Investigations of oxides of Cobalt and Copper as potential catalysts for mercury oxidation

Elemental mercury (Hg0) vapour is a toxic element that is released from a number of natural and man-made processes, with emissions from coal fired power plants being the main anthropogenic source. The most common method to control Hg0 emissions from power plants is by employing activated carbon sorption. However, this process is costly and results in the production of large volumes of mercury laden waste. Hence there has been significant interest in the development of new processes for controlling Hg0 emissions from coal fired power plants which are based on the catalytic oxidation of Hg0 vapour to oxidised mercury (Hg2+). In this work we investigate two metal oxide catalysts; cobalt oxide (CoO) and copper oxide (CuO) for their catalytic activity. The catalysts were prepared and characterised by XRD, BET and TEM, in addition to testing their activity in the presence of HCl, O2 and CO2 at concentration levels comparable to coal-fired power plant flue gas at an operating temperature of 150oC. The CoO and CuO materials were found to have Hg0 oxidation efficiencies of 17 % and 53 % respectively. The CuO was found to have a higher activity towards Hg0 oxidation due to its smaller particle size (40 to 45 nm) and higher surface area (126m2/g) over the CoO material which had particle size and surface area of ~35 nm and 53 m2/g, respectively.