A method of hydrotreatment of heavy hydrocarbon oil in the presence of catalysts which comprises hydrodemetallizing and hydrocracking the heavy hydrocarbon oil successively and thereafter hydrodesulfurizing and hydrodenitrogenating the treated heavy hydrocarbon oil. The hydrocracking is carried out in...http://www.google.es/patents/US5382349?utm_source=gb-gplus-sharePatente US5382349 - Method of treatment of heavy hydrocarbon oil
