Incorporation Of Titanium Research Articles

Direct synthesis and catalytic activity of ordered large pore titanium-substituted spherical SBA-15 molecular sieves

Titanium substituted highly ordered SBA-15 spheres with a diameter about 5 μm in a ternary P123-H2O-HCl-TEOS system were prepared by the hydrothermal method and the catalytic activity in the epoxidation of cyclohexene was studied. The synthesized materials were characterized by XRD, ICP-AES, FT-IR, BET and SEM, UV–Vis and N2 adsorption/desorption isotherms. The results show that incorporation of titanium into the framework of SBA-15 makes the surface area, pore diameter and pore volume increase and the pore walls slimmer than pure SBA-15. When the titanium content is above a critical value, TiO2 anatase forms on the material surface. The Ti-SBA-15 materials showed good catalytic activity for the oxidation of cyclohexene. The catalytic activity increases with an increase of Ti content and decreases when anatase TiO2 clusters are formed.

Poly(amic acid)‐Supported Heterogeneous Titanium‐Based Ziegler‐Natta Catalyst for Ethylene Polymerization in a Slurry Process

AbstractThe synthesis of a poly(amic acid) (PAA)‐supported Ziegler–Natta catalyst (PAA‐TiCl4) by the reaction of PAA and titanium tetrachloride (TiCl4) is reported. For ethylene polymerization, three catalysts were synthesized by varying the TiCl4/PAA weight ratio in a hexane medium. The resulting catalysts were characterized by Fourier‐transformed infrared (FT‐IR), ultraviolet (UV), scanning electron microscopy and energy dispersive x‐ray detector (SEM‐EDX), and x‐ray diffraction analysis (XRD). The acidity of the catalysts in an acetone/water solution was measured by a pH meter. Thermogravimetric analysis reveals that catalysts are stable up to 110–125°C. Because of their higher degree of thermal stability, these catalysts may potentially be used as a support in a conventional Ziegler–Natta catalyst for ethylene polymerization. Furthermore, because of the extensive reaction between the functional groups of PAA and TiCl4, the chain structure of the PAA was destroyed. The newly synthesized catalysts showed good storability, and the overall catalytic productivity is 4921 g PE/g Ti/h. A catalyst with titanium incorporation corresponding to 2.8 wt% showed the maximum activity. The productivity of the catalysts also depended on the titanium concentration in the polymer matrix. These catalysts are found to retain their catalytic activity for a long time (∼90 days), and a mild reaction condition is required for catalysis. © 2011 Wiley Periodicals, Inc. Adv Polym Techn 32: E119–E130, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20276

Nanobiotechnology approach to fabricate polycaprolactone nanofibers containing solid titanium nanoparticles as future implant materials

Abstract In this study, a good combination of electrospun poly(caprolactone) nanofibers incorporated with high purity titanium nanoparticles is introduced for hard tissue engineering applications. A simple approach to utilize the colloidal properties of poly(caprolactone) and titanium nanoparticles are exploited to form nanofibers by the simple electrospinning process. The prepared colloidal solutions were characterized using dynamic light scattering and electrophoratic light scattering which indicated unimodal size distribution and negative zeta potential. To investigate the bioactivity of the resultant nanofiber mats, they were incubated in simulated body fluid at 37 °C for 10 days. Field emission scanning electron microscopy in combination with energy-dispersive X-ray spectroscopy indicated that incorporation of titanium strongly activates precipitation of the apatite-like materials from the utilized simulated body fluid. Moreover, in-vivo experiments using experimental dogs revealed that nanofibers can yield good tissue regeneration on the surfaces of nanofibers.

Microstructure, corrosion resistance and biocompatibility of titanium incorporated amorphous carbon nitride films

Titanium incorporated amorphous carbon nitride films were deposited by direct current magnetron sputtering. The films change from amorphous to nanocomposite structure, the relative fraction of sp3 C–N bonding decreases significantly from 2.17 to 1.64 with the increase of Ti content from 2.7at.% to 12.3 at.%. For the films with high Ti content, the nanocrystalline TiN embedded in a-CNx matrix, while principally TiN did not appear to be well formed for the film containing low Ti content. Potentiodynamic polarization, in vitro human osteoblasts and murine fibroblast cell adhesion tests were employed to assess the corrosion performances of Ti6Al4V alloy coated with the films in Tyrode's solution, and the biocompatibility of Ti-incorporated a-CNx films, respectively. Titanium incorporation increases the corrosion resistance of a-CNx films, and the higher corrosion potential and lower corrosion current density are observed for the alloy coated with the film containing lower Ti content. The high osteoblast adhesion and activation demonstrate the enhanced biocompatibility of Ti alloy coated with Ti-incorporated a-CNx films. The improved biocompatibility in biological environment is attributed to structural change after titanium introduction.

Tribological Behavior of Mesophase Carbon Added with Titanium and Copper

Incorporation of metallic elements, titanium and copper, into carbonaceous mesophase (CM) was performed through mechanical alloying in a ball mill apparatus. The structures of the raw CM as well as the Ti/Cu-added CM were characterized by X-ray diffraction. The tribological behavior of the Ti/Cu-added CM used as lubricating additives was investigated by using a high temperature friction and wear tester. The results show that, compared with the raw CM, the Ti/Cu-added CM exhibits a drop in the crystallinity and a transition to the amorphous. The Ti/Cu-added CM used as lubricating additive displays an obvious high temperature anti-friction and wear resistance effect, and the lager the applied load, the lower the friction coefficient and the wear severity.

Spectroscopic Investigation of Ti-Modified Aluminum-Free Zeolite-Beta Crystallization

Crystallization of aluminum-free zeolite-Beta from viscous gel and incorporation of titanium into its framework were investigated by several spectroscopic techniques. Hydrothermal synthesis was stopped at different times and the gels obtained from the autoclaves were analyzed by liquid-state 29Si NMR spectroscopy. The gels were subsequently dried and inspected by solid-state 29Si NMR, Fourier-transform infrared, and X-ray absorption spectroscopy. NMR spectroscopy distinguished signals from oligomers and from two populations of nanoparticles with different typical dimensions. It also provided information about the composition of the oligomers and nanoparticles, in terms of the relative fractions of Qn units within them. Investigation showed that the synthesis of zeolite Ti-Beta started with a quick formation of oligomers. After 20 h of the hydrothermal treatment, oligomers with a high fraction of Q3 units gradually aggregated into primary nanoparticles with a diameter of ∼2 nm. During first 20 h, primary n...

Ti-MCM-41 with Various Ti Contents: Synthesis, Characterization and Catalytic Properties in Oxidation of .ALPHA.-Pinene

Ti-MCM-41 with various ratios Ti/Si was synthesized successfully and characterized by some measurements as XRD, DR-UV-Vis, TEM, EDAX and N2-Adsorption. The peak in bands 230 nm in DR-UV-Vis spectroscopy showed that Ti was in tetrahedral coordination. The TEM, EDAX images indicated that the obtained materials were of ordered mesoporous structures in the samples with low ratio of Ti/Si. Moreover, increasing the thickness of material wall calculated by BJH method was due to the incorporation of titanium in the framework. The oxidation of α-pinene over Ti-MCM-41 with various ratios Ti/Si indicated that the possibility of Ti in the tetrahedral coordination gave a priority to the selectivity of α-pinene oxide. The Ti content of materials system increased, consequently the conversion of the reaction and the pinandiol product yield increased. [DOI: 10.1380/ejssnt.2011.539]

Zr-SBA-15 as an efficient acid catalyst for FAME production from crude palm oil

The synthesis of Zr-SBA-15 materials from zirconocene dichloride as metal precursor has been investigated. These materials can be prepared with a high loading of zirconium while preserving good mesoscopic ordering. Zr-SBA-15 materials display acid properties which have revealed to confer high catalytic activity in the transesterification of crude palm oil with methanol for biodiesel synthesis, achieving yields to FAME over 70% in a batch reactor under the following reaction conditions: 200°C, 3h, methanol to oil molar ratio 30:1 and using 10wt.% catalyst loading referred to oil. Furthermore, Zr-SBA-15 materials display excellent stability in palm oil transesterification, being fully regenerated by calcination at 550°C after at least eight consecutive reaction runs. The incorporation of titanium, molybdenum and tungsten as doping metals produces slightly promotion of the acidity of Zr-SBA-15 materials, though this is not translated into higher catalytic activity.

Challenges in preparation of metal-containing nanocomposites; dispersion of titanium into plastics

AbstractMetal containing polymers are of great interest as they have proven to be the most promising materials for applications such as microelectronics, holography and magnetic recording of information. Metal containing polymers also provide an alternative to even the specialty glass materials conventionally used for optical applications. Metals such as barium, lead and lanthanum have been used to improve the optical properties such as refractive index and mechanical properties such as hardness of optical plastics. The metal-containing optical plastic materials with improved refractive index of as much as 1.60 along with the Abbe number of more than 30 have been successfully designed using these metals by the authors of this paper. To further increase the refractive index without any drop in Abbe number and to improve the hardness of the polymer matrix, titanium would be the most promising metal. Incorporation of titanium in plastic matrices to form homogeneous and optically clear compositions is a challenging task. This paper reviews the state-ofthe- art by which titanium can be dispersed in polymer matrices to form metal containing composites as optical plastics.

Remarkable effect of the incorporation of titanium on the catalytic activity and SO2 poisoning resistance of magnetic Mn–Fe spinel for elemental mercury capture

Tiantium (Ti) was incorporated into non-stoichiometric Mn–Fe spinel to improve its performance for elemental mercury capture. Although the number of Mn4+ cations on (Fe2TixMn1−x)1−δO4 was less than that on the corresponding (Fe3−xMnx)1−δO4, the number of usable cation vacancies for elemental mercury oxidization obviously increased. As a result, elemental mercury capture by Mn–Fe spinel was generally promoted by the incorporation of Ti. Furthermore, SO2 mainly reacted with ≡FeIII–OH and few Mn4+ cations on the surface reacted with SO2 at lower temperatures (100–150°C), so SO2 poisoning resistance improved at lower temperatures due to the incorporation of Ti. Especially, (Fe2Ti0.5Mn0.5)1−δO4 showed an excellent capacity (4.2mgg−1) for elemental mercury capture in the presence of a high concentration of SO2 at 150°C. Meanwhile, (Fe2Ti0.5Mn0.5)1−δO4 with the saturation magnetization of 30.6emug−1 can be readily separated from the fly ash using magnetic separation, leaving the fly ash essentially free of catalyst and adsorbed HgO. Therefore, nanosized (Fe2Ti0.5Mn0.5)1−δO4 may be a promising candidate catalyst for elemental mercury capture.

Preparation and investigation of PD/TI-SBA-15 catalysts for catalytic oxidation of benzene

The feasibility of Pd/Ti-SBA-15 catalysts in the elimination of benzene was explored comprehensively. The effects of the titanium incorporation on catalyst physicochemical property and activity were investigated by X-ray diffraction, N(2) adsorption/desorption, Fourier transform infrared spectroscopy, DRUV-vis, NH(3)-TPD, scanning electron microscope, and transmission electron microscope techniques. Only a certain quantity of titanium can be incorporated into the support, and titanium has a positive influence on active phase dispersion. Titanium-modified catalysts possess larger pore diameter than the pure Pd/SBA-15 and titanium can introduce the acid sites to the support. The evaluation result shows that the titanium incorporation can noticeably improve the catalytic activity, and all evaluated catalysts possess excellent stability, without obviously activity loss during 60 h test. (C) 2010 American Institute of Chemical Engineers Environ Prog, 29: 435-442, 2010

Effect of titanium incorporation on the structural, mechanical and biocompatible properties of DLC thin films prepared by reactive-biased target ion beam deposition method

Amorphous diamond like carbon (DLC) and titanium incorporated diamond like carbon (Ti-DLC) thin films were deposited by using reactive-biased target ion beam deposition method. The effects of Ti incorporation and target bias voltage on the microstructure and mechanical properties of the as-deposited films were investigated by means of X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy and nano-indentation. It was found that the Ti content in Ti-DLC films gets increased with increasing target bias voltage. At about 4.2 at.% of Ti, uniform sized well dispersed nanocrystals were seen in the DLC matrix. Using FFT analysis, a facility available in the TEM, it was found that the nanocrystals are in cubic TiC phase. Though at the core, the incorporated Ti atoms react with carbon to form cubic TiC; most of the surface exposed Ti atoms were found to react with the atmospheric oxygen to form weakly bonded Ti–O. The presence of TiC nanocrystals greatly modified the sp 3/sp 2 hybridized bonding ratio and is reflected in mechanical hardness of Ti-DLC films. These films were then tested for their biocompatibility by an in vitro cell culturing test. Morphological observation and the cell proliferation test have demonstrated that the human osteoblast cells well attach and proliferate on the surface of Ti incorporated DLC films, suggesting possible applications in bone related implant coatings.

Sol-Gel Titania and Titania-Silica Mixed Oxides Photocatalysts

This paper presents a review of the work published by the authors on the synthesis, characterization and evaluation of the photocatalytic activity of TiO2/SiO2 materials. The use of titania-silica mixed oxides photocatalysts is proposed basically as a process improvement to overcome the difficulties of recovering titania from the slurries after the photocatalytic treatment of contaminated waters. To understand the mechanism governing the photocatalytic activity of these materials, several titania-silica photocatalysts have been prepared through a sol-gel method that allows controlling the main variables to obtain materials with different textural properties, degree of titania incorporation, dispersion of the photoactive phase and crystallinity of titanium dioxide. The samples have been characterized in depth, looking for correlations between the main physicochemical properties (TiO2 crystallite size, band gap energy and titania surface area) and the activity shown in the photocatalytic oxidation of cyanide, selected as model pollutant. The results suggest that the photocatalytic activity is strongly influenced by the quality of the titania crystal network, which in turn is improved by the use of a hydrothermal crystallization procedure. Additionally, the evaluation of the fraction of the total surface area corresponding to titania is mandatory for comparing the catalytic activity of different materials in processes in which titanium dioxide is the only phase catalytically active and silica behaves as an inert support.

Corrosion protection of AA 2024-T3 aluminium alloys using 3, 4-diaminobenzoic acid chelated zirconium–silane hybrid sol–gels

Organic–inorganic polymers formed by hydrolysis/condensation reactions of alkoxide precursors, such as organically modified silanes (Ormosils) are used for several industrial applications such as electronic, optical and protective anticorrosion coatings. Such materials possess superior chemical stability, physical strength and scratch resistance characteristics when compared to organic polymers. Further performance improvement can be achieved through the incorporation of zirconium and titanium based nanoparticles, also formed through from precursors via the sol–gel process. However due to the inherent reactivity differences of the above precursors, they must be hydrolysed separately before being combined for final condensation. Zirconium precursors are commonly chelated using acetic acid or acetyl acetonate prior to hydrolysis, to lower the hydrolysis rate. In this body of work, 3,4-diaminobenzoic acid (DABA) and acetyl acetonate (acac) were compared as chelating ligands for controlling the hydrolysis reactions of zirconium n-propoxide to form nanoparticles within a silane sol matrix. The sols were applied as coatings on aerospace grade aluminium alloy AA 2024-T3 and characterised by physical, spectroscopical, microscopical, electrochemical and calorimetric techniques. The electrochemical properties of the coatings, as characterised by EIS and PDS, correlated with neutral salt spray evaluations confirming that the use of DABA as a chelating ligand significantly improved the coating performance when compared to the traditional diketone ligand. The data indicates the anticorrosion properties of the nitrogen rich chelate have a key role in protecting the alloy through the formation of smaller zirconium nanoparticles, thus improving the polymer network stability.

Dispersion Improvement of Platinum Catalysts Supported on Silica, Silica-Alumina and Alumina by Titania Incorporation and pH Adjustment

Platinum catalysts supported on silica, silica-alumina and alumina supports were prepared using four different cationic and anionic platinum precursors in order to examine the contribution of the precursors and supports to the platinum dispersion. The pH adjustment of the precursor suspension to obtain an opposing surface charge of the support to that on the platinum precursor ions considerably improved the platinum dispersion by strengthening their adsorption on the support. However, exceptional platinum dispersion was achieved, regardless of the precursor and support, by simultaneous pH adjustment and titania incorporation on the supports. The increase in the interaction between the platinum precursor and the titania-incorporated support raised the dispersion and stability of the platinum catalysts with high-loading, even after reduction at 400 °C. The physico-chemical states of platinum and titanium were investigated by XRD, TEM, XAFS spectroscopy and CO adsorption technique. The platinum catalysts supported on the titania-incorporated supports with pH adjustment exhibited highly dispersed platinum particles ranging in size from 1 to 3 nm. They also exhibited high catalytic activity in the oxidation of carbon monoxide because of its incorporated titania and partially oxidized, small platinum particles.

Effect of organic chelates on the performance of hybrid sol–gel coated AA 2024-T3 aluminium alloys

Sol–gels are organic–inorganic polymers formed by hydrolysis/condensation reactions of alkoxide precursors, primarily silanes, which have found applications as electronic, optical and protective coatings. These coatings possess important characteristics such as chemical stability, physical strength and scratch resistance. Further performance improvement is achieved through the incorporation of zirconium and titanium based nanoparticles, also formed through the sol–gel process. However due to the inherent difference in the reactivity of the precursors, the hydrolysis of each precursor must be carried out separately before being combined for final condensation. Zirconium precursors are commonly chelated using acetic acids, prior to hydrolysis, to lower the hydrolysis rate. In this body of work various ligands such as organic acids, acetyl acetone (AcAc) and 2,2′-bipyridine (Bipy) were used to control the zirconium hydrolysis reaction and form nanoparticles within the silane sol matrix. Nanoparticle modified coatings formed from the silane sol on AA 2024-T3 aluminium were characterised spectroscopically, electrochemically and calorimetrically to evaluate the potential effect of the different chelates on the final film properties while neutral salt spray tests were performed to study their anti-corrosion performance. Results indicate that the acid ligand modified coatings provided the best performance followed by AcAc, while Bipy was the poorest. In all cases the zirconium nanoparticle improved the protective properties of the sol–gel coating.

Synthesis of Titanium-Containing Mesoporous Silicas as Catalysts for Cyclohexene Epoxidation

Ti-containing mesoporous materials have been prepared by hydrothermal synthesis at 100 °C with two different Si/Ti ratios (20 and 60) in the synthesis mixture. A detailed study about the effect of synthesis time on the physicochemical properties of the materials has been carried out. The samples were characterized by XRD, DRUVvis, N2 adsorption, and pyridine adsorption analyzed by FT-IR. The samples synthesized using the lower Si/Ti ratio presented the higher titanium incorporation and the higher acid character. The synthesis time appears as an important parameter that affects the textural, structural, chemical, and acid properties of the final solids. For the lower Si/Ti ratio, a longer synthesis time is needed to obtain a more ordered structure. However, in both cases, short synthesis times do not allow a proper incorporation of titanium into the silica framework, which is reached with synthesis times of about 3 days. The results of catalytic activity indicate that the solids studied here present an int...

Incorporation of Titanium(IV) into Sterically Hindered Schiff Bases of Heterocyclic β -Diketones Involving Ketooximes and Glycol as Coligands: Preparation and Structural Considerations

Titanium(IV) complexes of the general formula TiL(OPr i )2 [where LH2 = R CH3 where R = ─C6H5, ─C6H4Cl(p)] were prepared by the interaction of titanium isopropoxide with sterically hindered Schiff bases derived from heterocyclic β -diketones in 1:1 molar ratio in dry benzene. The complexes TiL(OPr i )2 were used as versatile precursors for the synthesis of other titanium(IV) complexes. Titanium(IV) complexes of the type TiLL'(OPr i ) (where L'H═R1R2C═NOH, R1 = R2 = ─CH3; R1 = ─CH3,R2 = ─C6H5; R1 = ─COC6H5, R2 = ─C6H5) were synthesized by the reaction of TiL(OPr i )2 with ketooximes (L'H) in equimolar ratio in dry benzene. Another type of titanium(IV) complexes having the general formula TiLGH(OPr i ) (where GH2═HO─G─OH, G = ─CH2─CH2─) have been prepared by the reaction of TiL(OPr i )2 with glycol in 1:1 molar ratio in dry benzene. Plausible structures of these new titanium(IV) complexes have been proposed on the basis of analytical data, molecular weight measurements, and spectral studies.

Immobilization of Titanium Tetrachloride on Mixed Support of MgCl2 · xEB/Poly(methyl acrylate-co-1-octene): Catalyst for Synthesis of Broad MWD Polyethylene

TiCl4 immobilization on different compositions of mixed support of MgCl2 · xEB and poly(methyl acrylate-co-1-octene) (PMO; synthesized through ARGET ATRP) resulted in the formation of solid catalysts having variation in incorporation of titanium. The effect of mixed support composition onto the titanium immobilization, catalyst morphology and performance for ethylene polymerizations has been evaluated. The polyethylenes synthesized showed broad to bimodal MWD in GPC and DSC where the broadness was found to be dependent upon the ratio of mixed support MgCl2 · xEB/PMO. The morphological features of PE as elucidated using SEM lead to postulation of polymer formation mechanism.

Incorporation of titanium into polymorph C for catalytic epoxidation of cyclohexene

Incorporation of titanium into the framework of polymorph C of zeolite beta was attempted in a hydrothermal system using different titanium precursors of various contents in the synthesis gel. Samples were characterized using X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), inductive-coupled plasma-atomic emission spectrometer (ICP-AES), X-ray photoelectron spectroscope (XPS), and X-ray absorption near edge structure (XANES) techniques. Characterization results revealed that the incorporation of titanium into the framework of polymorph C can be achieved using Ti(NH 4) 2F 6 as the titanium precursor without significantly affecting the crystalline structure of polymorph C. The sample synthesized with a Si/Ti molar ratio of 20 was found to possess the highest catalytic activity while the sample synthesized with a Si/Ti molar ratio of 5 was observed to display the highest selectivity in the epoxidation of cyclohexene.