Method for upgrading liquefied waste plastics

A method for upgrading liquefied waste plastics, the method comprising:

• providing a liquefied waste plastics (LWP) material having a chlorine content ranging from 100 ppm by weight (wt.-ppm) to 4000 wt.-ppm and a first bromine number of the LWP material (BN1);
• pre-treating at least part of the LWP material to produce a pre-treated LWP material, wherein the pre-treated LWP material has a second bromine number (BN2) that, when divided by BN1, results in a BN2/BN1 ratio of 0.90 or more, and wherein no hydrogen is added during the pre-treating;
• blending the LWP material, the pre-treated LWP material or a combination thereof with a paraffinic material feed stream containing a paraffin content of 60 wt.-% or more, relative to a total weight of the paraffinic material feed stream, to obtain a cracker feed that meets requirements for chlorine content and olefins content of a steam cracker, wherein the paraffinic material feed stream contains at least 90 wt.-% of compounds having 5 or more carbon atoms;
• and
• steam cracking the cracker feed in the steam cracker to obtain a cracker product.