Solvent-Free Nitration of Toluene in the Presence of Nb2O5/SiO2 Catalyst

A series of Nb2O5/SiO2 catalysts with varying Nb2O5 loadings (5–25 wt%) were prepared using the sol-gel technique. The catalytic activity of the materials was evaluated by nitration of toluene. Nb2O5/SiO2 catalyst showed good catalytic activity, selectivity, and reusability for the nitration of toluene. Under the optimal conditions, conversion of toluene by 86% to mono-nitrotoluene was achieved with 100% selectivity. Experiments were designed by Minitab software, and the effect of reaction conditions was examined on the amount of meta isomer. The optimal reaction condition was also achieved for the lowest amount of meta isomer using this software. The reusability of the catalyst also was studied in this work at the same operating conditions, and the catalyst was stable for four runs without losing catalytic activity.