Melanoma

PMo or PW heteropoly acids supported on MCM-41 silica nanoparticles: Characterisation and FT-IR study of the adsorption of 2-butanol

“…6A and B) in agreement with results previously reported by other authors [47,48]. These bands are assigned to adsorption on weak Lewis-type acid sites or to weakly hydrogen-bonded pyridine.…”

“…9a) show bands at 3740 and 3550 (shoulder) cm À1 corresponding to the n(OH) vibration mode of the silanol groups (SiOH) inside the channels without and with strong hydrogen-bonding interaction, respectively [47,48]. The intense and broad band below 1350 cm À1 is assigned to Si-O stretching modes.…”

Catalyst Design by NH4OH Treatment of USY Zeolite

“…As H-USY(40) is obtained via severe dealumination, a signifi cant amount of lattice terminating silanol groups is present at 3745 cm −1 . [ 45 ] As a result of NH 4 OH treatment, the silanol intensity increases and a broader OH band is formed, pointing to the presence of hydrogen bound hydroxyls in an amorphous silica phase. [ 46 ] The zeolite sample appears to be predominantly amorphous after a long NH 4 OH treatment (e.g., 16 h for H-USY-D) from the point of view of XRD, IR and MAS NMR.…”

Ultrastable Mesoporous Aluminosilicates by Grafting Routes

“…[4,6] Catalytic cracking to benzene and propene was the main reaction with only trace amounts of a-methylstyrene (product of dehydrogenation over Lewis acid sites) being formed, indicating that the active sites are Brùnsted acid sites. [13] The catalytic data (Table 1) show that the grafted materials possess considerable catalytic activity which dramatically increases on refluxing (see also Figure 4 in the Supporting Information). The increase in activity is in line with the changes in acid content, which indicates that refluxing results in an increase in Brùnsted rather than Lewis acid sites; this was indeed confirmed by monitoring adsorbed pyridine using Fourier transform infrared (FT-IR) spectroscopy, which can distinguish between Brùnsted and Lewis acid sites.…”