Regioselective nitration of toluene to para‐nitrotoluene with NO2 over dealumination Hβ zeolite: Comparison of organic and inorganic acids

Abstract

AbstractThis work presents a novel heterogeneous catalytic system for the preparation of para‐nitrotoluene (p‐NT) with nitrogen dioxide (NO2) as a nitrating agent in the presence of oxygen (O2). By applying dealuminated Hβ zeolite treated with oxalic acid (Hβ‐Ox) as a catalyst, p‐NT can be obtained with high conversion (90.5%) and selectivity (72.6%). In addition, it can be recycled at least five times without a significant decrease in catalytic activity. This result demonstrates that the catalyst has high efficiency, good stability, and regenerability. Meanwhile, the characteristics of pristine Hβ and different dealuminated Hβ zeolites modified with organic and inorganic acids were systematic contrastive studied using X‐ray diffraction (XRD), nitrogen (N2) adsorption‐desorption, Fourier‐transform infrared (FT‐IR), scanning electron microscope (SEM), temperature‐programed desorption of ammonia (NH3‐TPD), pyridine adsorption infrared (Py‐FT‐IR), and solid state 27Al nuclear magnetic resonance (27Al MAS‐NMR). Finally, the higher conversion and para‐selectivity over Hβ‐Ox also give a reasonable explanation in this paper.