Ammonium Titanyl Oxalate Research Articles

PEDOT Films Doped with Titanyl Oxalate as Chemiresistive and Colorimetric Dual-Mode Sensors for the Detection of Hydrogen Peroxide Vapor.

Hydrogen peroxide (H2O2) is commonly used as an oxidizing, bleaching, or antiseptic agent. It is also hazardous at increased concentrations. It is therefore crucial to monitor the presence and concentration of H2O2, particularly in the vapor phase. However, it remains a challenge for many state-of-the-art chemical sensors (e.g., metal oxides) to detect hydrogen peroxide vapor (HPV) because of the interference of moisture in the form of humidity. Moisture, in the form of humidity, is guaranteed to be present in HPV to some extent. To meet this challenge, herein, we report a novel composite material based on poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) doped with ammonium titanyl oxalate (ATO). This material can be fabricated as a thin film on electrode substrates for use in chemiresistive sensing of HPV. The adsorbed H2O2 will react with ATO, causing a colorimetric response in the material body. Combining colorimetric and chemiresistive responses resulted in a more reliable dual-function sensing method that improved the selectivity and sensitivity. Moreover, the composite film of PEDOT:PSS-ATO could be coated with a layer of pure PEDOT via in situ electrochemical synthesis. The pure PEDOT layer was hydrophobic, shielding the sensor material underneath from coming into contact with moisture. This was shown to mitigate the interference of humidity when detecting H2O2. A combination of these material properties makes the double-layer composite film, namely PEDOT:PSS-ATO/PEDOT, an ideal sensor platform for the detection of HPV. For example, upon a 9 min exposure to HPV at a concentration of 1.9 ppm, the electrical resistance of the film increased threefold, surpassing the bounds of the safety threshold. Meanwhile, the colorimetric response observed was 2.55 (defined as the color change ratio), a ratio at which the color change could be easily seen by the naked eye and quantified. We expect that this reported dual-mode sensor will find extensive practical applications in the fields of health and security with real-time, onsite monitoring of HPV.

Investigation into Low-Temperature Urea-Water Solution Decomposition by Addition of Titanium-Based Isocyanic Acid Hydrolysis Catalyst and Surfactant

<div class="section abstract"><div class="htmlview paragraph">Mitigation of urea deposit formation and improved ammonia production at low exhaust temperatures continues to be one of the most significant challenges for current generation selective catalytic reduction (SCR) aftertreatment systems. Various technologies have been devised to alleviate these issues including: use of alternative reductant sources, and thermal treatment of the urea-water solution (UWS) pre-injection. The objective of this work was to expand the knowledge base of a potential third option, which entails chemical modification of UWS by addition of a titanium-based urea/isocyanic acid (HNCO) decomposition catalysts and/or surfactant to the fluid. Physical solid mixtures of urea with varying concentrations of ammonium titanyl oxalate (ATO), oxalic acid, and titanium dioxide (TiO<sub>2</sub>) were generated, and the differences in NH<sub>3</sub> and CO<sub>2</sub> produced upon thermal decomposition were quantified. It was found that addition of 2.0 mol % ATO to urea increased CO<sub>2</sub> production by 821 % and NH<sub>3</sub> production by 96 % at temperatures ≤ 215 °C, indicating significantly enhanced hydrolysis of HNCO. Conversely, it was demonstrated that addition of oxalic acid or TiO<sub>2</sub> to urea exhibited little effect on NH<sub>3</sub> and CO<sub>2</sub> production, indicating both the importance of titanium in the mixture and adequate catalyst-substrate contact. Previous work by the authors demonstrated that addition of ATO to UWS did indeed result in decreased deposit formation in the exhaust system when compared to conventional UWS, and the extent of deposit reduction could be further enhanced by addition of surfactant to the solution. In this work, six distinct surfactants were added to UWS both with and without ATO, and the effect on deposit formation was quantified. In all cases, addition of both surfactant and ATO resulted in superior deposit mitigation when compared to UWS treated with ATO or surfactant individually. Finally, various ammonium peroxo-hydroxo titanium coordination complexes were synthesized and evaluated for catalytic urea decomposition using TGA-FTIR and compared against the observed activity of ATO.</div></div>

One-pot pyrolytic synthesis of C–N-codoped mesoporous anatase TiO2and its highly efficient photo-degradation properties

Polycrystalline mesoporous C–N-codoped anatase TiO2 has been successfully fabricated using a simple but efficient controlled thermal decomposition approach and their photo-degradation properties were evaluated. In such a synthesis, ammonium titanyl oxalate was first prepared and used as precursor. The C–N-codoped anatase TiO2 was then directly generated via the pyrolysis of the ammonium titanyl oxalate precursor and the resultant nano-sized crystallites connected together to form a mesoporous structure. The as-prepared material by calcination at 300 °C at a heating rate of 0.5 °C min−1 possessed a high surface area and showed extraordinarily high photocatalytic degradation properties under visible irradiation.

Synthesis of star shaped Ba 1− xSr xTiO 3 (BST) powders

Uniform star shaped strontium substituted barium titanyl oxalate Ba 1− x Sr x TiO(C 2O 4) 2 (BSTO)/strontium substituted barium titanate, Ba 1− x Sr x TiO 3 (BST) powders were prepared via a simple chemical co-precipitation route with x = 0.15, 0.20, and 0.25. The process involved an addition of 0.1 M solution of titanium tetrabutoxide (BTM) in isopropanol (IPA) to 0.1 M oxalic acid in IPA containing 0.2 M of H 2O to produce titanyl oxalate precipitate which was further reacted with 0.1 M solution of ammonium oxalate to obtain 0.1 M clear homogeneous solution of ammonium titanyl oxalate (ATO) with pH 4.25 containing titanium in the form of soluble anionic oxalate species [TiO(C 2O 4) 2 2−]. Stoichiometric quantities of barium hydroxide and strontium nitrate were dissolved in distilled water and its pH was adjusted nearly equal to that of ATO (∼4.15) by drop wise addition of dilute HNO 3 solution 1:10 (v/v). The addition of this mixed cation precursor solution to ATO solution resulted in precipitation of strontium substituted barium titanyl oxalate (BSTO) having star shaped morphology. The calcination of BSTO precursors at 730 °C for 4 h in air produced cubic BST powders ( a 0 ∼4.001, 3.996 and 3.991 Å for x = 0.15, 0.20, 0.25, respectively) having star shaped morphology. SEM, XRD and FTIR techniques were used to characterize the BSTO/BST powders.

Synthesis of rutile from ATO and stearic acid

Nanocrystalline titanium dioxide in the rutile phase has been obtained from the solid state reaction between ammonium titanyl oxalate (ATO) and stearic acid at 400 °C in air. The fine powders of ATO and stearic acid are mixed well using acetone in an agate mortar and pestle for 2 h. This mixture (weight ratio of ATO to stearic acid > 5) on heating at 400 °C produces rutile powders. For the ratios of ATO to stearic acid < 5, a mixture of anatase and rutile phases is obtained. Pure ATO yields anatase phase on decomposition at 400 °C. These powders were characterized by X-ray diffraction (XRD), BET surface area measurements and transmission electron microscopy (TEM) studies.

Simple oxalate precursor route for the preparation of barium–strontium titanate: Ba 1− xSr xTiO 3 powders

A simple one-step cation-exchange reaction between the stoichiometric solutions of ammonium titanyl oxalate (ATO) and barium hydroxide+strontium nitrate at room temperature (RT) is investigated successfully for the quantitative precipitation of barium–strontium titanyl oxalate (BSTO): Ba 1− x Sr x TiO(C 2O 4) 2·4H 2O ( x=0.25) precursor powders with nearly theoretical yield (≥99%). The pyrolysis of BSTO at 730 °C/4 h in air produced barium–strontium titanate (Ba 1− x Sr x TiO 3; BST) powders. The characterization studies on BSTO and BST powders by using various physico-chemical techniques: micro- and chemical analysis, differential thermal analysis (DTA)/thermo-gravimetric analysis (TGA), XRD, FTIR, X-ray fluorescence (XRF) and scanning electron microscopy (SEM) revealed that the powders formed are cubic, highly pure, stoichiometric and sub-micron-sized with nearly uniform size and shape distribution. The ceramic compacts obtained by sintering the BST pellets at 1300 °C/4 h showed density ∼95%, dielectric constant ɛ(Tc)∼9500, tan δ∼0.15% and T C∼32 °C.

Preparation of TiO 2 thin films by modified spin-coating method using an aqueous precursor

Modified spin-coating method has been applied to grow thin films of titanium dioxide. With this modification, it is possible to use ammonium titanyl oxalate in the form of its aqueous solutions as starting material. The resulting thin films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectroscopy and X-ray photoelectron spectroscopy (XPS). The results show that aqueous precursor form anatase TiO 2 thin films, which are qualitatively comparable to the films grown by other wet chemical techniques.

Simplified chemical route for the synthesis of barium titanyl oxalate (BTO)

A simple chemical route is developed to obtain an important molecular precursor (leading to barium titanate powders), namely barium titanyl oxalate (BTO) with nearly theoretical yield. In this route, 0.1 M alcoholic solution of titanium tetrabutoxide is reacted with 0.1 M alcoholic solution of oxalic acid to form titanyl oxalate (TiOC2O4). This was further converted to soluble ammonium titanyl oxalate (ATO); (NH4)2TiO(C2O4)2.H2O by reacting with an equimolar aqueous solution of ammonium oxalate (pH 4.25). Instead of using available barium salts (halide/nitrate/acetate) solution, a modified barium precursor solution with controlled pH (=4.2) is prepared for carrying out cation-exchange reaction with ATO. For this purpose the modified Ba-precursor solution is freshly prepared by partial neutralization of a 0.1 M aqueous solution of barium hydroxide with controlled addition of dilute HNO3 (1.1 M) solution. The pH of this solution is the same as that of the ATO solution. The exchange reaction between equimolar ATO and modified Ba-precursor solution precipitated barium titanyl oxalate (BTO) with a quantitative yield at room temperature. Submicron-sized, stoichiometric, pure BaTiO3 powders were obtained by the controlled pyrolysis of BTO in air. The present communication deals with the detailed analysis of this simplified method in producing BTO/BT powders and their characterization employing various physicochemical techniques.

Preparation and characterization of TiO 2 incorporated Y-zeolite

A preparation of TiO 2-dispersed Y-zeolite has been attempted by a method comprising a substantial ion-exchange of ammonium titanyl oxalate (NH 4) 2TiO(C 2O 4) 2 and its decomposition. The modification of Y-zeolite was well controlled from the viewpoint of the incorporated amount of TiO 2. The framework of Y-zeolite was retained through the modification and TiO 2 was incorporated in the form of anatase microcrystals. Titanium species bound to the framework through Ti–O–Si bonds were also observed by IR analysis. The porosity change of Y-zeolite by the TiO 2 modification was analyzed by N 2 adsorption at 77 K, and the pore size of TiO 2 modified Y-zeolite proved to increase with the amount of incorporated TiO 2. Photolysis of ethanol to give methane was enhanced by the TiO 2-dispersed Y-zeolite; the rate of reaction in the Pt–TiO 2–zeolite system of an appropriate amount of TiO 2 was more than five times that in a conventional Pt–TiO 2 system.

A new and simple method for the preparation of active Ti-? zeolite catalysts

Incorporation of titanium into the framework of zeolite beta was achieved by simply treating Al-β zeolite with an ammonium titanyl oxalate solution followed by air calcinations; the material obtained is a very active catalyst for the epoxidation of olefins.

Preparation, characterization and photoreactivity of titanium(IV) oxide encapsulated in zeolites

The preparation, characterization and photoreactivity of titanium(IV) oxide encapsulated inside either sodium- or ammonium-exchanged zeolite Y (NaY and NH4Y), mordenite (NaM and NH4M) or potassium zeolite L (KL) are presented. The material was prepared by an ion-exchange method with ammonium titanyl oxalate monohydrate aqueous solution, (NH4)2TiO(C2O4)2·H2O. The results of X-ray photoelectron spectroscopy, chemical analysis and photolysis studies support the contention that the exchanged titanium species locate dominantly inside the zeolite cavities, and not on the external surfaces. The TiO2+-exchanged zeolite exhibits characteristics of TiO2, such as photoreduction of methyl viologen to methyl viologen radical cation. A significant blue shift of the UV–VIS reflectance spectrum (onset ca. 330 nm), compared with those of bulk anatase and rutile TiO2, and a lack of an X-ray diffraction pattern of TiO2 in the TiO2–zeolite samples indicate that the particle size of the TiO2 encapsulated inside the zeolite is on the nanometre scale.

Thermal decomposition and creation of reactive solid surfaces: VI. thermal genesis course of titania catalyst from a novel ammonium titanyl oxalate precursor

The thermal decomposition course of ammonium titanyl oxalate monohydrate (ATO), (NH 4) 2[TiO(C 2O 4) 2] · H 2O, was explored in view of its possible employment as a promising titania precursor in supported titania catalysts prepared by impregnation and subsequent calcination. The investigation implemented thermal analysis of ATO, and characterization of its gas and solid phase calcination products (at 100–800°C) by means of infrared spectroscopy and X-ray diffractometry, to elucidate the pathways of the solid state reactions involved. The results revealed the occurrence of four endothermic weight loss processes (at 145–290 ° C) leading to formation of amorphous (at ⩾ 200–300°C), anatase-structured (at 350–700 ° C) and rutile-structured (at ⩾ 800°C) titania, via weight-invariant exothermic processes (maximized at 337, 408 and 773°C). Non-isothermal kinetic parameters ( k, A and Δ E) were calculated on the basis of the temperature shifts experienced at various heating rates (5, 10, 20 and 30 °C min −1) by the thermal events encountered.

The oxalato complexes of titanium(IV)—II: Precipitation with lead(II) in 0.5 M NaClO 4 solution

Titration studies of ammonium titanyl oxalate solutions with Pb(NO 3) 2 at an ionic strength of 0.5 M (NaClO 4) have shown that at pH > 1.5 precipitates are formed consisting of three compounds: PbTiO(C 2O 4) 2·4H 2O, PbC 2O 4 and Ti(OH) 4. The solubility product of lead titanyl oxalate (PTO) is (35 ± 2) times the solubility product of lead oxalate, i.e. log K PTO = −6.90 ± 0.03, when log K PO = −8.45 for lead oxalate as found by Klatt. The solubility product [Ti(OH) 2 2+][OH −] 2 was found to have the value log K TH = −30.5 ± 0.25. At low pH lead oxalate and titanium hydroxide dissolve. It is necessary to include a lead titanyl complex of unknown nature in calculation models for simulating equilibrium concentrations during titrations in order to explain the anomalously high dissolved lead(II) concentration. The solubility product calculated for PTO is not very sensitive to the different models. Lead and titanium contents of solutions equilibrated with solid PTO differed from the expected values based on the models for titrations. A satisfactory explanation for the low Ti(IV) and high Pb(II) concentrations can not yet be given.

ChemInform Abstract: THE CRYSTAL AND MOLECULAR STRUCTURE OF AMMONIUM TITANYL OXALATE

Chemischer InformationsdienstVolume 6, Issue 8 Organoelement Compounds ChemInform Abstract: THE CRYSTAL AND MOLECULAR STRUCTURE OF AMMONIUM TITANYL OXALATE G. M. H. VAN DE VELDE, G. M. H. VAN DE VELDESearch for more papers by this authorS. HARKEMA, S. HARKEMASearch for more papers by this authorP. J. GELLINGS, P. J. GELLINGSSearch for more papers by this author G. M. H. VAN DE VELDE, G. M. H. VAN DE VELDESearch for more papers by this authorS. HARKEMA, S. HARKEMASearch for more papers by this authorP. J. GELLINGS, P. J. GELLINGSSearch for more papers by this author First published: February 25, 1975 https://doi.org/10.1002/chin.197508393AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume6, Issue8February 25, 1975 RelatedInformation

Thermal Decomposition of Oxalates of Ammonium and Potassium

The thermal decomposition of oxalates of ammonium and potassium was studied by simultaneous TGA, DTA, and EGA (effluent gas analysis). Of the simple oxalates, the potassium compound is more stable than the lithium compound, as has been observed for the corresponding carbonates and sulfates. Ammonium oxalate is much less stable than either of the alkali metal oxalates. Potassium titanyl oxalate is less stable than potassium oxalate, and ammonium titanyl oxalate is more stable than ammonium oxalate.

Preparation of standard titanium(IV) solutions

The preparation of standard titanium(IV) solutions from conventional standards is critically reviewed and compared with the superior potentialities of the newly proposed primary standard ammonium dioxalato-oxotitanate(IV)(ammonium titanyl oxalate), (NH4)2TiO(C2O4)2.H2O. Two simple, rapid procedures for preparing titanium(IV) solutions are discussed, one of which gives an alkali metal free solution. These procedures are equally good and compare favourably with the methods at present in use.

Ammonium dioxalato-oxotitanate(IV): a new standard compound

Pure ammonium dioxalato-oxotitanate(IV), (ammonium titanyl oxalate), (NH4)2[TiO(C2O4)2].H2O, has been shown to be an excellent multi-purpose titanium reagent as it is easier to handle and has wider applications than the similar primary standards previously used. It can also be useful as an oxalate primary standard. On low temperature ignition the complex yields high purity titanium dioxide which may be of use in monocrystal production.