MMA Modified Inorganic/Organic Hybrid Membranes by Sol–Gel Technology

Abstract

The inorganic/organic hybrid membranes modified by MMA were deposited on the porous α-Al2O3 substrates (pore size, 2 µm) by the sol–gel technology. It was found that the introduction of MMA can not only improve the membrane formation properties, but also increase the selectivity of O2/N2 and O2/CO2. On the other hand, the modified hybrid membranes have more dense structure.

Pore Size Determination of Supported Organic-Inorganic Hybrid Membranes by Modified Gas Permeation Method

“…This is consistent with gas separation results [6]. The introduction of MMA to the hybrid membrane improved the separation factor of O 2 /N 2 and O 2 /CO 2 , but reduced the permeation rate [7]. The gas permeation calculation also proved this point.…”

“…The error between the tested data and calculation value is small and the results are relatively credible. Gas separation performance showed that the hybrid membrane have good separation factor at relatively low pressure below 0.2 MPa, the gas transport in the membrane is mainly due to the surface diffusion and Knudsen diffusion [6][7]. When the pressure is above 0.2 MPa, the separation factor decreased with the pressure drop increase, the gas transport in the membrane is contributed to the Knudsen and Poiseuille diffusion.…”

“…The organic-inorganic hybrid layers were deposited on the porous alumina, in the between, an intermediate microporous alumina layer were formed beforehand. The detail about the preparation was published elsewhere [6][7]. In our case, the resistance of the porous substrate to gas were neglected due to the larger pore compared with the hybrid top layer.…”

“…16. From results of the experiments on the separation selectivity of the hybrid top membranes [6][7], the gas transport through the hybrid membrane is governed both by surface diffusion and Knudsen diffusion mechanisms; at lower pressure surface diffusion dominates, but at higher pressure Knudsen diffusion is controlled; the special affinities of O 2 and CO 2 molecules to the pore surface in hybrid membranes are almost the same, but much greater than that of N 2 . So for the permeation tests especially on top hybrid layer, in order to diminish the gas surface diffusion, nitrogen is used and relatively higher pressure conditions were chosen.…”