Under harsh reaction conditions and under the influence of the input materials, catalysts and their molded bodies undergo an aging process and may be deactivated in the short or long term. Load-flexible and dynamic reaction control as well as potential contaminants in the process gas (including water) also require a high degree of (hydro)thermal stability and resistance to poisoning. Some deactivation mechanisms, such as deposits or changes in the oxidation state of the catalytically active species, can be remedied relatively easily by thermal treatment, while others require challenging reactivation or even regular replacement of the catalyst. With regard to irreversible deactivation, investigations into the recycling of (precious) metals from catalysts are also relevant. This work should build on established recycling processes (e.g., exhaust gas catalysts from the automotive industry) and adapt and optimize them for the reprocessing of hydrogenation and dehydrogenation catalysts.