Titanium Silicate Research Articles

Controlled migration of oleic acid amide through adsorption on TS-1 zeolite for long-lasting anti-adhesive rubber composites

The adhesion of materials on the surface can affect the appearance, durability, and performance stability of rubber composites. Incorporating anti-adhesive additives into composites is an effective strategy to improve anti-adhesive properties, as these additives migrate to the surface to form an anti-adhesive layer. However, excessive migration rates can result in poor durability of the anti-adhesive layer and significant powder adhesion on the surface. This study prepared titanium silicate zeolite adsorbed with acid amide composite filler (OAA@TS-1) by adsorbing OAA onto the active sites of TS-1, which was then incorporated into natural rubber (NR). The adsorption effect reduces the migration rate of OAA within the rubber composite, allowing more OAA to remain in the matrix. Additionally, the adsorption is reversible, and the adsorbed OAA can overcome the adsorption through molecular thermal motion, which can migrate to the surface. After the anti-adhesive layer is worn, OAA can persistently migrate outward, effectively repairing the layer and enhancing the durability of the anti-adhesive properties. In comparison to rubber composites filled solely with OAA, the OAA@(TS-1) filled rubber composite exhibits a remarkable reduction of 55% in the amount of adherent powder on the composite surface and a 24% decrease in the coefficient of friction after three friction cycles. After slicing and leaving for 3 days, the contact angle increases by 18%. The long-lasting anti-adhesive rubber composite developed in this study demonstrates significant application potential in areas such as material conveyance and power transmission.

Elaboration and Characterization of Different Zirconium Modified ETS Photocatalysts for the Degradation of Crystal Violet and Methylene Blue.

In this study, Zirconium-modified Engelhard Titanium Silicate 4 (Na-K-ETS-4/xZr) catalysts were synthesized and evaluated for their photocatalytic efficiency in degrading crystal violet (CV) and methylene blue (MB) in aqueous solutions. The catalysts were characterized using XRD, FTIR, SEM, WDXRF, and nitrogen adsorption/desorption isotherms. The results confirmed the successful incorporation of Zr into the ETS-4 framework, with the highest Zr content reaching 9.2 wt %. The photocatalytic performance under visible light irradiation was studied at varying pH levels. The Na-K-ETS-4/6.3Zr catalyst exhibited the highest photodegradation efficiency for CV (76.6 %), while Na-K-ETS-4/8.9Zr achieved 86.6 % efficiency for MB. A combination of Engelhard Titanium Silicate 10, Na-K-ETS-10/6.3Zr and Na-K-ETS-4/8.9Zr significantly enhanced dye degradation, achieving up to 96.5 % efficiency for MB. Kinetic studies indicated that the degradation process follows a non-linear pseudo-first-order model. The catalysts also demonstrated excellent reusability, with minimal efficiency loss after five cycles, and full recovery after an ethanol wash. These findings suggest that Na-K-ETS-4/xZr is a promising candidate for environmental water treatment applications due to its efficient photodegradation performance and stability.

Preparation and oxidative desulfurization performances of modified SBA-15 supported polyacid metal oxolates

In this study, eight composite catalysts were prepared by loading (CTAB)3H3[PW9V3O40] (active components) onto amino-functionalized mesoporous titanium silicate Ti-SBA-15(supports). In order to study the effects of different Ti contents and different active components on the catalytic performances of the catalysts, 30 %(CTAB)3H3[PW9V3O40]/NH2–Ti-SBA-X (X = 0, 25, 50, 75, 100) and X%(CTAB)3H3[PW9V3O40]/NH2–Ti-SBA-50 (X = 20, 40, 50) were obtained and characterized. The oxidative desulfurization performances of the composite catalysts were explored. It was found that catalyst 40 %(CTAB)3H3[PW9V3O40]/NH2–Ti-SBA-50 exhibits the optimal oxidative desulfurization performance. This is because the incorporation of SBA-15 with an appropriate amount of Ti (n(Si)/n(Ti) = 50) can improve the acidity and stability of mesoporous silica. The successful substitution of CTAB (n(CTAB)/n(H6PW9V3O40) = 3) in the active component can reduce the mass transfer resistance and speed up the reaction rate. 3-Aminopropyltriethyl silane (APTES) acts as a silane coupling agent to graft amino groups onto mesoporous molecular sieve SBA-15, which can enhance the interaction between heteropolyacids and carriers. Under the synergistic effect of the active component and the support, the total removal rate of the optimal catalyst with a total concentration of 1000 ppm sulfur compounds in the simulated fuel was 94.44 %. After four cycles, the total desulfurization rate of the catalyst can reach 91.28 %.

Titanium Silicate‐1 Coupled with Sn and Er as Effective Catalysts for the Production of Lactic Acid from Saccharides

AbstractBiomass‐based saccharide valorization to produce lactic acid (LaA) via chemocatalysis has emerged as a promising approach to meet the substantial demand of the global LaA market, whereas the manufacture of prominent heterogeneous catalyst is still challenging. Herein, we fabricate a series of heterogeneous rare earth catalysts and indicate that Er supported onto titanium silicate‐1 (TS‐1) exhibits better activity than other rare earth catalysts for glucose transformation towards LaA. Remarkably, coupling Sn with Er onto TS‐1 enabled the sharp increment of LaA yield, and 3Sn15Er/TS‐1 catalyst outperformed other heterogeneous rare earth catalysts as reported to date, giving as high as 82.2% and 76.2% yields of LaA from sorbose and glucose, respectively. The catalyst characterization demonstrated the coexistence of Er2O3 and Sn2Er2O7 on 3Sn15Er/TS‐1 catalyst, both of which contributed to LaA production. Sn doping favored the formation of active particles in smaller size and increased the Lewis acidic sites when compared to single 15Er/TS‐1, thereby promoting the isomerization and retro‐aldol reaction of glucose to C3 intermediates. 3Sn15Er/TS‐1 catalyst also showed universal activity for diverse biomass‐based saccharides. This work might give useful insights to explore heterogeneous rare earth catalysts with superior activity in biomass valorization.

Epoxidation at Isolated Titanium Site Modeled by Ti‐Siloxy‐Polyoxometalates Built on [α–A–XW9O34]n− and [α–B–YW9O33]9−: Comparative Study of Their Hydrolytic Stability

AbstractThis report investigates the structural differences in a series of titanium complexes constructed from silanol functionalized polyoxometalate (SiloxPOMs) derivatives, designed to create a constrained coordination site for titanium (IV) cations, namely (THA)3[PW9O34(tBuSiO)3Ti(OiPr)] and (THA)3[SbW9O33(tBuSiO)3Ti(OiPr)]. The complexes serve as structural and functional models for titanium silicates, facilitating the epoxidation of allylic alcohols and alkenes by aqueous hydrogen peroxide solutions. The different activity and selectivity observed between the two derivatives are attributed to variations in the polyoxotungstic platform used, A‐type–[XW9O34]n− versus B‐type –[YW9O33]3−. A combined experimental and theoretical investigation highlights the influence of these structural differences on water interaction and hydrolytic stability, with A‐type structures proving more susceptible to hydrolysis. In addition, the study also delves into the nuclearity of the active sites, a monomeric titanium (IV)‐hydroperoxide [Ti]–(OOH) active species evidenced by diffusion NMR spectroscopy, and the influence of the presence of water on catalytic performance in epoxidation reaction, thus shedding light on the relationship between catalyst stability, intermediates formed and reaction pathway. The study finally demonstrates the suitability of B‐type SiloxPOM derivatives as models for titanium silicates, offering insights into their stability and catalytic activity for epoxidation reactions.

In English

Purifying aqueous solutions from radioactive contamination is an extremely relevant scientific topic today. Many organic and inorganic adsorbents can be recommended for the adsorption of heavy metal ions and radionuclides from aqueous solutions, or as carriers for storage and disposal of radioactive waste. Since radionuclides are sources of ionizing radiation, the radiation resistance of the adsorbent is an important characteristic. These studies aim to investigate the titanium silicate behavior and its adsorption properties' changes or their invariability in the field of intense β-radiation. Experimental techniques describe the synthesis of titanium silicate adsorbent by sol-gel method and the study of its adsorption capacity toward Ba2+ cations. The adsorption of Ba2+ cations was investigated under batch conditions with neutral pH of the solution. Initial and residual concentrations of Ba2+ cations were controlled by direct complexometric titration with Na-EDTA with Eriochrom Black T as an indicator. The study of the radiation resistance of the adsorbent to high-energy β-radiation was performed using a 90Sr-90Y β- - source “Sirius” installed in the Microtron Laboratory of the Uzhhorod National University. The distance from the source to the adsorbent samples was 20 cm. The flux of electrons at this distance was 108 el/cm2‧per second. The maximum energy of beta particles was 0.456 MeV for 90Sr and 2.28 MeV for 90Y. The maximum duration of exposure was 21 days, which corresponds to 1310 Gy. Raman spectroscopy of irradiated and nonirradiated samples of TiSi was performed using a Raman spectrometer XploRA PLUS installed in the Center for Collective Use of Scientific Equipment “Laboratory of Experimental and Applied Physics” of Uzhhorod National University. Results consist of kinetic of Ba2+ adsorption by titanium silicate and irradiated titanium silicate; isotherm of Ba2+ adsorption and Raman spectrum of nonirradiated, irradiated titanium silicate (TiSi) and TiSi after Ba2+ adsorption. Results showed that the value of the maximal adsorption was 140.5±9.2 mg/g (6.55 %) under a confidence level of 95 %. The adsorption values of barium ions by irradiated and non-irradiated titanium silicate coincide. This indicates that the adsorption properties of this adsorbent do not change under the influence of such a radiation dose. The Raman spectra of irradiated and non-irradiated titanium silicate coincide, while they do not identify free radicals, or ionic formations, which would indicate a change in the properties of the adsorbent under the influence of beta radiation. It can be argued that this adsorbent is radiation-resistant to beta-radioactivity, with a radiation dose of 1310 Gy. The main conclusion of the present work is that the studied sample of titanium silicate is radiation-resistant. It can withstand a radiation dose of 1310 Gy without changing its adsorption properties. Titanium silicate can be used for the adsorption of strontium radionuclides, it can be a carrier for the disposal of radioactive waste.

Engineering surface framework TiO6 single sites for unprecedented deep oxidative desulfurization.

Catalytic oxidative desulfurization (ODS) using titanium silicate catalysts has emerged as an efficient technique for the complete removal of organosulfur compounds from automotive fuels. However, the precise control of highly accessible and stable-framework Ti active sites remains highly challenging. Here we reveal for the first time by using density functional theory calculations that framework hexa-coordinated Ti (TiO6) species of mesoporous titanium silicates are the most active sites for ODS and lead to a lower-energy pathway of ODS. A novel method to achieve highly accessible and homogeneously distributed framework TiO6 active single sites at the mesoporous surface has been developed. Such surface framework TiO6 species exhibit an exceptional ODS performance. A removal of 920ppm of benzothiophene is achieved at 60°C in 60min, which is 1.67 times that of the best catalyst reported so far. For bulky molecules such as 4,6-dimethyldibenzothiophene (DMDBT), it takes only 3min to remove 500ppm of DMDBT at 60°C with our catalyst, which is five times faster than that with the current best catalyst. Such a catalyst can be easily upscaled and could be used for concrete industrial application in the ODS of bulky organosulfur compounds with minimized energy consumption and high reaction efficiency.

Dual effect of organic/inorganic artificial protective layer to construct high-performance zinc metal anode

Owing to their high specific capacity, low cost, environmental friendliness and safety, aqueous zinc ion batteries (AZIBs) have been one of the most popular battery systems. Nevertheless, dendrite growth, corrosion, hydrogen evolution and passivation on the anode side can seriously affect the lifetime of AZIBs. In view of this, this work constructs a protective layer compounded from inorganic (titanium silicate molecular sieve, TS) and organic (polyacrylonitrile, PAN) materials to realize the high-performance and dendrite-free zinc anode (Zn@PAN-TS). The cyano group in PAN has a coordination effect with zinc ions, which facilitates the transport of zinc ions. The porous TS can regulate the zinc ion flux through ion-confinement effect. Thus, the PAN-TS composite protective layer provides fast and orderly ion transport channels that modulate the uniform deposition of zinc through dual effect. Moreover, the experimental results show that the Zn@PAN-TS 50:1 anode has the best electrochemical performance. The corresponding MnO2 full cell maintained a high discharge capacity of 217.2 mAh·g−1 with a high retention rate of 81.1 % after 500 cycles at 0.3 A·g−1. This strategy offers fresh insight into constructing multifunctional hybrid interface for dendrite-free AZIBs.

Design of Novel Photoactive Modified Titanium Silicalites and Their Application for Venlafaxine Degradation under Simulated Solar Irradiation

Titanium silicalites (TS) are well‐known materials for their use in industrial oxidation reactions, and although they are used as photocatalysts, their activity is limited. Therefore, numerous synthetic strategies are investigated to improve their photocatalytic activity. Herein, three series of modified titanium silicalites are synthesized using three different organotriethoxysilanes at different molar percentages with the aim of modifying the structure of the zeolite, both at a porous and chemical level, to obtain materials with high photocatalytic activity. The study of their morphological, textural, chemical, and UV–vis light absorption properties through various characterization techniques has allowed the selection of the best candidates to test their photoactivity in the degradation of venlafaxine, an antidepressant drug that persists as a contaminant in wastewater and has serious neurotoxic effects. Materials synthesized using a 5% molar percentage of RTEOS and 10% of PhTEOS (Ph = phenyl) are able to degrade venlafaxine, whereas the reference material does not show any photocatalytic activity. These results lead the way to use this synthetic strategy to develop titanium silicates and optimize their photocatalytic activity in degradation reactions of different pollutants.

Photodegradation of Methylene Blue and Crystal Violet by Zr-Modified Engelhard Titanium Silicate 10

The present work focuses on the removal of dyes from polluted water, and, more precisely, the targets are crystal violet (CV) and methylene blue (MB). For this purpose, a series of Zr-modified catalysts based on microporous Engelhard Titanium Silicate 10 (ETS-10) were developed and synthesized. Aiming at improvement in the photodegradation efficiency and stability of ETS-10, Zr centers replacing part of Ti ones were introduced during the synthesis procedure. The obtained Na-K-ETS-10/xZr catalysts were characterized by X-ray powder diffraction (XRD), wavelength dispersive X-ray fluorescence (WDXRF), N2 physisorption and Fourier transform infrared spectroscopy (FTIR). The photocatalytic properties of Na-K-ETS-10/xZr- (x = 5, 10, 15 and 20 wt% Zr) catalysts were studied in terms of water purification from crystal violet and methylene blue. The Na-K-ETS-10/xZr wt% x = 6 catalyst appeared to be the most efficient in the photodegradation of CV and MB, removing nearly 100% of the dyes. Kinetic studies showed that the removal of CV and MB is a rapid process and one, which obeys the non-linear pseudo-second-order model.

Two Rinkite-Group (Seidozerite-Supergroup) Minerals: Nacareniobsite-(Y), a New Mineral from the Darai-Pioz Alkaline Massif, Tajikistan, and Crystal-Structure Refinement of Nacareniobsite-(Ce)

Abstract Nacareniobsite-(Y), ideally Na3Ca3YNb(Si2O7)2OF3, is a new rinkite-group (seidozerite-supergroup) TS-block mineral from the Darai-Pioz alkaline massif, Tien-Shan mountains, Tajikistan. The mineral is of hydrothermal origin. It occurs as prismatic crystals up to 1 mm long and 0.1 mm thick embedded in an aggregate of coarse-grained reedmergnerite. Associated minerals are reedmergnerite, leucophanite, nordite-(Ce), microcline, zeravshanite, polylithionite, kentbrooksite, yusupovite, fluornatropyrochlore, and quartz. Crystals are pale yellow, transparent, with a vitreous to translucent luster. Nacareniobsite-(Y) has a white streak, uneven to conchoidal fracture, and does not fluoresce under cathode or ultraviolet light. Cleavage is {100} very good, no parting was observed, Mohs hardness is 5, and it is brittle, Dmeas. = 3.49(2) g/cm3, Dcalc. = 3.515 g/cm3. It is biaxial (+) with refractive indices (λ = 590 nm) α = 1.662(2), β = 1.668(2), γ = 1.690(2); 2Vcalc. = 56°. It is nonpleochroic. Nacareniobsite-(Y) is monoclinic, space group P21/c, a = 7.4069(15), b = 5.6540(11), c = 18.787(4) Å, β = 101.36(3)°, V = 771.3(3) Å3. The six strongest reflections in the X-ray powder diffraction data [d(Å), I, (h k l)] are: 3.068, 100, (0 0 6, 1 2, 2 1 0); 2.944, 45, (2 1 1, 1 3); 2.707, 32, (0 2 2, 0 1 6); 5.44, 31, (0 1 1); 1.853, 29, ( 0 2, 2 1 7, 1 9); 3.59, 26, (1 0 4, 0 1 4). The empirical formula calculated on the basis of 18 (O + F) is Na2.82Ca3.06Sr0.14[Y0.37(Nd0.16Ce0.15Dy0.08Gd0.06Sm0.05La0.04Tb0.02Ho0.02Lu0.02Pr0.01Eu0.01Tm0.01Er0.01Yb0.01)Σ0.65]Σ1.02(Nb0.63Ti0.38)Σ1.01(Si4.00O14)O1.00F3.00, Z = 2. The ideal formula is Na3Ca3YNb(Si2O7)2OF3. The crystal structure was refined on a twinned crystal to R1 = 3.50% on the basis of 1788 unique reflections (Fo > 4σFo). It is a framework of TS (Titanium-Silicate) blocks where the TS block consists of HOH sheets (H = heteropolyhedral, O = octahedral) parallel to (100). In the O sheet, the Nb-dominant [6]MO(1) site is ideally occupied by one Nb apfu. The [8]MO(2) and [6]MO(3) sites are ideally occupied by one Na and two Na apfu, respectively. The H sheet contains two unique sites: the [7]MH site, ideally (CaY), is occupied by Ca1.23(Y0.37Ln0.40)Σ0.77, with <MH–φ> = 2.424 Å, and the [7]AP site, ideally Ca2, is occupied by Ca1.61Sr0.14Ln0.25, with <AP–φ> = 2.469 Å. The AP+ MH sites ideally give Ca2(CaY) apfu. The MH and AP polyhedra and Si2O7 groups constitute the H sheet. Linkages of the H and O sheets via common vertices of the MH and AP polyhedra, and Si2O7 groups with MO(1–3) polyhedra, results in the TS block. The TS block in nacareniobsite-(Y) exhibits linkage 1 and has a stereochemistry typical for the rinkite group (Ti + Nb + Zr = 1 apfu) of the seidozerite supergroup. For nacareniobsite-(Y), the ideal structural formula of the form AP2MH2MO4(Si2O7)2(XOM)2(XOA)2 is Ca2(CaY)Na3Nb(Si2O7)2(OF)F2. The mineral is named nacareniobsite-(Y), as it is structurally identical to nacareniobsite-(Ce), ideally Na3Ca3CeNb(Si2O7)2OF3, with Y as the dominant REE. The crystal structure of nacareniobsite-(Ce), has been refined to R1 = 6.80% for 1421 unique (Fo > 4σFo) reflections: space group P21/c, a = 7.4684(15), b = 5.6891(11), c = 18.891(4) Å, β = 101.37(3)°, V = 786.9(3) Å3, Z = 2, Dcalc. = 3.539 g/cm3. The composition of the MH and AP sites in the H sheet has been reassigned as follows: the [7]MH site is occupied by Ca1.28(Ln0.68Y0.04)Σ0.72 where Ce is the dominant lanthanoid, ideally (CaCe) apfu, <MH–φ> = 2.458 Å, and the [7]AP site is occupied by (Ca1.44Na0.09Sr0.04)Σ1.57Ln0.43, ideally Ca2apfu, <AP–φ> = 2.48 Å. The AP+ MH sites ideally give Ca2(CaCe) apfu [cf. (Ca,REE)2(Ca,REE)2apfu, Sokolova & Hawthorne (2008)]. For nacareniobsite-(Ce), the revised ideal structural formula of the form AP2MH2MO4(Si2O7)2(XOM)2(XOA)2 is Ca2(CaCe)Na3Nb(Si2O7)2(OF)F2.

Lamellar sodium titanium silicate assembled by nanostrips decorated with N-rich 3D carbon for sodium dual-ion batteries

Sodium dual-ion batteries have received tremendous attention owing to their appealing operating voltage (i.e. >4.0 V) and eco-friendly features. However, the exploitation of efficient sodium ion storage anode materials is one of the keys for driving the application of sodium dual-ion batteries in the grid-scale energy storage. Herein, a lamellar sodium titanium silicate (NTSO) woven by plentiful nanostrips grown in situ on the surface of N-rich 3D carbon has been prepared via a convenient synthetic strategy. Based on the synergistic effect both micro-nano composite spatial structure and energy storage mechanism based on conversion reaction of material bulk phase, the NTSO/3DC-N composite as anode delivers a high special capacity of 540.6 mAh/g at 0.05 A/g and 163.1 mAh/g at 5.0 A/g in sodium ion half-cell. More impressively, the sodium dual-ion batteries built with NTSO/3DC-N as anode and a N-rich 3D carbon as cathode exhibits a high reversible capacity of about 123.6 mAh/g at 0.05 A/g. The elaborate designing an interconnecting framework composed of layered titanium silicate sodium and heterogeneous atom doping carbon substrate provides a generally applicable strategy for enhancing the anode performance of sodium dual-ion batteries.

Selective Oxidation of Glucose using Hydrogen Peroxide as an Oxidant: On the Structure Sensitivity of the Apparent Activation Energy

AbstractThe selective oxidation of glucose to gluconic acid with hydrogen peroxide was studied using different heterogeneous catalysts with alumina (Al2O3) and titanium silicate (TS‐1, TiMWW) as supports and different noble (Au, Pd) and non‐noble metals (Fe, W) as the catalytically active phases. Supported tungsten oxide catalysts showed a moderate selectivity and activity compared to palladium and iron catalysts. The best performance in the selective oxidation of glucose among the studied catalysts was displayed by gold on alumina. For this kind of catalyst, the structure sensitivity in glucose oxidation was explored, revealing a maximum rate shifted to larger gold particle sizes at higher temperatures in comparison with other studies involving activation of molecular oxygen on gold particles. A significant change in the apparent activation energy was established while changing the particle size of gold. These changes of the activation energy were adequately explained by a theoretical model for the cluster size dependence of the apparent activation energy.

Molecular Structure Effect on the Epoxidation of 1-Butene and Isobutene on the Titanium Silicate Catalyst under Transient Conditions in a Trickle Bed Reactor.

Epoxidation of two butane isomers (1-butene and isobutene) on the commercial titanium silicate (TS-1) catalyst was studied in a laboratory-scale trickle bed reactor. The transient step response technique was used as the main tool in the investigation. The transient responses revealed different dynamics of product formation in continuous operation. The study of isomers showed the impact of the molecular structure on the transient and stationary states of the system. The four-carbon chain present in 1-butene displayed a dynamic behavior with a prominent maximum of the conversion as a function of time-on-stream. On the contrary, the behavior of isobutene was displayed to be closer to ethene and propene under similar conditions reaching a steady state after ca. 2 h. The structure of the epoxide was an important factor in order to achieve a high epoxide selectivity. In isobutene epoxidation, the primary product 1,2-epoxy-2-methylpropane was highly reactive, giving a spectrum of parallelly formed byproducts. Therefore, the selectivity of the epoxide from isobutene was limited to ca. 70%. In the epoxidation of 1-butene, 1,2-epoxybutane was displayed to be a highly stable product with a selectivity close to 99%. Based on the transient and stationary data, a reaction mechanism was proposed for the epoxidation and ring-opening reactions present in the system.

Glasses and Glass–Ceramics from Li2O-KF-TiO2-SiO2 System Doped with SiC

Unfamiliar invert host silicate glass from the system SiO2-TiO2-KF-Li2O was prepared together with SiC doped samples by traditional melt-quenching technique. Collective characterization of the prepared glasses through FTIR, optical, thermal and microhardness properties were measured to justify the effect of silicon carbide (SiC) on the resultant data. Silicon carbide is selected because its known high mechanical and thermal properties and extended applications of SiC- containing candidates in several domains. Structural FTIR characterization of the prepared glasses reveals familiar silicate network in spite of their invert percent together with the suggested sharing of Si-Ti or Ti-Ti or fluoride units. Optical spectra show only distinct UV absorption with additional small peaks at 380–420 nm in high percent of SiC. Such UV spectra are assumed to originate from unavoidable traces of ferric ions contaminated within the raw materials used for the preparation of glasses. The known high thermal and mechanical properties of silicon carbide are identified to be reflected on the measured thermal expansion and Vickers microhardness data. Samples from the parent glasses were thermally heated to produce their corresponding glass-ceramic derivatives. X-ray diffraction analysis indicate the formation of the peculiar orlovite crystalline phase as a major one due to the presence of all the constituents within the chemical composition of the invert glass. Also, some minor crystalline phases of lithium silicate or lithium titanium silicate are identified. It is assumed that the presence of self-nucleation Li2O and high negatively charged fluoride anions beside the conditional oxide of TiO2 facilitate the ease of nucleation and crystallization of the formed crystalline phase. SEM results confirm the x-ray data showing different crystalline features with the addition of SiC.

Ti-MWW Catalysts for Propylene Oxide Production: Influence of Si/Ti Ratio and Calcination Conditions

Titanium silicates of MWW structures with different Si/Ti ratios were prepared via hydrothermal synthesis using piperidine as the structure directing agent and boric acid as the crystallization agent. All the syntheses resulted in highly crystalline materials independent of the Si/Ti ratio. The observed morphology showed MWW-like well-defined thin hexagonal platelets. The synthesized Ti-MWW materials exhibited higher surface areas and partial meso-porosity compared to the commercial TS-1 catalyst. The coordination of the Ti-species was investigated by UV–vis- and IR-spectroscopy. The MWW titanium silicates were tested for the catalytic performance in the epoxidation of propylene in a laboratory-scale trickle bed reactor to compare their clear different physico-chemical properties with the commercial TS-1. The synthesized Ti-MWW materials showed significantly higher catalytic activities, up to 3.5 times, using acetonitrile as the solvent and enhanced epoxide selectivities partially up to 100% in methanol unlike TS-1. The effect of the Ti content in the MWW and the calcination conditions were investigated in propylene epoxidation, revealing the beneficial effect of a lower calcination temperature and an increased Ti content on the activity. The catalytic results were correlated with the physico-chemical properties of the synthesized materials.Graphical

Comparison of Adsorbents for Cesium and Strontium in Different Solutions

Adsorption is an effective method to remove cesium and strontium from a solution. Although a variety of adsorbents has been reported, it is difficult to compare their adsorption properties due to different experimental conditions (such as solution concentration, volume, composition, temperature, etc.). In this paper, a series of adsorbents for the adsorption of cesium and strontium (ammonium phosphomolybdate, Prussian blue, sabite, clinoptilolite, titanium silicate) were synthesized and characterized using XRD, IR and SEM, and their adsorption performance in mixed solution (containing Li, Na, K, Cs, Ca, Sr and Mg ions, 1 mmol L−1), artificial seawater and salt lake brine were studied under the same conditions; in addition, the adsorption mechanism was elucidated. The results showed that ammonium phosphomolybdate has the largest adsorption capacity for cesium in the mixed solution. In artificial seawater and salt lake brine, Prussian blue displays the highest cesium adsorption capacity and the best selectivity. The multi-adsorption mechanisms are beneficial to the selective adsorption of Prussian blue in complex solutions. These results are useful for choosing adsorbents for cesium and strontium in applications.

Plasma-Induced Selective Propylene Epoxidation Using Water as the Oxygen Source.

Propylene oxide (PO) is a critical gateway chemical used in large-scale production of plastics and many other compounds. In addition, PO is also used in many smaller-scale applications that require lower PO concentrations and volumes. These include its usage as a fumigant and disinfectant for food, a sterilizer for medical equipment, as well as in producing modified food such as starch and alginate. While PO is currently mostly produced in a large-scale propylene epoxidation chemical process, due to its toxic nature and high transport and storage costs, there is a strong incentive to develop PO production strategies that are well-suited for smaller-scale on-site applications. In this contribution, we designed a plasma-liquid interaction (PLI) catalytic process that uses only water and C3H6 as reactants to form PO. We show that hydrogen peroxide (H2O2) generated in the interactions of water with plasma serves as a critical oxidizing agent that can epoxidize C3H6 over a titanium silicate-1 (TS-1) catalyst dispersed in a water solution with a carbon-based selectivity of more than 98%. As the activity of this plasma C3H6 epoxidation system is limited by the rate of H2O2 production, strategies to improve H2O2 production were also investigated.

Selective Styrene Oxidation Catalyzed by Phosphate Modified Mesoporous Titanium Silicate

Selective oxidation of organics over an efficient heterogeneous catalyst under mild liquid phase conditions is a very demanding chemical reaction. Herein, we first report the modification of the surface of mesoporous silica MCM-41 material by phosphate for the efficient incorporation of Ti(IV) in the silica framework to obtain highly ordered 2D hexagonal mesoporous material STP-1. STP-1 has been synthesized by using tetraethyl orthosilicate, triethyl phosphate, and titanium isopropoxide as Si, P, and Ti precursors, respectively, in the presence of cationic surfactant cetyltrimethylammonium bromide (CTAB) under hydrothermal conditions. The observed specific surface area and pore volume of STP-1 were 878 m2g−1 and 0.75 ccg−1, respectively. Mesoporous STP-1 has been thoroughly characterized by XRD, FT-IR, Raman spectroscopy, SEM, and TEM analyses. Titanium incorporation (Ti/Si = 0.006) was confirmed from the EDX analysis. This mesoporous STP-1 was used as a heterogeneous catalyst for the selective oxidation of styrene into benzaldehye in the presence of dilute aqueous H2O2 as an oxidizing agent. Various reaction parameters such as the reaction time, the reaction temperature, and the styrene/H2O2 molar ratio were systematically studied in this article. Under optimized reaction conditions, the selectivity of benzaldehyde could reach up to 93.8% from styrene over STP-1. Further, the importance of both titanium and phosphate in the synthesis of STP-1 for selective styrene oxidation was examined by comparing the catalytic result with only a phosphate-modified mesoporous silica material, and it suggests that both titanium and phosphate synergistically play an important role in the high selectivity of benzaldehyde in the liquid phase oxidation of styrene.

Boosting the Dehydrogenation Properties of LiAlH4 by Addition of TiSiO4

Given its significant gravimetric hydrogen capacity advantage, lithium alanate (LiAlH4) is regarded as a suitable material for solid-state hydrogen storage. Nevertheless, its outrageous decomposition temperature and slow sorption kinetics hinder its application as a solid-state hydrogen storage material. This research's objective is to investigate how the addition of titanium silicate (TiSiO4) altered the dehydrogenation behavior of LiAlH4. The LiAlH4-10 wt% TiSiO4 composite dehydrogenation temperatures were lowered to 92 °C (first-step reaction) and 128 °C (second-step reaction). According to dehydrogenation kinetic analysis, the TiSiO4-added LiAlH4 composite was able to liberate more hydrogen (about 6.0 wt%) than the undoped LiAlH4 composite (less than 1.0 wt%) at 90 °C for 2 h. After the addition of TiSiO4, the activation energies for hydrogen to liberate from LiAlH4 were lowered. Based on the Kissinger equation, the activation energies for hydrogen liberation for the two-step dehydrogenation of post-milled LiAlH4 were 103 and 115 kJ/mol, respectively. After milling LiAlH4 with 10 wt% TiSiO4, the activation energies were reduced to 68 and 77 kJ/mol, respectively. Additionally, the scanning electron microscopy images demonstrated that the LiAlH4 particles shrank and barely aggregated when 10 wt% of TiSiO4 was added. According to the X-ray diffraction results, TiSiO4 had a significant effect by lowering the decomposition temperature and increasing the rate of dehydrogenation of LiAlH4 via the new active species of AlTi and Si-containing that formed during the heating process.