Single step conversion of benzene to phenol using hydrogen peroxide over modified V2O5–Al2O3 systems

Abstract

Alumina supported vanadia catalysts were prepared by the wet impregnation method. The effect of vanadium content was investigated with 1.92-16.93 wt% V 2 O 5 loading over the support. Physical characterization of the catalysts was done by techniques such as energy dispersive X-ray (EDX), X-ray diffraction (XRD), BET surface area measurement, FTIR spectroscopy and temperature programmed reduction (TPR) studies. Characterization techniques have revealed that vanadia is well dispersed over alumina up to 13.91 wt%, after which aggregation into vanadia crystallites was observed. Single step liquid-phase hydroxylation of benzene to phenol by hydrogen peroxide was studied over these catalysts. The phenol selectivity can be attributed to amorphous surface vanadyl units in the catalysts. The supported analogues were modified with oxides of iron and cerium. Ceria incorporation to alumina enhanced the activity towards hydroxylation of benzene.

Cerium promoted V-g-C 3 N 4 as highly efficient heterogeneous catalysts for the direct benzene hydroxylation

“…The TOF value of 17.1 h −1 based on the vanadium content also indicates that Ce 0.07 -0.07 V-g-C 3 N 4 is the most active catalyst. Thus, we deduce that a proper molar ratio of Ce/V possibly facilitates both the redox properties of V species and the efficient decomposition of H 2 O 2 , leading to the remarkable catalytic activity in the benzene conversion reaction [27]. …”

One-Step Catalytic or Photocatalytic Oxidation of Benzene to Phenol: Possible Alternative Routes for Phenol Synthesis?

“…The experimental results evidenced that, at 60 • C, the activity increases, with an increase in vanadia content up to 13.8%. After monolayer dispersion, i.e., above 14% V 2 O 5 , the percentage conversion of benzene decreased [44]. However, the weak interaction of V and support leads to the leaching of active phases from the support [45].…”

Synthesis of iron orthophosphate catalysts by solution and solution combustion methods for the hydroxylation of benzene to phenol

“…Without solvent benzene and hydrogen peroxide didn't mixed, solvent was necessary [36]. The activity is maximum in polar solvents [20]. Fig.…”

“…The direct hydroxylation of benzene to phenol is an attractive, economic, one-step method. Nitrous oxide [17,18], hydrogen peroxide [19,20], oxygen [21], and mixtures of oxygen and hydrogen [22,23] have been used as oxidants. Because of its environmental and economic advantages, hydrogen peroxide is preferred.…”