Determination of concentration of basic sites on oxides by IR spectroscopy

As it is commonly known, CO₂ reacts simultaneously with basic O^2- and basic OH sites on oxides forming carbonates and bicarbonates, which can be followed by infrared spectroscopy (IR). However, here, we succeeded to elaborate experimental conditions under which CO₂ reacted solely with O^2- forming CO₃^2- for ZrO₂ and CeO₂, and calculated the extinction coefficients of diagnostic bands of carbonate and bicarbonate species. For the first time, the developed IR method enabled the concentrations of O^2- and basic OH for ZrO₂, CeO₂, Al₂O₃ and CuO to be measured separately. Moreover, in the case of all IR studied oxides, the sum of concentrations of O^-2 and basic OH basic sites was comparable with the concentration determined by pulse adsorption of CO₂. Thus, the presented extinction coefficients can be applied for IR basicity studies of various basic catalysts. We also followed the effect of thermal treatment on basicity of oxides.