Catalytic pyrolysis characteristics of polystyrene by biomass char-supported nanocatalysts

Abstract

Plastics originate from the synthesis of chemical products, and the regeneration of chemical products from waste plastics through catalytic pyrolysis helps to reduce the dependence on fossil resources and improve the treatment of waste, which is an important aspect of current sustainable social development. In this study, metasequoia was used as a biomass precursor and three porous char-supported nanocatalysts (Fe-MEC, Ni-MEC, and Co-MEC) were synthesized via a simple and feasible microwave heating method, which were then used as catalysts for the preparation of high-quality liquid oil from polystyrene powder via an ex-situ catalytic pyrolysis method. The results indicate that Fe-MEC, Ni-MEC, and Co-MEC possessed good pore structures due to the microwave-heating and catalytic effect of these metals, and metal nanoparticles are generated and uniformly anchored on the matrix of the char support. Using these catalysts, the yield of liquid product from polystyrene pyrolysis decreased slightly, while the gas yield increased slightly. Fe-MEC catalysis reached the highest liquid yield of 91% among the three catalysts. The catalysts can improve the yield of a series of high-value liquid products such as toluene, ethylbenzene, and α-methyl styrene. The catalysts also exhibited excellent cycle stability, and carbon nanotubes were formed which are less prone to deactivation.