Degradation of o-, m-, p-cresol isomers using ozone in the presence of V₂O₅-supported Mn, Fe, and Ni catalysts

Abstract

Oxidative degradation of o-, m- and p-cresols using ozone in the presence of V2O5-supported metal (Mn, Fe, Ni) catalysts was studied under ambient reaction conditions. Metal (Mn, Fe, Ni) loaded V2O5 catalysts were prepared using a wet-impregnation method, thereafter, characterized, and analyzed by use of the XRD, FT-IR, SEM-EDX, TEM, and ICP-OES. Results show the effect of the amount of a metal that was loaded on the support, particularly, how it affects the resultant catalysts’ (i) crystallite size, (ii) dispersion of an active metal over the surface of a support, and (iii) catalytic activity. Mn-loaded catalysts were found to be relatively more active for the conversion of individual cresol isomers and the activity of this catalyst was significantly enhanced at a lower Mn to V2O5 ratio (2.5 wt%). Mn(2.5 %)/V2O5 catalyst led to conversions of 66.78, 71.01 and 73.68 % with o-, m-, and p-cresols respectively within 24 h of oxidation. Oxidation products were derivatized by ethanol and a few were positively detected using GC-MS. o-Tolyl acetate and 2,5-dihydroxy toluene were detected from o-cresol, m-tolyl acetate, and 2,3-dihydroxy toluene from m-cresol and p-tolyl acetate and 3,4-dihydroxy toluene from p-cresol oxidation. Dimethyl maleate and dimethyl oxalate were detected as common products in all three isomers’ oxidation.