Mesoporous isocyanurate-containing organosilica–alumina composites and their thermal treatment in nitrogen for carbon dioxide sorption at elevated temperatures

Abstract

Composite mesostructures consisting of organosilica with isocyanurate bridging groups and alumina have been synthesized using evaporation-induced self-assembly (EISA) in the presence of a triblock copolymer, Pluronic P123, in absolute ethanol solution. These mesostructures were prepared using aluminum isopropoxide and aluminum nitrate nonahydrate as alumina precursors and tris[3-(trimethoxysilyl)propyl]isocyanurate (ICS). The triblock copolymer was removed by extraction with 95% ethanol solution followed by additional thermal treatment of the extracted sample at 300 °C in flowing nitrogen; this process assured a complete removal of the polymeric template without degradation of the ICS bridging groups. The use of aluminum nitrate nonahydrate and a N-containing ICS precursor with a small amount of 3-aminopropyltriethoxysilane (AP) led to the hybrid materials with well-developed porosity and high specific surface area (200–450 m² g⁻¹). A controlled heating of these materials in nitrogen resulted in N-doped alumina–silica mesostructures showing high affinity towards CO₂ at elevated temperatures. The use of inexpensive aluminum nitrate instead of aluminum alkoxides in the EISA synthesis had a significant impact on the pore structure, surface area and adsorption properties of the resulting composite materials.