Evaluating synthesized nanostructure templated silica membrane performance in separation of carbon dioxide from flue gas stream

Carbon dioxide as one of the important combustion product of various industrial units is a greenhouse gas which has a significant influence on global warming. In recent years, porous inorganic membranes have extended for carbon dioxide separation from flue gas. In this study, the microporous silica membrane with nanometer size pores was prepared by template assisted sol-gel method using methyltriethoxysilane (MTES) as organic template and influence of the surface modification on the membrane separation performance was investigated. To fabricate the membrane, α-alumina macroporous support was prepared by gel casting method using ceramic alumina powder. The uniform γ-alumina mesoporous layers were selected as surface modification strategy, in which the supports were coated by alkoxide boehmite sol via dip coating method. The morphology of membrane layer was investigated by scanning electron microscope, indicating the formation of a uniform layer from γ-Al2O3 and silica. Permeance characteristics of the synthesized membrane were studied in two parts: permeance of pure gases such as carbon dioxide, nitrogen and hydrogen, and separation of 50/50 ratio (vol%) mixture of carbon dioxide and nitrogen. For the modified templated silica membrane, the CO2/N2 ideal selectivity and pure CO2 permeance were achieved 11 and 4×10-8 mol/m2.s.Pa, respectively. The real selectivity of CO2 in the mixture (CO2 and N2) with 50/50 ratio (vol%) was achieved 5.3.