mum zeolite/metallic component mass ratio being 1:1 [30].Although catalyst stability is a key factor for process viability, ithas not been studied in depth in the literature. Therefore, this paperfocuses on the cause of deactivation and its relationship with cat-alyst properties and operating conditions. Based on the relevantliterature on the deactivation of bifunctional catalysts using CuO-ZnO-Al2O3(CZA) as the metallic component and HZSM-5 zeolites(of different acidity) as the acid component, the possible causes ofthe deactivation of these catalysts in the SRD reaction are as fol-lows: (i) Cu sintering, above a threshold temperature [31–33]; (ii)coke deposition on the metal and/or acid active sites [12,14,19,21];(iii) Cu oxidation, enhanced by the high steam concentration in thereaction medium