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The light olefin product distribution of the methanol‐to‐olefin (MTO) reaction catalyzed by acid zeolites and zeotypes depends on the nature of the entrapped hydrocarbon pool species that act as co‐catalysts. The preferential stabilization by confinement effects of the cationic intermediates involved in the side‐chain or paring pathways of the aromatics‐based cycle of the MTO mechanism in small‐pore cage‐based zeolites is determined by the topology of the cavity, and can be quantitatively described through the Eint(7/5) parameter obtained from DFT calculations. In this work we extend the study of the Eint(7/5) parameter to a wide range of structures (ERI, LEV, AEI, CHA, DDR, AFX, RTH, ITE, SAV, UFI, RHO, KFI, and LTA) and discuss its applicability in small cages with steric constraints to host bulky intermediates, in zeolites with a tight fitting between the cavity and the hosted cations, and in large cages where confinement effects are lost in part and competitive processes occur. [ABSTRACT FROM AUTHOR]

The methanol‐to‐olefins reaction catalyzed by small‐pore cage‐based acid zeolites and zeotypes produces a mixture of short chain olefins, whose selectivity to ethene, propene and butene varies with the cavity architecture and with the framework composition. The product distribution of aluminosilicates and silicoaluminophosphates with the CHA and AEI structures (H‐SSZ‐13, H‐SAPO‐34, H‐SSZ‐39 and H‐SAPO‐18) has been experimentally determined, and the impact of acidity and framework flexibility on the stability of the key cationic intermediates involved in the mechanism and on the diffusion of the olefin products through the 8r windows of the catalysts has been evaluated by means of periodic DFT calculations and ab initio molecular dynamics simulations. The preferential stabilization by confinement of fully methylated hydrocarbon pool intermediates favoring the paring pathway is the main factor controlling the final olefin product distribution. [ABSTRACT FROM AUTHOR]

Abstract: From theoretical calculations and a rational synthesis methodology, it has been possible to prepare nanocrystalline (60–80 nm) chabazite with an optimized framework Al distribution that has a positive impact on its catalytic properties. This is exemplified for the methanol‐to‐olefin (MTO) process. The nanosized material with the predicted Al distribution maximizes the formation of the required MTO hydrocarbon pool intermediates, while better precluding excessive diffusion pathways that favor the rapid catalyst deactivation by coke formation. [ABSTRACT FROM AUTHOR]