New aspects in catalytic performance of novel metallosilicates having the pentasil pore-opening structure

A series of novel metallosilicates having the pentasil pore-opening structure were synthesized by replacing the Al ingredient with various metal salts at the stage of gel formation in the rapid crystallization method of ZSM-5, and their catalytic performances were examined for the conversions of methanol to hydrocarbon, light olefins to gasoline, and light paraffins to aromatics. The catalytic performance changed greatly with the kind of metal incorporated in the silicate crystal. In the methanol to hydrocarbon conversion, for example, silicates of Ga, Cr, and V were more selective than ZSM-5 for the formation of gasoline and aromatics, while those of Fe, Co, and Pt exhibited the best selectivity to the formation of lower olefins. Improvements in the preparation condition of the Fe-silicate led to a highly selective Fe-silicate catalyst for conversions of methanol to C₂-C₄ olefins and of light olefins to a high octane-number gasoline. The Gasilicate was more effective than the Ga ion exchanged H-ZSM-5 in the aromatization of light paraffins, and Pt ion exchange of the Gasilicate significantly increased the activity.