Abstract
This work was attempted to show that the sequential dealumination and desilication with the use of tetraalkylammonium cations as pore directing agents (PDA) are an effective procedure for the fabrication of hierarchical mordenite zeolites with preserved crystallinity and uniform intracrystalline mesoporosity. Additionally it was demonstrated that desilication performed in the presence of PDAs offered greater mesoporosity development when compared to pure NaOH treatment. IR studies employing ammonia and pyridine as probes exhibited considerably Bronsted acidity of the resulting materials. The strength of protonic sites was reduced upon the treatment; nevertheless their accessibility to hindered 2,6-di-tert-butylpyridine molecules became noticeably high owing to a more open hierarchical structure. Concentration of the acid sites, their strength, and accessibility were reflected in both catalytic activity and selectivity in the cracking of n-decane, 1,3,5-tri-isopropylbenzene, and vacuum gas oil.
