In order to solve the problem of resource utilization of industrially failed catalyst for methanol to olefins(MTO)and achieve the recycle of MTO catalysts,MTO catalysts with SAPO-34 molecular sieves as the active component were successfully prepared in a hydrothermal synthesis system using industrial failed MTO catalyst microspheres as raw materials through in-situ crystallization.XRD,SEM,N2 adsorption/desorption,XRF,NH3-TPD and infrared spectra of deuterated acetonitrile(CD3CN)were used to analyze the crystal structures,morphology characterizations,pore structures,elemental compositions and acidities of catalysts before and after in-situ crystallization.The catalytic performances of catalysts before and after in-situ crystallization in MTO reaction were evaluated in a fixed fluidized bed reactor.The research conditions were reaction temperature of 480℃,atmospheric pressure and methanol mass space velocity of 4 h-1,and raw material was pure methanol.The results show that compared with the catalyst before in-situ crystallization,the relative crystallinity of the catalyst after in-situ crystallization increases by 76%.And the specific surface area and content of B acid increase separately by 1.4 times and 1.1 times.In MTO reaction,the selectivity of dienes(ethylene and propylene)reaches the highest of 89.64%.Compared with the catalyst before in-situ crystallization,the selectivity of dienes increases by 3.3%.The contents(mass fraction)of dimethyl ether and heavy hydrocarbons such as C4 and C5+are significantly reduced,and the catalyst after in-situ crystallization has excellent stability.
failed catalystmethanol to olefinsmicrospheresin-situ crystallization
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