Novel Synthesis of Ordered MCM‐41 Titanosilicates with Very High Titanium Content via Ultrasound Radiation

Abstract

A novel synthetic strategy has been developed for the fabrication of mesostructured titanosilicate with very high titanium content. By the combination of ultrasound radiation and a separate hydrolysis procedure, highly ordered MCM-41 titanosilicates can be synthesized within 3 h from gels with Ti/Si ratios up to 1. The physicochemical properties of the materials were characterized by means of XRD, TEM, FT-IR, UV-Vis DRS, 29 Si MAS NMR, and liquid nitrogen adsorptiondesorption measurements. The results suggested that during crystallization, sonication re-dispersed and accelerated the condensation of inorganic species, and resulted in more condensed pore walls compared to those synthesized with the conventional methods. The presence of silica and ultrasound radiation remarkably suppressed the aggregation of titanium species, thus, at the medium titanium level, a relatively homogeneous dispersion of titanium within the MCM-41 framework was attained.

Acidity enhanced [Al]MCM-41 via ultrasonic irradiation for the Beckmann rearrangement of cyclohexanone oxime to ɛ-caprolactam

“…These properties are able to homogeneously disperse silica oligomers in the mixture for efficient fabrication of [Si]MCM-41 in small particle size and a higher condensation degree [48]. In the preparation of MCM-41 with high titanium content, ultrasonic irradiation promotes the re-dispersion and condensation of inorganic species, resulting in titanium homogeneously distributed into the MCM-41 framework [49]. Similarly, the ultrasonic irradiation assisted sol-gel method is promising to…”

Solid state NMR spectroscopy

“…141 29 Si MAS NMR spectra were able to determine the structure of highly-ordered MCM-41 titanosilicates, with Ti/Si ratios of up to 1. 142 1 H NMR data were reported for cubic e-ZrH 2 and non-stoichiometric tetragonal d-ZrH 2.3 . 143 1 H double-quantum solid-state NMR spectra were used to characterise the surface zirconium hydrides (RSiO) 3 Zr-H and (RSiO) 2 ZrH 2 .…”