Fe/Al2O3,Co/Al2O3 and Ni/Al2O3 catalysts were prepared by impregnation method.The catalytic pyrolysis catalyzed by Al2O3 and the above mentioned catalysts as well as the direct pyrolysis of polystyrene(PS)were investigated comparably.Comparing with direct pyrolysis of PS,a high conversion of PS and a high selectivity of styrene monomer(61.5%)could be obtained over Co/Al2O3,furthermore reduced carbon deposition was observed.The selectivity of monomer increased over Fe/Al2O3 and Ni/Al2O3 while the oil yield decreased.The loading of transition metal enhanced the basicity of Al2O3 support,which led to increase of β-chain-breaking and resulted in higher selectivity of styrene monomer(about 60 %)over Fe/Al2O3,Co/Al2O3 and Ni/Al2O3 than that over Al2O3.The three catalysts prevented effectively the cross-linking reaction of the newly formed monomers in PS pyrolysis.
