Study on microwave-assisted co-pyrolysis and bio-oil of Chlorella vulgaris with high-density polyethylene under activated carbon

The microwave-assisted co-pyrolysis of Chlorella vulgaris (C. vulgaris) and high-density polyethylene (HDPE) was analyzed by adding activated carbon (AC) as microwave absorbent. The co-pyrolysis characteristics of C. vulgaris/HDPE under different mixing ratios (1:0, 4:1, 2:1, 1:1, 1:2 and 1:4) and the effects of different AC amounts (10%, 20%, 30%, 40% and 50%) on the co-pyrolysis were studied. The results show that the C. vulgaris/HDPE = 1:1 (C1HP1) was the optimal mixing ratio while the 40% AC was the best addition with greatly improving the co-pyrolysis characteristics of the C1HP1. Moreover, the hydrocarbons and alcohols in bio-oil of the C1HP1 group increased significantly due to the participation of HDPE, while the nitrogen-containing compounds decreased by 75.75% compared with the Pure C. vulgaris (PC) group by promoting the formation of NH3 and HCN. With the addition of 40% AC to C1HP1, the hydrocarbons in bio-oil increased to 48.88%, and the oxygen-containing compound decreased by 45.62% compared with the PC group by promoting the formation of H2O, CO and CO2. In general, the participation of HDPE and AC improve the pyrolysis characteristics of C. vulgaris and have a good denitrification and deoxygenation effect on bio-oil. (C) 2022 Elsevier Ltd. All rights reserved.