Cu precipitate formed during the benzene oxidation catalyzed by supported Cu in the presence of ascorbic acid and O2

Liquid phase hydroxylation of benzene to phenol over Cu/ZnO catalysts

“…The oxidation of benzene to phenol using transition metal substituted polyoxometastable compounds in the presence of acetone and sulfonate [5] and V/Al 2 O 3 -SiO 2 catalysts [6] containing around 80% acetic acid and CuO/Al 2 O 3 catalysts [7] prepared by the co-precipitation method was also reported. Among the supported Cu catalysts studied in the literature, the Cu/Al 2 O 3 catalysts were found to be effective for phenol production [8,9]. This study reports the catalytic behavior of metallic copper particles supported on zinc oxide.…”

Direct hydroxylation of benzene to phenol by nitrous oxide on amorphous aluminium-iron binary phosphates

“…The reaction has been extensively investigated in the liquid phase as well as in the gas phase using different oxidant agents and homogeneous and heterogeneous catalysts. Thus, in the liquid phase the best results have been obtained using hydrogen peroxide with both homogeneous and heterogeneous catalysts based on transition metals [2][3][4][5], but the reaction in presence of molecular oxygen with a reducing reagent such as ascorbic acid, has also been widely investigated [6,7]. From the environmental point of view, the reaction in the gas phase is more advantageous than in the liquid phase although when using O 2 low conversion values (<5%) and severe deactivation are observed, as indicated by copper supported on ZSM-5 zeolites [8,9].…”

One-Step Oxidation of Benzene to Phenol over Cu/Ti/HZSM-5 Catalysts

“…However, the use of a mixture of H 2 and O 2 has the risk of explosion [13,14]. It has been more recently studied that molecular oxygen directly oxidizes benzene to phenol on various catalysts in the presence of reducing regent [15][16][17][18][19][20][21][22][23][24]. We have previously reported that the supported copper catalysts effectively oxidize the benzene in acetic acid solution to phenol with molecular oxygen in the presence of ascorbic acid as a reducing reagent [22][23][24].…”

“…It has been more recently studied that molecular oxygen directly oxidizes benzene to phenol on various catalysts in the presence of reducing regent [15][16][17][18][19][20][21][22][23][24]. We have previously reported that the supported copper catalysts effectively oxidize the benzene in acetic acid solution to phenol with molecular oxygen in the presence of ascorbic acid as a reducing reagent [22][23][24]. In these cases, copper ions have been indicated to have redox properties according to physic-chemical measurements [22][23][24][25][26][27][28].…”

“…We have previously reported that the supported copper catalysts effectively oxidize the benzene in acetic acid solution to phenol with molecular oxygen in the presence of ascorbic acid as a reducing reagent [22][23][24]. In these cases, copper ions have been indicated to have redox properties according to physic-chemical measurements [22][23][24][25][26][27][28]. However, the direct oxidation of benzene to phenol without reducing reagents is more desirable due to the industrialization.…”