Kinetics and selectivity of asphaltene hydrocracking

Thermal hydrocracking and catalytic hydrocracking over NiMo/γ-Al2O3 of a pentane-insoluble asphaltene were conducted in a microbatch reactor at 430 °C. The experimental data of asphaltene conversion fit second-order kinetics adequately, to give the apparent rate constants of 2.435 × 10−2 and 9.360 × 10−2 wt frac−1 min−1 for the two processes respectively. A three-lump kinetic model is proposed to evaluate rate constants of parallel reactions from asphaltenes to liquid oil (k1) and to gas + coke (k3), and consecutive reaction from liquid to gas + coke (k2). The evaluated k1 is 2.430 × 10−2 and 9.355 × 10−2 wt frac−1 min−1, k2 is 2.426 × 10−2 and 6.347 × 10−3 min−1, and k3 is 5.416 × 10−5 and 4.803 × 10−5 wt frac−1 min−1 for asphaltenes hydrocracking in the presence or absence of the catalyst, respectively. Analysis of selectivity shows that the catalytic hydrocracking process promotes liquid production and inhibits coke formation effectively.