Thermal analysis of quinolinium tetrachloroferrate(III)

Thermal decomposition of a compound consisting of a tetrachloroferrate(III) anion and a quinolinium cation, of general formula [QH][FeCl₄], has been studied using TG-FTIR, TG-MS, DTA and DTG techniques. The measurements were carried out in an argon atmosphere over the temperature range 20-800 °C. The solid products of the thermal decomposition were identified by IR, FIR and Mössbauer spectroscopy.     

Synthese,IR-Spektrum und Kristallstruktur von N,N'-Bis(trimethylsilyl)benzamidinium-tetrachloroferrat(III)

Synthesis, IR Spectrum, and Crystal Structure of N,N'-Bis(trimethylsilyl)benzamidinium Tetrachloroferrate(III) The title compound [C₆H₅? C(NHSiMe₃)₂][FeCl₄] is obtained by the reaction of FeCl₃ with N,N,N'-tris(trimethylsilyl)benzamidine in the presence of tetrahydrofurane, forming yellow, moisture sensitive crystals. The compound is characterized by its IR spectrum as well as by an X-ray structure determination. Space group P2₁/n, Z = 8, 5974 independent observed reflexions, R = 0.066. The lattice dimensions are at ?70°C: a = 2110.7, b = 1109.5, c = 2120.4 pm; β = 111.17º. The compound forms ion pairs, in which the H atoms of the amidinium cation are coordinated with one chlorine ligand of the FeCl₄^? ion in a chelating manner.     

Studies on the thermal decomposition of the silver group of alkali metal nitritocobaltates(III)

The thermal decomposition of nitritocobaltate(III) of the silver group of general formula M₂Ag[Co(NO₂)₆] (where M = K⁺, NH⁺₄, Rb⁺ or Cs⁺) has been investigated. Based on the thermal curves of the investigated compounds and chemical and diffractometric analysis, the mechanism of thermal decomposition has been determined. The results obtained indicate that the decomposition proceeds in three stages. As a result of decomposition in the first stage (300°C), nitrates of alkali metals, metallic silver and Co₃O₄ are formed. In the second stage (500°C), a partial decomposition of nitrates to alkali metal oxides occurs, and in the third stage the products are alkali metal oxides, silver and Co₃O₄. This paper also presents the dependence of the decomposition temperature of nitritocobaltates(III) of the silver group on the ionic radius of the outer-sphere cation.     

Thermisches Verhalten von Caesiumchloroferraten(III) und Caesiumchloroferrat(III)-Hydraten Zum Phasendiagramm des Systems CsCl?FeCl3

Thermal Behaviour of Cesium Chloroferrates(III) and Cesium Chloroferrate(III) Hydrates. On the Phase Diagram of the CsCl? FeCl₃ System The thermal behaviour of CsFeCl₄, Cs₂Fe(H₂O)Cl₅, and Cs₃FeCl₆ · H₂O has been studied by simultaneous thermal analysis up to 500°C, x-ray diffraction, and Raman spectroscopy. Anhydrous Cs₃FeCl₆ is metastable up to 280°C. Anhydrous Cs₂FeCl₅ does not exist. The decomposition of Cs₃Fe₂Cl₉ at 270°C yields CsCl and CsFeCl₄. This solid phase reaction is reversible. The corrected phase diagram of the system CsCl? FeCl₃ is presented basing on experimental results.     

Investigation of the Reaction of Roasted Serpentine Ore with Some Ammonium Salts

The reaction between roasted serpentine ore and ammonium sulfate was studied at the range of temperature 250–1000°C using different molar ratios to determine the maximum extraction of magnesia and also to characterize the different reaction products. The maximum extraction of MgO from the roasted ore reached 92.4% at 400°C. It was found from XRD that ammonium magnesium sulfate [(NH₄)₂Mg₂(SO₄)₃] was produced as the main product at 400°C, which decomposes to magnesium sulfate at 500–600°C. The last compound decomposes to magnesium oxide at 900–1000°C. Thermal analysis of the reaction mixture confirmed the results obtained by XRD. Extraction of magnesia by ammonium chloride at 300–400°C showed low percentage of extraction (7.8%). Comparison was made between using ammonium chloride instead of sulfate taking into consideration the thermal decomposition products of both ammonium salts. Extraction of magnesia from the roasted ore by aqueous ammonium sulfate or ammonium chloride showed good results.     

Evaluation of cation influence on the formation of M(II)Cr2O4 during the thermal decomposition of mixed carboxylate type precursors

This paper reports an investigation regarding the influence of the cation M(II) (M = Zn, Ni, Mg) on the formation of MCr₂O₄ by thermal decomposition of the corresponding M(II),Cr(III)-carboxylates (precursors) obtained by redox reaction between the corresponding metal nitrates and 1,3-propanediol. The decomposition products at different temperatures have been characterized by FT-IR spectroscopy and thermal analysis. Thus, we have evidenced that by thermal decomposition of the studied precursors in the range 250–300 °C, different amorphous oxidic phases mixtures form depending on the nature of metalic cation: (Cr₂O_3+x + ZnO) (Cr₂O_3+x + Ni/NiO) and (Cr₂O_3+x+MgO). In case of M = Zn, around 400 °C when the transition Cr₂O_3+x to Cr₂O₃ takes place, zinc chromite nuclei form by the interaction ZnO with Cr₂O₃. In case of M = Ni, due to the partial reduction of Ni(II) at Ni(0) during the thermal decomposition of the precursor the formation of nickel chromite by the reaction NiO + Cr₂O₃ is shifted toward 500 °C, when Ni is oxidized at NiO. The thermal evolution of the mixture (MgO + CrO₃) is different due to the formation as intermediary phase of MgCrO₄, which decomposes to MgCr₂O₄ around 560 °C. In order to investigate the chromites formation mechanism, we have studied the mechanical mixtures of single oxides obtained from the corresponding carboxylates. These mixtures (MO + Cr₂O₃) have been annealed at 400, 500, and 600 °C to study the evolution of the crystalline phases. It results in the prepared mixture behaving different from the mixtures obtained by thermal decomposition of the binary M(II),Cr(III)-carboxylates, recommending our synthesis method for obtaining binary oxides.     

Thermisches Verhalten von Caesiumchloroferraten(III) und Caesiumchloroferrat(III)-Hydraten. II. Die Rehydratation der Zersetzungsprodukte von Cs3[FeCl6] – Eine ramanspektroskopische Untersuchung unter definierter Wasserdampfatmosphäre [1]

The Thermal Behaviour of Caesiumchloroferrates(III) and Caesiumehloroferrate(III) Hydrates. II. The Rehydration of Decomposition Products of Cs₃[FeCl₆] — A Raman Spectroscopic Study under Definite Atmosphere of Water Vapour Cs₃[FeCl₆] formed by dehydration of Cs₃[FeCl₆] · H₂O at about 160°C does not change at normal atmosphere within 3 till 4 hours. Rehydration under the vapour pressure of the eliminated water yields the monohydrate in nearly the same time. In the same manner rehydration of the solid mixture of Cs[FeCl₄] and 2 CsCl formed by thermal decomposition of the metastable Cs₃[FeCl₆] (280°C) produces the intermediates Cs₃[Fe₂Cl₉] and Cs₂[Fe(H₂O)Cl₅] in mixtures with CsCl and, finally, Cs₃[FeCl₆] · H₂O. The formation of Cs₃[Fe₂Cl₉] from Cs[FeCl₄] and CsCl is accelerated by water. The reaction cycle has been studied using Raman and IR spectroscopy. The results will be discussed with respect to thermoanalytical data.     

Studies on the thermal decomposition of alkali metal thiosulphatobismuthates(III)

The thermal decomposition of thiosulphatobismuthates(III) of alkali metals was investigated. The general formulae of the thiosulphatobismuthates are M₃[Bi(S₂O₃)₃]·H₂O where M = Na, K, Rb or Cs, and M₂Na[Bi(S₂O₃)₃]·H₂O where M = K or Cs.Typical thermal curves for thiosulphatobismuthates(III) and the results obtained in thermal, X-ray, chemical and spectrophotometrical analyses of the decomposition products are shown. The results were used to determine three stages of the thermal decomposition. At the first stage, at about 200°C, hydrated compounds are dehydrated. At the second stage, above 200°C, there is a rapid decrease in mass which is caused by evolving sulphur dioxide; bismuth sulphide and an intermediate decomposition product are formed. At about 320°C the thermal decomposition products are bismuth sulphide and alkali metal sulphate.     

Thermal decomposition behaviour of lanthanum(III) tris-tartrato lanthanate(III) decahydrate

Lanthanum(III) tris-tartrato lanthanate(III) decahydrate, La[La(C₄H₄O₆)₃]·10H₂O has been synthesized and characterized by elemental analysis, IR, electronic spectral and X-ray powder diffraction studies. Thermal studies (TG, DTG and DTA) in air showed a complex decomposition pattern with the generation of an anhydrous species at ~170°C. The end product was found to be mainly a mixture of La₂O₃ and carbides at ~970°C through the formation of several intermediates at different temperature. The residual product in DSC study in nitrogen at 670°C is assumed to be a similar mixture generated at 500°C in TG in air. Kinetic parameters, such as, E*, ΔH, ΔS, etc. obtained from DSC are discussed. IR and X-ray powder diffraction studies identified some of the decomposition products. The tentative mechanism for the thermal decomposition in air of the compound is proposed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Waste poly(vinyl chloride) pyrolysis with hydrogen chloride abatement by steelmaking dust

Experimental study on PVC-based materials (PVC = poly(vinyl chloride)) pyrolysis; in the presence of various amounts of steelmaking dust was performed. Dust from steel manufacture employing zinc plated scrap contains a considerable amount of zinc oxide (ZnO) and its utilization in metallurgy is quite complicated. However, the dust can react with hydrogen chloride (HCl) released from heated PVC in the temperature range of 200–400°C. Material balance of the pyrolysis process was studied by thermogravimetry, and the data obtained were compared with the results of larger laboratory oven experiments. In excess of PVC, the amount of captured HCl stoichiometrically corresponds to the content of ZnO; additional HCl is probably captured by FeCl₂, while FeCl₃ is not formed at elevated temperatures. In excess of the dust, the captured amount of HCl is approximately 100%. The suggested co-pyrolysis seems to be a promising method to prevent the formation of dangerous chlorinated organic compounds during the thermal treatment of waste PVC. Furthermore, the obtained ZnCl₂ is a valuable material and the zinc depleted dust can be reused in metallurgy instead of its disposal.     

Research on pyrolysis of PCB waste with TG-FTIR and Py-GC/MS

The purpose of this study is to determine the pyrolysis characteristics and gas product properties of printed circuit board (PCB) waste. For this purpose, a combination of Thermogravimetry-Fourier Transform Infrared Spectrum (TG-FTIR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) techniques is employed. In the TG-FTIR experiment, a heating rate of 10?°C min^?1 and a terminal pyrolysis temperature of 600?°C are applied. The thermal decomposition temperature, weight losses, and the temperature trend of evolving gaseous products of PCB waste are investigated. Py-GC/MS is used for the qualitative and semi-quantitative analysis of the higher-molecular-weight volatile decomposition products. Associated with the analysis results of TG-FTIR and Py-GC/MS for the volatile products, PCB waste degradation could be subdivided into three stages. The main products in the first stage (<293?°C) are H₂O, CH₄, HBr, CO₂ and CH₃COCH₃. High-molecular-weight organic species, including bromophenols, bisphenol A, p-isopropenyl phenol, phenol, etc., mainly evolve in the second stage. In the last stage, at temperature above 400?°C, carbonization and char formation occur. This fundamental study provides a basic insight of PCB waste pyrolysis.     

Thermal decomposition of ammonium cerous carbonate

The thermal decomposition of ammonium ceryl(III) carbonate (ACeC) [NH₄CeO(CO₃)] was investigated by thermogravimetry, differential thermal analysis and X-ray diffraction. The results showed three endothermic stages of decomposition, each involving a loss in weight. The first stage, at 65.5 °C, is characteristic of the removal of adsorbed water, the second stage, at 214.8 °C, is associated with ammonia release, and the third stage, at 263.6 °C, relates to the removal of carbon dioxide.     

Thermal analysis and spectroscopic characteristics of tetrabutylammonium tetrachloroferrate(III)

The IR, far-IR, Raman and Mössbauer spectra have been utilized to identify a new compound consisting of a tetrachloroferrate(III) anion and a tetrabutylammonium cation [(C₄H₉)₄N][FeCl₄]. Its degradation has been studied by thermal analysis using TG, TG-MS, DTG and DTA, as well as DSC techniques. The measurements were run in static air and in argon atmosphere. Solid residues were identified by elemental analysis, far-IR and Mössbauer spectroscopy. The discussion was focused on processes proceeding during the first step of the thermal decomposition.     

Reactivity of Ammonium Halides: Action of Ammonium Chloride and Bromide on Iron and Iron(III) Chloride and Bromide

Ammonium chloride and bromide, (NH₄)Cl and (NH₄)Br, act on elemental iron producing divalent iron in [Fe(NH₃)₂]Cl₂ and [Fe(NH₃)₂]Br₂, respectively, as single crystals at temperatures around 450 °C. Iron(III) chloride and bromide, FeCl₃ and FeBr₃, react with (NH₄)Cl and (NH₄)Br producing the erythrosiderites (NH₄)₂[Fe(NH₃)Cl₅] and (NH₄)₂[Fe(NH₃)Br₅], respectively, at fairly low temperatures (350 °C). At higher temperatures, 400 °C, iron(III) in (NH₄)₂[Fe(NH₃)Cl₅] is reduced to iron(II) forming (NH₄)FeCl₃ and, further, [Fe(NH₃)₂]Cl₂ in an ammonia atmosphere. The reaction (NH₄)Br + Fe (4:1) leads at 500 °C to the unexpected hitherto unknown [Fe(NH₃)₆]₃[Fe₈Br₁₄], a mixed‐valent Fe^II/Fe^I compound. Thermal analysis under ammonia and the conditions of DTA/TG and powder X‐ray diffractometry shows that, for example, FeCl₂ reacts with ammonia yielding in a strongly exothermic reaction [Fe(NH₃)₆]Cl₂ that at higher temperatures produces [Fe(NH₃)]Cl₂, FeCl₂ and, finally, Fe₃N.     

A study of the thermal decomposition of Se2O2F8 and Te2O2F8, using molecular beam techniques

The thermal decomposition of the vapor phases of the oxygen bridged dimers Se₂O₂F₈ and Te₂O₂F₈ has been studied by mass spectrometry, electric deflection and flight time analysis on a molecular beam generated directly from the decomposition products. Se₂O₂F₈ begins to decompose at ?250°C; the principal products are SeF₄ and O₂, with SeOF₂ as a minor product. Decomposition is complete by ?500°C. There is some decomposition to monomeric SeOF₄ between 200 and 350°C. Te₂O₂F₈ did not begin to decompose until a temperature of 400°C was reached. Again, the principal products observed were TeF₄, O₂, and TeOF₂ with no evidence for decomposition to the monomeric TeOF₄.     

<Emphasis Type="Italic">In situ</Emphasis> powder X-ray diffraction study of the process of NiMoO<Subscript>4</Subscript>–SiO<Subscript>2</Subscript> reduction with hydrogen

An interest in NiMoО₄–SiO₂ reduction stems from its promising use as catalysts for hydrodeoxygenation and hydrodesulfurization processes. The work exploits in situ X-ray diffraction to investigate phase transformations during NiMoO₄–SiO₂ reduction with hydrogen in a temperature range of 30-700°C. The α-NiMoО₄ reduction is shown to proceed in two stages. In the first stage, at 400-500°C, an intermediate state (Ni,Mo,□)O mixed oxide and Ni_1–x Mo _x form. In the second stage, above 650°C, two solid solutions based on the Mo and Ni structures form. The structure of the intermediate state is refined by the Rietveld method. It is demonstrated that the Ni–Mo mixed oxide forms based on the NiO structure, which contains a certain number of cation vacancies.     

Polyhydrogenchloride: Bildung und Kristallstruktur der tiefschmelzenden Addukte Me2S · 4HCl und Me2S · 5HCl

Poly(hydrogen chlorides): Formation and Crystal Structure of the Low-melting Adducts Me₂S · 4HCl and Me₂S · 5HCl The melting diagram of the system dimethylsulfide-hydrogen chloride has been determined using difference thermal analysis. It shows the existence of three adducts Me₂S · nHCl with n = 1, 4 and 5 as well as melting points of ?91, ?53 and ?80°C (decomposition), respectively. The two phases richest in HCl have been further characterized by crystal structure analysis. Me₂S · 4HCl is orthorhombic with space group Pnma and Z = 4 formula units per unit cell of dimensions a = 14.842, b = 9.747 and c = 6.652 Å at ?150°C. Me₂S · 5HCl is monoclinic with P2₁/n and Z = 4 as well as a = 7.292, b = 12.537, c = 12.479 Å and β = 92.73° at ?168°C. The R values obtained with 1737 and 3047 independent observed reflections are 0.039 and 0.045, respectively. Both structures are ionic, according to [Me₂SH][Cl(HCl)_n?1], and shaped by hydrogen bonding.     

Characterization of the decomposition course of nickel acetate tetrahydrate in air

Thermogravimetry, differential thermal analysis, X-ray diffractometry and infrared spectroscopy showed that Ni(CH₃COO)₂·4H₂O decomposes completely at 500°C, giving rise to a mixture of Ni^o and NiO. The results revealed that the compound undergoes dehydration at 160°C and melts at 310°C. The water thus released hydrolyses surface acetate groups, acetic acid being evolved into the gas phase. At 330°C, the anhydrous acetate is converted into NiCO₃, releasing CH₃COCH₃ into the gas phase. The carbonate subsequently decomposes (at 365°C) to give NiO_(s), CO_2(g) and CO_(g). On further heating up to 373°C, a mixture of Ni^o and NiO is formed. Other gas-phase products were detected at 400°C, viz. CH₄ and (CH₃)₂CH=CH₂, which were formed in surface reactions involving initial gas-phase products. Non-isothermal kinetic parameters (A and ΔE) were calculated on the basis of temperature shifts experienced in the various decomposition processes as a function of heating rate (2–20 deg·min^?1).     

Synthesis of lithium ferrite by precursor and combustion methods: A comparative study

The thermal decomposition of lithium hexa(carboxylato)ferrate(III) precursors, (Li₃[Fe(L)₆]·xH₂O, L = formate, acetate, propionate, butyrate), has been carried out in flowing air atmosphere from ambient temperature upto 500 °C. Various physico-chemical techniques, i.e., TG, DTG, DTA, XRD, SEM, IR, Mössbauer spectroscopy, etc., have been employed to characterize the intermediates and end products. After dehydration, the anhydrous complexes undergo decomposition to yield various intermediates, i.e., lithium oxalate/acetate/propionate/butyrate, ferrous oxalate/acetate and α-Fe₂O₃ in the temperature range of 185–240 °C. A subsequent decomposition of these intermediates leads to the formation of nanosized lithium ferrite (LiFeO₂). Ferrites have been obtained at much lower temperature (255–310 °C) as compared to conventional ceramic method. The same nano-ferrite has also been prepared by the combustion method at a comparatively lower temperature (400 °C) and in less time than that of conventional ceramic method.     

Thermal decomposition of Prussian blue under inert atmosphere

The thermal decomposition of Prussian blue (iron(III) hexacyanoferrate) under inert atmosphere of argon was monitored by thermal analysis from room temperature up to 1000?°C. X-ray powder diffraction and ⁵⁷Fe M?ssbauer spectroscopy were the techniques used for phase identification before and after sample heating. The decomposition reaction is based on a successive release of cyanide groups from the Prussian blue structure. Three principal stages were observed including dehydration, change of crystal structure of Prussian blue, and its decomposition. At 400?°C, a monoclinic Prussian blue analogue was identified, while at higher temperatures the formation of various polymorphs of iron carbides was observed, including an orthorhombic Fe₂C. Increase in the temperature above 700?°C induced decomposition of primarily formed Fe₇C₃ and Fe₂C iron carbides into cementite, metallic iron, and graphite. The overall decomposition reaction can be expressed as follows: Fe₄[Fe(CN)₆]₃·4H₂O????4Fe?+?Fe₃C?+?7C?+?5(CN)₂?+?4N₂?+?4H₂O.