- Kinetics and mechanism of oxidation of 3,6-dioxa-1,8-octanedithiol and dl-dithiothreitol by a platinum(IV) complex
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A Pt(IV) complex [PtCl2(en)(heda)]Cl2 (heda = N-(2-hydroxyethyl)-ethylenediamine) has been synthesized and characterized by ESI-MS, 1H NMR, elemental analysis, and X-ray crystal structure analysis. Oxidations of dithiol compounds 3,6-dioxa-1,8-octanedithiol (DODT) and dl-dithiothreitol (DTT) by this complex were studied. The oxidation products were characterized as ten- and six-membered ring compounds for DODT and DTT, respectively, both containing an intramolecular disulfide bond. The kinetics of the oxidation reactions was followed by stopped-flow spectrophotometry over a wide pH range. The oxidations display an overall second-order character, being first-order each in [Pt(IV)] and in [dithiol]. A mechanism involving three parallel rate-determining steps is proposed, and the rate constants of the rate-determining steps have been evaluated.
- Lu, Yuyan,Hou, Xiaonan,Zhao, Xiaowei,Liu, Mengyu,Shen, Fugang,Ren, Yuanyuan,Liu, Yunxiao,Huo, Shuying,Shen, Shigang
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- Determination of chlorine in atmosphere by kinetic spectrophotometry
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A kinetic method for determination of chlorine in air was described in the present work. The method based on fading of methyl orange (MO) containing solution in air absorption process. A determination limit of 2.64 μg L -1 was found. With the present method, chlorine concentration could be determined in several minutes with convenient manipulation. As concentration variation of methyl orange in the absorption solution did not affect the experimental results, fabrication and preservation of the stock absorption is also convenient. The present method is promising in monitoring chlorine concentration in atmosphere.
- Meng, Jian-Xin,Wang, Xiao-Bo,Ruan, Ge-Lan,Li, Guo-Qiang,Deng, Zhao-Xia
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- Kinetic study of the chlorine electrode reaction on Ti/RuO2 through the polarisation resistance: Part III: Proposal of a reaction mechanism
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A kinetic mechanism for the chlorine electrode reaction (ClER) on Ti/RuO2 electrodes is proposed. The first step is the oxidation of the superficial sites, where the chloride ion is electroadsorbed giving the atomic chlorine intermediate. The later discharge of chlorine can take place either by recombination of two adsorbed intermediates or by the reaction between the intermediate and the chloride ion, being both chemical steps. The expression of the intrinsic polarisation resistance Rpo as a function of the activity of chloride aCl-o' and the partial pressure of chlorine p?Cl2 was obtained from the resolution of the kinetic mechanism and it was compared with experimental data. The correlations of the independent experimental relationships Rpo versus aCl-o' and Rpo versus p?Cl2 were remarkably good, giving strong evidence that the ClER takes place through the proposed mechanism on the RuO2 electrodes. The kinetic constants obtained from the correlations were used for the simulation of the dependences of the current density and the surface coverages on overpotential.
- Fernández,Gennero de Chialvo,Chialvo
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- Oxygen electrode reaction in a LiCl-KCl eutectic melt
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Oxygen electrode reaction was investigated on a boron-doped diamond electrode in a LiCl-KCl eutectic melt. The standard formal potential of O 2O2- decreases with the elevation of temperature. The potential at 773 K is 2.424±0.003 V v
- Kado, Yuya,Goto, Takuya,Hagiwara, Rika
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- Gas-phase reactions of ClONO2 with Cl-(D2O)n = 0-3 and NO2-
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The reactions of ClONO2 with the Cl-(D2O)n≤3 and NO2- ions were studied in a flow-tube apparatus at several temperatures in the range 170-298 K and at a helium buffer gas pressure of 0.28 Torr. Rate constants for these reactions were determined, establishing that all these ions react quite efficiently with ClONO2. The product ions observed in reaction sequences are reported, and reaction mechanisms are proposed to account for the findings. In the case of Cl- and NO2- the main product ion is NO3-, while the hydrates Cl-(D2O)n≤1-3 lead to production of the hydrated species, NO3-(D2O)m≤n-1. The main features of the observed secondary reactions can be described in terms of adduct formation and ligand switching. Limits on the bond energy of (NO3ClNO3)-, 14.6 kcal/mol≤D(NO3--ClONO2)≤26 kcal/mol, were determined. Finally, implications of these studies to atmospheric chemistry are discussed.
- Wincel,Mereand,Castleman Jr.
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- Mass transfer under bubble-induced convection in a vertical electrochemical cell
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Mass transfer under bubble-induced convection has been experimentally measured in a vertical cell. The cell consisted of two parallel vertical electrodes, upon one of which chlorine gas evolved and the other where the mass-transfer-controlled reduction of
- Shah,Jorne
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- Potentialities of low-temperature chlorination of aluminum and its alloys with uranium
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Potentialities of low-temperature (300-500°C) chlorination to remove the aluminum cladding of fuel elements and separate uranium and aluminum were studied.
- Lebedev,Sal'nikov,Tsvetov,Bychkov,Savochkin,Kormilitsyn
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- The hexakis(fluorosulfato)stannate(IV) ion
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Two synthetic routes to compounds containing the novel hexakis(fluorosulfato)stannate(IV) ion are discussed: Sn(SO3F)4 + 2ClO2SO3F → (ClO2)2[Sn(SO3F)6] and M2/su
- Yeats,Sams,Aubke
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- The oxidation of zinc and barium chlorides with oxygen to obtain chlorine and finely dispersed zinc oxide
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The regular features of the reaction of calcium, barium, and zinc chlorides with oxygen to form molecular chlorine and corresponding metal oxides are studied. The rate constants of the reaction were determined. The effective activation energies of oxidation of chloride ions were calculated with due to regard for the diffusion at the gas-chloride melt interface, which is especially pronounced at a temperature above 550°C. Zinc oxide being formed was separated from the reaction mixture, and the dispersion of its particles was determined. Pleiades Publishing, Ltd., 2010.
- Chekryshkin,Chudinov,Rozdyalovskaya,Fedorov
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- Crystal growth and crystal structures of six novel phases in the Mn/As/O/Cl(Br) system, as well as magnetic properties of α-Mn3(AsO4)2
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Chemical vapour transport reactions (900 °C → 820 °C, Cl2 or Br2 as transport agent) of in situ formed Mn3(AsO4)2 yielded the orthoarsenates(V) α-Mn3(AsO4)2 and β-Mn3(AsO4)2 as well as the oxoarsenate(V) halide compounds Mn7(AsO4)4Cl2, Mn11(AsO4)7Cl, Mn11(AsO4)7Br and Mn5(AsO4)3Cl. The crystal structures of all six phases were determined from single crystal X-ray diffraction data. The crystal structures of α-and β-Mn3(AsO4)2 are isotypic with the corresponding phosphate phases γ- and α-Mn3(PO4)2, respectively, and are reported here for the first time. A comparative discussion with other structures of general composition M3(AsO4)2 (М = Mg; divalent first-row transition metal) is given. The unique crystal structures of Mn7(AsO4)4Cl2 and that of the two isotypic Mn11(AsO4)7X (X = Cl, Br) structures are composed of two [MnO5] polyhedra, two [MnO4Cl2] polyhedra (one with site symmetry 1ˉ), two AsO4 tetrahedra, and one [MnO5] polyhedron, three [MnO6] octahedra (one with site symmetry.m.), one [MnO4X], one [MnO5X] polyhedron and four AsO4 tetrahedra, respectively. The various polyhedra of the three arsenate(V) halides are condensed into three-dimensional framework structures by corner- and edge-sharing. Mn5(AsO4)3Cl adopts the chloroapatite structure. The magnetic and thermal properties of pure polycrystalline samples of a-Mn3(AsO4)2 were investigated in more detail. The magnetic susceptibility proves all Mn atoms to be in the oxidation state +2 yielding an effective magnetic moment per Mn atom of 5.9 μB. Long-range antiferromagnetic ordering is observed below 8.2 K consistent with the negative Curie-Weiss temperature of ?50 K derived from the high temperature susceptibility data.
- Weil, Matthias,Kremer, Reinhard K.
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- The elusive halides VCl5, MoCl6, and ReCl6
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Vanadium pentachloride and molybdenum and rhenium hexachloride are all thermally unstable but can be prepared by metathesis from the corresponding fluorides with BCl3 at low temperatures. MoCl6 is structurally related to β-WCl6, and ReCl6 to α-WCl6. VCl5 is a dimer in the solid state (see structure; V red, Cl green). Copyright
- Tamadon, Farhad,Seppelt, Konrad
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- Oxidation of Co(II) by ozone and reactions of Co(III) in solutions of sulfuric acid
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Reactions of the oxidation of bivalent cobalt ions by ozone, of the spontaneous decomposition of trivalent cobalt, and of interactions between Co(III) and chloride ions in solutions of sulfuric acid are studied. The order and rate constant of the process of decomposition of Co(III) are determined. Information on the kinetics of the interaction between Co(III) and Cl– is obtained. Kinetic patterns of the accumulation of Co(III) during the ozonation of solutions of CoSO4 in sulfuric acid are explained. Molar absorption coefficients of Co(III) and Co2+ ions in the visible range of wavelengths are determined.
- Levanov,Isaikina, O. Ya.,Lunin
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- Kinetic study of the chlorine electrode reaction on Ti/RuO2 through the polarisation resistance: Part II: Mechanistic analysis
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A new methodology for the kinetic treatment of electrode reactions is presented. It is based on a theoretical analysis of the predictive capability of different mechanisms for the dependence of the polarisation resistance on the different operative variables. This procedure is applied in this case to the analysis of the chlorine electrode reaction on Ti/RuO2, for which the variation of the polarisation resistance on the activity of the chloride ions and on the partial pressure of the chlorine gas is derived. The descriptive capability of the mechanisms under discussion at present for this reaction is discussed and the theoretical dependences are compared with experimental data.
- Fernández,Gennero de Chialvo,Chialvo
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- Tensimetric investigation of the CrCl3-Cl2 system in the temperature range of 600-1200 K
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The sublimation pressure of chromium trichloride was measured by the static method with a quartz membrane-gauge manometer in the temperature range of 875-1230 K. An approximating equation for the sublimation pressure vs. temperature was found. The enthalpy (259.4±4 kJ mol-1) and the entropy (224.2±3.5 J mol-1 K-1) of sublimation at 298 K were calculated. For the process 2 CrCl3(g) + Cl2(g) = 2 CrCl4(g), the following values were obtained: Δr H°298 = -207.1±11.6 kJ mol-1 and Δr S°298 = -173.6±10 5 J mol-1 K-1.
- Zelenina,Semenova,Titov,Chusova
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- Nonlinear Optical Crystal Rb4Sn3Cl2Br8: Synthesis, Structure, and Characterization
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A new Sn-based halide compound, Rb4Sn3Cl2Br8, is synthesized by hydrothermal method. This compound crystallizes in orthorhombic noncentrosymmetric space group of Cmc21, and the structure is composed o
- Gong, Pifu,Luo, Siyang,Yang, Yi,Liang, Fei,Zhang, Shengzi,Zhao, Sangen,Luo, Junhua,Lin, Zheshuai
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- A novel monooxoruthenium(V) complex containing a polydentate pyridyl amine ligand. Syntheses, reactivities, and X-ray crystal structure of [RuIII(N4O)(H2O)](ClO4)2
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The syntheses and characterization of cis-[RuIII(tepa)Cl2]+, [RuIII(N4O)(H2O)]2+, and [RuV(N4O)O]2+ complexes are described [tepa = tris(2-(2-pyridyl)ethyl)amine, N4OH = bis(2-(2-pyridyl)ethyl)(2-hydroxy-2-(2-pyridyl)ethyl)amine]. The molar magnetic susceptibilities for [RuIII(N4O)(H2O)]2+ and [RuV(N4O)O]2+ complexes are 1.79 and 2.2 μB, respectively. The X-ray structure of [RuIII(N4O)(H2O)](ClO4)2 has been determined: [RuIII(C21H23N4O)(H 2O)](ClO4)2, M = 666.43, monoclinic, space group P2/c (no. 13), a = 11.644 (1) A?, b = 11.937 (3) A?, c = 18.856 (6) A?, β = 105.39 (2)°, V = 2527 (1) A?3, Z = 4, Dx = 1.753, Dc = 1.752 g cm-3, μ(Mo Kα) = 8.82 cm-1. The Ru-O(OH2) and Ru-O(N4O) distances are 2.115 (3) and 1.961 (4) A?, respectively. The [RuV(N4O)O]2+ complex shows an intense Ru=O stretch at 872 cm-1 which is absent in the [RuIII(N4O)(H2O)]2+ complex. The Ru(V) state in [RuV(N4O)O]2+ has also been confirmed by spectrophotometric redox titration in 0.1 M HClO4 by using [RuII(NH3)4(bpy)]2+ (bpy = 2,2′-bipyridine) as the redox titrant. A stoichiometry of 1:3 has been obtained. The cyclic voltammograms of both [RuIIIHN4O)(H2O)]2+ and [RuV(N4O)O]2+ complexs show two couples at 0.35 and 1.02 V vs SCE in aqueous medium at pH = 1, assignable to a Ru(III/II) and a Ru(V/III) couple, respectively. At 5.5 > pH > 3.5, the wave for the Ru(V/III) couple splits into two waves, a pH-independent one-electron wave for the Ru(V/IV) couple and a two-proton-one-electron wave with a slope of -117 mV/pH unit for the Ru(IV/III) couple. The Ru(IV) state is found to be thermodynamically unstable with respect to disproportionation into Ru(III) and Ru(V) at pH V(N4O)O]2+ complex is found to be an active oxidant, capable of oxidizing both activated C-H bonds and the C-H bond of cyclohexane. Studies on the reactions of [RuV(N4O)O]2+ with organic substrates indicated that the Ru(V)=O has a higher affinity for hydrogen atom/hydride abstraction than oxo-transfer reaction to C=C double bond.
- Che, Chi-Ming,Yam, Vivian Wing-Wah,Mak, Thomas C. W.
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- Chloride ion oxidation in molten alkaline-earth metal, magnesium, and zinc chlorides
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The interaction of molten alkaline-earth metal, magnesium, and zinc chlorides with oxygen has been investigated. The products of these reactions are molecular chlorine and the respective metal oxides. The reactivity of the chlorides increases linearly wit
- Chekryshkin, Yu.S.,Chudinov,Fedorov,Rozdyalovskaya
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- The regular features of chlorine formation in the systems NaCl-Me xOy-O2 and Ca(Zn)Cl2-Me xOy-O2
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The reaction of sodium, calcium, and zinc chlorides with atmospheric oxygen in the presence of transition metal oxides and antimony oxide at temperatures exceeding the melting temperatures of chlorides was studied. The content of chorine, product of oxida
- Rozdyalovskaya,Chekryshkin, Yu. S.,Chudinov,Fedorov
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- Two-dimensional cluster catalysts with superior thermal stability and catalytic activity for AP
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The preparation of catalysts with small particle size, large specific surface area and high atomic utilization has always been the focus of research in the field of catalysis. As for energetic materials, catalysts are always used to improve the thermal decomposition performance of ammonium perchlorate (AP) as it has significant effect on the power of engine. In this work, a two-dimensional metal clusters catalyst has been successfully prepared by solvothermal and heat treatment to improve thermal decomposition performance of AP. In detail, the transition metal ions were supported on the graphene oxide (GO) surface by organic ligands linking, followed by heat treatment to obtain two-dimensional rGO based metal clusters catalyst. The morphology and structure of the catalysts at different temperatures and their effect on AP decomposition were studied, the results show that catalyst at 300 °C has a particle size of 20 nm and uniformly distributed on rGO. The catalyst promotes the high temperature decomposition of AP by 73.7 °C with improved stability, and increases the heat release from 652.73 J/g to 1392.11 J/g. This may be attributed to good conductivity of GO and the strong gain-loss electron ability of the metal clusters. The presence of GO increased the active sites for cluster catalysis, additional, the metal clusters have a positive synergistic effect with GO. Thus, the thermal decomposition performance of AP was enhanced meanwhile thermal stability can also be improved.
- Guo, Yanli,Liang, Taixin,Liu, Wei,Song, Ruidong,Wang, Chao,Xiao, Fei,Zhang, Jiangbo
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- Effects of the Support-Crystal Size on the Catalytic Performance of RuO2/TiO2 in the Deacon Process
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RuO2/TiO2 catalysts with different TiO2 crystal sizes were prepared via a dry impregnation method, and these prepared catalysts were applied in the oxidation of HCl. The results show that decreasing the support-crystal size is an effective method to enhance the dispersion of RuO2 on TiO2, which is helpful to increase the catalytic activity significantly. Graphic Abstract: [Figure not available: see fulltext.].
- Wang, Xue,Liu, Yupei,Xu, Chunhui,Lu, Xinqing,Ma, Rui,Fu, Yanghe,Wang, Shuhua,Zhu, Weidong
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p. 2346 - 2354
(2021/01/07)
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- Investigation of kinetic parameters for ammonium perchlorate thermal decomposition in presence of gCN/CuO by TG-MS analysis and kinetic compensation correction
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The desire to develop a benign burn rate modifier for propellants has accentuated polymeric carbon nitride (gCN) as a potential candidate for the thermal decomposition of ammonium perchlorate (AP). Here, we have synthesized composites of leaf-shaped CuO and gCN via a facile sonochemical approach. From DSC analysis, the addition of gCNCuO1 reduced the decomposition temperature of AP by 59°C and increased the heat release by ~ 1.4 times that of pure AP. The kinetics of AP decomposition was well investigated via in-situ TG-MS technique. From evolved gas analysis evolution of NO, Cl, HCl, N2O/CO2, NO2 and Cl2 fragments were detected. The quantitative interpretation of kinetic parameters for AP decomposition was done using Coats-Redfern method and the normalization of E values were carried out by applying Kinetic Compensation Correction (KCC). After normalization, E values were decreased by 17 ?kJ/mol and 18 ?kJ/mol for the first and second stages respectively.
- Jos, Jisna,Mani, Gladiya,Mathew, Suresh,Radhakrishnan Nair, P.
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- PhICl2is activated by chloride ions
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A study on the potential activating role of pyridine in the electrophilic chlorination of anisole by PhICl2has led to the discovery that soluble sources of chloride ions activate PhICl2in the reaction at catalytic loadings, greatly increasing the rate of chlorination. It is further shown that presence of chloride increases the rate of decomposition of PhICl2into PhI and Cl2. The specific mechanism by which chloride induces electrophilic chlorination and decomposition of PhICl2remains an open question.
- Tania,Poynder, Tiffany B.,Kaur, Aishvaryadeep,Barwise, Lachlan,Houston, Sevan D.,Nair, Akshay J.,Clegg, Jack K.,Wilson, David J. D.,Dutton, Jason L.
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supporting information
p. 11986 - 11991
(2021/09/06)
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- Three-dimensionally ordered macroporous Cr2O3?CeO2: High-performance catalysts for the oxidative removal of trichloroethylene
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Three-dimensionally ordered macroporous (3DOM) CeO2, 3DOM Cr2O3, 3DOM xCr2O3?CeO2 (x (the weight percentage of Cr2O3) = 3.5, 5.5, and 8.0 wt%), and 5.5 wt% Cr2O3/3DOM CeO2 samples were prepared using the polymethyl methacrylate (PMMA)-templating and incipient wetness impregnation methods, respectively. A number of techniques were used to characterize physicochemical properties of the materials, and their catalytic activities were evaluated for the oxidation of trichloroethylene (TCE). These samples possessed a good-quality 3DOM structure and a surface area of 35?47 m2/g. The 3DOM 5.5Cr2O3?CeO2 sample performed the best (the temperature at TCE conversion = 90% = 255 °C at a space velocity of 20,000 mL/(g h)). Effects of water vapor and carbon dioxide on activity of the 5.5Cr2O3?CeO2 sample were also examined. It is observed that partial deactivation induced by H2O introduction of the 5.5Cr2O3?CeO2 sample was reversible, while that induced by CO2 addition was irreversible. Based on the activity data and characterization results, it is concluded that the good catalytic activity and thermal stability of 3DOM 5.5Cr2O3?CeO2 was associated with its high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between Cr2O3 and CeO2. We believe that the 3DOM 5.5Cr2O3?CeO2 catalyst is promising in the application for oxidative removal of chlorinated volatile organic compounds.
- Zhang, Xing,Liu, Yuxi,Deng, Jiguang,Zhao, Xingtian,Zhang, Kunfeng,Yang, Jun,Han, Zhuo,Jiang, Xiyun,Dai, Hongxing
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p. 200 - 209
(2019/02/14)
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- Green molten salt synthesis and Li-ion storage performance of sodium dimolybdate
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A facile and fast molten salt strategy is developed, for the first time, to synthesis sodium dimolybdate (Na2Mo2O7). The process is based on a thermodynamically favorable reaction between naturally available precursors MoS2 and NaCl to produce Na2Mo2O7 as well as a gas phase that leaves the system. The product is characterized by electron microscopy and energy-dispersive X-ray spectroscopy (EDX) as well as X-ray diffraction (XRD) and Raman spectroscopy. The prepared Na2Mo2O7 in combination with molten salt-synthesized graphene nanosheets is examined as anode material for Li-ion batteries, exhibiting an interesting performance, with the first cycle discharge and charge capacities of 1363 and 857 mAh g?1, respectively, at 100 mA g?1. A reversible Li storage capacity of 506 mAh g?1 can still be observed after 100 cycles. The results are rather interesting towards the development of low-cost and high-performance Na2Mo2O7 anode materials.
- Kamali, Ali Reza,Zhu, Wenhui
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- Effect of the Composition of Supported Copper-Containing Salt Catalysts on Their Activity in the Deacon Reaction: Dependence of the Rate of the Deacon Reaction on the Ratio between Copper and Potassium Chlorides in a Supported CuCl2–KCl Salt Catalyst
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Abstract: The effect of KCl/CuCl2 molar ratios from 0 to 2.5 in the СuCl2–KCl catalyst (support) on its activity in the Deacon reaction was studied by a gradientless method in a temperature range of 350–425°C. The essential role of the hydration processes of the salt catalyst components in the homogenization of a reaction layer was established. The experiments did not contradict the previously proposed reaction kinetics and mechanism. A possible explanation of the experimental results was given based on the polarization representations used earlier in the reaction mechanism.
- Aglulin
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p. 290 - 296
(2019/06/27)
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- Binding of halogens by a Cr8 metallacrown
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A Cr8 metallacrown binds halogens X2 (Cl2, Br2 and I2) without loss of crystallinity; the binding has been studied by X-ray diffraction and thermodynamic techniques.
- Sava, Daniel Florin,Zheng, Nan,Vitórica-Yrezábal, I?igo J.,Timco, Grigore A.,Winpenny, Richard E. P.
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supporting information
p. 13771 - 13775
(2018/10/20)
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- DUAL BIOCIDE GENERATOR
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Methods and apparatus for generation of dual biocides are provided. The electrolytic generation of chlorine as a biocide is employed for further generation of additional biocides within a single system or generator, including bromine, iodine, chlorine dioxide, fluorine, or chloramines from their respective salts and/or precursors. A single on-site generating system produces a combination of biocides for applications of use providing cost, safety and efficacy improvements. Methods of using the disinfecting biocides provide a synergistic effect through simultaneous or sequential applications.
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Paragraph 0096; 0097; 0098; 0099
(2016/02/21)
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- Enhancement of the photocatalytic activity of europium(III) oxide by the deposition of gold for the removal of atrazine
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Europium(III) oxide nanoparticles were prepared using a hydrothermal method. Gold was deposited by a photo-assisted deposition method. Europium(III) oxide and gold deposited europium(III) oxide were characterized using different techniques. The results demonstrated that gold was present as a metallic gold, and it was well-dispersed on the europium(III) oxide surface. The photocatalytic activity of europium(III) oxide and gold deposited europium(III) oxide was measured by the degradation of atrazine using visible light irradiation. The photocatalytic activity of gold deposited europium(III) oxide is higher than that of europium(III) oxide. This finding can be attributed to the synergic effect between europium(III) oxide and gold. Moreover, the results revealed that an increase in the weight percent of gold increases the photocatalytic activity of europium(III) oxide, and the most active photocatalyst is 0.20 wt % gold deposited europium(III) oxide. The photocatalyst of 0.20 wt % gold deposited europium(III) oxide has high photocatalytic stability and can be reused five times without a decrease in photocatalytic activity.
- Aazam
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p. 344 - 349
(2016/03/09)
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- LACTATE PRODUCTION PROCESS
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A process for producing lactic acid is provided. The process comprises (a) reacting a stream rich in saccharide with sodium hydroxide in the presence of water to produce a reaction mixture comprising sodium lactate; (b) reacting at least a portion of the sodium lactate with HCl to produce lactic acid and sodium chloride; (c) converting at least a portion of the sodium chloride to chlorine and sodium hydroxide; and (d) recycling at least a portion of the sodium hydroxide produced in step (c) to step (a). Also provided are processes for the production of alkyl lactate, oligomeric lactic acid, lactide, alkyl lactyllactate, poly-lactic acid, propylene glycol and acrylic acid.
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Page/Page column 24
(2015/03/28)
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- The electrocatalytic activity of IrO2-Ta2O5 anode materials and electrolyzed oxidizing water preparation and sterilization effect
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Ti/IrO2-Ta2O5 anode electrocatalysts with different contents and preparation temperatures were prepared by thermal decomposition in this work. The crystallite characterization and morphology were examined via XRD and SEM. The electrochemical properties were examined via cyclic voltammetry (CV) in 0.5 M H2SO4 and linear sweep voltammetry (LSV) in saturated sodium chloride. Through the study of different series of Ti/IrO2-Ta2O5 anodes, we find that the preparation conditions have a great impact on the electrode catalytic activity. Experimental results indicate that the electrochemically active surface area is determined by the content and morphology of the anode coating. When the IrO2 content and the preparation temperature are 70% and 500 °C, the surface of the electrode is aggregated with segregated crystallite flower-like particles, which brings about the best electrode catalytic activity. The current density in the chlorine evolution reaction of IrO2-Ta2O5 (70% and 500 °C) is 0.4 A cm-2 in saturated sodium chloride. The properties and sterilization effect of EO water are closely related to the electrode catalytic activity. The higher the current density is in chlorine evolution, the higher the available chlorine and HClO content. When the IrO2 content is 70% and the preparation temperature is 500 °C, the maximum values of the killing logarithm value and killing rate are 3.01-3.05 and 99.9023-99.9109%, respectively. In addition, when the Ti substrate undergoes 40 minutes of activation treatment, the Ti/IrO2-Ta2O5 anodes have the highest stability.
- Ren, Zhandong,Quan, Shanshan,Gao, Jie,Li, Wenyang,Zhu, Yuchan,Liu, Ye,Chai, Bo,Wang, Yourong
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p. 8778 - 8786
(2015/03/05)
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- The effect of Ce on catalytic decomposition of chlorinated methane over RuOx catalysts
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Ru oxide catalysts supported on Ce-Al2O3 with various Ce contents were prepared by wet impregnation with RuCl3 aqueous solution and characterized by XRD, N2 adsorption, TEM/HRTEM, H 2-TPR, Raman and N
- Ran, Le,Wang, Zhengyi,Wang, Xingyi
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p. 442 - 450
(2014/04/03)
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- Use of 3-[18F]fluoropropanesulfonyl chloride as a prosthetic agent for the radiolabelling of amines: Investigation of precursor molecules, labelling conditions and enzymatic stability of the corresponding sulfonamides
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3-[18F]Fluoropropanesulfonyl chloride, a recently proposed prosthetic agent for fluorine-18 labelling, was prepared in a two-step radiosynthesis via 3-[18F]fluoropropyl thiocyanate as an intermediate. Two benzenesulfonate-based radiolabelling precursors were prepared by various routes. Comparing the reactivities of 3-thiocyanatopropyl nosylate and the corresponding tosylate towards [18F]fluoride the former proved to be superior accounting for labelling yields of up to 85%. Conditions for a reliable transformation of 3-[18F]fluoropropyl thiocyanate to the corresponding sulfonyl chloride with the potential for automation have been identified. The reaction of 3-[18F]fluoropropanesulfonyl chloride with eight different aliphatic and aromatic amines was investigated and the identity of the resulting 18F-labelled sulfonamides was confirmed chromatographically by comparison with their nonradioactive counterparts. Even for weakly nucleophilic amines such as 4-nitroaniline the desired radiolabelled sulfonamides were accessible in satisfactory yields owing to systematic variation of the reaction conditions. With respect to the application of the 18F-fluoropropan-sulfonyl group to the labelling of compounds relevant as imaging agents for positron emission tomography (PET), the stability of N-(4-fluorophenyl)-3-fluoropropanesulfonamide against degradation catalysed by carboxylesterase was investigated and compared to that of the analogous fluoroacetamide.
- Loeser, Reik,Fischer, Steffen,Hiller, Achim,Koeckerling, Martin,Funke, Uta,Maisonial, Aurelie,Brust, Peter,Steinbach, Joerg
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supporting information
p. 1002 - 1011
(2013/07/19)
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- Superior activity of rutile-supported ruthenium nanoparticles for HCl oxidation
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The activity of supported Ru-based catalysts in the oxidation of HCl to Cl2 is shown to be strongly affected by active phase-support interactions and by the way of incorporation of the Ru species. Depositing colloidally prepared Ru nanoparticles on a rutile carrier results in catalysts attaining very high and stable HCl conversion levels under industrially-relevant conditions using ruthenium loadings as low as 0.16 wt%.
- Kondratenko, Evgenii V.,Amrute, Amol P.,Pohl, Marga-Martina,Steinfeldt, Norbert,Mondelli, Cecilia,Perez-Ramirez, Javier
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p. 2555 - 2558
(2013/09/24)
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- X-ray crystallographic and first-principles theoretical studies of K 2[TcOCl5] and UV/Vis investigation of the [TcOCl 5]2- and [TcOCl4]- ions
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Dipotassium pentachloridooxidotechnetate, K2[TcOCl5], has been isolated as green single crystals by the dissolution of (NH 4)TcO4 in 12 M HCl at 0 °C and careful precipitation with KCl. The structure of this compound was determined by single-crystal X-ray diffraction analysis [a = 13.0815(9), b = 9.8982(6), c = 6.7623(4) A; V = 875.605 A3, orthorhombic, Pnma, Z = 4] and compared with the corresponding molybdenum and rhenium analogues. The structure of K 2[TcOCl5] was also investigated by density functional theory, and the results are in agreement with the crystallographic data. The oscillator strengths of the electronic transitions in the C4v complex anions [TcOCl5]2- and [TcOCl4]- were also calculated by using time-dependent density functional theory and compared with the experimental UV/Vis spectra. Dipotassium pentachloridooxidotechnetate has been isolated as single crystals and its structure investigated by crystallographic and first-principles theoretical techniques. Copyright
- Johnstone, Erik V.,Weck, Philippe F.,Poineau, Frederic,Kim, Eunja,Forster, Paul M.,Sattelberger, Alfred P.,Czerwinski, Kenneth R.
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p. 1097 - 1104
(2013/03/28)
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- Performance, structure, and mechanism of CeO2 in HCl oxidation to Cl2
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Experimental and theoretical studies reveal performance descriptors and provide molecular-level understanding of HCl oxidation over CeO2. Steady-state kinetics and characterization indicate that CeO2 attains a significant activity level, which is associated with the presence of oxygen vacancies. Calcination of CeO2 at 1173 K prior to reaction maximizes both the number of vacancies and the structural stability of the catalyst. X-ray diffraction and electron microscopy of samples exposed to reaction feeds with different O2/HCl ratios provide evidence that CeO2 does not suffer from bulk chlorination in O2-rich feeds (O2/HCl ≥ 0.75), while it does form chlorinated phases in stoichiometric or sub-stoichiometric feeds (O2/HCl ≤ 0.25). Quantitative analysis of the chlorine uptake by thermogravimetry and X-ray photoelectron spectroscopy indicates that chlorination under O2-rich conditions is limited to few surface and subsurface layers of CeO2 particles, in line with the high energy computed for the transfer of Cl from surface to subsurface positions. Exposure of chlorinated samples to a Deacon mixture with excess oxygen rapidly restores the original activity levels, highlighting the dynamic response of CeO2 outermost layers to feeds of different composition. Density functional theory simulations reveal that Cl activation from vacancy positions to surface Ce atoms is the most energy-demanding step, although chlorine-oxygen competition for the available active sites may render re-oxidation as the rate-determining step. The substantial and remarkably stable Cl2 production and the lower cost of CeO2 make it an attractive alternative to RuO2 for catalytic chlorine recycling in industry.
- Amrute, Amol P.,Mondelli, Cecilia,Moser, Maximilian,Novell-Leruth, Gerard,Lopez, Nuria,Rosenthal, Dirk,Farra, Ramzi,Schuster, Manfred E.,Teschner, Detre,Schmidt, Timm,Perez-Ramirez, Javier
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p. 287 - 297
(2012/03/12)
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- An integrated approach to Deacon chemistry on RuO2-based catalysts
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Rationally designed RuO2-based Deacon catalysts can contribute to massive energy saving compared to the current electrolysis process in chemically recycling HCl to produce molecular chlorine. Here, we report on our integrated approach between state-of-the-art experiments and calculations. The aim is to understand industrial Deacon catalyst in its realistic surface state and to derive mechanistic insights into this sustainable reaction. We show that the practically relevant RuO2/SnO2 consists of two major RuO2 morphologies, namely 2-4 nm-sized particles and 1-3-ML-thick epitaxial RuO2 films attached to the SnO2 support particles. A large fraction of the small nanoparticles expose {1 1 0} and {1 0 1} facets, whereas the film grows with the same orientations, due to the preferential surface orientation of the rutile-type support. Steady-state Deacon kinetics indicate a medium-to-strong positive effect of the partial pressures of reactants and deep inhibition by both water and chlorine products. Temporal Analysis of Products and in situ Prompt Gamma Activation Analysis strongly suggest a Langmuir-Hinshelwood mechanism and that adsorbed Cl poisons the surface. Under relevant operation conditions, the reactivity is proportional to the coverage of a specific atomic oxygen species. On the extensively chlorinated surface that can be described as surface oxy-chloride, oxygen activation is the rate-determining step. DFT-based micro-kinetic modeling reproduced all experimental observations and additionally suggested that the reaction is structure sensitive. Out of the investigated models, the 2 ML RuO2 film-covered SnO2 gives rise to significantly higher reactivity than the (1 0 1) surface, whereas the 1 ML film seems to be inactive.
- Teschner, Detre,Farra, Ramzi,Yao, Lide,Schloegl, Robert,Soerijanto, Hary,Schomaecker, Reinhard,Schmidt, Timm,Szentmiklosi, Laszlo,Amrute, Amol P.,Mondelli, Cecilia,Perez-Ramirez, Javier,Novell-Leruth, Gerard,Lopez, Nuria
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p. 273 - 284
(2012/03/13)
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- Spectroscopic, thermogravimetric and antibacterial studies for some bivalent metal complexes of oxalyl-, malonyl- and succinyl-bis(4-p- chlorophenylthiosemicarbazide)
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Anodic oxidation of Co, Cu, Zn, and Sn metals in an anhydrous acetone solution of 1,1-oxalyl-, malonyl- or succinyl-bis(4-p- chlorophenylthiosemicarbazide) yields a new polynuclear complexes. The isolated complexes have the general composition [M2(L)(H2O) 6], L = pClSuTS and M = Co(II), Cu(II) or Sn(II), [M 2(L)(H2O)n]·nH2O where M = Cu(II), Co(II) or Sn(II), L = pClOxTS and n = 2 or 6, and [M2(L)(ac) 2]·nH2O where M = Co(II) or Zn(II), L = pClOxTS or pClSuTS and n = 2. The thermogravimetry (TG) and derivative thermogravimetry (DTG) have been used to study the thermal decomposition of the investigated bisthiosemicarbazide ligands and their metal complexes. The kinetic thermodynamic parameters such as: E, ΔH, ΔS and ΔG are calculated using Horowitz-Metzger (HM) and Coats-Redfern (CR) equations. The kinetic thermodynamic parameters such as: E, ΔH, ΔSand ΔG are calculated from the DTG curves. The tested compounds show a reasonable activity against four strains of Gram-negative bacteria; Escherichia coli, Pseudomonas aeruginosa species and Gram-positive bacteria; Bacillus cereus and Staphylococcus aureus.
- Amin, Ragab R.,Yamany, Yamany B.
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- A novel hydrolysis method to synthesize chromium hydroxide nanoparticles and its catalytic effect in the thermal decomposition of ammonium perchlorate
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A procedure for the preparation of spherical Cr(OH)3 nanoparticles was developed based on the aging of chromium nitrate aqueous solutions in the presence of sodium fluoride, urea, and polyvinylpyrrolidone. Using scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy, the morphological characteristics of Cr(OH) 3 were controlled by altering the molar ratio of fluoride ion to chromium ion, as well as the initial pH and chromium ion concentration. The prepared nanosized Cr(OH)3 decreased the temperature required to decompose ammonium perchlorate from 450 °C to about 250 °C as the catalyst. The possible catalytic mechanism of the thermal decomposition of ammonium perchlorate was also discussed.
- Li, Ping,Zhou, Zhen,Xu, Hongbin,Zhang, Yi
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- ORGANIC ELECTROLUMINESCENCE DEVICE
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An organic electroluminescence device material comprising a metal complex having a neopentyl group, for example, as shown below; and an organic electroluminescence device comprising a substrate having thereon a pair of electrodes and at least one organic layer between the electrodes, the organic layer containing a light emitting layer, wherein any one of the organic layer contains the organic electroluminescence device material.
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- Improve the catalytic activity of α-Fe2O3 particles in decomposition of ammonium perchlorate by coating amorphous carbon on their surface
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Sphere- and pod-like α-Fe2O3 particles have been selectively synthesized using NH3·H2O and NaOH solution to adjust the pH value of the designed synthetic system, respectively. The sphere-like α-Fe2Os
- Zhang, Yifu,Liu, Xinghai,Nie, Jiaorong,Yu, Lei,Zhong, Yalan,Huang, Chi
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p. 387 - 390
(2011/04/22)
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- Study of the temperature effect on the process of rubidium hexachlorotellurite decomposition
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Thermal dissociation of rubidium hexachlorotellurite in inert atmosphere (argon) and in atmosphere with air access was studied. The DTG and DTA curves for the process of rubidium hexachlorotellurite thermal dissociation in the argon atmosphere are given. Their character is defined by the behavior of TeCl4, which is liberated on the decomposition of samples.
- Lyakh,Sizyakov,Zaitsev,Pigova,Ugolkov
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p. 1507 - 1509
(2011/05/07)
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- Vanadium selenoether and selenolate complexes, potential single-source precursors for CVD of VSe2 thin films
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Reactions of VCl4 with one mol equiv. of L-L (L-L = MeSe(CH 2)2SeMe, MeSe(CH2)3SeMe, nBuSe(CH2)2SenBu) in anhydrous CH2Cl2 solution at
- Hector, Andrew L.,Jura, Marek,Levason, William,Reid, Stuart D.,Reid, Gillian
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p. 641 - 645
(2009/05/30)
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- One- versus two-electron oxidation with peroxomonosulfate ion: reactions with iron(II), vanadium(II), halide ions, and photoreaction with cerium(III)
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The kinetics of the redox reactions of the peroxomonosulfate ion (HSO 5-) with iron(ll), vanadium(IV), cerium(lll),chloride, bromide, and iodide ions were studied. Cerium(lll) is only oxidized upon illumination by UV light and cerium
- Lente, Gabor,Kalmar, Jozsef,Baranyai, Zsuzsa,Kun, Aliz,Kek, IIdikoe,Bajusz, David,Takacs, Marcell,Veres, Lilla,Fabian, Istvaen
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p. 1763 - 1773
(2009/06/17)
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- Photochemistry of SO2/CI2/O2 gas mixtures: Synthesis of the new peroxide CISO2OOSO2CI
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Photochemically induced gas-phase reactions of CI2/SO 2/O2 mixtures at -78 °C have been investigated on a preparative scale. The sulfuryl chlorides CISO2(OSO2) nCI, n = 0,1, or 2, along wit
- Romano, Rosana M.,Vedova, Carlos O.Della,Beckers, Helmut,Willner, Helge
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p. 1906 - 1910
(2009/07/18)
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- Halogen photoreductive elimination from gold(III) centers
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Monomeric complexes of the type Au III (PR 3 )X 3 and bimetallic complexes of the type Au 2 I,III [μCH 2 (R 2 P) 2 ]X 4 and Au 2 III,III [μ-CH 2 (R 2 P) 2 ]X 6 (R = Ph, Cy, X = Cl - , Br - ) undergo facile photoelimination of halogen. M-X bond activation and halogen elimination is achieved upon LMCT excitation of solutions of Au III complexes in the presence of olefin chemical traps. As opposed to the typical one-electron redox transformations of LMCT photochemistry, the LMCT photochemistry of the Au III centers allows for theunprecedented (i) two-electron photoelimination of X 2 from a monomeric center and (ii) four-electron photoelimination of X 2 from a bimetalllic center. The quantum yields for X 2 photoproduction, in general, are between 10percent and 20percent for all species, showing only minimal dependence on the identity of the ligands about gold, or the nuclearity of the complex. Efficient X 2 photoelimination is observed in the absence of a chemical trap, providing a rare example of authentic, trap-free halogen elimination from a transitionmetal center.
- Teets, Thomas S.,Nocera, Daniel G.
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p. 7411 - 7420
(2009/10/17)
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- Preparation of NdCrO3 nanoparticles and their catalytic activity in the thermal decomposition of ammonium perchlorate by DSC/TG-MS
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Orthorhombic structural perovskite NdCrO3 nanocrystals with size of 60 nm were prepared by microemulsion method, and characterized by XRD, TEM, HRTEM, SEM, EDS and BET. The catalytic effect of the NdCrO3 for thermal decomposition of
- Yu, Zongxue,Sun, Yuxi,Wei, Wenxian,Lu, Lude,Wang, Xin
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p. 903 - 909
(2009/12/25)
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- ENERGY-ACTIVATED COMPOSITIONS FOR CONTROLLED SUSTAINED RELEASE OF A GAS
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A composition for energy-controlled generation and release of at least one gas, which includes an energy-activated catalyst capable of being activated by electromagnetic energy, and a solid or a liquid containing anions capable of being oxidized by the activated catalyst or reacted with species generated during activation of the catalyst to generate at least one gas. The composition, when exposed to electromagnetic energy, is capable of generating and releasing the gas after activation of the catalyst and oxidation or reaction of the anions.
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Page/Page column 12; 9/13; 10/13; 11/13
(2008/06/13)
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- Mechanism of HCl oxidation (Deacon process) over RuO2
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The catalytic oxidation of hydrogen chloride to chlorine (Deacon reaction) is an attractive means to recover Cl2 from HCl-containing waste streams in the chemical industry. Recently, RuO2 supported on TiO2 rutile has been industrially implemented for large-scale chlorine manufacture. However, detailed understanding of the reaction mechanism over claimed catalysts has not been acquired. Our tests in a fixed-bed reactor at ambient pressure concluded that RuO2 powder is highly active for Cl2 production. Characterization of the fresh and used RuO2 samples by ex situ XRD and XPS revealed no appreciable alteration of the bulk structure and limited chlorination of the catalyst. Ab initio thermodynamics predicted that the initial state of the RuO2(110) surface is partially over-oxidized, while the surface after reaction contains both oxygen and chlorine. DFT described the Deacon reaction with a Mars-van Krevelen type mechanism consisting of five steps: hydrogen abstraction from HCl, recombination of atomic chlorine, hydroxyl recombination, water desorption, and dissociative oxygen adsorption. An increased chlorine production was observed experimentally when increasing the feed O2-to-HCl ratio. This can be ascribed both to the lower recombination energy of chlorine atoms to gas-phase Cl2 at high coverages and the faster surface reoxidation due to higher partial oxygen pressures.
- Lopez, Nuria,Gomez-Segura, Jordi,Marin, Raimon P.,Perez-Ramirez, Javier
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- Effect of chloride ion on the kinetics and mechanism of the reaction between chlorite ion and hypochlorous acid
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The effect of chloride ion on the chlorine dioxide formation in the ClO2--HOCl reaction was studied by following ?ClO2 concentration spectrophotometrically at pH 5-6 in 0.5 M sodium acetate. On the basis of the earlier experimental data collected without initially added chloride and on new experiments, the earlier kinetic model was modified and extended to interpret the two series of experiments together. It was found that the chloride ion significantly increases the initial rate of ?ClO2 formation. At the same time, the ?ClO2 yield is increased in HOCl but decreased in ClO2- excess by the increase of the chloride ion concentration. The two-step hydrolysis of dissolved chlorine through Cl2 + H2O ? Cl 2OH- + H+ and Cl2OH- ? HOCl + Cl- and the increased reactivity of Cl 2OH- compared to HOCl are proposed to explain these phenomena. It is reinforced that the hydrolysis of the transient Cl 2O2 takes place through a HOCl-catalyzed step instead of the spontaneous hydrolysis. A seven-step kinetic model with six rate parameters (constants and/or ratio of constants) is proposed on the basis of the rigorous least-squares fitting of the parameters simultaneously to 129 absorbance versus time curves measured up to ~90% conversion. The advantage of this method of evaluation is briefly outlined.
- Kormanyos, Balazs,Nagypal, Istvan,Peintler, Gabor,Horvath, Attila K.
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p. 7914 - 7920
(2009/02/08)
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- FLUORIDATION METHOD
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The invention relates to a method for preparing a meta-fluoro pyridyl compound which comprises reaction of a compound of formula (I): with a fluoride ion source, suitably a [18F]fluoride source, wherein: the pyridyl ring is optionally substituted by 1 to 4 organic substituents.
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Page/Page column 10
(2010/11/29)
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- Suppressing microbial growth in pulp and paper
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A composition for anti-microbial effect in a water system such as a pulp and paper processing line with an aqueous slurry. The composition comprises a free chlorine-generating biocide comprising a chlorine source, urea, and an alkali in a concentration sufficient to provide a pH greater than 10, and typically at least pH 11.
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Page/Page column 2-4
(2008/06/13)
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- Br2 production from the heterogeneous reaction of gas-phase OH with aqueous salt solutions: Impacts of acidity, halide concentration, and organic surfactants
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This study reports the first laboratory measurement of gas-phase Br 2 production from the reaction between gas-phase hydroxyl radicals and aqueous salt solutions. Experiments were conducted at 269 K in a rotating wetted-wall flow tube coupled to a chemical-ionization mass spectrometer for analysis of gas-phase components. From both pure NaBr solutions and mixed NaCl/NaBr solutions, the amount of Br2 released was found to increase with increasing acidity, whereas it was found to vary little with increasing concentration of bromide ions in the sample. For mixed NaCl/NaBr solutions, Br2 was formed preferentially over Cl2 unless the Br - levels in the solution were significantly depleted by OH oxidation, at which point Cl2 formation was observed. Presence of a surfactant in solution, sodium dodecyl sulfate, significantly suppressed the formation of Br2; this is the first indication that an organic surfactant can affect the rate of interfacial mass transfer of OH to an aqueous surface. The OH-mediated oxidation of bromide may serve as a source of active bromine in the troposphere and contribute to the subsequent destruction of ozone that proceeds in marine-influenced regions of the troposphere.
- Frinak, Elizabeth K.,Abbatt, Jonathan P. D.
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p. 10456 - 10464
(2008/10/09)
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- The oxidation of chlorine ions under the joint action of ozone and permanganate ions
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The oxidation of chlorine ions in the system O3 + MnO 4 - + H+ + Cl- with the formation of Cl2 in the gas phase was studied. The phenomenon of transfer catalysis of the reaction between O3 and Cl- by the MnO 4 - ion was observed (the products of the reduction of MnO 4 - by the chlorine ion are oxidized by ozone to recover MnO 4 - ). The rate of the formation of Cl2 in the O3 + MnO 4 - + H+ + Cl - system was higher than the sum of the corresponding rates in the oxidation of Cl- by O3 and MnO 4 - separately. A scheme explaining the trends observed experimentally for the formation of Cl2 and changes in MnO 4 - concentration was suggested. The formation of MnO 4 - in the oxidation of Mn3+ with ozone in acid media was studied. Pleiades Publishing, Inc., 2006.
- Levanov,Kuskov,Antipenko,Lunin
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p. 557 - 561
(2007/10/03)
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- APPARATUS FOR POLYISOCYANATE PRODUCTION AND APPARATUS FOR GAS TREATMENT
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An apparatus for polyisocyanate production in which chlorine can be stably produced from hydrogen chloride generated as a by-product, carbonyl chloride can be stably reacted with a polyamine, and the by-product hydrogen chloride gas can be efficiently treated. A hydrogen chloride gas control part (32) controls a flow control valve (23), whereby the amount of hydrogen chloride to be fed to a hydrogen chloride oxidation tank (6) through a second hydrogen chloride gas connection line (11) from a hydrogen chloride purification column (4) is kept constant. The hydrogen chloride gas control part (32) further controls a pressure control valve (22) based on the internal pressure of the hydrogen chloride purification column (4) inputted from a pressure sensor (25) to discharge hydrogen chloride gas to a hydrogen chloride absorption column (5) through a first hydrogen chloride gas connection line (10) from the hydrogen chloride purification column (4) so that the internal pressure of the hydrogen chloride purification column (4) is constant.
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Page/Page column 15; 1/4
(2008/06/13)
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- Thermal behavior of ammonium perchlorate and metal powders of different grades
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The effects of aluminum (Al) and nickel (Ni) powders of various grain sizes on the thermal decomposition of ammonium perchlorate (AP) were investigated by TG and DSC in a dynamic nitrogen atmosphere. The TG results show that Al powders have no effect on the thermal decomposition of AP at conventional grain size, while the nanometer-sized Ni powders (n-Ni) have a great influence on the thermal decomposition of AP with conventional and superfine grain size. The results obtained by DSC and an in situ FTIR analysis of the solid residues confirmed the promoting effects of n-Ni. The effects of n-Ni have been ascribed to its enhancement on the gas phase reactions during the second step decomposition of conventional grain size AP.
- Zhi,Tian-Fang,Shu-Fen,Feng-Qi,Zi-Ru,Cui-Mei,Yang,Shang-Wen,Gang-Zhui
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p. 315 - 320
(2008/10/09)
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- Kinetic mechanism of ClONO2 uptake on polycrystalline film of NaCl
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Kinetic studies and the mechanism determination of ClONO2 uptake on polycrystalline NaCl were carried out using a coated-insert flow tube reactor combined with high-resolution, low-energy electron-impact mass spectrometer under the following conditions: p =1-2 Torr, linear flow velocity v = 3.5-75 m s-1, T = 293 and 387 K, [ClONO2] = (0.5-25) × 1012 molecules cm-3. The salt was deposited as a film from nonsaturated aqueous solution on the sliding rod. The temporal dependences of the uptake coefficient and the partial uptake coefficients leading to a formation of the prime Cl2 and HOCl products were measured for different ClONO2 concentrations. These dependences are established to be described by γ = γ0 exp(-t/τ) + γs, γ0.s-1 = a0.S + b0.s[ClONO2]. In the framework of the proposed kinetic model, the data are explained and the main elementary kinetic parameters of the uptake are evaluated. The model is based on a combination of Langmuir adsorption, formation of surface complexes on initial active sites, Z ch, followed by their unimolecular decomposition. Decomposition is proposed to proceed concurrently in two channels, one of which is a released surface site that conserves the properties of the initial site. In the other channel, the initial Zch transforms into Zph followed by steady-state uptake and reproduction of final Zph. The model gives an analytical expression for experimental parameters γ0, γs, and τ in terms of elementary rate constants and the reactant volume concentration. The final objective of the proposed model is the extrapolation of γ0, γs, and r parameters to real tropospheric conditions.
- Zelenov,Aparina,Kashtanov,Shestakov,Gershenzon
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p. 6771 - 6780
(2008/10/09)
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- Influence of atmosphere kind on temperature programmed decomposition of noble metal chlorides
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The hydrated chlorides of noble metals located in the 8-10 groups of Periodic System were used in this work: Ru, Rh, Pd, Ir and Pt. The common mechanism of chloride compounds decomposition in oxidative, inert and reductive atmospheres was postulated and mutual similarities and differences were discussed. These compounds play a significant role in heterogeneous catalysis, as starting materials for metal/oxide catalysts, and also in analytical chemistry and industry.
- Jó?wiak, Wojciech K.,Maniecki, Tomasz P.
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p. 151 - 161
(2008/10/09)
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