Surface Potassium Promotion of Co₄MnAlO _x in Direct NO Decomposition Generates the Same Type of Active Sites as Bulk Promotion

K/Co4MnAlO x mixedoxidesare active in direct NO decomposition. This work investigates theeffect of the preparation method and K precursor type. Using the incipientwetness impregnation method, the modification by the required amountof K was ensured. Regardless of the K precursor type, similar NO conversionswere reached for samples modified by 4 wt % K. The optimal amountof K from the KNO3 precursor was evaluated as 2-6wt %. The physicochemical properties were carefully explored usingatomic absorption spectroscopy, X-ray photoelectron spectroscopy,X-ray diffraction, Fourier transform IR spectroscopy, N-2 physisorption, H-2 temperature-programmed reduction, CO2 and NO temperature-programmed desorption, scanning electronmicroscopy, and transmission electron microscopy, correlated withcatalytic properties in transient and steady state and compared withthe results obtained in our previous study using bulk modified samples.The present study underlines the effect of the preparation methodon the Brunauer-Emmett-Teller surface area (S (BET)) of prepared catalysts and thus the amountof active sites available for catalytic reaction. Moreover, the resultsemphasize the importance of catalyst basicity, which affects the amountof adsorbed NO2 (-) species, the key intermediatesin the direct NO catalytic reaction.