FCC process with improved yield of light olefins

A process for fluidized catalytic cracking of a hydrocarbon feed stream to obtain light olefins, said process comprising:

• contacting the hydrocarbon feed stream with a blended catalyst at an initial temperature of 621° to 677° C. (1150° to 1250° F.) in a riser to crack hydrocarbons in said feed stream and obtain a cracked stream containing hydrocarbon products including light olefins and coked catalyst, said blended catalyst comprising regenerated catalyst and coked catalyst, said catalyst having a catalyst composition including a first component comprising a large pore zeolite and/or an active amorphous material and a second component comprising a molecular sieve with no greater than medium average pore size;
• passing said cracked stream out of said riser at a temperature of 538° to 593 ° C. (1000° to 1100° F.) such that said hydrocarbon feed stream is in contact with the blended catalyst in the riser for less than 2 seconds on average;
• separating said hydrocarbon products including light olefins from said coked catalyst;
• passing a first portion of said coked catalyst to a regeneration zone and combusting coke from said catalyst to produce regenerated catalyst, said regenerated catalyst having substantially the same relative proportions of the first catalyst component and the second catalyst component as the blended catalyst that contacts the hydrocarbon feed stream;
• blending a second portion of said coked catalyst with said regenerated catalyst;
• and
• introducing said blended catalyst to said reactor conduit.