Systematic investigation of the pore structure and surface properties of SBA-15 by water vapor physisorption

• Systematic investigation of material property influences on water vapor sorption.
• A broad library of SBA-15 materials with varying properties was produced.
• The materials were investigated by water vapor sorption at 20 °C.
• Low aging temperature during synthesis is beneficial for higher uptake at low p/p0.
• Gentle template removal, i.e. by extraction, leads generally to a high uptake.

In order to establish a structure-property correlation in water vapor sorption, various sets of the ordered mesoporous silica SBA-15 with systematically varying properties were synthesized and characterized. General trends concerning the surface polarity, aging temperature during synthesis and micropore volume were observed. Calcining the materials with increasing temperatures of 300–800 °C decreases the performance in water vapor sorption which correlates mainly with the amount and type of silanol groups on the silica surface. Furthermore, the aging temperature during synthesis influences the water vapor sorption capacity of SBA-15 at low relative pressure. The best results in terms of an increased uptake of water over a broad range of relative pressure can be obtained for materials with high micropore volume and high surface polarity. They can be tailor-made by using a routine to remove the template, i.e., a combination of extraction with ethanol and subsequent calcination at 300 °C.

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