Enhancing jet fuel range hydrocarbons production from catalytic co-pyrolysis of Douglas fir and low-density polyethylene over bifunctional activated carbon catalysts

Low-cost and high-efficiency catalysts are vital to the conversion of solid wastes into biofuels or chemicals. In this study, a bifunctional activated carbon catalyst modified with Fe (Fe/AC) was obtained and applied to the catalytic co-pyrolysis of Douglas fir (DF) and low-density polyethylene (LDPE) using a facile fixed bed reactor. The effects of Fe loading amount, catalyst to feedstock ratio, and pyrolysis temperature on the product yields and distributions were studied. Results showed that the highest yield of bio-oil (53.67%) was achieved using 10Fe/AC at a pyrolysis temperature of 500 °C with a catalyst to feedstock ratio of 1. The main chemical compositions of the obtained catalytic bio-oil were aromatics, alkanes, and phenols. Increasing the temperature (450–600 °C) and catalyst to feedstock ratio (0.5–2) enhanced the selectivity of aromatics at the expense of phenols and alkanes. Compared to the AC catalyst, Fe/AC exhibited excellent performance on aromatics production (especially mono-aromatics) due to the newly created acid sites. The catalytic synergistic effect over 10Fe/AC significantly promoted the formation of aromatics through hydrogen transfer reactions which facilitated the dehydroxylation and demethoxylation of phenols. The present work provides a promising approach of converting biomass and plastic wastes directly into jet fuel range hydrocarbons by using green inexpensive carbon-based catalysts.