Process for the steam-cracking of heavy feedstocks

摘要

A fresh charge containing aromatic hydrocarbons is hydrotreated in admixture with a recycle fraction, in the presence of a bifunctional catalyst, a portion of the effluent is subjected to steam-cracking, thereby recovering a gas oil fraction which is subjected to hydrogenation and forms said recycle fraction. The mixture of recycle fraction and charge is advantageously treated with hydrogen in the presence of a monofunctional catalyst to hydrogenate olefins, at a lower temperature than the hydrotreatment, and then passed to the hydrotreatment zone.