Purification of waste plastic based oil via a two steps hydrotreatment

A process to produce olefins and aromatics via a purification of a hydrocarbon stream comprising the following steps:

• a) providing a hydrocarbon stream having a starting boiling point of at least 15° C., a diene value of at least 1.0 g I2/100 g as measured according to UOP 326 and a bromine number of at least 5 g Br2/100 g as measured according to ASTM D1159 and containing at least 10 wt % of pyrolysis plastic oil the other part of said hydrocarbon stream being a first diluent or alternatively providing a hydrocarbon stream containing only pyrolysis plastic oil;
• and wherein at least 10 wt. % of said hydrocarbon stream has a boiling point of at least 150° C. based on the total weight of said hydrocarbon stream,
• b) performing a first hydrotreating step at a temperature of at most 225° C.;
• c) performing a second hydrotreating step at a temperature of at least 200° C.,
• d) recovering a purified hydrocarbon stream wherein at least a part of this purified hydrocarbon stream is sent to a steam cracker to produce olefins and aromatics and wherein said purified hydrocarbon stream is mixed with naphtha, gasoil or crude oil to have a pyrolysis plastic oil concentration at the inlet of the steam cracker ranging from 0.01 wt % to at most 50 wt % and wherein said steam cracker has an outlet temperature ranging from 800° C. to 1200° C. and wherein the residence time in said steam cracker through the radiation section of the reactor where the temperature is between 650 and 1200° C. ranges from 0.005 to 0.5 seconds and wherein the steam cracking is done in presence of steam in a ratio of 0.1 to 1.0 kg steam per kg of hydrocarbon feedstock.