Thermal stability of synthetic aurichalcite - implications for making mixed metal oxides for use as catalysts

Abstract

TG combined with MS has been used to study the thermal decomposition of a synthetic aurichalcite with varying copper-zinc ratios from 0.1:0.9 to 0.5:0.5. In general, five decomposition steps are observed at 235, 280, 394, 428 and 805 degrees Celsius. The principal mass loss step increases in temperature from 255 degrees Celsius (0.1/0.9) to 300 degrees Celsius (0.5/0.5). MS using ion current curves show that the OH units and carbonate units decompose simultaneously and the two decomposition steps after the main decomposition are attributed to the decomposition of ZnCO3 and CuCO3. A higher temperature decomposition at around 805 degrees Celsius, based upon the ion current curves is assigned to the decomposition of CuO to Cu. The thermal decomposition of aurichalcite offers a method of preparing metal oxides mixed at the molecular level making the thermally activated aurichalcites as suitable for use as catalysts