Characterization of Al- and Ti-modified MCM-41 using adsorption techniques

Influence of Aluminum Addition in the Framework of MCM-41 Mesoporous Molecular Sieve Synthesized by Non-Hydrothermal Method in an Alkali-Free System

“…In regard to the acid properties of the mesoporous samples (Table 2), the amount of desorbed NH 3 from pure siliceous MCM-41 exhibited a total acidity of one order of magnitude smaller than that obtained with Al-MCM-41(50) and Al-MCM-41(15) [33][34][35] . The reduced acidity of the pure siliceous MCM-41 may be attributed to the presence of Si-OH groups in its surface from adsorbed water molecules 26,[36][37][38] .…”

“…In Figure 5 is shown the FT-IR samples profiles as-synthesized (not calcined) and after calcined in synthetic air stream at 813 K, corresponding to siliceous pure MCM-41 and Al-containing samples like Al-MCM-41(50) and Al-MCM-41 (15). In as-synthesized samples were observed bands at 2921, 2852, 1477 and 719 cm -1 corresponding to the deformation vibration of the C-H bonds present in the CH 2 and CH 3 groups of the surfactant molecules, CTAB, used as pore template agent 25,26,35,39 . After calcination, those bands disappear completely, indicating that the CTAB molecules were completely removed from the pores of the molecular sieves.…”

“…In the after calcined samples, the broad band around 3438 cm -1 and the small one at 1630 cm -1 are attributed to OH -groups from adsorbed water molecules 36,31,35,37 . The adsorption bands noticed at 1224 and 1076 cm -1 correspond to external and internal asymmetric stretching vibrations of Si-O-Si bonds, respectively, and the band at 798 cm Other bands around 462 and 961 cm -1 are attributed to tetrahedral bending of Si-O bonds and stretching vibrations of the Si-OH bonds, respectively 17,26,35 .…”

“…The adsorption bands noticed at 1224 and 1076 cm -1 correspond to external and internal asymmetric stretching vibrations of Si-O-Si bonds, respectively, and the band at 798 cm Other bands around 462 and 961 cm -1 are attributed to tetrahedral bending of Si-O bonds and stretching vibrations of the Si-OH bonds, respectively 17,26,35 . Some authors suggest that the band around 961 cm -1 also correspond to the incorporation of heteroatoms into the framework of the mesoporous silica materials, Si-O-M + (where M = Al) 17,38 .…”

Studies of the structure and chemistry of SBA-15 organosilicas functionalized with amine, thiol, vinyl and phenyl groups

“…Possibility of introduction of different organic moieties into the framework as well as onto the surface makes OMSs very attractive for sensing devices, environmental applications and particularly, for catalytic and adsorption processes (Andersson et al 2004;Olkhovyk et al 2004;Rosenholm et al 2004;Gierszal et al 2005;Olkhovyk and Jaroniec 2005). Such organically modified materials are known as ordered mesoporous organosilicas (OMOs).…”