Synthesis of SSZ-13 zeolite membrane and investigation of the effect of lithium, sodium, and potassium ions on the permeance of carbon dioxide, methane, and nitrogen

SSZ-13 zeolite membrane was successfully syntesized by secondary growth method. In this paper, the effect of sodium, potassium and lithium as the extra-framework cations on the membrane performance was investigated for carbon dioxide, methane and nitrogen gases. The synthesized membrane containing sodium cation showed a high carbon dioxide permeance of 3.67 × 10-7 mol.m-2.s-1.Pa-1 and ideal selectivities of CO2/CH4 = 44.6 and CO2/N2 = 11 at 300K and 2bar pressure difference. Then, the sodium caions of the membrane layer were exchanged by both potassium and lithium caions to investugate the permeance of the aforementioned gases at different temperatures and pressures. The effect of temperature was studied by calculation of the activation energies of premeations. The results revealed that the presence of lithium in the membrane layer caused a decrease in the carbon dioxide permeance to 1.13 × 10-7 mol.m-2.s-1.Pa-1. However, that was much more for methane, i.e. from 4.51 × 10-9 mol.m-2.s-1.Pa-1 to 5.30 × 10-11 mol.m-2.s-1.Pa-1, and nitrogen, i.e. from 3.31 × 10-8 mol.m-2.s-1.Pa-1 to 5.30 × 10-9 mol.m-2.s-1.Pa-1. Thus, CO2/CH4 and CO2/N2 selectivities increased from 44 to 97 and 11 to 19, respectively. In the ion-exchanged membrane with potassium, the carbon dioxide permeance decreased sharply to 9.81 × 10-8 mol.m-2.s-1.Pa-1. That resulted in sharp reduction in CO2/CH4 and CO2/N2 selectivities from 44 to 2.7 and 11 to 3.87, respectively. Therefor, potassium cation exchange is not suggested for SSZ-13 membrane.