Patent ID: 7135602
Filing Date: 2006-11-14
Classification: C07C,C10G,Y02P

Abstract:
1. A method for selective steam cracking of hydrocarbons into light olefins comprising ethylene and propylene, said method comprising the steps of: a) feeding steam and the hydrocarbons to a thermal cracking zone of a reactor, said thermal cracking zone comprising a low-surface area, porous and thermally resistant material and being maintained at a given first temperature between 660 and 720° C., thereby providing a partially cracked hydrocarbon output stream comprising selectivity modifiers consisting essentially of diolefins capable of modifying the cracking reactions occurring downstream firm said thermal cracking zone; b) directing the output stream from said thermal cracking zone to a catalytic cracking zone of said reactor, said catalytic cracking zone being heated to a second temperature, being the same or lower than the first temperature and also being between 660 and 720° C., said catalytic cracking zone comprising a zeolite-based catalyst responsive to said selectivity modifiers present in the output stream from said thermal tracking zone, thereby obtaining a cracked hydrocarbon output stream rich in light olefins, wherein said olefins comprise ethylene and propylene; c) recovering the cracked hydrocarbon output stream from said reactor.