Effect of precursor synthesis on catalytic activity of Co3O4 in N2O decomposition

Series of precursors was prepared by precipitation of cobalt nitrate in aqueous solutions using various precipitation agents (NH3·H2O, NaOH, Na2CO3) and reactions conditions (OH/Co molar ratio, aging time). Powder XRD showed different phase composition of the obtained precursors, in which β-Co(OH)2, CoII–CoIII layered double hydroxide, and basic cobalt carbonate were identified. Only Co3O4 spinel-like oxide was found in products after heating at 500 °C in air but different N2O conversions were observed over the examined oxide catalysts. Especially the catalysts obtained from β-Co(OH)2 precursors showed high catalytic activity in N2O decomposition. The correlation between methods of preparation, phase composition of precursors, catalytic properties of the related oxide catalysts, and the role of the cobalt ions as catalytic active sites is discussed.