Patent ID: 7763165

Claim:
A process for catalytically cracking a heavy hydrocarbon feedstock and obtaining selected hydrocarbon fractions, the process comprising: contacting a heavy hydrocarbon feedstock with a hydrocarbon cracking catalyst having a catalyst composition including a first component comprising a large pore molecular sieve and a second component comprising a zeolite with no greater than medium pore size to produce a hydrocarbon effluent comprising a range of hydrocarbon products, said zeolite with no greater than medium pore size comprising at least 1.0 wt. % of the catalyst composition; separating the hydrocarbon effluent in a separation section to form at least one separator liquid stream and a separator vapor stream, the at least one separator liquid stream comprising C 4 + hydrocarbons, the separator vapor stream comprising C 4 − hydrocarbons; deethanizing at least a portion of the separator vapor stream in a deethanizer to at least form a first deethanizer process stream comprising C 2 − hydrocarbons including a quantity of ethylene and a second deethanizer process stream comprising C 3 + hydrocarbons including a quantity of propylene; depropanizing the second deethanizer process stream to form a first depropanizer process stream comprising C 3 hydrocarbons and a second depropanizer process stream comprising C 4 + hydrocarbons including a quantity of C 4 -C 7 olefins; splitting at least a portion of the second depropanizer process stream in a naphtha splitter to at least form a first naphtha splitter process stream comprising primarily compounds containing four to six carbon atoms; cracking at least a portion of the C 4 -C 7 olefins to form a cracked olefin effluent comprising C 2 and C 3 olefins; depropanizing at least a portion of the cracked olefin effluent to form a first cracked olefin effluent process stream comprising C 3 − hydrocarbons including C 2 and C 3 olefins and a second cracked olefin effluent process stream comprising C 4 + hydrocarbons; and recovering at least a portion of the C 2 and C 3 olefins from the first cracked olefin effluent process stream.