Confinement effects in methanol to olefins catalysed by zeolites. A computational review

[EN] Small pore zeolites, containing 8-rings as the largest, are widely employed as catalysts in the process of methanol-to-olefins (MTO). Reactants and products diffuse with constraints through 8-rings and this is one of the reaction bottlenecks related to zeolite micropore topology. Small pore zeolites and silicon-aluminophosphates (SAPOs) containing cavities, where olefins are mainly formed through the hydrocarbon pool (HP) mechanism, are frequently tested for MTO. Shape selectivity of transition states within the side-chain methylation will be reviewed as this is one of the controlling steps of the MTO process, with particular attention to the role of hexamethylbenzene (HMB) and heptamethylbenzenium cation (HeptaMB(+)), which are the most tipically detected reaction intermediates, common to the paring and side-chain routes within the HP mechanism. The relative stability of these and other species will be reviewed in terms of confinement effects in different cage-based zeolites. The role of the different alkylating agents, methanol, dimethyl ether (DME), and surface methoxy species (SMS) will also be reviewed from the computational viewpoint.This work has been made on the framework of a collaboration with professors Michel Waroquier, Veronique Van Speybroeck and Karen Hemelsoet. Useful discussions and exchange of ideas are gratefully acknowledged. Ministerio de Economia y Competitividad of Spain is thanked by the provision of funding through the excellence programme 'Severo Ochoa' (SEV-2012-0267).Sastre Navarro, GI. (2016). Confinement effects in methanol to olefins catalysed by zeolites. A computational review. Frontiers of Chemical Science and Engineering. 10(1):76-89. https://doi.org/10.1007/s11705-016-1557-3768910