Integrated hydrotreating steam cracking process for the production of olefins

An integrated process for converting a hydrocarbon feedstock having components boiling above about 100° C. into steam cracked products, which process comprises:

• a) passing said hydrocarbon feedstock in the presence of a hydrogen source and a first hydrotreating catalyst through a first hydrotreating zone at an elevated temperature and a pressure in the range of from about 400 psig and about 1,250 psig to reduce the levels of organic sulfur and/or nitrogen compounds contained therein,
• wherein the first hydrotreating catalyst comprises a component selected from the group consisting of Group VIB metals, oxides, sulfides, Group VIII metals, oxides, sulfides and mixtures thereof, supported on an amorphous carrier,
• b) passing the product from said first hydrotreating zone to a second hydrotreating zone wherein said product is contacted at a pressure in the range of from about 400 psig and about 1,250 psig and a temperature in the range of from about 200° C. to about 550° C. with a hydrogen source and a second hydrotreating catalyst comprising one or more hydrogenating components selected from the group consisting of Group VIB metals, oxides, sulfides, Group VIII metals, oxides, sulfides and mixtures thereof supported on an acidic carrier, to effect reduction of the sulfur level to below about 100 parts per million and reduction of the nitrogen level to below about 15 parts per million,
• c) passing the product from said hydrotreating zone to a steam cracking zone wherein said product is contacted with steam at temperatures greater than about 700° C., and
• d) recovering hydrogen and C1-C4 hydrocarbons, steam cracked naphtha, steam cracked gas oil and steam cracked tar therefrom, wherein the amount of steam cracked tar produced is reduced by at least about 15 percent, basis the starting hydrocarbon feedstock which has not been subject to hydrotreating
• wherein the yields of ethylene and propylene and butadiene in the H2 and C1-C4 hydrocarbons fraction are each increased by at least about 5 percent, and the yields of isoprene, cis-pentadiene, trans-pentadiene, cyclopentadiene and benzene in the steam cracked naphtha fraction are each increased by at least about 10 percent, basis the hydrocarbon feedstock which has not been subjected to hydrotreating.