Catalytic performance of spinel-type Ni-Co Oxides for Oxidation of Carbon Monoxide and Toluene

This study aims to investigate the catalytic activity of spinel-type oxides (NixCoyO4) for the oxidation of toluene and carbon monoxide at low temperatures. A series of Ni/Co catalysts with different mole ratios were synthesized via citric acid assisted sol-gel method and the influence of the nickel to cobalt ratios on the properties and catalytic performance of NixCoyO4 were investigated by characterization such as XRD, SEM-EDX, BET, H2–TPR. The results indicate that the catalyst with the Ni/Co atomic ratio of 1.5/1.5 exhibits the highest complete toluene oxidation activity, with 85% toluene conversion rate at 100 – 250 °C and complete toluene oxidation at 300 °C. However, for the complete oxidation of CO, the Ni/Co atomic ratio of 1/2 exhibits higher activity, converting 100% CO at 150 °C. The results show that NiO and CoOx are proved to be more active than the other for the oxidation of toluene and CO, respectively. The characteristic results show that high surface area, small particle size, good temperature reducibility, and oxygen species with high mobility in low-temperature regions are responsible for the catalytic performance of nickel cobalt spinel-type catalyst for toluene and carbon monoxide oxidation. The good stability of the Ni-Co oxide catalysts for the oxidation reactions originates from the strong Ni-Co interaction.