The surface acidity of mesoporous silicoaluminophosphates: A FTIR study

Benzene co-reaction with methanol and dimethyl ether over zeolite and zeotype catalysts: Evidence of parallel reaction paths to toluene and diphenylmethane

“…Traditionally, it has been assumed that methanol dehydrates rapidly to DME over zeolitic materials under MTH conditions [34,47], and therefore the two oxygenates are lumped together and attributed to the weakly acidic P-OH groups in zeotype materials [43,193], while no references to the activity of Si-OH groups in zeolites towards the mentioned reaction have been described in the literature. Indeed, the acid strength of P-OH is intermediate between that of strong Brønsted sites in zeolites and zeotypes, and that of weak silanols, Si-OH [249].…”

Recent Advances in the Preparation and Application of Mesoporous Aluminophosphate-Based Materials

“…The acidity of mesoporous SAPO materials was studied using Fourier transform infrared (FTIR) spectroscopy coupled with adsorbed CO and NH 3 . Al-OH, P-OH and Si-OH groups are found on the surface of these porous solids, however, the overall acidity was found to be weaker than the Bronsted acid sites found on zeolites [36,37].…”

A Step toward Control of the Surface Structure of Biomimetic Hydroxyapatite Nanoparticles: Effect of Carboxylates on the {010} P-Rich/Ca-Rich Facets Ratio

“…In addition to calcium cations, surface P–OH can also act as adsorption centers for CO, producing an IR band at ca. 2170 cm –1 . Indeed, a weak band at ca.…”

“…2170 cm −1 . 69 Indeed, a weak band at ca. 3680 cm −1 monitored the presence of such P−OH groups at the surface of both HA-1 and HA-2 (curves f in the insets of panel C).…”

“…As a consequence of this interaction, the νOH signal due to P−OH was downshifted to 3590 cm −1 (Figure S9 in the Supporting Information), with a Δν = 90 cm −1 probing that these groups should exhibit a weak acidity. 29 Nevertheless, an evaluation based on literature data 69 of the ratio between the integrated intensity of the νOH band of unperturbed P−OH and that expected for the stretching band of CO adsorbed on them suggested that the latter should contribute for a negligible part of the νCO signal observed when dosing the probe molecules on both HA-1 and HA-2 Spectra are reported after subtraction of the spectrum of the material before CO adsorption. Panel C: spectra at maximum CO coverage of HA-1 (blue curve) and HA-2 (red curve), the same as curves "a" in both A and B panels.…”