Amine Functionalized and Cation Exchanged Zeolites for Selective Adsorption of Carbon Dioxide over Nitrogen and Methane

Abstract

This Ph.D. research works addressed enhanced COand#8322; capture through the adsorption-based processes and with Zeolite-Y as the primary support material. To assess alternate commercial as well as synthesized sorbents, single gas sorption experiments with CO2, N2 and CH4 were conducted. Among alternate sorbents, Zeolite-Y was selected after comparing its COand#8322; adsorption capacity (highest of 1.89 mmol g-1 at 303K and 1bar) with respect to other commercial zeolites (Beta and ZSM-5 commercial sorbents). After selecting Zeolite Y as the primary support material, the study followed a three-phase approach. Among these, firstly, Zeolite-Y was functionalized with mono-, di-, and triethanolamine. Thereby, the monoethanolamine-loaded samples exhibited the highest COand#8322; uptake (up to 2.26 mmol/g at 303 K and 1 bar). The adsorption behavior was modeled with the Langmuir and Virial isotherm, and selectivity was assessed via IAST. In the second phase, cation-loaded Zeolite-Y (Liand#8314;, Naand#8314;, Kand#8314; at 5 wt.%) were prepared and the sorbents exhibited enhanced COand#8322; selectivity and for the loading order of Kand#8314; gt Naand#8314; gt Liand#8314;. Among all, potassium loaded Zeolite Y sorbent exhibited highest CO2 uptake (2.89 mmol g-1 at 303K and 1bar). The third phase examined Kand#8322;COand#8323;-impregnated Zeolite-Y. Accordingly, the variant carbonate loadings affirmed optimal COand#8322; capacity at 10 wt.% loading of the carbonate (3.61 mmol g-1 at 303K and 1bar). Also, the synthesized functional materials exhibited excellent cyclic stability and selectivity. In summary, the Ph.D. thesis research works novelty can be mentioned in terms of cation-carbonate loading for cost-effective, stable and high-performance zeolite-based adsorbents and for the proximity towards industrial-scale COand#8322; capture.