Cu/UiO-66: a novel nanocatalyst obtained by a microwave-assisted protocol in DMF-free media for the efficient phenol removal via catalytic wet peroxide oxidation

Abstract

This paper analyzes the microwave-assisted synthesis of the zirconium-based metal-organic framework (MOF) UiO-66 using acetone as a solvent, in replacement of the traditional and toxic N,N-Dimethylformamide (DMF). It also studies the subsequent loading of this MOF with high amounts of dispersed copper species to be used as catalyst in the advanced oxidation of phenol. To this purpose, the structural development of UiO-66 was monitored studying the effect of synthesis variables such as stirring, temperature, treatment time and volume of the mixture. In this way, a high-crystallinity UiO-66 was obtained with high yields (88 %) at short times (6 h) and under mild conditions (80 °C) in a DMF-free media. Subsequently, by studying treatment conditions, a Cu/ UiO-66 catalyst supporting high loadings (10 wt. %) of highly dispersed copper species (Cu+/Cu2+) was obtained. This nanocatalyst, which was obtained following sustainability criteria, exhibited a high performance in the catalytic wet peroxide oxidation (CWPO) of phenol, quickly converting all the phenol at 70 °C in the first 5 min and reaching a mineralization (TOC removal) of 88 % and a H2O2 consumption efficiency of 30 % at 120 min. Cu/UiO-66 represents a new nanostructured catalyst based on highly dispersed copper species to be applied in CWPO processes.