Removal of Greenhouse Gas (N2O) by Catalytic Decomposition on Natural Clinoptilolite Zeolites Impregnated with Cobalt

In this work, natural zeolite, clinoptilolite were treated with acid (0.6 N HCl; code “Z-AM”) and alkaline solutions (1.5 N NaOH; code “Z-BM”). Thereafter, non-modified (as parent zeolite; code “Z-NM”) and modified zeolites were impregnated with cobalt using wet incipient impregnation method (Codes: “Z-AM-Co-0.5,1,1.5”, “Z-BM-Co-0.5,1,1.5”, “Z-NM-Co-0.5,1,1.5”). The prepared zeolites were characterized by XRD, ICP-OES, BET, NH3-TPD and H2-TPR. Also, these materials were studied for the catalytic decomposition of nitrous oxide (a greenhouse gas) to nitrogen and oxygen. The obtained results showed that the applied modifications had no significant influence (destruction) on the main structure of the zeolites including clinoptilolite, quartz and cristobalite. In addition results showed that acid modification increases the nitrous oxide decomposition because of surface area increment and the higher amount of CO/Al as well as the strong acid sites of this zeolite compared to other zeolites. Also, experiments showed that the main active species in nitrous oxide decomposition are mono-atomic (Co2+ cations) and other species exhibit much lower activity. In conclusion, natural clinoptilolite zeolites treated with acid and impregnated with Cobalt (Z-AM-CO-1.5) could be a very effective and cost-benefit catalyst for reducing N2O as a greenhouse gas, due to its very low price, high chemical stability and high availability.