Complete removal of CO at ambient conditions using copper manganese oxide (CuMnOx) catalysts synthesised via co-precipitation with ultrasonic irradiation

Abstract

This present work investigates the novel method of synthesising copper manganese oxide (Hopcalite) catalysts with a Cu:Mn ratio of 1:2 by using a facile ultrasound-assisted co-precipitation synthesis technique. The CuMnOx catalysts were synthesised using an ultrasonic bath or an ultrasonic probe with varying ultrasonic powers. The catalysts were further characterised and evaluated for the oxidation of carbon monoxide (CO). Characterisation results revealed that samples prepared using the ultrasonic method exhibited enhanced physical properties, such as highly dispersed particles with a larger surface area and pore size. Besides, the presence of mixed copper and manganese oxide phases was detected, which provided synergistic interactions to facilitate and enhance CO oxidation. The amorphicity and reducibility of the catalysts were also improved, thus indicating the presence of more active sites. Furthermore, the catalyst prepared using the ultrasonic probe at a power of 23.3 W with a 15 min sonication time was found to be the most active, with the capability of oxidising CO to CO2 to completion (100 %) at ambient conditions. It also possessed high catalytic stability, in which catalytic activity was not compromised for as long as 200 min. On the whole, this work has ascertained that by incorporating a simple ultrasonic irradiation step into the synthesis procedure of copper manganese oxide catalysts, the overall performance of the catalyst can be greatly improved compared to those already found in the literature, which demonstrates the potential application of this new method on a wider, commercial scale for carbon monoxide removal.