L-glutamic monosodium amino acid-assisted approach to mordenite zeolite synthesis with application in the catalytic cracking of n-hexane

Mordenite was synthesized at 170 ºC under stirring (60 rpm) with different contents of L-glutamic acid monosodium salt (MSG) between 4 and 48 h. The materials were characterized by XRD, EDX, NH3-TPD, TG/DTG, SEM and N2 physisorption. The catalytic activity of zeolites was evaluated in the n-hexane cracking reaction at 550 ºC for 180 min. Mordenite was obtained with high relative crystallinity (83 ˗ 101%). The insertion of the amino acid salt reduced the acidity of the zeolites from 0.788 to 0.612 mmol g-1. Thermal analyses indicated the complete removal of MSG from the zeolite structure after washing, eliminating the calcination process and consequently, reducing costs. The micrographs revealed crystals of < 10 μm. N2 physisorption isotherms showed an increase in microporosity (SMicro from 411 to 445 m2 g-1 and VMicro from 0.165 to 0.178 cm3 g-1) and a higher degree of mesoporosity (VMeso from 0.009 to 0.012 cm3 g-1) for the samples with the lowest contents of MSG, indicating an optimal range for the addition of amino acid salt. The results of the n-hexane cracking reaction over mordenite samples revealed a higher tendency for the production of light olefins. The Mor/6Glut sample demonstrated high activity and a slower deactivation rate than conventional mordenite, due to the synergy of its lower acidity and mesoporosity.