing Date: 2000-07-25
Classification: C10G

Abstract:
A process for selectively producing C.sub.3 olefins from a naphtha feedstream in a process unit comprised of a reaction zone, a stripping zone, a catalyst regeneration zone, and a fractionation zone, which process comprises:a) reacting the naphtha stream containing from about 10 to 30 wt. % paraffins and from about 15 to 70 wt. % olefins in the reaction zone containing a fluidized bed of catalyst comprised of a crystalline zeolite having an average pore diameter of less than about 0.7 nm and wherein the reaction zone is operated at a temperature from about 500.degree. to 650.degree. C., a hydrocarbon partial pressure of 10 to 40 psia, a hydrocarbon residence time of 1 to 10 seconds, and a catalyst to feed ratio, by weight, of about 4 to 10, thereby producing a reaction product wherein no more than about 20 wt. % of paraffins are converted to olefin and wherein propylene comprises at least about 90 mol. % of the total C.sub.3 products;b) passing the catalyst through a stripping zone where volatiles are stripped by use of a stripping medium;c) passing the stripped catalyst from the stripping zone to a catalyst regeneration zone where any coke deposits are burned in the presence of an oxygen containing gas;d) recycling the regenerated catalyst to the reaction zone where it contacts fresh feed;e) fractionating the vapor product stream to produce a C.sub.3 fraction, a C.sub.4 fraction rich in olefins, and optionally a C.sub.5 fraction rich in olefins; andf) passing the C.sub.4 fraction to the reaction zone or the stripping zone, or both.