Tailoring catalyst acidity and hierarchical pore structure for enhanced BTX yields in plastic waste pyrolysis

The exponential increase in global plastic production, coupled with the limited efficiency of current recycling technologies, calls for innovative and scalable waste management solutions. Catalytic pyrolysis has emerged as a promising method to upcycle plastic waste into valuable chemicals and fuels. However, a major challenge remains in efficiently converting complex municipal plastic waste into valuable downstream products, which requires improving the product distribution toward the aromatic fraction, particularly benzene, toluene, and xylene compounds (BTX), which hold significant value in refinery operations. BTX are key building blocks in the chemical industry, used in the production of polymers, solvents, detergents etc. Their recovery from plastic waste not only adds economic value but also supports circular economy goals by reducing reliance on fossil-derived aromatics. This study addresses these challenges by designing and evaluating catalysts with tailored acidity and hierarchical pore structures to enhance the productivity of BTX. A comparative analysis was performed on the microporous zeolites (HZSM5), mesoporous catalysts (mesocellular foams, MCF), and hierarchical variants synthesized via top-down modifications, benchmarked against an equilibrium fluid catalytic cracking (FCC) catalyst for BTX production. Feedstock characterization revealed a heterogeneous composition with a substantial inorganic fraction, highlighting the need for robust catalytic systems. Systematic evaluation reveals hierarchical zeolite and zeolitized mesocellular foams, outperforming conventional catalysts by balancing acid site concentration with pore accessibility. The hierarchical structures improve mass transport, reduce over-cracking, and increase BTX selectivity. These findings offer valuable insights for refinery-integrated plastic conversion and support the development of more efficient and sustainable plastic waste valorization strategies.