CHARACTERIZATION OF SMALLPORE ZEOLITES WITH CO_2 ADSORPTION

Smallpore zeolites(3A, 4A and 5A zeolites) were characterized by N2 and CO2 adsorption at 77K and 273K, respectively.It was shown that N2 adsorption could not detect the pore of 4A zeolite, while CO2 could.It was enough for adsorption equilibration on 4A and 5A zeolites within 35s, but for 3A zeolite the equilibration could not be achieved after 100s.HK(Horvath-Kawazoe) model for cylindrical pore was not suitable for the pore analysis of 4A and 5A zeolites, but they could be analyzed perfectly with HK model for spherical pore.Micropore volumes for 4A and 5A zeolites were calculated by maximum adsorption capacity, D-A(Dubinin-Astakhov) model and Langmuir-Freundlich model, respectively.The results indicated that the micropore volumes both based on maximum adsorption capacity and D-A model were in agreement with the data from literature.