Transition-Metal-Exchanged Nanocrystalline ZSM-5 and Metal-Oxide-Incorporated SBA-15 Catalyzed Reduction of Nitroaromatics

Nanocrystalline ZSM-5 was synthesized by a one-step synthetic route using the conventional ZSM-5 synthesis composition but in the presence of propyltriethoxysilane as an additive. Transition metal ion-exchanged nanocrystalline ZSM-5 catalysts were obtained by the ion exchange of nanocrystalline ZSM-5. The one-step direct synthetic route was used to prepare metal-oxide-incorporated SBA-15 catalysts under milder acidic conditions than are conventionally employed for the synthesis of Si-SBA-15. The catalysts were investigated in the reduction of nitroaromatics in the presence of sodium borohydride as a reducing agent. Among the catalysts investigated, copper ion-exchanged nanocrystalline ZSM-5 exhibited the highest activity. Although the copper ion-exchanged nanocrystalline ZSM-5 is recyclable, but for efficient recycling (with no loss in activity), it is better for the catalyst to be ion-exchanged once before being used in the next cycle.