Research on in-situ crystallization of industrial failed catalyst microspheres for methanol to olefins
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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