Distinction of Acid-type on Solid Acid Surface by Comparison of Adsorption Heats of Nitrogen and Argon

The heats of adsorption of N2 and Ar on solid acids were compared by applying the Clausius–Clapeyron equation to isotherms. The heats on H-mordenite and H4SiW12O40 supported on SiO2 decreased gradually with increasing the adsorption amount in parallel with each other, while sulfated zirconia and Al2O3 gave large difference between N2 and Ar in low adsorption range more than 30 and 15 kJ mol^-1, respectively, enabling the result to distinguish the Br?nsted- and Lewis-acid types.