Role of Cadmium Addition in Promoting the Direct N2O Decomposition of Co3O4 Spinel

Background: Increased environmental protection concerns urge more effort to develop new catalysts for the abetment of greenhouse gases. N2O is known as a powerful greenhouse gas. The literature review revealed that various catalysts have been developed for the direct decomposition of N2O. Special attention was given to the cobalt-based spinel oxides. However, there is a lack of information about the performance of the cadmium promoted spinels for N2O abetment. Objective: This paper addresses the nitrous oxide direct decomposition over a novel series of Cd- Co catalysts. Method: These catalysts, with Cd/(Cd + Co) ratios 0.00-0.333, were prepared with the aid of the co-precipitation route, which is followed by calcination at 500 °C. Characterization of these catalysts was performed employing TGA-DTA, XRD, FTIR, N2O adsorption/desorption, and atomic absorption spectrophotometry. Results: Phase analysis revealed the absence of a solid-state interaction between CdO and Co3O4. However, it was found that increasing the Cd/(Cd + Co) ratio is associated with continuous enhancement of the N2O decomposition activity. The activity was correlated with the presence of catalyst's redox couples. Moreover, the role of the Cd presence in improving the activity was discussed. Finally, the activity performance change accompanying the calcination temperature raise was also investigated. Conclusions: Presence of cadmium has a positive effect on the N2O decomposition performance of Co3O4. Activity increased continuously with Cd/(Cd + Co) ratio increase over the examined range 0.083–0.333 structural, textural, and electronic roles of cadmium were proposed.