Octa(aminophenyl)silsesquioxane fabrication on chlorofunctionalized mesoporous SBA-15 for CO2 adsorption

Chlorofunctionalized mesoporous SBA-15 was synthesized by a direct method, through one-step condensation of sodium silicate solution obtained from rice husk ash (RHA) and chloropropyltrimethoxysilane in presence of Pluronic 123 (surface directing agent). Octa(3-aminophenyl)octasilsesquioxane (OAPS) was grafted on chlorofunctionalized mesoporous silica SBA-15 and characterized by XRD, FTIR, BET and Si-29 MAS-NMR. CO2 adsorption/desorption profiles of OAPS grafted chlorofunctionalized SBA-15 (Cl-SBA-15/OAPS) at 25, 50 and 75 degrees C were obtained by TGA under atmospheric pressure. A maximum of 8 wt.% CO2 adsorption capacity (80 mg/g of adsorbent) was achieved over Cl-SBA-15/50% OAPS and it was also shown that the absorbent was recyclable, selective and thermally stable. Neat OAPS adsorbs almost no CO2 due to internally hydrogen-bonded amine. Cl-SBA-15/OAPS withstands high temperature (180 degrees C) significantly higher than the sorbent polyethyleneimine (PEI), which decomposes beyond 115 degrees C. Therefore, the use of rice husk ash (RHA) as silica source and high thermal stability of Cl-SBA-15/OAPS are advantageous for CO2 adsorption. Thus, grafting of octa(3-aminophenyl)silsesquioxanes on mesoporous SBA-15 broadens the applications of polyhedral oligomeric silsesquioxanes (POSS) compounds and verified to be a new candidate for CO2 capture. (C) 2010 Elsevier Inc. All rights reserved.