Regulating the Acid Sites Distribution in ZSM-5 Zeolite and Its Catalytic Performance in the Conversion of Methanol to Olefins

The catalytic performance and reaction mechanism of ZSM-5 zeolite in the conversion of methanol to olefins (MTO) is closely related to the distribution of acid sites in framework. In this work, it was demonstrated that adding proper content of Na+ ions during synthesis can increase the proportion of acid sites in the intersection cavity of ZSM-5; the concentration of acid sites in the intersection cavity can promote the formation of higher polymethylbenzene (polyMBs) and the propagation of aromatic cycle, forming more ethene. In contrast, in the Na+ ions free synthesis system, more acid sites are distributed in the sinusoidal and straight channels of ZSM-5, which is more encouraging for the alkene cycle and conduces to producing more propene and higher alkenes(C3+).