钪改性ZSM-5分子筛的制备及其在甲醇制烯烃反应中的催化性能OACHSSCDCSTPCD

Scandium(Sc)was successfully incorporated into the framework of ZSM-5 catalysts via an in-situ synthesis method,maintaining the original MFI-type topological structure of ZSM-5 zeolites.X-ray diffraction(XRD)analysis and scanning electron microscopy(SEM)of Sc-ZSM-5 revealed no significant changes in crystal structure,with no coexisting phases detected.SEM and nitrogen adsorption-desorption assays demonstrated that the accumulation of small crystals led to the formation of a pronounced micro-mesoporous composite hierarchical pore structure.Characterization utilizing X-ray photoelectron spectroscopy(XPS),energy-dispersive X-ray spectroscopy(EDS),and inductively coupled plasma atomic emission spectroscopy(ICP-AES)confirmed the successful integration of Sc atoms into the ZSM-5 catalyst framework.The ion-exchanged H-form Sc-ZSM-5 zeolite was employed in the methanol-to-olefins(MTO)reaction and compared with conventional ZSM-5 zeolites.Sc-ZSM-5 exhibited a marginally enhanced catalytic lifetime due to its more open pore structure.Furthermore,the introduction of Sc into the modified zeolite significantly improved the selectivity towards propylene and lower olefins by modulating the acidity and the spatial distribution of Al within the ZSM-5 framework.