Catalytic Liquid Phase Oxidation of Toluene to Benzoic Acid

Abstract

The production of benzoic acid from toluene in the liquid phase with pure oxygen was studied. Investigations have been carried out with a view to determining the most suitable reaction conditions with respect to operating variables including oxygen flow rate, reaction temperature, batch time and catalyst loading. In a series of batch experiments carried out at 4 atm, the optimum values of mole ratio of oxygen to toluene, temperature, reaction time, and catalyst loading were found to be 2, 157°C, 2 h and 0.57 g/L, respectively. In addition, a kinetic study was carried out by taking into consideration the optimum reaction conditions. The model dependent on the formation of benzyl radical was found to be feasible for describing the catalytic oxidation of toluene to benzoic acid in the liquid phase. The activation energy was determined as 40 kJ/mol.

Phenyl modification of Mn‐containing mesoporous silica and catalytic oxidation of toluene

“…Catalytic selective oxidation of hydrocarbons with dioxygen is a fundamental industrial technology because oxidized products are important intermediates for many fine chemicals 1–4. Industrially, the liquid phase oxidation of toluene to benzoic acid is a key step for synthesizing ε‐caprolactam in the Snia–Viscosa process where significant progress has been made in the application of homogenous catalysis 5–9. However, one of the major problems of homogenous catalysis is the difficult separation of the catalyst from the reaction mixture, which is often energy intensive and generates a large volume of waste 10.…”

Highly Efficient Oxidation of Toluene to Benzoic Acid Catalyzed by Manganese Dioxide and N-Hydroxyphthalimide

“…For obtaining the high or complete conversion of toluene, this process was operated mostly under stringent conditions including high temperatures (around 200°C) and pressures (around 10 atm), meanwhile, it suffered from low energy efficiencies and low selectivity as well as generation of environmentally hazardous waste and byproducts of decarboxylation and over oxidation [2][3][4][5]. Various studies on this process had been performed to optimize the operating conditions in order to improve its selectivity and minimize the over oxidation, however, the reaction temperatures still were as high as over 150°C and the conversions were kept low [6][7][8][9]. Therefore, a major attention in this field is to find reaction pathways that afford benzoic acid with high selectivity at high conversion of toluene.…”

Radical Propagation Facilitating Aerobic Oxidation of Substituted Aromatics Promoted by Tert‐Butyl Hydroperoxide

“…In order to reduce the induction period and facilitate the radical propagation, numerous metal (Au, Pd, Cu, Co et al) or metal free (g-C 3 N 4 , N-hydroxyphthalimide, carbon materials et al) based catalysts have been developed. [15,17,[20][21][22][23][24][25][26][27][28][29][30][31][32][33] However, these metal or metal-free catalysts are expensive, complexly prepared or harmful to the environment.…”

“…or metal free (g‐C 3 N 4 , N‐hydroxyphthalimide, carbon materials et al.) based catalysts have been developed [15,17,20–33] . However, these metal or metal‐free catalysts are expensive, complexly prepared or harmful to the environment.…”