Microwave catalytic co-pyrolysis of sugarcane bagasse and Chlorella vulgaris over metal modified bio-chars: Characteristics and bio-oil analysis

Bio-char (BC) is a cheap, environmentally friendly and easy-to-produce material, which is widely used as pyrolysis catalyst. In this study, the modified catalysts (Fe/BC, Co/BC and Mg/BC) were prepared using BC produced by the co-pyrolysis of sugarcane bagasse and Chlorella vulgaris. The characterization of the modified catalysts showed that they had a higher surface area (SBET) and pore volume compared with BC. Besides, the influence of modified catalysts on co-pyrolysis was analyzed at different additions. Except for 10% Mg/BC, the catalysts effectively increased the average weight loss rate (Rv) and decreased the reaction time (ts) of co pyrolysis at all additions, and 40% Fe/BC addition had the highest Rv and lowest ts. The catalyst addition increased the bio-oil yield of the co-pyrolysis, and the maximum bio-oil yield (25.94%) was obtained under 40% Mg/BC addition. Moreover, the catalysts not only facilitated the formation of hydrocarbons, but also suppressed the generation of amines/nitriles and acids/esters. After adding 40% Fe/BC, the hydrocarbons content reached the highest (26.01%), while the amines/nitriles content (3.23%) and acids/esters content (4.66%) reached the lowest. The results provided theoretical support for improving microwave pyrolysis characteristics and bio-oil quality using modified BC catalysts.