Equilibrium Adsorption of Nitrogen, Oxygen, and Argon on Silver-Exchanged Hierarchical ETS-10
Aadesh R. Shrotri, Prashant S. Niphadkar, Vijay V. Bokade, Sachin U. Nandanwar
Abstract
Silver-exchanged hierarchical ETS-10 (Ag-H-ETS-10) was synthesized using Ag + exchange with hierarchical Engelhard titanosilicate (H-ETS-10) using silver nitrate solution. The physical properties of the adsorbent were analyzed using X-ray diffraction (XRD), BET surface area, nitrogen adsorption–desorption, pore volume, energy dispersive spectroscopy (EDS), and high resolution-transmission electron microscopy (HR-TEM). N 2 physisorption data confirmed that a micro-mesoporous (bimodal) structure was created in the Ag-H-ETS-10. The equilibrium adsorbent data of pure gases N 2, O 2, and Ar were investigated in the temperature range from 288 to 318 K up to 10 bar. The equilibrium adsorption capacity of Ag-H-ETS-10 was found to be 1.12 mmol g –1 for N 2, 0.87 mmol g –1 for O 2, and 1.09 mmol g –1 for Ar at 298 K and ∼10 bar. ∼20% higher adsorption capacity was found for N 2 and Ar in Ag-H-ETS-10 compared to Ag-ETS-10. The higher sorption capacity was attributed to the formation of a bimodal structure and π-complexation interaction by the Ag cation, which allows a multilayer of N 2 and Ar molecules. The Sips isotherm model was well fitted for the Ag-H-ETS-10 experimental data among Langmuir, Freundlich, Toth, and Temkin models. The measured equilibrium adsorption data for Ag-H-ETS-10 can be useful for the O 2 purification process.