DIFFERENTIAL HEATS OF ADSORPTION FOR PYRIDINE ON SEVERAL Y-ZEOLITES

Differential heats of adsorption for pyridine on NaY, CaY, REY and HY zeolites in the temperature range from ambient temperature to 620 K have been measured By a micro calorimeter, Experimental results show that there are two types of different acidic site in these four Y-zeolites. One type is B acid site and the other one is non active L acid site, Acid strength of B acid site would increase and non active L acid site would decrease as the temperature is raising Only Na+ ions act as the non active L acid sites on NaY surface and H+ as the B acid sites on HY surface for pyridine adsorption, but both B sites and L sites present on the surface of REY and CaY simultaneously, At higher temperatures the adsorption of pyridine prefers to occur on the strong B acid sites