Advanced characterization techniques for the coking process of zeolites: a comprehensive review

Abstract

Zeolites, as a class of inorganic porous materials with ordered pore structures, are widely utilized in heterogeneous catalysis, petrochemical processes, environmental protection, and biomedicine due to their excellent selectivity, ion-exchange capacity, high thermal stability, and tunable acidity. However, during catalytic reactions, the gradual deposition of carbonaceous intermediates leads to coke formation, resulting in pore blockage and active site coverage in zeolites. This significantly reduces their catalytic activity and service life. The coking process is highly complex and limits the industrial applications of zeolites, making it essential to employ advanced characterization techniques for an in-depth study of coking behavior to better understand and address this critical issue. In this paper, we detail the important role played by various characterization techniques in the in-depth study of coking in the following four aspects: i) origin of coke; ii) factors affecting coke formation; iii) types of coke; and iv) impacts of coking on zeolites. Our review provides an effective scientific basis for the development of new zeolite catalysts with excellent carbon build-up resistance and efficient regeneration techniques, thus improving the stability and catalytic efficiency of zeolite catalysts in industrial applications.