Synthesis and Characterization of Titanosilicate with the Structure of Umbite

A zeolitic titanosilicate with the composition of K_2TiSi_3O_9·H_2O, a structural analogue of natural mineral umbite K_2ZrSi_3O_9·H_2O, was hydrothermally synthesized in the SiO_2-TiO_2-K_2O-H_2O system and characterized by means of powder X-ray diffraction, SEM, IR and thermal analysis. The effects of TiO_2/SiO_2 and OH -/SiO_2 ratios on the crystallization of the umbite were discussed. The influence of the organic additives on the morphology of the crystal was also investigated and the crystals with different shapes were obtained.

A novel synthesis process of ETS-4 titanosilicate using commercial anatase in the absence of fluoride ions

A novel synthesis process for ETS-4 titanosilicate using commercial anatase as the titanium source in the absence of fluoride ions was studied. Fluoride ions and traced ETS-4 seeds have important roles in forming ETS-4 structures. However, the method using ETS-4 seeds instead of fluoride ions to improve product purity and productivity is environment-friendly. ETS-4, ETS-4（NS）, and ETS-4（NaF） were respectively synthesized using traced ETS-4 seeds, without seeds, and with fluoride ions. The as-synthesized samples were identified by X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. Adsorption isotherms and adsorption heats of nitrogen and methane on the prepared ETS-4 were also measured. The results showed that ETS-4 samples could be prepared using anatase in the absence of fluoride ions, with good purity, comparable physicochemical properties, and excellent adsorption properties.

Recent Progresses in Titanosilicates

Titanosilicates, with tetrahedrally coordinated Ti4＋ ions in highly crystalline zeolite frameworks, are a class of unique heterogeneous catalysts useful for the liquid-phase selective oxidation reactions. The great success of green Ti-zeolites/H2O2 reaction system has aroused considerable scientific and industrial interests. The catalytic properties of titanosilicates relay on zeolite topologies, crystal morphology, the content and micro-environment of tetrahedral Ti4＋ ions. The ever-growing needs for the oxidation catalysts in processing bulky molecules in petrochemical and fine chemical industries have set off a new tide of developing novel titanosilicates with significantly improved cat- alytic performance than traditional ones. This mini review summarizes recent progresses in developing the titano- silicates with novel topology, morphology as well as chemically modified micro-environment.

Enhancement of Alkene Epoxidation Activity of Titanosilicates by Gas-Phase Ammonia Modification

Novel ammonia-treated titanosilicates have been prepared by heating the samples of Ti-MWW, TS-l and Ti-Beta under pure ammonia gas flow at 673 K for a period of time. The ammonia modification improved their catalytic performance in liquid-phase oxidations. Especially, the catalytic activities of ammonified Ti-MWW, N-Ti-MWW, were enhanced greatly in the epoxidation of 1-hexene with H2O2. The reason that the ammonia treat- ment played such an important role in post-modification of titanosilicate was investigated in details. In comparison to the parent Ti-MWW catalyst, N-Ti-MMW was more robust and produced less coke in oxidation reactions.

Controllable synthesis and photocatalytic activities of rod-shaped mesoporous titanosilicate composites with varied aspect ratios

Rod-shaped mesoporous titanosilicate composites （RMTSs） with controllable aspect ratios （ARs） were fabricated using cetyltrimethylammonium bromide （CTAB） and ammonium hydroxide （NH4OH） at a continuous stirring rate, resulting in ARs ranging from 1 to 5. Slowing the stirring rate or increasing the concentration of CTAB mainly impacted the length growth, whereas NH4OH affected the width growth. Photocatalytic activity studies revealed that the length of RMTSs played a more significant role than the width at lower ARs in their photocatalytic activity.

Synthesis of single crystal-like hierarchically mesoporous titanosilicate Ti-SBA-1

Hierarchically mesoporous titanosilicate Ti-SBA-1 was synthesized with organic mesomorphous complexes of polyelectrolyte（poly（acrylic acid）（PAA）） and cationic surfactant（hexadecyl pyridinium chloride（CPC）） as template, tetraethylsiloxane as silica source and titanium ethoxide as titanium source.By adjusting the amount of titanium ethoxide in the synthesis, a series of Ti-SBA-1 particles with different Si/Ti ratio（79–180） were prepared. After incorporation of Ti into the silica framework the wellordered cubic Pm3n mesostructure remained, as well as the morphology, particle size. UV–vis DR spectra of the Ti-SBA-1 materials indicated that incorporated titanium species existed in a highly dispersed state and exhibited tetrahedral and octahedral coordination in the silica framework.

A Simple Approach for Synthesis of TAPO-11 Molecular Sieve with Controllable Space Group

A TAPO-11 molecular sieve with the space group lcm2 was synthesized successfully. The samples with different space group were controlled simply only by adjusting the crystallization temperature （CT） in the hydrothermal system. In the system of gel with a molar composition of 0.7R- xTiO2： P2O5： Al2O3： 30H2O, where x is 0.01-0.10 and the R is a mixture of di-n-propylamine and diisopropylamine as templates. When CT was between 150-160℃, the calcined sample showed the space group of Icm^2, while it showed Pna21 at CT larger than 190℃. The characterizations of UV-Vis and FT-IR confirmed that Ti was incorporated into the AEL framework successfully.

Theoretical research into low-voltage Na_(2)TiSiO_(5)anode for lithium-ion battery

Na_(2)TiSiO_(5)(NTSO)is a low-cost Li-ion battery anode with great application potential,such as the tetragonal NTSO(T-NTSO)with a high capacity and a low voltage.In addition to the tetragonal structure,NTSO has two other polymorphs.However,the basic understanding of the structure,ion insertion and transport mechanisms of these new materials is still lacking.Herein,we present a combined experimental and computational investigation of the tetragonal and orthorhombic NTSO to reveal the intrinsic mechanism leading to the superior electrochemical performance of T-NTSO.We determined that the insertion site with a flexible Ti^(4+)/Ti^(3+)redox pair is critical for Li+insertion stability.The large number of such flexible sites in the T-NTSO results in a higher capacity and higher ionic conductivity than those of orthorhombic polymorph.The understanding of intrinsic properties will accelerate the development and utilization of titanosilicates as the next generation low-voltage anode of Li-ion battery.

Post-synthesis and catalytic performance of FER type sub-zeolite Ti-ECNU-8

A titanosilicate Ti-ECNU-8 with a FER type sub-zeolite structure was developed by pots-synthesis and applied to the epoxdiation of alkenes with hydrogen peroxide.A controlled acid treatment on the pure silica layered precursor PLS-3 of FER topology gave rise to a sub-zeolite ECNU-8.Composed of a collection of FER sheets without an ordered stacking manner along layer related[100]direction,the structure of ECNU-8 was constructed by a reorientation of interlayer hydrogen bond moieties caused by partial removal of interlayer organic structure directing agent.ECNU-8 possessed an external surface area enlarged by ca.30% in comparison to corresponding three-dimensional FER zeolite.Through a solid-gas reaction with TiCl4 vapor,tetrahedral Ti active sites were introduced into the framework.The resultant Ti-ECNU-8 retained the structural properties of ECNU-8,and exhibited an excellent catalytic performance for the epoxidation of cycloalkenes owing to the accessible Ti sites located in open reaction space.