Pyrolysis of Waste Polystyrene to Recover Styrene over Alkaline Mesoporous Molecular Sieve K2O-BaO/MCM-41

Mesoporous molecular sieve BaO/MCM-41 catalyst was synthesized under hydrothermal conditions and K₂O-BaO/MCM-41 molecular sieve was prepared by impregnating BaO/MCM-41 with KNO₃. The obtained K₂O-BaO/ MCM-41 was used in catalytic pyrolysis of polystyrene(PS). The effects of catalyst kind, content of K₂O, reaction temperature, pressure and time on pyrolysis results of PS were examined. The results showed that K₂O-BaO/MCM-41 had better catalytic performance. Under the conditions of m(catalyst)/m(PS) = 2%, temperature 410°C, pressure 0.01MPa and time 20 min, the conversion of PS was ≥98%, the yield of liquid product was ≥96% and the content of styrene in liquid product was ≥73%. The reusability of the catalyst was investigated and there was no obvious decrease in conversion of PS, yield of liquid products and content of styrene in liquid products after the catalyst was reused for 5 times. Moreover, K₂O-BaO/MCM-41 was characterized by XRD.