The Study Of Mesoporous Molecular Sieves Used In Catalytic Pyrolysis Of Waste Polystyrene Plastic

Recently, the waste plastics were paid more and more attention all over the world for its serious environmental problem. Most waste plastics were treated by landfill, incineration, thermal pyrolysis, catalytic pyrolysis etc. The catalytic pyrolysis, conversion of waste plastics into feedstock or fuels, considered as an effective approach to treatment of waste plastics. Catalytic pyrolysis of waste plastics usually uses zeolites (HZSM-5, beta zeolite, etc.) as catalyst. However, the catalytic pyrolysis of wast plastics over above-mentioned zeolites was limited by the small pore size of the zeolite. Mesoporous molecular sieves, with a hexagonal arrangement of porous structure and large surface areas, have been considered an ideal catalyst in catalytic pyrolysis of waste plastics.In this paper, the catalysts (MoO3/MCM-41, TiO2/MCM-41) were prepared by impregnation and characterized by X-ray diffraction (XRD), N2 adsorption-desorption, diffuse reflectance ultraviolet-visible spectroscopy (DR UV-vis), high resolution transmission microscopy (HRTEM) and thermal analysis (TG/DSC). The results shown that MoO3/MCM-41 still exhibited hexagonal p6m pore architectures, high surface area (SBET=585m2/g), and large pore volume (V=0.66 cm3/g). The surface area, high pore volume and uniform pore distribution of TiO2/MCM-41 were 892 m2/g,1.01 cm3/g and 2.82 nm, respectively.MCM-41, MoO3/MCM-41 and TiO2/MCM-41 were used to catalytic pyrolysis of waste PS plastic. The liquid products were detected by gas chromatograph-mass spectrometer (GC-MS). The results shown that, comparing with MCM-41 and TiO2/MCM-41, both the liquid yield and the selectivity to styrene were greatly improved after using MoO3/MCM-41 as catalyst.