The influence of Ti-loading on the acid behavior and on the catalytic efficiency of mesoporous Ti-MCM-41 molecular sieves

Mesoporous Silicates with Spherical Morphology Modified with Vanadium Highly Active in Oxidation of Cyclohexene with H2O2

“…The objective is to take advantage of the large pore size of these materials, which will facilitate the flow of reactant and product molecules in and out of the pore system. Large pore systems are needed for shape-selective conversions of bulky molecules such as those increasingly encountered in the refining industry during the upgrading of heavy fractions, oxidation of heavy organics from industrial wastewaters, and in the manufacture of fine chemicals and pharmaceuticals [4][5][6].…”

Selectively Obtaining ε-Caprolactam from Cyclohexanone Oxime Over Al-MCM-41 Catalysts

“…All our samples show bands at 1597 and 1447 cm -1 assigned to pyridine bonded to silanol groups whose hydroxyls are not capable to protonate pyridine [3,24,25,[27][28][29][30]. However, some contribution (overlapping these bands) from pyridine bonded to Lewis acid sites on the Al-M samples, due mainly to the presence of extra-framework aluminum oxide, could be considered [3,24,25,27,28,31,32]. Thus, the fact that, upon evacuation at 100°C, the integrated absorbance of the bands at 1597 and 1447 cm -1 is slightly higher for the Al-M samples than for the purely siliceous material would be giving account for these Lewis sites capable to retain the pyridine until 100°C.…”

Microwave preparation of Ti-containing mesoporous materials. Application as catalysts for transesterification

“…The samples show two bands at around 1596 cm −1 and 1445 cm −1 , respectively. The band at 1596 cm −1 can be attributed to hydrogen-bonded pyridine [45]. The band at 1445 cm −1 corresponds to vibration of pyridine chemisorbed on the Lewis acid sites [46].…”