Synthesis and physicochemical properties of zeolites containing framework titanium

Dartt, C. B.; Khouw, C. B.; Li, H.-X.; Davis, Mark E.

doi:10.1016/0927-6513(94)00009-3

Cited by 48 publications

(29 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[1][2][3][4][5]7,8 However, recent work suggests that this band corresponds to a Si-O vibration in a Si-OR (R = H, tetraalkylammonium) group in siliceous materials (e.g., Al-beta and pure MCM-41 silica). 23,24 In our case, this band was also observed in all samples before and after calcination. Therefore, we exclude its appearance as evidence of the incorporation of Ti into the framework of mesoporous titanosilicates.…”

Section: Resultssupporting

confidence: 67%

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

Tang

Wen

Huang

et al. 2004

Israel Journal of Chemistry

View full text Add to dashboard Cite

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.

show abstract

Section: Resultssupporting

confidence: 67%

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

Tang

Wen

Huang

et al. 2004

Israel Journal of Chemistry

View full text Add to dashboard Cite

show abstract

“…band is a necessary but insufficient characterization of Ticontaining materials, 48 since even some non-Ti-containing Beta zeolites are also reported to have 960 cm −1 band. 43 We clearly see that intensity of the 960 cm −1 band is negligible for DZ-1 (Fig. 7a), but, in stark contrast, this band is strong for Ti-DZ-1 (Fig.…”

Section: Ftir Spectroscopic Characterizationmentioning

confidence: 99%

“…7b), which is very similar to what has been reported for Silicate-1 and TS-1. 43 Therefore, the presence of the 960 cm…”

Section: Ftir Spectroscopic Characterizationmentioning

confidence: 99%

Novel surfactant-free route to delaminated all-silica and titanosilicate zeolites derived from a layered borosilicate MWW precursor

et al. 2014

View full text Add to dashboard Cite

a Layered borosilicate zeolite precursor ERB-1P (Si/B = 11) is delaminated via simultaneous deboronation and SDA removal, to yield material DZ-1 consisting of silanol nests, using a simple aqueous Zn(NO 3 ) 2 treatment. Characterization of this synthesis process by PXRD shows loss of long-range order, and transmission electron microscopy (TEM) demonstrates transformation of rectilinear layers in the layered zeolite precursor to single and curved layers in the delaminated material. N 2 physisorption confirms the expected decrease of micropore volume and increase in external surface area for delaminated materials relative to their calcined 3D zeolite counterpart. Elemental analysis shows loss of B and absence of Zn in the delaminated material. Resonances corresponding to silanol nests are evident via 29Si solid-state NMR spectroscopy in DZ-1, which should be located within 12-MR pockets near the external surface. We have successfully utilized these nests as tetrahedral recognition sites for incorporation of Ti within an isolated framework coordination environment in material Ti-DZ-1. Diffuse-reflectance ultraviolet (DR-UV) spectroscopy of Ti-DZ-1 confirms isolated framework Ti sites, which are assigned to bands in the range of 210 nm-230 nm. Infrared spectra of Ti-DZ-1 consist of a distinct absorption band at 960 cm, which is absent in DZ-1 prior to Ti incorporation and has been previously correlated with the presence of framework Ti species. Infrared spectra after pyridine adsorption demonstrate bands consistent with Lewis-acid sites in the resulting Ti-substituted delaminated zeolite. The accessibility of these Lewis-acid sites is confirmed when using Ti-DZ-1 as a catalyst for cyclohexene epoxidation using tert-butyl hydroperoxide as the organic oxidant -a reaction for which both DZ-1 and TS-1 are inactive.

show abstract

“…From Table 2 it is seen that the ratio for the set I samples increases from 0.41 to 0.6 with the crystallization time, while that for set II samples is almost independent of the synthesis time and reaches 0.6 already after 3 h of crys tallization. However, there are publications in the lit erature that the band at 960 cm -1 can also be due to Si-O vibrations of silicate intraframework voids with out incorporation of titanium in the structure [14,15], a finding that does not allow a rigorous quantitative conclusion about the degree of inclusion of titanium.…”

Section: Chemical Compositionmentioning

confidence: 99%

Formation of active sites in titanium-containing zeolites with MFI structure in propylene epoxidation with hydrogen peroxide

et al. 2016

View full text Add to dashboard Cite

Propylene epoxidation with hydrogen peroxide on titanosilicates with different Si/Ti ratios and various states of titanium in the catalysts, prepared by hydrothermal crystallization according to two different procedures, has been investigated. It has been demonstrated that a change in the pH of the crystallizing gel leads to a change in the sequence of titanium insertion in the zeolite structure at a hydrothermal synthesis temperature of 170°C. It was shown that titanium incorporated in the zeolite framework in the tetrahedral positions is an active site in the epoxidation reaction, whereas titanium in the form of titanium dioxide leads to unproductive degradation of hydrogen peroxide.

show abstract

Synthesis and physicochemical properties of zeolites containing framework titanium

Cited by 48 publications

References 10 publications

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

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

Novel surfactant-free route to delaminated all-silica and titanosilicate zeolites derived from a layered borosilicate MWW precursor

Formation of active sites in titanium-containing zeolites with MFI structure in propylene epoxidation with hydrogen peroxide

Contact Info

Product

Resources

About