Tuning the properties of the cobalt-zeolite nanocomposite catalyst by potassium: Switching between dehydration and dehydrogenation of ethanol

•The strong effect of potassium on the performance of the CoY catalyst in the ESR process.•Influence of speciation and localization of potassium on its effect in the CoY catalyst.•Enhanced interaction of cobalt phase with zeolite upon K-doping via IE and IWI routes.•Stronger ethanol adsorption on Co(K)Y prepared via the ion-exchange (IE) route.•Undesired reduction of the cobalt work function in the IWI-prepared K/CoY catalysts.