KINETICS OF ASPHALTENE HYDROCONVERSION .1. THERMAL HYDROCRACKING OF ACOAL RESIDUE

An asphaltenic residue from deasphalting a synthetic crude obtained by direct liquefaction of a Spanish subbituminous coal was submitted to several upgrading routes. This paper reports the results from thermal hydroprocessing. Solubility-based lumped kinetics with parallel reacti ons for oils, gases and coke formation are proposed. Conversion data f it second-order kinetics for asphaltene conversion and for oil, gas an d coke formation. Coke formation was inhibited except under the harshe st reaction conditions. Two pathways for coke formation are proposed: one as primary reaction product after an induction period and the othe r as secondary product from a sequence of polymerization steps. The pr esence of hydrogen strongly inhibits the primary coke formation. Struc tural analyses show higher aromaticity of the oils from products obtai ned at 475 degrees C than at 450 degrees C, which supports the propose d condensation mechanism for coke production at high temperatures. (C) 1997 Elsevier Science Ltd.