SAPO-34 molecular sieve has the problems of low olefin selectivity and easy carbon deposition of acidic sites in MTO reaction.In this article,Metal Co was introduced into the pores of SAPO-34 through equal volume impregnation method,and the effect of Co addi-tion on the catalytic performance and carbon deposition behavior of Co/SAPO-34 catalyst in the MTO reaction was systematically investi-gated.The results indicate that metal Co can serve as a central site for dehydrogenation reactions,weaken hydrogen ion transfer,inhibit the generation of alkanes,and effectively improve the selectivity of olefins in the reaction.At the same time,the introduction of Co met-al can also precisely regulate the strength of acid centers on the surface of SAPO-34,increase the ratio of weak acid to strong acid,there-by weakening the carbon deposition effect of strong acid centers and inhibiting the deactivation of catalyst.By combining characteriza-tion methods such as NH3-TPD,H2-TPD,BET,TG,XPS,GC-MS,etc.,this paper deeply explored the carbon deposition behavior of Co/SAPO-34 catalyst in MTO reaction.It is found that key carbon deposition precursors like polymethyl-substituted benzene are preferen-tially deposited on micropores and strong acid sites,and significantly promote the generation of polycyclic aromatic hydrocarbons.The rela-tively large pore volume and appropriate weak acid concentration can synergistically promote the decomposition and transformation of car-bon deposition precursors,inhibiting the formation of hard coke.The calculation of carbon deposition rate shows that Co0.5/SAPO-34 with appropriate acidity and pore structure has the highest methanol conversion rate,low-carbon olefin selectivity and the longest catalytic life.
Co/SAPO-34impregnationmethanol to olefincoke resistancedeactivationselectivity
维普
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