Xn:Harmful;12190-71-5Relevant articles and documents
Mesoporous carbon supported platinum nanocatalyst: Application for hydrogen production by HI decomposition reaction in S-I cycle
Tyagi, Deepak,Varma, Salil,Bharadwaj, Shyamala R.
, p. 2177 - 2184 (2017)
Platinum supported on carbon as a catalyst is widely reported and have a wide range of applications ranging from fuel cell application to hydrogenation reactions, where structure and properties of carbon support play an important role in the functioning of the catalyst. Mesoporous carbon supported platinum nanocatalyst was synthesized by hard templating route using mesoporous silica as template. The catalyst prepared has been characterized by X-ray diffraction, Raman, SEM, TEM, XPS and BET surface area. This catalyst has been employed for liquid phase HI decomposition reaction of sulfur iodine thermochemical cycle for production of hydrogen. The catalyst was evaluated for its activity for HI decomposition reaction and stability in the reaction environment. From present study we conclude that Pt supported on mesoporous carbon is a suitable and stable catalyst for liquid phase HI decomposition reaction.
Studies of chemical reactivity in the condensed phase. I. The dynamics of iodine photodissociation and recombination on a picosecond time scale and comparison to theories for chemical reactions in solution
Harris, A. L.,Berg, M.,Harris, C. B.
, p. 788 - 806 (1986)
Picosecond transient absorption measurements from 1000-295 nm are used to monitor the recombination dynamics of iodine after photodissociation in a variety of inert solvents.The high time resolution and signal-to-noise ratio of these measurements permits the development of a detailed model of this reaction, which should resolve disagreements over the time scales of geminate recombination and vibrational relaxation and over the role of excited electronic state trapping.Most of the atoms which undergo geminate recombination do so in 15 ps, in agreement with the predictions of existzng molecular dynamics simulations.The subsequent vibrational and electronic energy relaxation of the recombined molecule is relatively slow and accounts for most of the transient absorption dynamics.The relaxing X state vibrational population distribution is extracted with an approximate method using calculated spectra of the excited vibrational levels and is compared to recent models.Vibrational relaxation times vary from ca. 15 ps near the middle of the ground state well to ca. 150 ps for complete relaxation to v = 0.The vibrational relaxation rates do not provide support for the predicted role of resonant vibration-to-vibration energy transfer to chlorinated methane solvents, but some evidence for this mechanism is found in alkane solvents.B-state predissociation times of 10-15 ps and A '-state lifetimes of 65-2700 ps are found depending on the solvent.Current theory is not able to satisfactorily explain the large variation of the A '-state lifetime in various solvents.
Photochemistry of alkyl halide dimers
Fan, Y. B.,Randall, K. L.,Donaldson, D. J.
, p. 4700 - 4706 (1993)
Dimers and other small clusters of CH3I, C2H5I, i- and n-C3H7I, HI, CF3I, CH3Br, and C2H5Br formed in a supersonic expansion are irradiated at 248 and 193 nm and the halogen molecule product probed via laser induced fluorescence spectroscopy.Both dimers and larger clusters of RI (R = H, alkyl) excited at each wavelength yield I2 in its ground electronic state with very little internal energy.Clusters of CF3I and those containing alkyl bromides do not give halogen molecule products after excitation at either wavelength.A model for the dynamics in the dimer excited state which explains these results is presented.
Chlorite-Iodide Reaction: A Versatile System for the Study of Nonlinear Dynamical Behavior
Kepper, Patrick De,Boissonade, Jacques,Epstein, Irving R.
, p. 6525 - 6536 (1990)
The autocatalytic reaction between chlorite and iodide ions exhibits a remarkable range of dynamical behavior.In a stirred tank reactor it shows bistability between steady states and between a steady and an oscillatory state.It forms the core of a large f
The Decomposition of Hydrogen Iodide and Separation of the Products by the Combination of an Adsorbent with Catalytic Activity and a Temperature-swing Method
Oosawa, Yoshinao
, p. 2908 - 2912 (1981)
The decomposition of hydrogen iodide and the separation of the products by the combination of a column packed with an adsorbent with catalytic activity (platinum-supported active carbon, 2.3 wtpercent) and a temperature-swing method (450-900 K) are carried out, and the features and the problems of the method are examined.A one-step conversion of hydrogen iodide, 70percent, is obtained at 450 K, where the equilibrium conversion is 13percent.It is shown that the products of the decomposition of hydrogen iodide containing water are separated from each other.
Bi2(IO4)(IO3)3: A new potential infrared nonlinear optical material containing [IO4]3- anion
Cao, Zhenbo,Yue, Yinchao,Yao, Jiyong,Lin, Zheshuai,He, Ran,Hu, Zhanggui
, p. 12818 - 12822 (2011)
A new potential infrared (IR) nonlinear optical (NLO) material Bi 2(IO4)(IO3)3 was synthesized by hydrothermal method. Bi2(IO4)(IO3)3 crystallizes in the chiral orthorhombic space group P212 121 (No. 19) with a = 5.6831(11) A, b = 12.394(3) A, and c = 16.849(3) A. It exhibits a threedimensional framework through a combination of the IO3, IO4, BiO8, and BiO9 polyhedra and is the first noncentrosymmetric (NCS) structure containing [IO4]3- anion. Bi2(IO 4)(IO3)3 has an IR cutoff wavelength of 12.3 ?m and belongs to the type 1 phase-matchable class with a moderately large SHG response of 5 × KDP, which is in good agreement with the theoretical calculations.
The Oscillatory Briggs-Rauscher Reaction. 1. Examination of Subsystems
Furrow, Stanley D.,Noyes, Richard M.
, p. 38 - 42 (1982)
In acidic aqueous solution at 25 deg C, only slow or nonexistent reaction is observed for any two of three species iodate ion, hydrogen peroxide, and manganous ion.However, if all three species are present, 0.002 M Mn2+ catalyzes the iodate oxidation of peroxide at a rate almost 1000 times that in the absence of a catalyst! This remarkable observation, which has already been reported by Cooke, can be explained by postulating that the radical oxidant *IO2 is very sluggish at abstracting hydrogen atoms from the species like H2O2 but can oxidize Mn2+ by electron transfer.A detailed mechanism has been proposed that models semiquantitatively not only the manganous catalyzed iodate oxidation of peroxide but also the simultaneous induced disproportionation of the peroxide and the fact that the concentration of elementary iodine does not increase to a limiting value but rises to a maximum and then decreases toward a small value.Despite this single extremum, the subsystem does not exhibit oscillatory behavior.
Formation of volatile iodine compounds under hot concentrated acid conditions (nitric acid or aqua regia) and in diluted acid solutions with or without thiocyanate
Badocco, Denis,Romanini, Francesca,Di Marco, Valerio,Mondin, Andrea,Pastore, Paolo
, p. 25 - 28 (2017)
It is reported that iodine volatilization can occur in any elemental analysis of total iodine by ICP-MS. This problem affects the accuracy of the results, and it has been neither rationalized nor solved up to now. In this work, the formation of volatile iodine compounds in concentrated acid solutions (nitric acid or aqua regia) under microwave heating was studied by UV–Vis spectrophotometry, linear sweep voltammetry, and cyclic voltammetry. It was evidenced that molecular iodine (I2) can unexpectedly form in concentrated hot HNO3solutions, irrespective of the starting iodine compound (iodide, iodate, periodate, 3-iodo-L-tyrosine, 3,5-diiodo-L-tyrosine dehydrate). I2is produced by the nitrogen oxides existing in these conditions. The formation of volatile iodine is minimized in aqua regia, as chloride is able to keep iodine in solution due to the formation of charged chloro-iodo complexes (e.g. I2Cl?). The dilution of the concentrated acid solution, required prior to the ICP-MS analysis, causes the disruption of I2Cl?so that I2can again volatilize. To avoid this, 0.1 M thiocyanate can be added, as it forms a strong I2SCN?complex which keeps I2in solution as ion. Also other iodine species possibly occurring in the explored conditions, iodide and iodate, were demonstrated to be converted to I2SCN?in diluted HNO3solutions and in the presence of 0.1 M thiocyanate. Recovery tests demonstrated that iodine volatilization is minimized if samples containing iodine are treated in aqua regia and, after dilution, they are added with 0.1 M thiocyanate.
Synthesis and Characterization of 2-Pyridinylmethylene-2-quinolyl Hydrazone Cobalt(III) Complexes. Reactivity Trends and Solvent Effect on the Initial and Transition States of Base Catalyzed Hydrolysis
Mohamad, Ahmad Desoky M.
, p. 1575 - 1595 (2017)
The complexes of pyridine-2-aldehyde-2-quinolylhydrazone Co(III) nitrate [Co(paqh)2](NO3)2, methyl-2-pyridylketone-2-quinolinhyrazone Co(III) nitrate [Co(mpkqh)2](NO3)2, and phenyl-2-pyridylketon-2-quinolinhyrazone Co(III) nitrate [Co(ppkqh)2](NO3)2 were prepared and characterized. Solubilities of Co(III)–hydrazone complexes were measured. Transfer chemical potentials were calculated from the measured solubilities of the Co(III) complexes in aqueous methanol mixtures at 25?°C. The reactivity trends in the transfer chemical potentials are discussed in terms of the nature of the bonded ligands. Kinetics of the base hydrolysis of Co(III)–hydrazone complexes in the aqueous methanol mixtures have been studied at 25?°C, and follow the rate law kobs?=?k2[OH?]. The solvent effects on the reactivity trends of Co(III) complexes are analyzed into initial state (is) and transition states (ts) components. The reaction rates are reduced by the increase of methanol content. The destabilization of the transition state is remarkable compared to the initial state in the aqueous methanol mixtures. The initial state is more hydrophobic in nature than the transition state for Co(III) complex reactions.
Quantum yields for the photodissociation of iodine in compressed liquids and supercritical fluids
Schwarzer,Schroeder,Schroeder
, p. 183 - 195 (2001)
Quantum yields of photodissociation were determined for iodine in compressed liquid n-alkanes and supercritical CO2 and xenon after laser excitation at 532 nm. The quantum yield decreases nearly linearly with increasing density. No cluster effe
