Titanium Phosphonate Research Articles

Zirconium titanium phosphonates for enhanced lanthanide recovery from acidic wastes

Metal phosphonates show promise for recovery of valuable lanthanide (Ln) elements from acidic waste streams due to their selectivity, high capacity, fast kinetics and chemical stability. To optimise these properties, a balance is needed between free phosphonate groups available to bind Ln and P-O-metal linkages to provide stability. This work demonstrates how astute choice of metal precursors can be used to control the phosphonate structure and maximise both sorption and stability. Relative to single metal zirconium phosphonate, mixed metal zirconium titanium phosphonate sorbents had more free phosphonate groups and greater porosity, increasing Ln capacity by 30 % and the kinetic rate constant by 90 %. Acid stability was also improved upon Ti inclusion. Use of metal propoxide and tert-butoxide precursors were also compared, revealing different reactivities with Zr versus Ti. Specifically, the tert-butoxide precursor increased P-O-Zr linkages and acid stability with Zr, but increased formation of leachable P-O-Na2 groups in the presence of Ti that decreased acid stability. The optimised zirconium titanium phosphonate sorbent used metal propoxide precursors and a Zr:Ti molar ratio of 1:1 to achieve (1) selectivity for Ln over Co, Sr and Cs, (2) sorption capacity of approximately 70 mg Eu/g, (3) fast kinetics with > 99 % sorption in 10 min and (4) retention of 60 % sorption capacity after contact with 5 M nitric acid. The enhanced chemical stability, capacity and kinetics achieved via incorporating Ti drastically improves the practicality of these sorbents for Ln recovery from acidic leachates of magnets, phosphors and other wastes.

In situ synthesis of titanium phosphonate by a non-hydrolytic sol-gel route within a viscous polymer medium

In situ synthesis of titanium phosphonate by a non-hydrolytic sol-gel route within a viscous polymer medium

Sol–gel reaction of titanium phosphonate alkoxide cluster

AbstractThe synthesis and properties of titanium phosphonate cluster molecules have been investigated; however, nothing has been done to study not only the catalytic ability of a hydrolyzed cluster but also a behavior of hydrolysis–polycondensation by solvents. The sol–gel reaction of [Ti4(μ3‐O)(OiPr)5(μ‐OiPr)3(O3PPh)3]·thf (Ti4P3Ph) was performed in tetrahydrofuran (THF), toluene, and acetone. The hydrolysis–polycondensation of Ti4P3Ph proceeded in THF and toluene, while Ti4P3Ph in acetone proceeded in two paths (hydrolysis–polycondensation and nonhydrolysis–polycondensation). The hydrolyzed Ti4P3Ph retained its cluster structure, while the calcined Ti4P3Ph at 300°C contained a collapsed cluster structure. The specific surface areas of the hydrolyzed Ti4P3Ph in THF, toluene, and acetone were 154, 302, and 7 m2 g−1, respectively. The photodegradation ability of the hydrolyzed Ti4P3Ph for methylene blue was confirmed by ultraviolet irradiation at 365 nm; however, that of the calcined Ti4P3Ph was not. It was considered that the calcined Ti4P3Ph did not retain its cluster structure. The photocatalytic ability of the hydrolyzed Ti4P3Ph was high in the order of toluene > THF > pristine > acetone. The gels retained cluster structure have higher photocatalytic ability than pristine cluster; however, the gel contained a collapsed cluster structure was found no catalytic ability.

Efficient oxidative desulfurization over highly dispersed molybdenum oxides supported on mesoporous titanium phosphonates

Abstract The nature of the support for the supported heterogeneous catalysts plays a vital role in catalytic reactions, for example, oxidative desulfurization (ODS). Herein, mesoporous titanium phosphonates (MTP) with sufficient organophosphonic ligands are synthesized as the support of molybdenum oxides for ODS. The homogeneous organophosphonic ligands in MTP facilitate the effective adsorption of Mo7O246−; after subsequent low-temperature annealing, the highly dispersed molybdenum oxides on MTP (Mo/MTP) with strong coupling effect are prepared. The electron-donating effect of organophosphonic ligands endows Mo active sites with high electron density. In addition, the mesoporous structure and large specific surface area of MTP are beneficial for improving the local concentration of reactants around the active sites. The 5%Mo/MTP-350 exhibits excellent ODS catalytic activity with 100% desulfurization in 30 min at 40 °C and robust recycling stability. This work presents a successful example for the application of MTP supported active components, and provides some inspirations for the potential applications of metal phosphonates as catalyst support in energy and environmental catalysis.

Highly Stable Phosphonate-Based MOFs with Engineered Bandgaps for Efficient Photocatalytic Hydrogen Production.

Photoactive metal-organic frameworks (MOFs) represent one of the most promising materials for photocatalytic hydrogen production, but phosphonate-based MOFs have remained largely underdeveloped compared to other conventional MOFs. Herein, a photocatalyst of 1D titanium phosphonate MOF is designed through an easy and scalable stirring hydrothermal method. Homogeneous incorporation of organophosphonic linkers can narrow the bandgap, which is due to the strong electron-donating ability of the OH functional group that can efficiently shift the top of the valence band, moving the light absorption to the visible portion of the spectrum. In addition, the unique 1D nanowire topology enhances the photoinduced charge carrier transport and separation. Accordingly, the titanium phosphonate nanowires deliver remarkably enhanced photocatalytic hydrogen evolution activity under irradiation of both visible light and a full-spectrum simulator. Such concepts of engineering both nanostructures and electronic states herald a new paradigm for designing MOF-based photocatalysts.

Organic–inorganic hybrids based on poly(bisphenol A-co-epichlorohydrin) containing titanium phosphonate clusters

Organic–inorganic hybrid films were prepared by transalkoxylation of poly(bisphenol A-co-epichlorohydrin) (PBE) and titanium phosphonate clusters, such as [Ti4(μ3-O)(OiPr)5(μ-OiPr)3 (O3PPh)3]·thf (Ti4P3), [Ti(OiPr)(acac)(O3PPh)]4 (Ti4P4; acac = acetylacetonato), and Ti7(μ3-O)2 (OiPr)6(μ-OiPr)6(O3PBnBr)6 (Ti7P6). The formation of covalent bonds between PBE and clusters was confirmed by the appearance of νC–O–Ti in the Fourier transform infrared spectra. In addition, the acetylacetonato group in Ti4P4 was dissociated by the hydroxyl group in PBE. The structure of the clusters in PBE was verified by a model reaction of these clusters with alcohols, such as ethanol and isopropyl alcohols, as monitored by nuclear magnetic resonance spectroscopy. The influence of the cluster structure was estimated based on the transmittance, thermal stability, and swelling tests with tetrahydrofuran. The transmittance of the hybrid films was worse than that of pure PBE. The temperature of 5% weight loss (Td5) of the hybrid films was lower than that of pure PBE because Ti–O–C bonding was formed. The solvent uptake of the hybrid films was clearly dependent on the clusters. The swelling ratio increased in the order of Ti7P6 < Ti4P4 < Ti4P3; hence, Ti7P6 showed the highest cross-linking efficiency. We synthesized poly(bisphenol A-co-ephichlorohydrin)–titanium phosphonate clusters (Ti4P3: [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(O3PPh)3]·thf; Ti4P4: [Ti(OiPr)(acac)(O3PPh)]4; Ti7P6: Ti7(μ3-O)2 (OiPr)6(μ-OiPr)6(O3PBnBr)6). From the result of swelling test using tetrahydrofuran, Ti7P6 cluster showed highest cross-linking efficiency.

Properties and surface morphologies of organic–inorganic hybrid thin films containing titanium phosphonate clusters

Organic–inorganic hybrid thin films containing [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(O3PPh)3]·THF (TiOPPh) were prepared via the hybridization of TiOPPh with poly(vinyl phenol) (PVP), poly(styrene-co-allyl alcohol) (PSA), and poly(bisphenol A-co-epichlorohydrin) (PBE) using spin coating. These thin films were characterized in terms of their transmittance, pencil hardness, and surface morphologies. The transmittance values of the PVP hybrid thin films decreased with the addition of TiOPPh because of the formation of Ti–O–Ph bonds. The pencil hardness values of the hybrid thin films were in the order PVP > PBE > PSA hybrids. Using confocal laser scanning microscopy and atomic force microscopy, the pencil hardness values were determined to be strongly dependent on the surface morphology, such as the roughness and presence of pin holes. The model cluster was synthesized by the reaction of TiOPPh with excess ethanol to study the structures of the TiOPPh in hybrids. From the nuclear magnetic resonance spectroscopy and single-crystal X-ray structure analyses, the main core structure of the model cluster was found to retain the core structure of TiOPPh. Organic–inorganic hybrid thin films containing [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(O3PPh)3]·THF (TiOPPh) as element blocks were prepared via hybridization with the hydroxyl-substituted organic polymers (PVP, PSA, or PBE) by spin-coating. The hybrid thin films were characterized by AFM, DSC, and pencil hardness. The pencil hardness values of the PVP hybrid thin films were in the order 20 > 40 > 0 wt% and were dependent on the surface smoothness. When TiOPPh was reacted with excess ethanol, the core was retained. Therefore, the core of TiOPPh will be retained in the hybrid polymers.

Synthesis, characterization and properties of titanium phosphonate clusters

Titanium phosphonate clusters were synthesized by the reactions of titanium tetraisopropoxide (Ti(OiPr)4) with arylphosphonic acids (ArPO3H2, Ar = Ph, 1-Nap, 4-MeOPh, 4-FPh, 4-ClPh, 4-BrPh, and 4-BrBn) and H2O in tetrahydrofuran (THF) at room temperature. [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(O3PAr)3]·solv (Ar = Ph (1), 1-Nap (2), 4-MeOPh (3), 4-FPh (4), 4-ClPh (5); solv = thf for 1 and 2 or 2-propanol for 3–5) were isolated as new Ti4P3-type clusters, while Ti7(μ3-O)2(OiPr)6(μ-OiPr)6(O3PBnBr)6 (6) was isolated as a Ti7P6-type cluster. A co-crystal of Ti4P3- (7a) and Ti7P6-type (7b) clusters were obtained when 4-BrPhPO3H2 was used, and [Ti(OiPr)(acac)(O3PPh)]4 (8), a new cage cluster, was obtained when Ti(acac)2(OiPr)2 (Hacac = acetylacetone) was reacted with PhPO3H2.

Titanium Phosphonate Based Metal–Organic Frameworks with Hierarchical Porosity for Enhanced Photocatalytic Hydrogen Evolution

AbstractPhotocatalytic hydrogen production is crucial for solar‐to‐chemical conversion process, wherein high‐efficiency photocatalysts lie in the heart of this area. A photocatalyst of hierarchically mesoporous titanium phosphonate based metal–organic frameworks, featuring well‐structured spheres, a periodic mesostructure, and large secondary mesoporosity, are rationally designed with the complex of polyelectrolyte and cathodic surfactant serving as the template. The well‐structured hierarchical porosity and homogeneously incorporated phosphonate groups can favor the mass transfer and strong optical absorption during the photocatalytic reactions. Correspondingly, the titanium phosphonates exhibit significantly improved photocatalytic hydrogen evolution rate along with impressive stability. This work can provide more insights into designing advanced photocatalysts for energy conversion and render a tunable platform in photoelectrochemistry.

Titanium Phosphonate Based Metal-Organic Frameworks with Hierarchical Porosity for Enhanced Photocatalytic Hydrogen Evolution.

Photocatalytic hydrogen production is crucial for solar-to-chemical conversion process, wherein high-efficiency photocatalysts lie in the heart of this area. A photocatalyst of hierarchically mesoporous titanium phosphonate based metal-organic frameworks, featuring well-structured spheres, a periodic mesostructure, and large secondary mesoporosity, are rationally designed with the complex of polyelectrolyte and cathodic surfactant serving as the template. The well-structured hierarchical porosity and homogeneously incorporated phosphonate groups can favor the mass transfer and strong optical absorption during the photocatalytic reactions. Correspondingly, the titanium phosphonates exhibit significantly improved photocatalytic hydrogen evolution rate along with impressive stability. This work can provide more insights into designing advanced photocatalysts for energy conversion and render a tunable platform in photoelectrochemistry.

Preparation and ammonia adsorption performance of titanium phosphonate adsorbent materials with hierarchically porous structure

Titanium phosphonate adsorbent materials with hierarchically porous structure were fabricated using the hydrolysis of tetrabutyl titanate in different organophosphonic acids solutions. Based on the macroporous structure of 100-2000 nm in size, a worm-hole like mesostructure was in the macropore walls, which was supported by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 sorption analysis. Fourier transform infrared spectroscopy (FT-IR) data indicated the organic groups inside the solid materials framework. NH3 adsorption detection was performed using titanium phosphonate adsorbent materials and some significant results were obtained. The adsorption mechanism was also discussed in this study. Large adsorption amount (75.2 mg/g) was mainly attributed to the acid site via acid-base reactions and the physical adsorption site via Van der Waals forces. Resultant materials could effectively restrain the desorption of adsorbent NH3 back into air causing secondary pollution, so it could make a promising potential use in decontamination of gas pollutants in the future.

Preparation and properties of organic–inorganic hybrid materials using titanium phosphonate cluster

Organic–inorganic hybrids containing [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(O3PPh)3]·thf as element-blocks were prepared by hybridization with poly(dimethylsiloxane), poly(methylsilsesquioxane), poly(ethoxysilsesquioxane), poly(methyl methacrylate), poly(vinyl alcohol), poly(4-vinylphenol), poly(styrene-co-allyl alcohol) or poly(bisphenol A-co-epichlorohydrin). The concentration of the titanium cluster was increased to 40 wt% to form crack-free films with high transparency. The temperature at which 10 wt% weight loss occurred increased with the concentration of the titanium cluster because an alcohol exchange reaction was expected between the titanium cluster and polymers. The mechanical strengths and strains of poly(dimethylsiloxane) hybrids were very low. The tensile strengths and elongations of poly(methyl methacrylate) hybrids increased with the increase in the titanium cluster concentration. The tensile strengths and elongations of poly(vinyl alcohol) hybrids were highest when the titanium cluster concentration was 10 wt%. Organic–inorganic hybrids containing [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(O3PPh)3]·thf (TiOPPh) as element-blocks were prepared by hybridization with silicone polymers (poly(dimethylsiloxane) (PDMS), poly(methylsilsesquioxane) (PMS) or poly(ethoxysilsesquioxane) (PEOS)), the hydroxyl groups substituted organic polymers (poly(vinyl alcohol) (PVA), poly(4-vinylphenol), poly(styrene-co-allyl alcohol) or poly(bisphenol A-co-epichlorohydrin) (PBE)) or poly(methyl methacrylate) (PMMA). The concentration of TiOPPh was increased to 40 wt% to form free-standing hybrid films with PDMS, PMS, PVA and PBE polymers. The tensile strengths and elongations of PMMA and PVA films were higher improved than only polymers because TiOPPh acted good crosslinkers.

Preparation and properties of organic–inorganic hybrid polymer films using [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(PhPO3)3]·thf

Titanium phosphonate (TiOPPh: [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(PhPO3)3]·thf) was synthesized. TiOPPh was mixed with poly(methyl methacrylate) (PMMA) or poly(vinyl alcohol) (PVA) to prepare organic–inorganic hybrid polymer films. The film using PMMA was formed by the interaction between organic and inorganic components. The temperatures of 10% weight loss of TiOPPh–PMMA were 30 °C higher than that of PMMA only. The film using PVA was formed by the alcohol exchange reaction between TiOPPh and PVA. The transparency of TiOPPh-PVA in the visible region was higher than that of PVA only.

Acid–Base Bifunctional Periodic Mesoporous Metal Phosphonates for Synergistically and Heterogeneously Catalyzing CO2 Conversion

Integrating multiple functions into one host for improved catalytic performance is challenging and promising for both catalysis and material science. Herein a new acid–base bifunctional periodic mesoporous titanium phosphonate hybrid material is synthesized by a facile one-pot hydrothermal method, using alendronate sodium trihydrate as a coupling molecule. The new material possesses highly periodic mesopores with a large specific surface area of 540 m2 g–1 and pore volume of 0.43 cm3 g–1, favoring the smooth mass transport of reactants and products during the catalytic reaction. It also has an organic–inorganic hybrid framework with homogeneously incorporated phosphonate groups, in which a large number of accessible acidic P–OH and basic −NH2 sites can, respectively, activate aziridine and CO2, synergistically leading to the high conversion (>99%), yield (98%), and regioselectivity (98:2) for the CO2 cycloaddition reaction. The catalytic activity is better than that of the scarcely reported heterogeneous ...

Applications of mesoporous titanium phosphonate functionalized with carboxylic groups

Mesoporous titanium phosphonate functionalized with –COOH was synthesized by a simple co-condensation process with the use of 2-phosphonoacetic acid and titanium tetrachloride under acid conditions. The obtained mesoporous materials show high surface area and large pore volume, which were supported by XRD, TEM, SEM and N2 adsorption analysis. The integrity of the organophosphonate groups were further characterized by FTIR and NMR. Palladium nanoparticles were successfully supported onto the materials combined with a metal adsorption–reduction procedure, showing high activity for the Suzuki reaction. Furthermore, the obtained catalyst can be recovered and reused without significant decrease in catalytic activity.

Adsorption of Methylene Blue from Aqueous Solution by Periodic Mesoporous Titanium Phosphonate Materials

Periodic mesoporous titanium phosphonate (PMTP-1) materials were synthesized and used as an adsorbent for the removal of a cationic dye, methylene blue (MB), from aqueous solutions. The PMTP-1 powder has a uniform mesopore size of 2.9 nm with high surface area of 606 m2/g. The batch-dye adsorption experiments were performed under various conditions including contact time, adsorbent dose, initial MB concentration, solution pH and temperature. The adsorption equilibrium was achieved after 30 minutes of contact time, and the adsorption of MB on PMTP-1 was best fitted to the Langmuir isotherm model with the maximum monolayer adsorption capacity of 617.28 mg/g. Thermodynamic parameters such as ΔG, ΔH and ΔS were calculated. Results of kinetic studies indicated that the adsorption process followed the pseudo-second-order model, which suggests that the process might be a chemisorption. The study results indicate that the PMTP-1 powder could be used as an efficient adsorbent for the removal of textile dyes from e...

Self-assembled titanium phosphonate nanomaterial having a mesoscopic void space and its optoelectronic application

Here we report the synthesis of a new crystalline titanium phosphonate material (HTiP-7) having a self-assembled nanostructure and a mesoscopic void space without the aid of any surfactant or templating agent. The material has been synthesized hydrothermally through the reaction between benzene-1,3,5-triphosphonic acid (BTPA) and titanium(iv) isopropoxide at neutral pH at 453 K for 24 h. This hybrid phosphonate material has been thoroughly characterized by powder X-ray diffraction, N2 sorption, HR TEM, FE SEM, TG-DTA, FT IR and UV-Vis diffuse reflectance spectroscopic studies. Two very well-known software packages, REFLEX and CELSIZ unit cell refinement programs, are employed to establish the triclinic crystal phase of this hybrid material (HTiP-7). Very tiny nanocrystals of HTiP-7 self-aggregated to form spherical nanoparticles of dimension ca. 25 nm together with a mesoscopic void space and good BET surface area (255 m(2) g(-1)). The framework is thermally stable up to 650 K. The material showed excellent carrier mobility for photocurrent generation in the presence of a photosensitizer molecule (Rose Bengal). To the best of our knowledge this is the first report of a photon-to-electron energy transfer process over a dye doped titanium phosphonate nanomaterial.

Achiral Ruthenium Catalyst Encapsulated in Titanium Phosphonate Homochiral Peptide-Based Solids for Enantioselective Hydrogenation of Ketones to Secondary Alcohols

Asymmetric homogeneous catalysis is well established, but the design of new chiral catalysts and the optimization of an existing catalytic system are time- and manpower-exhausting processes. Desirable, heterogeneous, chiral analogues to facilitate catalyst recovery are relatively rare or function poorly. Here we further develop our strategy for facile adaptation of known reactions involving homogeneous achiral catalysts to those involving heterogeneous asymmetric catalysts by use of a homochiral solid scaffold and show the generality of this concept, from hydrolysis and oxidation reactions to hydrogenations. In this case, an inexpensive “off-the shelf” achiral hydrogenation catalyst, RuIICl2(R2PCH2CH2NH)2, R = Ph, i-Pr, or t-Bu, embedded within a homochiral matrix is an enantioselective, recyclable heterogeneous catalyst for ketone hydrogenation. The amorphous matrix consists of tripodal poly(phenylglycine) capped with phosphonate moieties and cross-linked with titanium oxide. Hydrogenation of acetophenone derivatives can proceed with high enantioselectivity (up to 95% ee), and catalyst recycling by filtration is very effective.

Increasing the H+ exchange capacity of porous titanium phosphonate materials by protecting defective P–OH groups

Hierarchically macro-/mesoporous titanium phosphonates with enlarged H(+) exchange capacity were synthesized in the presence of a series of alkyl amines that acted as protective groups for the defective P-OH, which were used as promising solid acid catalysts to replace conventional liquid acid catalysts and acidic resins in some acid-catalytic reactions.

Hierarchical mesostructured titanium phosphonates with unusual uniform lines of macropores

Organic-inorganic hybrid materials of mesostructured titanium phosphonates with unusual uniform lines of macropores were synthesized by using bis(hexamethylenetriamine) penta(methylenephosphonic acid) (BHMTPMP) as the coupling molecule, through a one-pot hydrothermal process without any surfactant assistance. A wormhole-like mesostructure and many uniform parallel lines of macropores divided by solid ridges in the same direction were confirmed by N(2) sorption, SEM and TEM observations. This novel macropore architecture has never been observed in other metal phosphonate materials, which may be directly related to the structure nature of BHMTPMP with extra long alkyl chains. The structural characterization of FT-IR and MAS NMR revealed the integrity of organic groups inside the hybrid framework. The hybrid materials were also used as adsorbents for heavy metal ions and CO(2), in order to clarify the impacts of the organic contents and organic types on the physicochemical properties of the synthesized hierarchical macro-/mesoporous phosphonate materials.