Effect of desilication of HZSM-5 on the catalytic pyrolysis of polystyrene

Desilicated HZSM-5 (DeHZSM-5) was prepared by the desilication of HZSM-5 (SiO₂/Al₂O₃: 30) and applied to the catalytic pyrolysis of polystyrene (PS) by thermogravimetric analysis (TGA) and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS). TGA showed that HZSM-5 lowered the decomposition temperature and apparent activation energies of PS. DeHZSM-5 led a lower decomposition temperature and Ea values than HZSM-5. The main pyrolyzates of PS, styrene monomer, dimer, and trimer, were converted to smaller aromatic hydrocarbons, such as benzene and toluene. The increased pore size and acidity of DeHZSM-5 formed by the desilication of HZSM-5 led to the efficient diffusion of large molecular pyrolyzates with the increased formation of smaller molecular aromatic hydrocarbons confirming the higher catalytic cracking efficiency.