Organolithium complex as a gas sensing material for oxides from ab initio calculations and molecular dynamics simulations

Gas sensing study of C₂H₄Li complex toward oxides viz. CO, CO₂, NO, NO₂, SO, and SO₂ gas molecules has been carried out using ab initio method. Different possible configurations of gas molecule adsorption on C₂H₄Li complex are considered. The structural parameters of most stable configuration of gas molecule adsorbed complexes are thoroughly analysed. Electronic properties are studied using total density of states (DOS) plot. Charge transferred between the gas molecule and the substrate is studied using NBO charge analysis. Gas sensing of all the six gas molecules is possible at ambient conditions. Atom centred density matrix propagation (ADMP) molecular dynamics simulations confirmed that all the gas molecules remain adsorbed on C₂H₄Li complex at room temperature during the simulation. This study suggests that the C₂H₄Li complex acts as a novel gas sensing material for CO, CO₂, NO, NO₂, SO, and SO₂ gas molecules at ambient conditions, below room temperature as well as at high pressure.     

Cu?Ti?O catalyst for complex purification of gases

Cu–Ti–O catalysts activity in the reactions of complete oxidation of CO and C₄H₁₀, selective catalytic reduction of NO by ammonia, SO₂ oxidation to SO₃, as well as the catalyst resistance to sulfur poisoning were studied. We suggest these catalysts for the combined removal of NO, CO and toxic organics from flue gases.     

Alkalimetall-Cluster im Zeolith Y Darstellung,Eigenschaften, Reaktionen

Alkali Metal Clusters in Zeolite Y. Preparation, Properties, Reactions Alkali metal clusters (Type AB₃³⁺) were synthesized by reaction of alkali metal A (Li, Na, K, Rb, Cs) with the cations B (alkali, alkaline earth, and rare earth metals) of zeolite Y. The compounds were characterized by UV/VIS spectroscopy, oxidation by carbon oxides and organic halides, and adsorption of gases and polar molecules. The clusters are less reactive than the free alkali metals, the redox potential depends on the alkali metal as well as the cation of zeolite. Chemical interactions with typical ligands and with N₂, Ar, Kr, CO, CO₂, Benzene, and n-Hexane were observed. Reaction with ammonia leads to solvated electrons in zeolite's super-cage, stable up to 240 K.     

Effects of additional gases on the catalytic decomposition of N2O over Cu-ZSM-5

N₂O decomposition into N₂ and O₂ was investigated in the presence of O₂, NO, CO₂, CO, CH₄, SO₂ and water vapor. Activity inhibition was observed in the presence of water vapor, and oxidant gases, whilst the reductant gases, enhanced the catalytic activity, in the temperature range of 350–550°C.     

Chemical lasers produced from O(3P) atom reactions. III. 5-μm CO laser emission from the O + CH reaction

Very strong laser emission at 5 μm was detected when SO₂ and CHBr₃ were flash photolyzed in the vacuum ultraviolet (λ ≥ 165 nm) in the presence of a large amount of diluent (SF₆, He, or Ar). About 110 vibration–rotation transitions ranging from Δv = 18 → 17 to 3 → 2, except 16 → 15, were identified. The primary reactions leading to the CO stimulated emission are as follows: The product analysis results and the variation of laser intensity with flash energy and SO concentration indicate that the following side reactions are also occurring. Addition of a small amount of O₂ enhances the laser output by both eliminating these side reactions and simultaneously producing vibrationally excited CO via reaction (8), which has been previously shown to generate CO stimulated emission. The effects of various reactive (NO and H₂) and inert (He, Ar, SF₆, CO, N₂, N₂O, and CO₂) gases have been examined. All additives (P ≤ 20 torr), except NO and H₂, increase the total laser output. N₂O enhances the power most efficiently, whereas CO, N₂, and CO₂ are less effective and have similar efficiencies. The enhancement of the laser intensity by these near-resonant gases is ascribed to the depletion of CO population at lower levels which thus increases the rates cascading from higher levels. NO and H₂ quench the laser output by chemically reducing the concentration of the CH radical.     

Al-doped B80 fullerene as a suitable candidate for H2, CH4, and CO2 adsorption for clean energy applications

Dispersion-corrected density functional theory method was performed to report on a high-performance adsorbent for removal of CO₂ from the precombustion and natural gases. At first, the effect of Al atom impurity on the structural and electronic properties of B₈₀ fullerene is studied. Then, the adsorption geometries and energies of gases (H₂, CH₄, or CO₂) on the B₈₀ and AlB₇₉ (amphoteric adsorbents) are explored. The Al atom enhances reactivity of the cage toward the gases and the adsorption processes are more exothermic with low and high energy barriers for chemisorption of H₂ and CO₂, respectively. Stable chemisorption of CO₂ on the AlB₇₉ is validated by the high adsorption energy and large charge transfer, while the CH₄ is just physically adsorbed on the AlB₇₉. Further, the physisorbed gases can enhance field emission current of the AlB₇₉ and in the continuous capturing of the gases, the magnetic moment of the cage is quenched. Furthermore, dependency of the electronic structure of the adsorbent on the gas adsorption is intensively studied. We suggest that the AlB₇₉ could be a promising material for capture, storage, and separation of the gases and as a novel material for sustainable energy and sweetening process in the petroleum industry.     

Multiscale simulation of pollution gases adsorption in porous organic cage CC3

A general multiscale simulation procedure is proposed to accurately predict the uptakes of pollution gases such as CO₂, SO₂, H₂S, and CO in one of the most investigated porous organic cages CC3 by using a sophisticated force field vdW3 fitted by double hybrid functional (B2PLYP) with a dispersion correction (D3) separately for gas–gas and CC3‐gas interactions. The fitted vdW3 was used in grand canonical Monte Carlo simulations. Good comparison with the coupled cluster single and double excitation and the perturbative triples (CCSD(T))/complete basis set (CBS) limit interaction energies make the B2PLYP‐D3 results reliable for our purpose. The good agreement of simulated CO₂ loading with experimental one and the low deviation in the fitting procedure for H₂S and CO make our approach available in predicting gases in novel porous materials. © 2013 Wiley Periodicals, Inc.     

Experimental and kinetic modeling study of the effect of NO and SO2 on the oxidation of CO?H2 mixtures

The effect of NO and SO₂ on the oxidation of a CO? H₂ mixture was studied in a jet‐stirred reactor at atmospheric pressure and for various equivalence ratios (0.1, 1, and 2) and initial concentrations of NO and SO₂ (0–5000 ppm). The experiments were performed at fixed residence time and variable temperature ranging from 800 to 1400 K. Additional experiments were conducted in a laminar flow reactor on the effect of SO₂ on CO? H₂ oxidation in the same temperature range for stoichiometric and reducing conditions. It was demonstrated that in fuel‐lean conditions, the addition of NO increases the oxidation of the CO? H₂ mixture below 1000 K and has no significant effect at higher temperatures, whereas the addition of SO₂ has a small inhibiting effect. Under stoichiometric and fuel‐rich conditions, both NO and SO₂ inhibit the oxidation of the CO? H₂ mixture. The results show that a CO? H₂ mixture has a limited NO reduction potential in the investigated temperature range and rule out a significant conversion of HNO to NH through reactions like HNO + CO ?? NH + CO₂ or HNO + H₂ ?? NH + H₂O. The chain terminating effect of SO₂ under stoichiometric and reducing conditions was found to be much more pronounced than previously reported under flow reactor conditions and the present results support a high rate constant for the H + SO₂ + M ?? HOSO + M reaction. The reactor experiments were used to validate a comprehensive kinetic reaction mechanism also used to simulate the reduction of NO by natural gas blends and pure C₁ to C₄ hydrocarbons. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 564–575, 2003     

Li＋, Na＋//SO42－, CO32－-H2O交互四元体系288 K介稳相平衡研究

采用等温蒸发法研究了四元体系Li^＋, Na^＋// SO₄^2－, CO₃^2－-H₂O 288 K介稳相平衡及平衡液相的密度、电导率、折光率、粘度和pH值, 测定了该四元体系288 K条件下介稳平衡溶液溶解度及物化性质. 根据实验数据绘制了相应的介稳相图. 研究发现: 该体系介稳平衡中有复盐Na₃Li(SO₄)₂•6H₂O形成. 其介稳相图中有3个共饱点, 7条单变量曲线, 平衡固相为: Li₂SO₄•H₂O, Na₂SO₄, Na₃Li(SO₄)₂•6H₂O, Li₂CO₃, Na₂CO₃•10H₂O. 复盐Na₃Li(SO₄)₂•6H₂O和一水硫酸锂(Li₂SO₄•H₂O)的结晶区较小, 而Li₂CO₃的结晶区最大; 该四元体系介稳平衡条件下未发现Na₂SO₄•10H₂O的结晶区.     

REACTIONS OF CARBONYLSULPHIDE WITH [Rh(PPh3)3CI] AND [Pt(PPh3)3]

Abstract

Activation of small inorganic molecules (H₂, N₂, O₂, CO, NO, CO₂, SO₂, CS₂) by the complexes of transition metal ions like Rh(I), Ir(I), Pt(O) and Ru(II) have gained considerable interest during the last decade.^1–8 Because of the similarity of CO₂ and CS₂ molecules with COS, one would expect COS to form complexes with the transition metal ions analogous to those of CO₂ and CS₂. In addition, COS being susceptible to decomposition into CO and S, could also form carbonyl complexes. Until now, the only reaction of COS that has been successfully carried out is with [Pt(PPh₃)₃] which resulted in the formation of [Pt(COS)(PPh₃)₂] and [Pt₂S(CO) (PPh₃)₃]. ^8,9 It will, therefore, be interesting to study further the reactions of COS with the complexes of transition metal ions. The results of a preliminary study of such reactions with [Rh(PPh₃)₃Cl] and [Pt(PPh₃)₃] are reported in this communication.     

Dipole moment derivatives from MINDO/3 semi-empirical MO calculations

Dipole moment derivatives for CO, NO, CO₂, H₂O, HCN, BF₃, CH₄, C₂H₄, C₂H₆, CH₃F, F₂CO and H₂CO molecules have been evaluated using MINDO/3 MO calculations. The values are compared with those obtained by other semi-empirical MO methods.     

Analysis and perspectives concerning CO<Subscript>2</Subscript> chemisorption on lithium ceramics using thermal analysis

CO₂ removal from flue gas has been proposed as one of the most reliable solutions to mitigate global greenhouse emissions. Lithium ceramics are among several materials that have potential applications in CO₂ removal. Lithium ceramics are able to chemisorb CO₂ in a wide temperature range, presenting several interesting properties. All lithium ceramics present a similar CO₂ chemisorption reaction mechanism that has been described at the micrometric scale. However, there are several issues that have not been fully elucidated. The aim of this study is to re-analyze different experiments related to the CO₂ chemisorption on lithium ceramics and to propose how different factors control this process. This study focuses on diffusion controlled CO₂ chemisorption, which has been shown to be the limiting step of the CO₂ chemisorption process. Diffusion controlled CO₂ chemisorption appears to be mainly influenced by the chemical composition of a product’s external shell.     

Pseudo-spectral dipole oscillator-strength distributions for SO2, CS2 and OCS and values of some related dipole—dipole and triple-dipole dispersion energy constants

Pseudo-spectral dipole oscillator strengths and excitation energies, which are discrete representations of the original continuous dipole oscillator-strength distributions (DOSDs), are presented for the ground-state SO₂, CS₂ and OCS molecules. These pseudo-DOSDs, together with previously published pseudo-DOSDs, are used to evaluate the dipole—dipole and triple-dipole dispersion-energy coefficients for all the two- and three-body interactions between SO₂, CS₂ and OCS and between these molecules and H₂, N₂, O₂, NO, N₂O, H₂O, NH₃, CO, CO₂, CH₄, C₂H₆, C₄H₁₀ and C₆H₁₄, with an estimated uncertainty of 1–2%. The importance of results of this type is discussed briefly.     

Sulfur gas tolerance and toxicity of co-utilizing and methanogenic bacteria

Anaerobic bacteria have been shown to be capable of converting CO, H₂, and CO₂ in synthesis gas to valuable products, such as acetate, methane, and ethanol. However, synthesis gas also contains small quantities of sulfur gases such as H₂S and COS, that may inhibit the performance of these organisms. This paper compares the performance of several CO-utilizing and methanogenic bacteria in converting CO, CO₂, and H₂ to products in the presence of various concentrations of H₂S and COS. The sulfur gas toxicity levels, growth, substrate uptake, and product formation for each organism are compared.     

Selective sorption of water vapor from gas mixtures containing H<Subscript>2</Subscript>S,SO<Subscript>2</Subscript>, NO<Subscript>2</Subscript>, NO,and CO on KU-2 sulfonic styrene cation exchanger in different ion forms

Sorption of water vapor and some acid gases (H₂S, SO₂, NO₂, NO, and CO) on Ku-23-15/100 macroporous sulfonic cation exchanger in different ion forms and on commercial KSM silica gel and NaX artificial zeolite was studied under equilibrium and dynamic conditions. The equilibrium isotherms of water vapor sorption were measured for all the adsorbents examined. The mechanism of water sorption on the sulfonic cation exchanger was discussed.     

Recent Advances in Catalytic Decomposition of N<Subscript>2</Subscript>O on Noble Metal and Metal Oxide Catalysts

Catalytic decomposition of nitrous oxide (N₂O) is one of the most efficient methods for the removal of N₂O which is of high greenhouse potential and ozone-depleting property. Recent progress in the decomposition of N₂O has been reviewed with the focus on noble meal and metal oxide catalysts. The influence factors, such as catalyst support, preparation method, alkali metal additives and the reaction conditions (including O₂, H₂O, SO₂, NO and CO₂), on the performance of deN₂O catalysts have been discussed. Finally, future research direction for the catalytic decomposition of N₂O is proposed.     

The chemical reduction of small inorganic gases in an electrothermal plasma reactor

Chemical reduction of small inorganic gases is accomplished using an electro-thermal plasma reactor. This benchscale reactor maintains a highly reactive plasma zone in a fluidized bed of carbon particles through which an electrical current is discharged. The carbon particles function as current-controlling media, heat sinks and reaction sites. Chemicals introduced into this medium are subjected to a variety of energy sources and chemically reactive species, which result in chemical reduction. It is shown that the inorganic gases, H₂O, CO₂, NO, NO₂ and SO₂, are chemically reduced in the plasma zone of the reactor. The end products consist of hydrogen, carbon monoxide and nitrogen gases. Additionally, elemental sulfur is deposited onto the carbon particles.     

Repulsive potentials for the interaction of oxygen atoms with the noble gases and atmospheric molecules

Repulsive potentials between about 0.2 eV and 20 eV are determined for interactions of oxygen atoms with the noble gas atoms and with H₂, N₂, O₂, NO, CO, CO₂ and H₂O molecules from incomplete total scattering cross sections. Good agreement with theory is obtained for the noble gases. The potentials for the interaction with molecules obtained by assuming spherically symmetric potentials are compared with the same potentials computed by averaging the cross sections for different orientations of the molecules. By introducing reduced variables, the problem of finding two isotropic potential parameters is simplified to a search for one, the other being determined by a least-squares constraint.     

A Combined Experimental and Theoretical Study of the Versatile Reactivity of an Oxocerium(IV) Complex: Concerted Versus Reductive Addition

A combined experimental and theoretical investigation on the cerium(IV) oxo complex [(L_OEt)₂Ce(=O)(H₂O)] ⋅ MeC(O)NH₂ ( 1 ; L_OEt⁻=[Co(η⁵-C₅H₅){P(O)(OEt)₂}₃]⁻) demonstrates that the intermediate spin-state nature of the ground state of the cerium complex is responsible for the versatility of its reactivity towards small molecules such as CO, CO₂, SO₂, and NO. CASSCF calculations together with magnetic susceptibility measurements indicate that the ground state of the cerium complex is of multiconfigurational character and comprised of 74 % of Ce^IV and 26 % of Ce^III. The latter is found to be responsible for its reductive addition behavior towards CO, SO₂, and NO. This is the first report to date on the influence of the multiconfigurational ground state on the reactivity of a metal–oxo complex.     

Tuning the Surface Polarity of Microporous Organic Polymers for CO2 Capture

CO₂ capture is very important to reduce the CO₂ concentration in atmosphere. Herein, we report the preparation of microporous polymers with tunable surface polarity for CO₂ capture. Porous polymers functionalized with ‐NH₂, ‐SO₃H, and ‐SO₃Li have been successfully prepared by using a post‐synthesis modification of microporous polymers (P‐PhPh₃ prepared with 1,3,5‐triphenylbenzene as the monomer and AlCl₃ as the catalyst) by chemical transformations, such as nitration–reduction, sulfonation, and cationic exchange. The CO₂ adsorption selectivity (CO₂/N₂ and CO₂/H₂) and isosteric heats of the microporous polymers increase markedly after modification, P‐PhPh₃‐NH₂ and P‐PhPh₃‐SO₃Li afford higher CO₂ uptake capacity than P‐PhPh₃ at pressures of less than 0.15 bar due to the enhanced interaction between CO₂ and the ‐NH₂ and ‐SO₃Li functional groups. Moreover, functionalized porous polymers could be stably used for CO₂ capture. Surface modification is an efficient approach to tune the CO₂ capture properties of porous polymers.