Abstract: The acidity properties of MOR and RIZ zeolites for C8 aromatics isomerization were investigated by the temperature program desorption method. The m-xylene disproportionation / isomerization reactions were used to analyze the catalytic performance of the two zeolites. The desorption activation energies of strong acid sites calculated by NH3-TPD desorption kinetics model is 115.4 kJ/mol and 178.9 kJ/ mol for MOR and RIZ, respectively. RIZ has two types of strong acid sites and 3 times the total amount of strong acid sites than MOR. The results of the m-xylene disproportionation / isomerization reactions at 370℃and atmospheric pressure indicate the higher activity of RIZ than MOR. The disproportionation over RIZ significantly decreases with on-stream time. The initial activity of disproportionation over RIZ is proportional to strong acid amount but is independent of the acid strength.

Key words: zeolite, temperature program desorption, acidity, isomerization, disproportionation