Seven-Lump Kinetic Model for Non-catalytic Hydrogenation of Asphaltene

Abstract

Non-catalytic hydrogenation with a hydrogen donor is a beneficial way for effective conversion of asphaltene to distillate with minimal coke formation. In this work, detailed product distribution, which includes gas, light oil [initial boiling point (IBP)–350 °C], middle oil (350–540 °C), heavy oil (>540 °C), asphaltene, and coke, obtained from non-catalytic hydrogenation of asphaltene with tetralin as a hydrogen donor, was investigated in an autoclave. The effects of reaction conditions, including reaction time, reaction temperature, and hydrogen donor/asphaltene weight ratio, on asphaltene conversion, detailed product distribution, liquid product yield, and liquid product selectivity were studied. Results showed that through controlling the reaction condition, asphaltene conversion and total liquid yield reached 72.72 and 70.34 wt %, respectively, and produced only 2 wt % coke and 0.34 wt % gas. We then developed a seven-lump kinetic model, including an active hydrogen lump to describe the reaction behaviors of asphaltene hydroliquefaction. Activation energies ranged from 106.07 to 237.50 kJ mol–1. The activation energies of the main reaction that asphaltene decomposed and hydrogenated by active hydrogen to produce heavy oil and middle oil were 106.07 and 109.06 kJ mol–1, respectively, which were lower than those of thermal cracking. The activation energy of distillate formation from active hydrogen combined with macromolecule radicals was 143.78 kJ mol–1. The detailed product yield predicted by the developed seven-lump kinetic model exhibited good consistency with the experimental data.