Fluid catalytic cracking process for upgrading a gasoline-range feed

A fluid catalytic cracking process for simultaneously cracking a gas oil feed and upgrading gasoline-range hydrocarbon feed which process comprises the steps of:

• a. contacting the gasoline-range feed with freshly regenerated catalyst in a relatively upstream portion of a short-time dilute-phase riser reaction zone which portion is maintained at first catalytic cracking conditions including a gasoline-range-feed residence time of less than about 0.5 seconds in the presence of said catalyst, a temperature within the range of about 1,250.degree. F. to about 1,500.degree. F. and a catalyst-to-gasoline-range-feed weight ratio of at least about 75 to 1;
• b. contacting the gas oil feed with used catalyst in a relatively downstream portion of the short-time dilute-phase riser reaction zone which portion is maintained at second catalytic cracking conditions including a gas-oil residence time of less than about 10 seconds in the presence of used catalyst, a temperature in the range of from about 900.degree. F. to about 1,100.degree. F. and a catalyst-to-gas-oil-feed weight ratio of from about 4 to about 25 to 1;
• c. passing catalyst and feed streams in admixture through the riser reaction zone to produce spent catalyst, containing coke, and product components including gasoline;
• d. discharging the mixture from said reaction zone into cyclone separators to effect the separation of spent catalyst from product components and any unreacted feed;
• e. recovering product components and any unreacted feed;
• f. passing spent catalyst to a regeneration zone maintained at oxidizing conditions including the presence of fresh regeneration gas, a temperature within the range of from about 1,250.degree. F. to about 1,500.degree. F., a pressure from about atmospheric to about 50 psig. and a catalyst residence time of from about 2 to about 5 minutes and therein oxidizing at said oxidizing conditions coke from spent catalyst and CO, resulting from coke oxidation, to produce freshly regenerated catalyst and spent regeneration gas, said oxidizing conditions being sufficient to substantially completely oxidize said CO to CO.sub.2 and said CO oxidation being effected in contact with said freshly regenerated catalyst;
• g. transferring at least a portion of the heat of CO combustion to regenerated catalyst thereby heating said catalyst to a temperature of from about 1,250.degree. F. to about 1,500.degree. F.;
• and,
• h. returning heated regenerated catalyst to said reaction zone of step (a) above.