Kinetics of asphaltene thermal cracking and catalytic hydrocracking

A pentane-insoluble asphaltene was processed by thermal cracking and catalytic hydrocracking over NiMo/γ-Al2O3 in a microbatch reactor at 430 °C. Kinetic analysis shows that the first-order kinetics fits the data of conversion in reaction times ≤ 30 min approximately, but deviates from the data of times over 30 min significantly; whereas the second-order kinetics fits the data of the reaction times up to 60 min adequately, to give the apparent rate constants of 1.704 × 10−2 and 9.360 × 10−2 wt frac−1min−1 for the two cracking processes. Furthermore, a three-lump kinetic model is proposed to include parallel reactions of asphaltenes to produce liquid oil (k1) and gas + coke (k3), and consecutive reaction from liquid to gas + coke (k2). The evaluated value of k1 is 1.697 × 10−2 and 9.355 × 10−2 wt frac−1min−1, k2 is 3.605 × 10−2 and 6.347 × 10−3 min−1 , and k3 is 6.934 × 10−5 and 4.803 × 10−5 wt frac−1min−1 for asphaltenes thermal cracking and catalytic hydrocracking, respectively. Selectivity analysis shows that the catalytic hydrocracking process promotes liquid production and inhibits coke formation effectively.