Synthesis of ZSM-23 (MTT) zeolites with different crystal morphology and intergrowths: effects on the catalytic performance in the conversion of methanol to hydrocarbons
A series of zeolite ZSM-23 samples prepared with different organic structure-directing agents, gave rise to crystalline phases, which show a large variety of particle dimensions. A detailed analysis of the structure of these materials revealed the presence of different levels of stacking fault defects when using different recipes. The effect of crystal size and morphology was investigated in the methanol to hydrocarbon reaction at 400 °C, showing a predominant production of hydrocarbons in the range C3-C6+ and negligible amount of aromatics (<3%) in all cases. More importantly, we show that methanol conversion and catalytic lifetime are strongly influenced by small differences in crystal size and morphology due to a preferential crystal growth along the microchannel direction.