Microwave-assisted pyrolysis of waste cooking oil for bio-based hydrocarbons over Chem-CaO@SiC catalyst

Bio-based hydrocarbons derived from biomass pyrolysis is an important supplement to the fossil resources. The inhomogeneous temperature of catalytic bed is one of the important reasons for catalyst deactivation. Chem-CaO@SiC catalyst was synthesized for the conversion of waste cooking oil (WCO) to bio-based hydrocarbons in this paper. Compared with the catalyst prepared from physical mixing, the catalyst prepared by chemical reaction was performed better in maintaining the bio-oil yield and increasing the relative content of hydrocarbons in bio-oil. Catalyst characterization showed that CaO was well supported on the SiC-powder surface. Then the effects of SiC-ball bed temperature and CaO loading rate on product yield and distribution were investigated. Also, the deoxygenation pathway was discussed. More polycyclic aromatics were produced when the SiC-ball bed temperature was 550 °C and above. And the composite catalyst could inhibit the formation of PAHs. The bio-oil yield increased and high heating value of gas products decreased with the decrease SiC-to-CaO ratio, and more energy from the WCO flowed into bio-oil. The catalyst remained 0.622 times of the initial activity after 5 cycles.