An investigation of the acid properties of UL-ZSM-5 by FTIR of adsorbed 2,6-ditertbutylpyridine and aromatic transalkylation test reaction

Effect of aluminium incorporation by the “pH-adjusting” method on the structural, acidic and catalytic properties of mesoporous SBA-15

“…However, because the progressive incorporation of aluminium results in an increased intensity of the broad band at 3700-3400 cm À1 and consistent with the gradual increase in the content of Al VI detected by 27 Al MAS NMR, the major contribution at this band may come from Al-OH groups. It must be noted that no IR bands at $3610 cm À1 typical of bridging hydroxyl groups SiO(H)Al (i.e., Brönsted acid sites in zeolites) were detected in the direct FTIR spectra of dehydrated samples, anticipating that the majority of Brönsted acid sites in Al-SBA-15 materials prepared by ''pH-adjusting'' are of different nature than those found in zeolites or semicrystalline zeolitic-mesoporous aluminosilicates and very similar to those than we previously observed in mesostructured amorphous aluminosilicates with wormhole-like pore structure [48].…”

“…7B, positive bands appear and are ascribed to different contributions of Brönsted and Lewis acid sites, as reported in literature [29,[46][47][48]. Hence, the positive bands at 1639 and 1549 cm À1 are due to pyridinium ion (PyH + ) and characterize the Brönsted acid sites (BAS), whereas the main positive bands at 1623 and 1455 cm À1 are due to pyridine coordinated on Lewis acid sites (LAS) with strong acid strength.…”

Effect of surface modification with silica on the structure and activity of Pt/ZSM-22@SiO2 catalysts in hydrodeoxygenation of methyl palmitate

“…We chose propionaldehyde as the probe molecule to investigate the effect of external acid sites on the adsorption of aldehyde intermediates. IR spectra showed negative peaks at 3746 and 3607 cm À1 , which are attributed to SiAOH and SiAOHAAl, respectively [41,42]. They appeared negative because the hydroxyl groups were consumed by interaction with the propionaldehyde.…”

Gold Nanoclusters Confined in a Supercage of Y Zeolite for Aerobic Oxidation of HMF under Mild Conditions

“…It has been evidenced that pyridine can easily penetrate through the aperture of the supercage and completely poison the ÀOH groups of the supercage, whereas 2, 6-ditert-butylpyridne can only block the external surface ÀOH groups because it is too large to penetrate through the micropore of Y zeolite. [46][47][48][49][50][51][52][53][54] Poisoning experiments with pyridine and DTBPy were carried out to further confirm the influence of the À OH groups of the supercage. By this method, the location of effective À OH groups can be distinguished.…”