A synergistic effect during the co-pyrolysis of Nannochloropsis sp. and palm kernel shell for aromatic hydrocarbon production

In this study, catalytic co-pyrolysis of Nannochloropsis sp. (NC) and palm kernel shell (PKS) was conducted in a fixed-bed reactor to synergistically produce aromatic hydrocarbons, followed by characterization using gas chromatography-mass spectrometry. The activities of various catalysts were also examined, and the effects of the NC-to-PKS mass ratio, reaction temperature and catalyst type on the aromatics yield and selectivity were assessed. The relative content of aromatics from the sole pyrolysis of NC and PKS were 11.79 and 2.96 area%, respectively; while a value of 30.39 area% was obtained from co-pyrolysis of NC/PKS at 600 °C and an NC-to-PKS mass ratio of 1:1, suggesting a synergistic effect for aromatics production during the co-pyrolysis. The synergistic production of aromatics was attributed to the substitution reactions of free radicals with phenols in the primary bio-oil from the co-pyrolysis. Cu/HZSM-5 was found to be a promising catalyst for aromatics production, a result that is attributed to its channel structure and surface acidity, the introduction of Cu can effectively reduce the amounts of surface strong acid sites. The addition of Cu/HZSM-5 to the co-pyrolysis of NC/PKS significantly improved the relative content of aromatics, resulting in a 42.65 area% yield.