Interaction of O2, CO and CO2 with Co films

Metastable impact electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS(HeI)) and x‐ray photoelectron spectroscopy (XPS) were applied to study the interaction of O₂, CO and CO₂ with Co films at room temperature. The films were produced on Si(100) surfaces under the in situ control of MIES, UPS and scanning tunnelling microscopy (STM). For O₂, dissociative adsorption takes place initially and then incorporation of oxygen starts at exposures of ～5 L. Comparison of the MIES and UPS spectra with those published for CoO shows that near‐stoichiometric CoO films can be obtained by co‐deposition of Co and O₂. The CO is adsorbed molecularly up to a maximum coverage of ～0.6 monolayer, with the C‐end pointing towards the surface. The CO₂ adsorption is dissociative, resulting in the formation of Co–CO bonds at the surface. The resulting oxygen atoms are mostly incorporated into the Co layer. For all studied molecules the interaction with Co is similar to that with Ni. Copyright © 2005 John Wiley & Sons, Ltd.     

Photocatalytic Oxidation of CO on TiO2: Chemisorption of O2, CO,and H2

On the surface : Adsorption of O₂ at the surface oxygen vacancy (SOV) sites of TiO₂ reconstructs the lattice oxygen (healing SOVs), resulting in a decrease of the photocatalytic activity of oxidizing CO over vacuum‐pretreated TiO₂ with increasing temperature (see scheme). Adsorption of H₂ produces new SOVs at the TiO₂ surface and stabilizes the photocatalytic activity.

     

Activation and desoxygenation of CO, CO2, and SO2 with sulfur-rich azide and amide

The azide and amide complexes (NBu4)[Ni(N3)('S3')] (2) and (NBu4)[Ni[N(SiMe3)2]('S3')] (4) were found to react with CO, CO2, and SO2 under very mild conditions at temperatures down to -50 degrees C. Depending on the N oxidation state of the nitrogen ligands, addition or partial to complete desoxygenation of the oxides takes place. The reaction between 2 and CO gives (NBU4)[Ni(NCO)('S3')] (3). The reactions between 4 and CO, CO2, and SO2 afford selectively the cyano, isocyanato, and sulfinylimido complexes (NBu4)[Ni(X)('S3')] with X = CN- (5), NCO- (3), and NSO- (6). The silyl groups act as oxygen acceptors. Mechanisms are suggested which have in common the formation of reactive five-coordinate (NBu4)[Ni(L)(L')('S3')] intermediates. In these reactions, highly activated L and L' react with each other. The complexes were characterized by standard methods, and (NBu4)[Ni(CN)('S3')] (5) was also analyzed by X-ray crystallography.     

Thermodynamics and kinetics of CO2, CO, and H+ binding to the metal centre of CO2 reduction catalysts

In our developing world, carbon dioxide has become one of the most abundant greenhouse gases in the atmosphere. It is a stable, inert, small molecule that continues to present significant challenges toward its chemical activation as a useful carbon end product. This tutorial review describes one approach to the reduction of carbon dioxide to carbon fuels, using cobalt and nickel molecular catalysts, with particular focus on studying the thermodynamics and kinetics of CO(2) binding to metal catalytic sites.     

Comparative theoretical study of the dissociation process of the isoelectronic molecules BH3CO,CH2CO,HNCO, CO2 and BH3N2, CH2N2, HN3, N2O

Anab initio study of the electronic structure of several 22-electrons molecules is presented. The equilibrium geometries of their ground state are calculated at the SCF level using the 6–31G basis set and are found to be in good agreement with the experimental geometries. The dissociation process of these molecules leading to the isoelectronic products CO or N₂ on the one hand and BH₃, CH₂, NH and O on the other hand is studied. The least-energy dissociation paths of the ground states determined at the SCF level are compared on the basis of electron density interactions. The dissociation energies corresponding to the two lowest dissociation channels are calculated. In these calculations, the correlation energy is taken into account using a non-variational method developed previously. The calculated values of dissociation energies are in good agreement with the existing experimental values. The results permit to predict values for HNCO, BH₃CO and CH₂N₂ and to confirm the instability of BH₃N₂.Aspirant du Fonds National Belge de la Recherche Scientifique.     

H2, N2, CO, and CO2 sorption properties of a series of robust sodalite-type microporous coordination polymers

H2, N2, CO, and CO2 are readily incorporated in the porous, 3D sodalitic frameworks of coordination polymers of the [ML2]n type, with M = Pd(II) or Cu(II) and HL = 2-hydroxypyrimidine or 4-hydroxypyrimidine. The metal ion and ligand functionalization modulate their sorption properties, making these materials suitable for gas storage and separation purposes.     

H2,CO和H2/CO在ZrO2催化剂上吸附行为研究

用insituFTIR法研究了H₂、CO及CO/H₂在ZrO₂表面的吸附行为.结果表明,H₂在ZrO₂表面吸附存在两种形态的羟基(即ZrOH和ZrOHZr),吸附温度增加,羟基数量增加.CO在200℃易与ZrO₂表面羟基作用形成甲酸盐物种,吸附温度升高时,该物种逐渐分解生成CO和ZrOH.当CO和H₂共存时,表面甲酸盐的量明显增加,并随温度增加,逐渐加氢形成甲氧基,最后生成甲烷.甲氧基的加氢过程较慢,所需反应温度也较高,被认为是CO加氢合成醇的速控步骤.     

Initial quantum levels of captured muons in CO,CO2, and COS

The role of valence electrons for the muon capture process by molecules is experimentally investigated with the aid of cascade calculations. Low-momentum muons are introduced to gas targets of CO, CO₂, and COS below atmospheric pressure. The initial states of captured muons are determined from the measured muonic X-ray structure of the Lyman and Balmer series. We propose that the lone pair electrons in the carbon atom of CO significantly contribute to the capture of a muon with large angular momenta.

     

Primary, secondary, and tertiary amines for CO2 capture: designing for mesoporous CO2 adsorbents

CO(2) emissions, from fossil-fuel-burning power plants, the breathing, etc., influence the global worming on large scale and the man's work efficiency on small scale. The reversible capture of CO(2) is a prominent feature of CO(2) organic-inorganic hybrid adsorbent to sequester CO(2). Herein, (3-aminopropyl) trimethoxysilane (APTMS), [3-(methylamino)propyl] trimethoxysilane (MAPTMS), and [3-(diethylamino) propyl] trimethoxysilane (DEAPTMS) are immobilized on highly ordered mesoporous silicas (SBA-15) to catch CO(2) as primary, secondary, and tertiary aminosilica adsorbents. X-ray photoelectron spectroscopy was used to analyze the immobilized APTMS, MAPTMS, and DEAPTMS on the SBA-15. We report an interesting discovery that the CO(2) adsorption and desorption on the adsorbent depend on the amine type of the aminosilica adsorbent. The adsorbed CO(2) was easily desorbed from the adsorbent with the low energy consumption in the order of tertiary, secondary, and primary amino-adsorbents while the adsorption amount and the bonding-affinity increased in the reverse order. The effectiveness of amino-functionalized (1(o), 2(o), and 3(o) amines) SBA-15s as a CO(2) capturing agent was investigated in terms of adsorption capacity, adsorption-desorption kinetics, and thermodynamics. This work demonstrates apt amine types to catch CO(2) and regenerate the adsorbent, which may open new avenues to designing "CO(2) basket".     

Determination of Trace Impurities of H2, O2, Ar, N2, CO, CO2, and Hydrocarbons in High-Purity Monosilane by Gas Chromatography

Procedures were proposed for the determination of impurities of permanent gases (H₂, O₂, Ar, N₂, and CO), carbon dioxide, and hydrocarbons in high-purity monosilane by gas chromatography with detection limits of 1–3 ppm, 2 ppm, and 0.02–0.04 ppm, respectively, which are lower by 1–2 orders of magnitude than those published in the literature. The procedures make it possible to check the compliance of the purity of monosilane with present standards of microelectronics (TU 48-0513-057.0-91).     

Correction of mass spectrometric isotope ratio measurements for isobaric isotopologues of O2, CO,CO2, N2O and SO2

Gas isotope ratio mass spectrometers usually measure ion current ratios of molecules, not atoms. Often several isotopologues contribute to an ion current at a particular mass‐to‐charge ratio (m/z). Therefore, corrections have to be applied to derive the desired isotope ratios. These corrections are usually formulated in terms of isotope ratios (R), but this does not reflect the practice of measuring the ion current ratios of the sample relative to those of a reference material. Correspondingly, the relative ion current ratio differences (expressed as δ values) are first converted into isotopologue ratios, then into isotope ratios and finally back into elemental δ values. Here, we present a reformulation of this data reduction procedure entirely in terms of δ values and the ‘absolute’ isotope ratios of the reference material. This also shows that not the absolute isotope ratios of the reference material themselves, but only product and ratio combinations of them, are required for the data reduction. These combinations can be and, for carbon and oxygen have been, measured by conventional isotope ratio mass spectrometers. The frequently implied use of absolute isotope ratios measured by specially calibrated instruments is actually unnecessary. Following related work on CO₂, we here derive data reduction equations for the species O₂, CO, N₂O and SO₂. We also suggest experiments to measure the required absolute ratio combinations for N₂O, SO₂ and O₂. As a prelude, we summarise historic and recent measurements of absolute isotope ratios in international isotope reference materials. Copyright © 2008 John Wiley & Sons, Ltd.     

色谱法同时测定羰化反应尾气中的O2、CO、CO2

提出用特制活性炭填充柱分离,热导检测器检测,以外标法定量,同时测定O2、CO、CO2.探讨了该方法的校正因子、各组分的线性相关性及微量氧气的分离和定量等.在选定的色谱条件下,O2与CO的分离度达1.7,各组分的相对标准偏差＜0.18%,绝对误差＜0.04%.     

Relaxation, incubation, and dissociation in CO2

The dissociation and relaxation of CO2 has been reexamined in the incident shock wave with the laser-schlieren technique. These new experiments covered 1377-6478 K, and 42-750 Torr, and improvements partly described herein have permitted accurate determination of both rate and incubation time. In general the steady rate measurements are in agreement with other recent determinations. The one anomaly is that the new rates are not fully second order; they vary about 50% over 70-600 Torr. This unexpected feature is actually quite consistent with the recent literature, which shows a similar trend. However, attempts to produce this result with RRKM calculations were unsuccessful. Relaxation times are in agreement with available literature, and incubation time to relaxation time ratios lie between 1.5 and 3 over 4000-6600 K, consistent with findings for other molecules. These ratios are much smaller than those recently derived from reflected-shock experiments by Oehlschlaeger et al. (Z. Phys. Chem. 2005, 219, 555). A simple argument suggests such large values are indeed anomalous, although why they are too large is not clear.     

三通道气相色谱法监测大气中CH_(4)、CO、CO_(2)、N_(2)O和SF_(6)北大核心CSCD

我国正处于“碳达峰、碳中和”的关键时期,准确认识我国温室气体浓度时空格局以及变化对于评估“碳达峰”和“碳中和”行动成效非常重要。当前我国近地面温室气体高精度监测主要依赖进口的光学监测主机,单台仪器成本高且监测要素有限。为此,该研究基于传统的气相色谱法,自主设计了一套三通道气相色谱分析系统,在单台仪器上实现了5种主要长寿命温室气体(CH_(4)、CO、CO_(2)、N_(2)O和SF_(6))的高精度监测。对该系统的精密度、线性响应情况和准确度进行的针对性测试实验表明系统检测性能满足世界气象组织/全球大气观测(WMO/GAW)质控标准。针对环境浓度的CH_(4)、CO、CO_(2)、N_(2)O和SF_(6)的连续分析精密度分别达0.08%、1.90%、0.05%、0.08%、0.66%。准确度测试中,5种气体(CH_(4)、CO、CO_(2)、N_(2)O和SF_(6))使用回归方程计算所得值与标称摩尔分数间的偏差分别达0.15×10-9、0.20×10-9、0.37×10-6、0.35×10-9、0.02×10-12(摩尔分数),CH_(4)、CO、CO_(2)、N_(2)O和SF_(6)仪器响应值与标称摩尔分数的线性拟合相关系数(R2)均为0.9999,线性拟合残差和准确度基本达到WMO/GAW拓展质控目标。该系统对杭州城区大气温室气体在线连续监测结果显示,2021年5~7月期间大气CH_(4)、CO、CO_(2)和N_(2)O呈明显的日变化特征,主要受人为活动影响。综合测试和试运行结果表明,该研发系统具备良好的精密度、准确度、线性和稳定性,与目前国内广泛进口的仪器相比,具有技术自主可控、运行成本更低、自动化水平更高等优势,能满足多种温室气体在线监测研究的需求。     

色谱法同时测定羰化反应尾气中的O2、CO、CO2

提出用特制活性炭填充柱分离,热导检测器检测,以外标法定量,同时测定O2、CO、CO2。探讨了该方法的校正因子、各组分的线性相关性及微量氧气的分离和定量等。在选定的色谱条件下,O2与CO的分离度达1．7,各组分的相对标准偏差＜O．18％,绝对误差＜0．04％。