Dynamic adsorption of volatile organic compounds on organofunctionalized SBA-15 materials

Organofunctionalized SBA-15 materials, including methyl-SBA-15 and phenyl-SBA-15, were synthesized by co-condensation method of tetraethyl orthosilicate (TEOS) and organosilanes such as methyltriethoxysilane (MTES) and phenyltriethoxysilane (PTES) under acidic conditions, and used as adsorbents for the VOCs abatement. These adsorbents were characterized by powder X-ray diffraction, N-2 adsorption/desorption isotherms and FT-IR spectroscopy techniques. The results indicated that all samples showed a highly ordered two dimensional hexagonal mesostructure and the organic groups were chemically incorporated into the pore surface of SBA-15 substrate. The dynamic adsorption behaviors of single VOC component (benzene) on methyl-SBA-15 and phenyl-SBA-15 adsorbents were evaluated via breakthrough curves. It was found that the adsorbent with the PTES/TEOS molar ratio at 1:10 had the largest capacity (0.650mmol/g(adsorbent)) in the single component dynamic adsorption and the phenyl groups had stronger attractive interaction with benzene than the methyl groups. A mathematical model for the organofunctionalized SBA-15 adsorbents was successfully employed to describe the adsorption breakthrough curves of benzene. For binary component adsorption, the phenyl-SBA-15 exhibited the pi-relectrons effect between the adsorbate and the adsorbent, as the phenyl-SBA-15 materials preferred to adsorb benzene to cyclohexane. The larger dynamic VOCs capacity of the organofunctionalized SBA-15 materials was attributed to the synergetic effect between the amount of organic groups and the total pore volume. (C) 2008 Elsevier B.V. All rights reserved.