Synthesis and characterization of an efficient and stable Al/Fe pillared clay catalyst for the catalytic wet air oxidation of phenol

John Moma; Jeffrey Baloyi; Thabang Ntho

doi:10.1039/c8ra05825c

Synthesis and characterization of an efficient and stable Al/Fe pillared clay catalyst for the catalytic wet air oxidation of phenol

RSC Adv. 2018 Aug 24;8(53):30115-30124. doi: 10.1039/c8ra05825c.

Authors

John Moma¹, Jeffrey Baloyi^{1

2}, Thabang Ntho²

Affiliations

¹ Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand Johannesburg South Africa john.moma@wits.acza.
² Advanced Materials Division, MINTEK 200 Malibongwe Drive, Randburg 2125 South Africa.

Abstract

A facile method for synthesizing Al/Fe pillared clays (PILCs) from natural bentonite clay, by using ultrasonic treatment during the aging and intercalation steps, has been established. Single metal (Fe-PILCs and Al-PILCs) and mixed metal (Al/Fe-PILCs, with varying compositions of the pillaring precursors) pillared clays were prepared and characterized with a combination of chemical and instrumental methods. The pillared clays were evaluated as catalysts in the catalytic wet air oxidation (CWAO) of phenol and the mixed metal pillared clay catalysts, especially with an Al/Fe ratio of 3 : 1, were found to be highly active and stable, with superior properties such as surface areas, basal spacing, high porosity and thermal stability. The catalysts could also be reused several times without significant loss of activity. The results of the study show that Al/Fe-pillared clay catalysts are effective catalysts for the oxidation of phenol and removal of TOC in aqueous solutions. The main intermediate products in the CWAO of phenol were hydroquinone, pyrocatechol, and benzoquinone and oxalic, formic, malonic, oxalic, malonic and maleic acids.