Process for producing polypropylene from C3 olefins selectively produced in a fluid catalytic cracking process

A process for producing polypropylene comprising the steps of:

• (a) feeding a naphtha stream comprising from about 10 to 30 wt. % paraffins and between about 15 to 70 wt. % olefins to a process unit comprising a reaction zone, a stripping zone, a catalyst regeneration zone, and a fractionation zone;
• (b) contacting the naphtha stream with a fluidized bed of catalyst in the reaction zone to form a cracked product, the catalyst comprising a 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° C. to 650° C., a hydrocarbon partial pressure of 10 to 40 psia, a hydrocarbon residence time of 1 to 10 seconds, and a catalyst to feed weight ratio between about 4 and about 10, thereby producing a reaction product wherein no more than about 20 wt. % of paraffins are converted to olefins and wherein propylene comprises at least about 90 mol. % of the total C3 products;
• (c) passing the catalyst through said stripping zone;
• (d) passing the stripped catalyst from the stripping zone to the catalyst regeneration zone where the catalyst is regenerated in the presence of an oxygen-containing gas;
• (e) recycling the regenerated catalyst to the reaction zone;
• (f) fractionating the cracked product to produce a C3 fraction, a C4 fraction rich in olefins, and optionally a C5 fraction rich in olefins;
• (g) passing the C4 fraction to the reaction zone or the stripping zone, or both;
• and,
• (h) separating propylene from the C3 fraction and polymerizing the propylene to form polypropylene.