The Application of 1,3,5-trinitrobenzene as a Spin Probe for the Surface Basic Sites Study of MgAl Double Oxides by EPR Spectroscopy

Abstract In current work the features of 1,3,5-trinitrobenzene (TNB) transformation into paramagnetic products on the surface of aluminum/magnesium oxides calcined at 550°C, as well as MgAl double oxides, were investigated by EPR spectroscopy. It was shown that the increase of basicity (i.e. MgO content) leads to the increase in the concentration of formed radical anions, wherein the presence of acidic sites contributes to their stabilization on the surface. The effect of n-hexane and toluene used as solvents in the transformation of adsorbed TNB radical anions was established, and a new probe EPR technique for using TNB to determine the concentration of the basic sites in MgAl double oxides was proposed. The results of the proposed technique are in good agreement with the data on the basic sites concentration obtained from the adsorption capacity CO2 of the corresponding samples.