Pyrolysis characteristics of Longkou oil shale under optimized condition

Factors influencing the pyrolysis process of Longkou oil shale, such as nitrogen flow rate, pyrolysis temperature, particle size, and heating rate, were investigated in order to optimize the pyrolysis condition and reduce the secondary reactions. Oil yield reached the maximum value, 17.46 %, higher than Fischer assay oil yield, at heating rate 15 °C min−1 up to 550 °C under 0.6 L min−1 nitrogen flow rate for 2- to 3-mm oil shale particles. Compared with the retorting gas obtained from Fischer assay, the retorting gas under optimized condition had a higher organic/inorganic gas ratio and alkanes/alkenes (C1–C5), due to the inhibition of the gas cracking or secondary gas phase reactions. And the shale oil obtained from optimized condition had a lower IBP and higher distilled mass percent when reaching the same end temperature, 750 °C. The content of total alkanes and alkenes in the shale oil under optimized condition was 401 and 181 mg goil−1, which were higher than those from Fischer assay, but the C8–C10 alkenes were lower, proving that optimizing pyrolysis condition was beneficial to reducing the secondary reactions.