Hydrocarbon conversion processes

A hydrocarbon conversion process, comprising:

• (A) providing a raw hydroprocessor feed comprising a mixture of steam cracker gas oil and steam cracker tar, wherein:
• the raw hydroprocessor feed has a reactivity R(raw) in terms of bromine number, where R(raw) >28,
• the raw hydroprocessor feed comprises olefins,
• at least 70 wt % of the steam cracker gas oil has a normal boing point of at least 200° C.,
• at most 10 wt % of the steam cracker gas oil has a normal boiling point of at least 275° C.,
• the steam cracker tar contains free radicals, has a density at 15° C. of at least 1.10 g/cm3, as measured according to ASTM D70/D70M-21, and has a viscosity at 50° C. of at least 1,000 cSt, as measured according to ASTM D445-21, and
• at least 70 wt % of the steam cracker tar has a normal boiling point of at least 290° C.;
• (B) heating the raw hydroprocessor feed to a temperature in a range of from 200° C. to 400° C. for a residence time in a range of from at least 1 minute to 45 minutes to produce a heat-treated raw hydroprocessor feed comprising heat-treated steam cracker gas oil and heat-treated steam cracker tar, wherein the heat-treated raw hydroprocessor feed has a reactivity in terms of bromine number R(ht-raw), where R(ht-raw)≤28;
• (C) feeding a hydroprocessor feed comprising the heat-treated raw hydroprocessor feed into a hydroprocessor;
• and
• (D) hydroprocessing the hydroprocessor feed in the hydroprocessor to produce a hydroprocessor effluent comprising hydroprocessed steam cracker gas oil and hydroprocessed steam cracker tar.