A novel production of monocyclic aromatic hydrocarbons via one-step catalytic conversion of pine sawdust and waste plastics over Pd/trap-HZSM-5

Abstract

A novel method is proposed to one-step convert pine sawdust (PW) and high-density polyethylene (HDPE) into monocyclic aromatic hydrocarbons under solvent-free conditions. The aim is to strengthen the collision ability of small molecules and stabilize active oxygenates by using pressurization and hydrogen atmospheres, so as to significantly enhance the thermal interaction between PW and HDPE. A series of Pd/trap-HZSM-5 catalysts were prepared by different methods. Among them, self-reduction Pd/trap-HZSM-5 catalyst with smallest Pd nanoparticle size and highest hydrogen adsorption capabilities combined with hydrogenation ability and moderate acidity bi-functions, so it shows the highest activity. Under the optimal conditions (400℃, 1 MPa H2, Si/Al ratio of 50, catalyst-to-reactant ratio of 0.1, and plastics-to-biomass ratio of 4), both the high selectivity of aromatic hydrocarbons in bio-oil (88.9%) and the high yield of bio-oil (45.5 wt%) are ensured. The calculated total aromatic hydrocarbons yield reached 40.5 wt%, of which only 0.7 wt% were polycyclic aromatic hydrocarbons, and the vast majority were moncyclic aromatic hydrocarbons. The synergistic effect between PW and HDPE relatively increased the yield of aromatic hydrocarbons by 44.5%.