Permeation properties of BTESE–TEOS organosilica membranes and application to O2/SO2 gas separation

• A novel strategy was proposed to control the pore size of organosilica membranes.
• The pore structure of silica networks was tuned by a BTESE–TEOS precursor.
• The hybrid silica membrane was effective for the selective O2/SO2 separation.
• Organosilica membranes showed good thermal stability and chemical resistance.
• The effective molecular size of SO2 permeates through a membrane was discussed.

In the present study, a BTESE–TEOS mixed precursor was proposed for control of the pore sizes of organosilica networks in organic–inorganic hybrid silica membranes. FT-IR spectrometry confirmed the formation of a partially cross-linked polysiloxane structure with hydrocarbon units in a BTESE–TEOS-derived silica network produced by the co-hydrolysis and condensation of BTESE with TEOS, which also showed an improved thermal stability. Single gas permeation measurements and normalized Knudsen-based permeance (NKP) established the order of the average membrane pore sizes as follows: BTESE>BTESE–TEOS>TEOS. The organosilica membranes derived from BTESE–TEOS exhibited a superior O2 permeance that was higher than 10−8 mol m−2 s−1 Pa−1 with an O2/SO2 selectivity of 7.3, which indicated that the pore size control in organosilica networks using BTESE–TEOS as a precursor was effective for selective O2/SO2 separation. Moreover, the effective molecular size of SO2 permeates through organosilica membranes was discussed.

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