The dynamics of ammonia sorption and n-octane hydroconversion over dealuminated ZSM-5 zeolites

The dynamics of NH3 sorption of H-ZSM-5 zeolites dealuminated by steaming was examined using the frequency response (FR) method. Two sorption processes with different rates were distinguished: a slower process (process i), related to the formation of NH4+ ions on the Brِnsted acid sites, and a faster process (process j) assigned to sorption on Lewis acid sites, which were predominantly, on the NH4+ ions. The ZSM-5 preparations were used as acid supports of Pt-containing bifunctional catalysts that were tested in the hydroconversion of n-octane. Correlations were established between the rate constant of NH3 adsorption (ka(j)) and desorption (kd(j)) and the site-specific hydroconversion activity.