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1.
Preliminary tests of the chlorination of two iron oxides (wüstite and hematite) in various chlorinating gas mixtures were performed by thermogravimetric analysis (TGA) under non-isothermal conditions. Wüstite started to react with chlorine from about 200 °C generating ferric chloride and hematite as the final reaction products. The presence of a reducing and oxidizing agent in the chlorinating gas mixtures influenced the chlorination reactions of both iron oxides, during non-isothermal treatment, only at temperatures higher than 500 °C.The chlorination kinetics of hematite with Cl2 have been studied in details between 600 and 1025 °C under isothermal chlorination. The values of the apparent activation energy (Ea) were about 180 and 75 kJ/mol in the temperature ranges of 600–875 and 875–1025 °C, respectively. The apparent reaction order with respect to Cl2 was found to be 0.67 at 750 °C. Mathematical model fitting of the kinetics data was carried out to determine the most probable reaction mechanisms. 相似文献
2.
The coupling of propiolic acid with aryl iodides afforded the aryl alkynyl carboxylic acids and aryl alkynes in generally good yields. Aryl alkynyl carboxylic acids were obtained when the reaction was performed in the presence of Pd(PPh3)2Cl2 (2.5 mol %), dppb (5.0 mol %) and DBU (5 equiv) at 50 °C. For the synthesis of the terminal aryl alkynes, the reaction was conducted in the presence of Pd(PPh3)2Cl2 (2.5 mol %), dppb (5.0 mol %), DBU (5.0 equiv), and Cu(acac)2 (10 mol %) at 25 °C for 5 h, and further reacted at 60 °C for 6 h. 相似文献
3.
Gasification uses steam increases H2 content in the syngas. Kinetics of gasification process can be improved by using K2CO3 catalyst. Controlled heating rate in pyrolysis step determines the pore size of charcoal that affects yield gas and H2 and CO content in the syngas. In previous research, pyrolisis step was performed without considering heating rate in pyrolysis step. This experiment was performed by catalytic steam gasification using lignite char from pyrolysis with controlled heating rate intended to produce maximum yield of syngas with mole ratio of H2/CO ≈ 2. Slow heating rate (3 °C/min) until 850 °C in the pyrolysis step has resulted in largest surface area of char. This study was performed by feeding Indonesian lignite char particles and K2CO3 catalyst into a fixed bed reactor with variation of steam/char mole ratio (2.2; 2.9; 4.0) and gasification temperature (750 °C, 825 °C, and 900 °C). Highest ratio of H2/CO (1.682) was obtained at 750 °C and steam/char ratio 2.2. Largest gas yield obtained from this study was 0.504 mol/g of char at 900 °C and steam/char ratio 2.9. Optimum condition for syngas production was at 750 °C and steam/char mole ratio 2.2 with gas yield 0.353 mol/g of char and H2/CO ratio 1.682. 相似文献
4.
《Solid State Sciences》2007,9(2):205-212
SrSi2O2N2 is an important host lattice for Eu2+ doped phosphors. Its crystal structure (space group P1, a = 7.0802(2) Å, b = 7.2306(2) Å, c = 7.2554(2) Å, α = 88.767(3)°, β = 84.733(2)°, γ = 75.905(2)° and V = 358.73(2) Å3, Z = 4) is isotypic with EuSi2O2N2: highly condensed silicate layers are separated by Sr2+. The samples are characterized by pronounced real structure effects owing to pseudosymmetry of partial structures. Polysynthetic twinning with domains of various sizes is ubiquitous and oriented intergrowth of domains with different orientations has also been observed and analysed in detail by means of electron diffraction and high-resolution electron microscopy. These effects also affect the X-ray powder pattern and were taken into account in a Rietveld refinement. 相似文献
5.
Robert T. Butcher Louise N. Dawe Christopher P. Landee Mark M. Turnbull 《Polyhedron》2009,28(9-10):1710-1713
The reaction of copper(II) bromide with 2-methylthiopyrazine (meSpz) in THF/CH2Cl2 gave crystals of [Cu(meSpz)Br2]n. The compound crystallizes in the monoclinic space group C2/m: a = 13.754(6) Å, b = 6.825(2) Å, c = 9.731(4) Å, β = 104.598(8)°. The structure comprises ladders where the rungs of the ladder are formed by bridging bromide ions and the rails are formed by bridging meSpz molecules. Magnetic susceptibility data over the range 1.8–325 K was fit to a strong-rung ladder model resulting in J/krung = ?39.79(17) K and J/krail = ?18.0(4) K. 相似文献
6.
《Tetrahedron: Asymmetry》2006,17(4):566-573
A highly enantioselective cyano-phosphorylation of aldehydes catalyzed by a YLi3tris(binaphthoxide) complex YLB 1 is described. The slow addition of diethyl cyanophosphonate 4 to aldehydes 5 in the presence of YLB 1 (10 mol %), H2O (30 mol %), tris(2,6-dimethoxyphenyl)phosphine oxide 3a (10 mol %), and BuLi (10 mol %) afforded cyanohydrin O-phosphates 6 in up to 98% yield and 97% ee. Mechanistic studies revealed that the addition of cyanide to aldehydes is irreversible and determines the enantioselectivity. The reaction mechanism is also discussed in detail. 相似文献
7.
《Electrochemistry communications》2007,9(1):149-154
Olivine LiCoPO4 phase grown LiCoO2 cathode material was prepared by mixing precipitated Co3(PO4)2 nanoparticles and LiCoO2 powders in distilled water, followed by drying and annealing at 120 °C and 700 °C, respectively, for 5 h. As opposed to ZrO2 or AlPO4 coatings that showed a clearly distinguishable coating layer from the bulk materials, Co3(PO4)2 nanoparticles were completely diffused into the surface of the LiCoO2 and reacted with lithium of LiCoO2. An olivine LiCoPO4 phase was grown on the surface of the bulk LiCoO2, with a thickness of ∼7 nm. The electrochemical properties of the LiCoPO4 phase, grown in LiCoO2, had excellent cycle life performance and higher working voltages at a 1C rate than the bare sample. More importantly, Li-ion cells, containing olivine LiCoPO4, grown in LiCoO2, showed only 10% swelling at 4.4 V, whereas those containing bare sample showed a 200% increase during storage at 90 °C for 5 h. In addition, nail penetration test results of the cell containing olivine LiCoPO4, grown in LiCoO2 at 4.4 V, did not exhibit thermal runaway with a cell surface temperature of ∼80 °C. However, the cell containing bare LiCoO2 showed a burnt-off cell pouch with a temperature above 500 °C. 相似文献
8.
A new flow-through system for the production of [11C]phosgene, a versatile labelling agent in radiochemistry for PET, is described. Cyclotron-produced [11C]CH4 is mixed with Cl2 and converted into [11C]CCl4 by passing the mixture through an empty quartz tube at 510 °C. The outflow is directed through a Sb-filled guard that takes out Cl2 and then, without intentional O2 addition, through a second empty quartz tube at 750 °C, giving rise to [11C]phosgene in 30–35% radiochemical yield. 相似文献
9.
Rie Fredrickson Takagi Daisy Torino Hjelmqvist Mats Johnsson Sven Lidin 《Solid State Sciences》2009,11(1):13-17
The compounds CaCo2Te3O8Cl2, SrCo2Te3O8Cl2 and SrNi2Te3O8Cl2 were synthesized via solid–gas reactions and investigated using single-crystal X-ray diffraction. While the compound CaCo2Te3O8Cl2 formed large enough single crystals to allow for a detailed structural analysis, crystals of the Sr-containing compounds yielded evidence that they are isostructural. CaCo2Te3O8Cl2 crystallizes in the monoclinic system, space group P21/c, a = 6.537(2) Å, b = 9.088(2) Å, c = 19.500(9) Å, β = 113.36(4)°, Z = 4. It exhibits [CoO5Cl] helical chains along the [010] direction, connected by [CaO8] polyhedra, [TeO3E] tetrahedra and [TeO4E] trigonal bipyramids (the lone pair of electrons on TeIV is designated as E) to form a layer. The layers are held together only by weak van der Waals forces; the shortest interlayer distance is a Te?Cl contact of 3.432(4) Å. 相似文献
10.
Enrique Quiroga-González Christian Näther Wolfgang Bensch 《Solid State Sciences》2010,12(7):1235-1241
The new compound {[In(C6H14N2)2]2Sb4S8}Cl2 was prepared under solvothermal conditions reacting InCl3, Sb and S using 1,2-trans-diaminocyclohexane as solvent and structure directing molecule. The compound crystallizes in the monoclinic space group C2/c with a = 29.0259(12), b = 6.7896(2), c = 24.2023(12) Å, β = 99.524(4)°, V = 4703.9(3) Å3. The central structural motif is the thioantimonate(III) anion [Sb4S8]4? acting as a tetradentate ligand thus joining two symmetry related In3+ centered complexes. This binding mode was never observed before for the [Sb4S8]4? anion. The optical band gap was determined as 2.03 eV in agreement with the red color of the compound. The thermal decomposition was monitored with in-situ X-ray diffraction experiments. After the emission of the amine molecules an amorphous intermediate is formed followed by the crystallization of InSbS3 which is stable up to about 590 °C. On further heating, InSbS3 is destroyed and reflections of γ-In2S3 appear being contaminated with some elemental Sb. Temperature dependent in-situ X-ray powder diffractometry performed between 30 and 220 °C reveals an unusual reversible negative and positive thermal expansion. The decrease of the a-axis in the temperature range is about 0.74 Å and the increase of the c-axis ca. 0.54 Å. Interestingly, the b-axis exhibits also a thermal expansion, i.e., a biaxial positive and an uniaxial negative thermal expansion coexist which is very unusual. The relative negative expansion coefficients for the a-axis of ?194 × 10?6K?1 (30–120 °C) and ?82 × 10?6K?1 (120–220 °C) are in the region of so-called colossal thermal expansion. 相似文献
11.
Kyle M. Lancaster James B. Gerken Alec C. Durrell Joshua H. Palmer Harry B. Gray 《Coordination chemistry reviews》2010,254(15-16):1803-1811
The properties of RuII complexes involving the imidazole moiety are discussed. Complexes [Ru(bpy)2(L)]2+ [bpy = 2,2′-bipyridine, L = 2-(2′-pyridyl)imidazole (2-pimH) and 4-(2′-pyridyl)imidazole (4-pimH)] have been synthesized and fully characterized. Reduction potentials are 0.76 V vs. Fc+/Fc0 for both complexes in acetonitrile solution, and the deprotonated complexes undergo irreversible electrochemical oxidation at 0.38 V vs. Fc+/Fc0. Density functional theory (DFT) calculations suggest that oxidation of the protonated complexes is primarily metal-based and that of the deprotonated complexes is ligand-centered. The pKa of the 4-pimH complex was found to be 9.7 ± 0.2; the pKa of the 2-pimH complex is 7.9 ± 0.2. Luminescence lifetimes (L = 4-pimH, 277 ns; 2-pimH, 224 ns; 4pim?, 40 ns; 2pim?, 34 ns in 5% methanol/water solution) combined with quantum yield data and acid–base behavior suggest that the non-coordinated imidazole nitrogen tunes deactivation pathways. 相似文献
12.
《Journal of molecular catalysis. A, Chemical》2007,261(1):79-87
Dioxomolybdenum(VI) complexes of general formula [MoO2X2L2] (X = Cl, OSiPh3; L2 = 2-(1-butyl-3-pyrazolyl)pyridine, ethyl[3-(2-pyridyl)-1-pyrazolyl]acetate) were prepared and characterised by 1H NMR, IR and Raman spectroscopy. The assignment of the vibrational spectra was supported by ab initio calculations. A single crystal X-ray diffraction study of the complex [MoO2Cl2{ethyl[3-(2-pyridyl)-1-pyrazolyl]acetate}] showed that the compound is monomeric and crystallises in the tetragonal system with space group P41. The four complexes are active and selective catalysts for the liquid-phase epoxidation of olefins by tert-butylhydroperoxide. Selectivities to the corresponding epoxides were mostly 100% (for conversions of at least 34%) for the substrates cyclooctene, cyclododecene, 1-octene, trans-2-octene and (R)-(+)-limonene. For styrene epoxidation, the corresponding diol was also formed in significant quantities. The turnover frequencies for cyclooctene epoxidation at 55 °C were around 340 mol molMo−1 h−1 for the chloro complexes and 160 mol molMo−1 h−1 for the triphenylsiloxy complexes. The addition of co-solvents (1,2-dichloroethane or n-hexane) had a detrimental effect on catalytic activities. Kinetic studies for the two complexes bearing the ligand ethyl[3-(2-pyridyl)-1-pyrazolyl]acetate revealed an apparent first order dependence of the initial rate of cyclooctene conversion with respect to cyclooctene or oxidant concentration. 相似文献
13.
《Radiation Physics and Chemistry》2006,75(11):1916-1920
X-ray absorption spectroscopy is used to investigate the speciation of sorbed copper in heated fly ash. CuO and Cu(OH)2 are determined to be the principal copper species in the Cu-sorbing fly ash heated at 500 °C for 2 h. Heating the Cu-sorbing fly ash to 900 °C or 1100 °C can result in the formation of CuSO4, representing 41% and 32% of the total copper, respectively. Ash sintering and/or co-melting at 900 and 1100 °C occur, thereby triggering chemical reaction between CuO/Cu(OH)2 and sulfur compounds. 相似文献
14.
B. Ganapayya A. Jayarama Ravish Sankolli Venkatesha R. Hathwar S.M. Dharmaprakash 《Journal of Molecular Structure》2012
3-(2,3-Dimethoxyphenyl)-1-(pyridin-2-yl)prop-2-en-1-one (DMPP) a potential second harmonic generating (SHG) has been synthesized and grown as a single crystal by the slow evaporation technique at ambient temperature. The structure determination of the grown crystal was done by single crystal X-ray diffraction study. DMPP crystallizes with orthorhombic system with cell parameters a = 20.3106(8) Å, b = 4.9574(2) Å, c = 13.4863(5) Å, α = 90°, β = 90°, γ = 90° and space group Pca21. The crystals were characterized by FT-IR, thermal analysis, UV–vis–NIR spectroscopy and SHG measurements. Various functional groups present in DMPP were ascertained by FTIR analysis. DMPP is thermally stable up to 80 °C and optically transparent in the visible region. The crystal exhibits SHG efficiency comparable to that of KDP. 相似文献
15.
The evolution of gases and volatiles during Sulcis coal pyrolysis under different atmospheres (N2 and H2) was investigated to obtaining a clean feedstock of combustion/gasification for electric power generation. Raw coal samples were slowly heated in temperature programmed mode up to 800 °C at ambient pressure using a laboratory-scale quartz furnace coupled to a Fourier transform infrared spectrometer (FTIR) for evolved gas analysis. Under both pyrolysis and hydropyrolysis conditions the evolution of gases started at temperature as low as 100 °C and was mainly composed by CO and CO2 as gaseous products. With increasing temperature SO2, COS, and light aliphatic gases (CH4 and C2H4) were also released. The release of SO2 took place up to 300 °C regardless of the pyrolysis atmosphere, whilst the COS emissions were affected by the surrounding environment. Carbon oxide, CO2, and CH4 continuously evolved up to 800 °C, showing similar release pathways in both N2 and H2 atmospheres. Trace of HCNO was detected at low pyrolysis temperature solely in pure H2 stream. Finally, the solid residues of pyrolysis (chars) were subjected to reaction with H2 to produce CH4 at 800 °C under 5.0 MPa pressure. The chars reactivity was found to be dependent on pyrolysis atmosphere, being the carbon conversions of 36% and 16% for charN2 and charH2, respectively. 相似文献
16.
2-Phosphonoacrylates containing four chiral alcohol auxiliaries were efficiently prepared and evaluated in Lewis acid mediated Diels–Alder reactions. Under the activation of SnCl4, all reactions performed in CH2Cl2 at ?65 °C exclusively afforded the endo (endo-to-carboxylate) cycloadducts with dr’s ranging from 50:50 to >99:1. The best facial selectivity was obtained from the substrate bearing a (?)-phenylmenthyl group, to give adducts as (dr >99:1) or almost as (dr = 99:1) single diastereomers. Detailed strategies for the structural elucidation of the cycloadducts as well as a rationalization of the observed stereoselectivity are described. 相似文献
17.
《Solid State Sciences》2007,9(11):1012-1019
Two novel inorganic–organic hybrid compounds composed of Keggin tungstocobaltate framework and cobalt(II)–N coordination complexes, K[Co(phen)2(H2O)]2[HCoW12O40]·2H2O (1) (phen = 1,10-phenanthroline) and [Co(2,2′-bipy)3]1.5{[Co(2,2′-bipy)2(H2O)][HCoW12O40]·0.5H2O (2) (bipy = bipyridine), have been synthesized under hydrothermal conditions by directly using Keggin POMs as starting materials, which were characterized by elemental analyses, IR, TG analyses and X-ray single crystal diffraction. Crystal data for compound 1: C48H41Co3KN8O44W12, triclinic, space group P-1, a = 10.918(5) Å, b = 13.401(5) Å, c = 13.693(5) Å, α = 69.291(5)°, β = 71.568(5)°, γ = 78.421(5)°, V = 1768.9(12) Å3, Z = 1; for compound 2: C130H104Co7N26O83W24, orthorhombic, space group, C2/c, a = 46.839(9) Å, b = 14.347(3) Å, c = 26.147(5) Å, α = β = γ = 90°, V = 17,570(6) Å3, Z = 4. Compound 1 exhibits a pseudo-1D chainlike structure, in which potassium ions act as linkages of Keggin unit doubly grafted by [Co(phen)2(H2O)] complex. Compound 2 represents a [Co(2,2′-bipy)2(H2O)]2+ mono-grafted Keggin tungstocobaltate derivative with 1.5[Co(2,2′-bipy)3]2+ countercations. The cyclic voltammetric behavior of 1-CPE is similar to the parent 3-CPE, but the cyclic voltammetric behavior of CoII shows a little difference. Variable-temperature magnetic susceptibility measurement of compound 1 demonstrates the presence of antiferromagnetic interactions. 相似文献
18.
N. K. Gusarova S. I. Shaikhudinova T. I. Kazantseva B. G. Sukhov V. I. Dmitriev L. M. Sinegovskaya Yu. V. Smetannikov N. P. Tarasova B. A. Trofimov 《Chemistry of Heterocyclic Compounds》2001,37(5):576-580
The phosphorylation of 2-vinyl- and 4-vinylpyridines by white phosphorus and active modifications of red phosphorus (obtained by thermal polymerization of white phosphorus in the presence of graphite or the action of ionizing radiation in benzene) in the KOH/DMSO superbase system at room temperature leads to the formation of tris[2-(2-pyridyl)ethyl]- and tris[2-(4-pyridyl)ethyl]phosphine oxides in 58-72% yield. These oxides are promising ligands for design of metal complex catalysts. These vinylpyridines react less efficiently with ordinary red phosphorus and the yield of the corresponding tris(2-pyridylethyl)phosphine oxides does not exceed 10%. 相似文献
19.
《Solid State Sciences》2007,9(6):455-458
The calcium trimellitate, Ca(H2O)[(O2C)2–C6H3–CO2H], was hydrothermally synthesized from a mixture of calcium hydroxide, 1,2,4-benzenetricarboxylic (or trimellitic) acid and water at 180 °C for 24 h (under autogenous pressure). Its crystal structure has been determined by single-crystal X-ray diffraction analysis using synchrotron radiation (station 9.8, SRS Daresbury, UK). It consists of infinite chains of calcium bicapped trigonal prismatic polyhedra connected to each other through the 1,2,4-benzenetricarboxylate ligand. The eight-fold coordinated calcium cation is bonded to one terminal water molecule, two carboxylate groups with a chelating conformation and three carboxylate groups in a monodentating mode. One of the monodentate carboxylate is terminal with the occurrence of protonated C–OH bonding.Triclinic space group P-1 with a = 6.9073(4) Å, b = 6.9917(4) Å, c = 10.3561(6) Å, α = 87.178(1)°, β = 83.233(1)°, γ = 69.576(1)°, V = 465.41(5) Å3. 相似文献
20.
《Solid State Sciences》2007,9(6):531-534
The most condensed crystalline fluoride that appears in the Al(OH)3-tren-HFaq.-ethanol system at 190 °C is found to be [H4tren]3/2·(Al6F24)·3H2O. The structure is monoclinic, P21/c, with a = 21.939(1) Å, b = 6.7180(2) Å, c = 23.329(1) Å, β = 111.324(2)°. ∞(Al6F24) chains result from the connection of (Al7F30)9− polyanions by opposite AlF6 octahedra. Hydrogen bonds are established between the ∞(Al6F24) chains and ordered or disordered [H4tren]4+ cations and water molecules. 相似文献