Microwave-assisted solvothermal synthesis of ZSM-22 zeolite with controllable crystal lengths

• ZSM-22 (TON) zeolite was synthesized using microwave-assisted solvothermal method.
• Different co-solvents such as ethanol, propanol, glycol were adopted in ZSM-22.
• Co-solvent addition resulted in elongated ZSM-22 crystal.
• Addition of co-solvent stimulated the appearance of ZSM-5 zeolite as an impurity.

ZSM-22 (TON) zeolite crystal morphology was successfully controlled using a microwave-assisted solvothermal fabrication method. Different co-solvents, including ethanol, 2-propanol, glycerol, and ethylene glycol, were also applied in the synthesis mixture. The effects of various parameters such as the aging time, the type and amount of co-solvent on the ZSM-22 crystal aspect ratio were investigated. When employing this microwave irradiation synthesis, a long aging time was crucial to obtain smaller and more uniform crystal sizes. The addition of co-solvent resulted in elongated ZSM-22 crystals, regardless of the actual co-solvent used, although ZSM-22 zeolite crystallinity was sensitive to the co-solvent type. In general, the use of a co-solvent stimulated the appearance of ZSM-5 zeolite as an impurity and the amount of this impurity was proportional to the concentration of co-solvent in the synthesis mixture.

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