From wood plastic composite waste to high-value aromatics via catalytic pyrolysis over an activated carbon

Abstract

The catalytic pyrolysis of cornstalk/high density polyethylene composite (CHC) over H3PO4 activated carbon (AC) catalyst was carried out in a fixed bed reactor. The effects of pyrolysis temperature and AC to CHC ratio on product yield and chemical composition were investigated. Results showed that the pyrolysis oil yield was in the range of 20.4–49.1 %, which decreased with increasing temperature and AC to CHC ratio. The gas yield exhibited a different trend with the pyrolysis oil. With the increase of pyrolysis temperature and AC to CHC ratio, the yield of aromatics first increased and then decreased, reaching its maximum at 578 °C and AC to CHC ratio of 1.75. The AC catalyst was reused five times and was characterized by BET, FTIR and SEM-EDS. The yield of aromatics exhibited a positive linear correlation with pore volume and BET surface area. As the reuse time of AC catalyst increased to five, the yield of aromatics decreased due to the significant reduction in BET surface area and pore volume of AC catalyst. The number of P-containing functional groups partly disappeared, which was also associated with a decrease in the catalytic activity of AC catalyst.