Evaluating the Role of Descriptor- and Spectator-Type Reaction Intermediates During the Early Phases of Zeolite Catalysis

The philosophy of "Ikigai"-a reason for being-could be extended to rationalize the role of organic reaction intermediates in zeolite catalysis. Each reaction intermediate's ikigai is specific under the confined microenvironment of the zeolite: either controlling the product selectivity (i.e., "descriptor"-type reaction intermediates) or promoting the catalyst deactivation (i.e., "spectator"-type reaction intermediates). Based on the process conditions and zeolite topologies, the ikigai of reaction intermediates could be altered, where the "descriptor" character could turn into a "spectator" depending on the working environment. Although the spectroscopy-/mechanism-driven development of catalytic technologies has been accelerated in the past decade and can now identify "elusive" zeolite-trapped reaction intermediates, it still does not always necessarily imply their "positive" impact during catalysis. Therefore, future research activities should be dedicated to recognizing the true ikigai of identified reaction intermediates: i.e., differentiating their spectator role from the catalytically relevant descriptor. Considering its potential industrial application, we will present our account and philosophy on the current status and future impact of mechanism-driven development of zeolite-mediated catalytic technologies in this Perspective.