Non-catalytic and In-situ catalytic co-pyrolysis of Huadian oil shale and microalgae using several additives as catalyst

The non-catalytic and in-situ catalytic co-pyrolysis of Huadian oil shale (OS) and microalgal powder (MP) were performed using a modified aluminum retort. By comparing the product yields and compositions for non -catalytic and catalytic pyrolyses, the catalytic effect of several additives, including MgO, CaO, ZrO2, Al2O3, zeolite Y, and zeolite ZSM-5, was investigated. This study focused on the deoxygenation performance of the pyrolytic oil. The oil yield increased with increasing MP addition in non-catalytic co-pyrolysis trials. At the OS/ MP blending ratio of 3/1, the oil yield was 12.42 wt %, and the oxygen content and H/C ratio of oil were 11.54 wt % and 1.571, respectively. Both CaO and Al2O3 significantly decreased the oxygen content of the oil to <7 wt % with less oil loss (<1 wt %). CaO catalysis facilitated the dehydrogenation of free radicals to release H2, thereby increasing alkene formation and decreasing the H/C ratio of the oil to 1.441. Al2O3 catalysis increased the H/C ratio to 1.656 and improved the oil quality. ZSM-5 preferentially catalyzed the reaction between n- alkenes and nitrogenates to yield nitriles, and the catalytic performance for deoxygenation was negligible. Hence, Al2O3 was selected as the most suitable additive for the co-pyrolysis of OS and MP.