MgO-modified mesoporous silicas impregnated by potassium carbonate for carbon dioxide adsorption

Mesoporous adsorbents for carbon dioxide capture were prepared by introducing of magnesium oxide and potassium carbonate into SBA-15, SBA-16 silicas and MCM-48-like-silica. In order to avoid destruction of silica supports, a novel procedure based on the precipitation of magnesium acetate on the silica surface was developed. Subsequent in situ chemical conversion of magnesium acetate provided magnesium oxalate, while final magnesium oxide was formed by calcination. To introduce potassium carbonate, silica modified with MgO was impregnated with potassium oxalate followed by its conversion to carbonate. All prepared mesoporous adsorbents preserved characteristic features of mesoporous molecular sieve. The comparison of carbon dioxide isotherms obtained on prepared samples reveals that their adsorption properties are decisively influenced by the type of mesoporous structure. Modified sample of SBA-15 silica has shown the most steep adsorption isotherm and higher CO2 adsorption capacity than adsorption capacity of samples prepared from SBA-16 and MCM-48-ls silicas. (C) 2012 Elsevier Inc. All rights reserved.