Nitration of Benzene Using Mixed Oxide Catalysts

Abstract

Vapor phase nitration of benzene has been carried out, using dilute nitric acid as the nitrating agent, over Fe/Mo/SiO 2 solid acid catalyst with more than 80% benzene conversion and 99% selectivity for mononitrobenzene. A series of Fe/Mo/SiO 2 catalysts with various compositions were prepared using a sol-gel technique and characterized using X-ray diffraction analysis (XRD), BET specific surface area analysis, temperature-programmed desorption (TPD) of ammonia, and FTIR spectroscopic analysis of adsorbed pyridine. The results are correlated with structure and acidity of the catalysts.

In search of efficient catalysts and appropriate reaction conditions for gas phase nitration of benzene

“…Some works [21,46] were based on gas phase nitration using diluted nitric acid (30 wt%). One important advantage of using diluted nitric acid was the possibility of increasing the maximum reaction temperature for nitration up to 200 °C, whereas the diluted acid shows less oxidative behavior and higher resistance to the decomposition processes (reduction of SNO).…”

Liquid-phase Catalytic Continuous-Flow Aromatic Nitration Reactions with Conc. HNO3 on Modified Mixed-Metal Oxide Composites as High-Yielding Solid Acid Catalysts

“…Certain zeolites, − modified metal oxides, − and silica-supported heteropolyacids − have been studied to achieve efficient liquid–solid nitration reactions without using sulfuric acid. It is not surprising that nitration using potent solid catalysis coupled with continuous-flow chemistry can be an ideal way to address the issues associated with this process; indeed, several examples have been developed for vapor-phase flow nitration reactions using solid acid catalysts. − A representative work by Koskin et al described a comparison of solid acid candidates under vapor-phase flow conditions with concentrated and diluted nitric acid as nitration agents and revealed that MoO 3 /SiO 2 had the best catalytic activity, giving the product in 95% yield at 1.42 h –1 weight hourly space velocity (WHSV) . Nevertheless, trials for liquid-phase reactions that expand the scope of applicable substrates for aromatics are lacking.…”