Controlled and rapid growth of MTT zeolite crystals with low-aspect-ratio in a microwave reactor

The nucleation and growth of MTT zeolite, an important 10-membered ring (10 MR) zeolite, was controlled by a microwave-assisted hydrothermal synthesis. The effect of irradiation time (12,18, and 24 h), seed-assisted synthesis with 1 wt.% seeds for 6 h and desilication under microwave irradiation on crystallinity and porosity were investigated. Under microwave-assisted synthesis, uniform crystal size, with lower crystal aspect-ratio and suppressed phase-impurity has been obtained. The tendency of column-like crystal to form bundle of columns was reduced significantly. Seeded growth further reduced synthesis time to 6 h. Post-synthetic treatment was used to obtain larger pore volume of MTT zeolites. Some of the protonated MTT samples were tested in n-hexane cracking as model reaction. Characterization techniques such as XRD, FE-SEM, N-2 adsorption-desorption, Al-27 MAS NMR and NH3-TPD have been carried out to obtain insight in the physico-chemical properties of zeolite catalysts. (C) 2013 Elsevier B.V. All eights reserved.