ESR MEASUREMENTS OF CONCENTRATION FOR STRONG SURFACE ACCEPTOR CENTERS ON ZEOLITES AND AL2O3 USING NITROXIDE RADICAL TEMPON

A method to measure concentrations of strong surface acceptor centers on aluminosilicate catalysts by their titration with a solution of TEMPON (2,2,6,6-tetramethyl-4-oxypiperidine-1-oxyl) is suggested. The concentration of these centers corresponds to that of CO test molecules for the strongest acceptor centers (νCO ⩾2210 cm−1) obtained using IR spectroscopy. It is shown that for ZSM-5 zeolites most of these centers are localized on their external surface.