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1.
《Journal of Photochemistry》1980,12(2):93-107
The absorption spectra of some chlorine-containing methanes (CCl4, CCl3F, CClF3, CHCl3, CH2Cl2 and CH2ClF) and ethanes (CCl2FCClF2, CClF2CClF2, CF3CClF2, CF3CH2Cl, CH3CCl3, CH3CClF2 and CH3CH2Cl) and also of N2O were determined at wavelengths near 220 nm. Some of these spectra were obtained at both 298 and 208 K. Additionally, a chemical method was used to determine the absorption cross section of CCl3F at λ = 253.7 nm and the absorption properties at wavelengths above 280 nm. It is concluded from these experiments that the tropospheric decay rate of CCl3F is less than 10−10 s−1 for the homogeneous gas phase photolysis. 相似文献
2.
Adsorption separation of carbon dioxide,methane, and nitrogen on Hβ and Na-exchanged β-zeolite
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Xiaoliang Xu Xingxiang Zhao Linbing Sun Xiaoqin Liu 《天然气化学杂志》2008,17(4):391-396
Adsorption isotherms of carbon dioxide (CO2), methane (CH4), and nitrogen (N2) on Hβand sodium exchanged β-zeolite (Naβ) were volumetrically measured at 273 and 303 K. The results show that all isotherms were of Brunauer type I and well correlated with Langmuir-Freundlich model. After sodium ions exchange, the adsorption amounts of three adsorbates increased, while the increase magnitude of CO2 adsorption capacity was much higher than that of CH4 and N2. The selectivities of CO2 over CH4 and CO2 over N2 enhanced after sodium exchange. Also, the initial heat of adsorption data implied a stronger interaction of CO2 molecules with Na+ ions in Naβ . These results can be attributed to the larger electrostatic interaction of CO2 with extraframework cations in zeolites. However, Naβ showed a decrease in the selectivity of CH4 over N2, which can be ascribed to the moderate affinity of N2 with Naβ. The variation of isosteric heats of adsorption as a function of loading indicates that the adsorption of CO2 in Naβ presents an energetically heterogeneous profile. On the contrary, the adsorption of CH4 was found to be essentially homogeneous, which suggests the dispersion interaction between CH4 and lattice oxygen atoms, and such interaction does not depend on the exchangeable cations of zeolite. 相似文献
3.
A. Robledo-Cabrera A. López-Valdivieso J. E. Pérez-López O. A. Orozco-Navarro 《Journal of Thermal Analysis and Calorimetry》2018,133(2):991-999
Isoperibol (pseudo-adiabatic) titration microcalorimetry was used to study the adsorption of various xanthates [CH3(CH2)nOCS2?] at the PbSO4/aqueous solution interface. The effect of the xanthate alkyl chain length (1n–3n) on the adsorption heat was evaluated. Xanthate adsorption isotherms were also determined. Furthermore, the amount of SO4 into the aqueous solution was quantified to correlate it with the xanthate uptake by PbSO4. The adsorption isotherms and the adsorption heat of the xanthates showed two steps. The first step occurred within a sub-monolayer xanthate coverage and was attributed to chemisorption of the xanthates exchanging surface hydroxyls to form CH3(CH2)nOCS2Pb. Lead xanthate (CH3(CH2)nOCS2)2Pb multilayers formed in the second step, which was attributed to an ionic exchange chemical reaction between the xanthates and PbSO4(aq). In the chemisorption step, the heat was found to be independent of the xanthate alkyl chain length and to linearly decrease in magnitude with the xanthate adsorption. In the multilayer formation step, the magnitude of the integral heat increased with the chain length of the xanthate. Heat contributions due to both the alkyl chain length and the interaction between the xanthate polar group and PbSO4(aq) for the formation of lead xanthates are presented. Raman spectroscopy was used to characterize the lead xanthate multilayers on PbSO4. 相似文献
4.
Dr. Javeed Mahmood Seok‐Jin Kim Hyuk‐Jun Noh Dr. Sun‐Min Jung Ishfaq Ahmad Dr. Feng Li Jeong‐Min Seo Prof. Jong‐Beom Baek 《Angewandte Chemie (International ed. in English)》2018,57(13):3415-3420
A three‐dimensional (3D) cage‐like organic network (3D‐CON) structure synthesized by the straightforward condensation of building blocks designed with gas adsorption properties is presented. The 3D‐CON can be prepared using an easy but powerful route, which is essential for commercial scale‐up. The resulting fused aromatic 3D‐CON exhibited a high Brunauer–Emmett–Teller (BET) specific surface area of up to 2247 m2 g?1. More importantly, the 3D‐CON displayed outstanding low pressure hydrogen (H2, 2.64 wt %, 1.0 bar and 77 K), methane (CH4, 2.4 wt %, 1.0 bar and 273 K), and carbon dioxide (CO2, 26.7 wt %, 1.0 bar and 273 K) uptake with a high isosteric heat of adsorption (H2, 8.10 kJ mol?1; CH4, 18.72 kJ mol?1; CO2, 31.87 kJ mol?1). These values are among the best reported for organic networks with high thermal stability (ca. 600 °C). 相似文献
5.
Linda Nelson Imelda Shanahan Howard W. Sidebottom Jack Treacy Ole J. Nielsen 《国际化学动力学杂志》1990,22(6):577-590
The reaction mechanisms for oxidation of CH3CCl2 and CCl3CH2 radicals, formed in the atmospheric degradation of CH3CCl3 have been elucidated. The primary oxidation products from these radicals are CH3CClO and CCl3CHO, respectively. Absolute rate constants for the reaction of hydroxyl radicals with CH3CCl3 have been measured in 1 atm of Argon at 359, 376, and 402 K using pulse radiolysis combined with UV kinetic spectroscopy giving ??(OH + CH3CCl3) = (5.4 ± 3) 10?12 exp(?3570 ± 890/RT) cm3 molecule?1 s?1. A value of this rate constant of 1.3 × 10?14 cm3 molecule?1 s?1 at 298 K was calculated using this Arrhenius expression. A relative rate technique was utilized to provide rate data for the OH + CH3 CCl3 reaction as well as the reaction of OH with the primary oxidation products. Values of the relative rate constants at 298 K are: ??(OH + CH3CCl3) = (1.09 ± 0.35) × 10?14, ??(OH + CH3CClO) = (0.91 ± 0.32) × 10?14, ??(OH + CCl3CHO) = (178 ± 31) × 10?14, ??(OH + CCl2O) < 0.1 × 10?14; all in units of cm3 molecule?1 s?1. The effect of chlorine substitution on the reactivity of organic compounds towards OH radicals is discussed. 相似文献
6.
Abstract Ferrocene- and iron-arene salts can photoinitiate polymerization of pyrrole in the presence of halogenated solvents, such as CH2CH2Cl2, CHCl3, and CCl4, when irradiated with UV light (254 nm). The polypyrroles obtained are black colloidal powders and have low conductivity in the range of 10?5 S cm?1 and rather poor electrochemical properties, which can be the result of loss of conjugation by halogenation. Polypyrrole samples contain both covalently bounded CCl3 groups (from CCl4) and ionic FeCl? 4. A mechanism of photoinitiated polymerization of pyrrole has been proposed. 相似文献
7.
Additive manufacturing or 3D printing is the advanced method of manufacturing monolithic adsorbent materials. Unlike beads or pellets, 3D monolithic adsorbents possess the advantages of widespread structural varieties, low heat and mass transfer resistance, and low channeling of fluids. Despite a large volume of research on 3D printing of adsorbents having been reported, such studies on porous carbons are highly limited. In this work, we have reported direct ink 3D printing of porous carbon; the ink consisted of commercial activated carbon, a gel of poly(4-vinylphenol) and Pluronic F127 as plasticizer, and bentonite as the binder. The 3D printing was performed in a commercial 3D printer that has been extensively modified in the lab. Upon 3D printing and carbonization, the resultant 3D printed porous carbon demonstrated a stable structure with a BET area of 400 m2/g and a total pore volume of 0.27 cm3/g. The isotherms of six pure-component gases, CO2, CH4, C2H6, N2, CO, and H2, were measured on this carbon monolith at 298 K and pressure up to 1 bar. The selectivity of four gas pairs, C2H6/CH4, CH4/N2, CO/H2, and CO2/N2, was calculated by Ideally Adsorbed Solution Theory (IAST) and reported. Ten continuous cycles of adsorption and desorption of CO2 on this carbon confirmed no loss of working capacity of the adsorbent. 相似文献
8.
Cristina Dubceac Dr. Alexander S. Filatov Dr. Alexander V. Zabula Prof. Andrey Yu. Rogachev Prof. Marina A. Petrukhina 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(41):14268-14279
A detailed structural overview of a family of bowl‐shaped polycyclic aromatic carbocations of the type [C20H10R]+ with different R functionalities tethered to the interior surface of corannulene (C20H10) is provided. Changing the identity of the surface‐bound groups through alkyl chains spanning from one to four carbon atoms and incorporating a different degree of halogenation has led to the fine tuning of the bowl structures and properties. The deformation of the corannulene core upon functionalization has been revealed based on X‐ray crystallographic analysis and compared for the series of cations with R=CH3, CH2Cl, CHCl2, CCl3, CH2CH3, CH2CH2Cl, and CH2CH2Br. The resulting carbocations have been isolated with several metal‐based counterions, varying in size and coordinating abilities ([AlCl4]?, [AlBr4]?, [(SnCl)(GaCl4)2]?, and [Al(OC(CF3)3)4]?). A variety of aggregation patterns in the solid state has been revealed based on different intermolecular interactions ranging from cation–anion to π–π stacking and to halogen???π interactions. For the [C20H10CH2Cl]+ ion crystallized with several different counterions, the conformation of the R group attached to the central five‐membered ring of corannulene moiety was found to depend on the solid‐state environment defined by the identity of anions. Solution NMR and UV/Vis investigations have been used to complement the X‐ray diffraction studies for this series of corannulene‐based cations and to demonstrate their different association patterns with the solvent molecules. 相似文献
9.
The chlorination of singly and multiply charged C60 cations has been investigated with the selected-ion flow tube technique. Observations are reported for the reactions of C60·+, C602+ and C60·3+ with Cl2, CCl4, CDCl3, CH2Cl2 and CH3Cl at room temperature (295 ± 2 K) in helium at a total pressure of 0.35 ± 0.02 Torr. C60·+ and C602+ were observed not to chlorinate, or react in any other way, with these five molecules. Chlorine also did not react with C60·3+, but bimolecular chloride transfer and electron transfer reactions, reactions that result in charge reduction/charge separation, were observed to occur with CCl4, CDCl3, CH2Cl2 and CH3Cl. Chloride transfer was the predominant channel seen with CCl4, CDCl3 and CH2Cl2 while electron transfer dominates the reaction with CH3Cl. These results are consistent with trends in chloride affinity and ionization energy. The reluctant chlorination of the first two charge states of C60 is attributed to the energy required to distort the carbon cage upon bond formation, while the observed chloride transfer to C60·3+ is attributed to the greater electrostatic interactions with this ion. 相似文献
10.
The synthesis and characterization of CuX2L; (X = CH3CH2COO?, ClCH2CH2COO?, CH3CHClCOO? or CH3CCl2COO?; and L = 4-acetylpyridine N-oxide) is reported. The characterization of these compounds was based on electronic, infrared and EPR spectra, as well as magnetic measurements over the temperature range. Several correlations between the spectral and magnetic data as well as pKa values of the respective acids were found and discussed. On the basis of spectral and magnetic data the structures of the compounds are discussed. 相似文献
11.
The methods of temperature-programmed reaction/desorption (TPR/TPD) are used to study azomethane (CH3N=NCH3) decomposition and the reactions of the products of its pyrolysis (CH
3
*
radicals and N2) on the polycrystalline molybdenum surface. A TPR spectrum of adsorbed azomethane decomposition shows mainly N2, H2, and unreacted azomethane. Upon preliminary adsorption of azomethane pyrolysis products on a catalyst sample, a TPR spectrum
shows N2, H2, and CH4 in comparable amounts. The difference in the composition of desorption products found for these two types of experiments
shows that, in the decomposition of adsorbed azomethane, surface methyl moieties are not formed. The rate constants were calculated
for the dissociation of adsorbed CH3, CH2, and CH, recombination of hydrogen atoms with each other and with CH3 and CH2, and the recombinative desorption of nitrogen atoms.
Deceased. 相似文献
12.
The variations of concentrations of volatile halocarbons (CHCl3, CCl4, CH2Cl—CH2Cl, CCl3—CH3, CHCl—CCl2, and CCl2=CCl2) in rural and urban air are demonstrated by two series of air sampling carried out in Southern Germany. The interpretation of the changes in concentrations for the individual compounds is based on specific local input for the chlorinated solvents and on changing weather conditions during the sampling periods.Dedicated to Professor J. F. K. Huber on the occasion of his 65th birthday 相似文献
13.
A. L. Chistyakov I. V. Stankevich N. P. Gambaryan I. S. Akhrem 《Russian Journal of Organic Chemistry》2006,42(11):1606-1614
Simulation of fragments of potential energy surface for systems CH4 + CBr 3 + , CH4 + CBr 3 + AlBr 4 ? , CH4 + CCl 3 + AlCl 4 ? , and CH4 + CCl 3 + Al2Cl 7 ? was performed by DFT-B3LYP and DFT-PBE methods. The important role of nucleophilic assistance in methane halogenation by these superelectrophiles was confirmed. These reactions occur with a synchronous hydride transfer from methane to the electrophile within the cyclic transition states in linear C-H-C fragment of the rings and a generation of a C-Hlg bond between the carbon atom of the arising methyl group and the halogen atom of the electrophile. The nucleophilic assistance from the unshared electron pair of this halogen atom provides the lowering of the potential barriers to methane halogenation by complexes CBr 3 + AlBr 4 ? , CCl 3 + AlCl 4 ? , and CCl 3 + Al2Cl 7 ? to the values of the order of 20 kcal mol?1. These essential features of the mechanism of methane halogenation are independent of the halogen nature and are retained on going from the model electrophiles to the real ones. 相似文献
14.
F. K. Velichko V. I. Dostovalova N. A. Kuzmina E. I. Fedin R. Kh. Freidlina 《Magnetic resonance in chemistry : MRC》1975,7(1):46-50
The study of 28 specially selected compounds containing chlorine shows that 13C NMR signals of the CCl3, CCl3CH2 and CH2Cl groups are registered in the ranges of 93 to 105, 49 to 71 and 38 to 59 ppm (from TMS), respectively and are readily identified in 13C NMR spectra of polychloro compounds. The weak electron withdrawing ability of the CCl3CHCl and CH2Cl groups, as well as the extremely strong influence of CCl3 and CH2Cl groups on the methylene group between them in 1,1,1,3-tetrachloropropane, is noted. 相似文献
15.
The thermal dehydrochlorination CF2ClCH3→CF2(DOUBLEBOND)CH2+HCl has been studied in a static system between 597 and 664 K in the presence of CCl4, C2Cl6, CF2(DOUBLEBOND)CH2, HCl, and CF3CH3. A kinetic radical and molecular reaction model has been developed. In addition to describing earlier results on the acceleration of the pyrolysis by CCl4 and the further acceleration by HCl, this model describes quantitatively up to conversions of 20% (i) the dependence of the catalytic effect of CCl4 at low concentrations, (ii) the stronger catalytic effect of C2Cl6, and (iii) the inhibitory effect of added CF2CH2 and CF3CH3 when CCl4 is used as a catalyst. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 359–366, 1998 相似文献
16.
Gasanov R. G. Tumanskii B. L. Guseva T. I. Sencheniya N. G. Golding I. R. 《Russian Chemical Bulletin》2001,50(12):2356-2359
The rate constants for the addition of ·CH(Ph)CH2CCl3, ·CH2Ph, ·CH2Prn, and ·CCl3 radicals to the ethyl 2-cyanoacrylate molecule were determined by ESR spectroscopy using the spin trapping technique. 相似文献
17.
The photolysis and desorption of CH2I2, CH3I, CCl4, CHCl3, CH2Cl2, CF2Cl2, and CHF2Cl molecules adsorbed on fused silica under the action of XeF and XeCl laser radiation absorbed by these molecules have been studied. The desorption of molecules that occurs due to expansion to the long-wavelength region of the absorption spectrum of molecules in the adsorbed state, compared to the gas phase, predominates. The laser desorption is characterized by a strong nonlinear dependence on the density of radiation energy. Depending on the relationship between the laser radiation wavelength and the spectrum of electronic states of molecules, photolysis is observed upon absorption of either one or two photons. At an increased fluence of laser radiation energy, the one-photon detachment of the primary CH2I fragment from the CH2I2 molecule changes into the three-photon process. A similar behavior is revealed for the desorption of CH3I molecules from clusters formed on the surface in multilayer adsorption coverages. 相似文献
18.
R. G. Gasanov 《Russian Chemical Bulletin》2000,49(1):46-49
The rate constants for reactions of Cl abstraction from CCl4 by CCl3CH2·CHR radicals and Br abstraction from CCl3CH2CHBrR (R=Bun, AcO, OCNC4H8, CN) by·Re(CO)5 radicals were determined by ESR spectroscopy using spin trapping technique. Replacement of H atoms at the C(β) atom by O
or N atoms reduces the reactivity of the radicals in the reactions of Cl abstraction from CCl4 by approximately an order of magnitude. The presence of two polar groups at the C(β) atom results in appreciable decrease
in the strength of the C−Br bond in CCl3CH2CHBrR adducts.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 45–48, January, 2000. 相似文献
19.
The world is faced with intrinsic environmental issues. Among these issues, the minimization of greenhouse gas emission to acceptable levels presents a high priority. This study seeks to help to reduce the greenhouse effect in sustainable manner. A resorcinol–formaldehyde xerogel was synthesized at specific conditions and used to prepare an activated carbon xerogel (RF-ACX). RF-ACX exhibited micropores in range of 1.2–1.4 nm, a surface area of 496 m2/g and a cumulative pore volume of 0.81 cm3/g. Scanning electron microscopy showed that it is made of microspherical particles with an almost uniform particle size of 1.3 ± 0.2 μm. Equilibrium and kinetic studies for the adsorption of CO2, CH4 and N2 on RF-ACX were conducted at five temperatures (293, 303, 313, 323, and 333 K) and pressures of up to 1 MPa. The adsorption capacity on RF-ACX was highest for CO2, followed by CH4 and then N2. Isosteric heats of adsorption and adsorption rates were investigated. The measured adsorption equilibria were fitted with the extended multisite Langmuir adsorption model and further used to predict adsorption equilibria of their corresponding binary systems. 相似文献
20.
R. G. Gasanov 《Russian Chemical Bulletin》1990,49(1):46-49
The rate constants for reactions of Cl abstraction from CCl4 by CCl3CH2·CHR radicals and Br abstraction from CCl3CH2CHBrR (R=Bun, AcO, OCNC4H8, CN) by·Re(CO)5 radicals were determined by ESR spectroscopy using spin trapping technique. Replacement of H atoms at the C(β) atom by O
or N atoms reduces the reactivity of the radicals in the reactions of Cl abstraction from CCl4 by approximately an order of magnitude. The presence of two polar groups at the C(β) atom results in appreciable decrease
in the strength of the C−Br bond in CCl3CH2CHBrR adducts.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 45–48, January, 2000. 相似文献