Adsorption behavior of low-concentration nitrous oxide on natural mordenite zeolite

Nitrous oxide (N2O), the third most important greenhouse gas, is discharged from various anthropogenic sources and causes severe environmental problems. Herein, the natural mordenite zeolite is demonstrated to be an effective adsorbent to capture low-concentration N2O (below 30 ppm). An adsorption capacity of 0.076 mmol g-1 can be achieved at -7 degrees C with 1 ppm N2O in the dynamic adsorption test, 6.3 times as high as that at 25 degrees C. The density functional theory calculations reveal that the Ca-exchanged MOR-type zeolite has stronger interactions with N2O compared with the Na-exchanged one. However, as evidenced by the isosteric adsorption enthalpy analysis and the Fourier transform infrared spectroscopy, the natural mordenite zeolite with both Na+ and Ca2+, as well as the synthesized analogue, demonstrates stronger and distinctive interactions with trace N2O in comparison to the MOR-type zeolites with single kind of extra-framework cation. These results provide experimental and theoretical foundations for the establishment of efficient N2O removal system using well designed zeolite-based adsorbents under proper operating conditions.