The compton defect in ammonia as observed using 35 keV incident electrons

Using a 35 keV electron beam incident on NH₃, precision measurements of the energy loss position of the Compton peak have been performed. The observed Compton peak is found to be at larger energy losses than predicted for an electron scattered through the same angle from a stationary unbound electron. This defect has been studied for the momentum transfer range 0.5 au < K < 11 au, and is shown to be nonzero even at large K values. A sudden increase in the magnitude of the defect is observed when the inner electrons start contributing to the maximum of the Compton profile. This could suggest the possibility that the defect is related to the binding energies of the target electrons.     

Collision-induced absorption of infrared radiation by N2, O2 and CO2

The collision-induced absorption of the symmetric vibration of CO₂ has been observed in the pure gas at densities from 20.0 to 40.0 amagat and at temperatures of 273, 298, and 323 K using infrared techniques. From the integrated intensities of the bands and using the (exp ?4) model of van Kranendonk, it is possible to deduce a value for the first derivative of the quadrupole moment with respect to the vibrational coordinate. For CO₂ the contribution from quadrupole distortion to the binary absorption coefficient is reported for several temperatures. The (exp ?4) model of van Kranendonk is used to calculate the binary absorption coefficients for the fundamental vibrational bands of N₂ and O₂ at temperatures from 70 to 340 K. The parameters λ and p/σ describing the magnitude and range of the short-range collision-induced dipole moments were determined using the known experimental absorption coefficients. The contributions from atomic distortion and quadrupole distortion to the binary absorption coefficient are calculated for N₂ and O₂.     

Intermolecular forces for D2, N2, O2, F2 and CO2

The intermolecular potentials for D₂, N₂, O₂, F₂ and CO₂ are determined on the basis of the second virial coeffincients, the polarizabilities parallel and perpendicular to the molecular axes, and the electric quadrupole moment. The repulsive parts of the potentials are taken from the corresponding Kihara core-potentials. Effects of the octopolar induction are taken into consideration in a unique way. The potential depends on relative orientations of the two molecules as well as the distance r between the molecular centers. This dependence is shown in graphs. A measure of the anisotropy of the potential depth is 0.72 for CO₂ 0.36 for D₂, and smaller than 0.27 for N₂ O₂ and F₂. The remarkable anisotropy for CO₂ and D₂ is due to strong electrostatic quadrupole interactions.     

Effect of CO2 laser treatment on cotton surface

In this study, CO₂ laser was used for treating cotton fabric to create surface effects which were found to vary with laser process parameters, i.e. resolution and pixel time. The resolutions used were 40, 50 and 60 dpi while the pixel time used were 100, 110 and 120 μs. Both physical and chemical properties at the surface of fabrics treated with different combinations of resolution and pixel time were analysed by the Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy with Attenuated Total Reflection mode (FTIR-ATR), and X-ray Photoelectron Spectroscopy (XPS). SEM investigation revealed the appearance of various numbers of pores, cracks and fragments present on the fibre surface after laser treatment. FTIR-ATR spectra showed that the laser-treated cotton fabric suffered changes in chemical structure with the hydroxyl (–OH) stretching group being oxidised to carbonyl/carboxyl groups. The XPS analysis revealed a change in surface elemental composition after laser treatment. Furthermore, the wicking property of the laser-treated cotton fabrics was evaluated.     

Reductive carboxylation of alkyl halides with CO2 by use of photoinduced SmI2/Sm reduction system

Upon visible-light irradiation, reductive carboxylation of alkyl halides takes place by using a SmI₂/Sm mixed system under atmospheric CO₂ to afford the corresponding carboxylic acids in good to excellent yields.     

Hydrogenation of CO2

The hydrogenation of CO₂ has been studied on three different series of catalysts: Fe/MgO, Ni/Ti, Cr/Zn doped with potassium. Reaction was carried out in a conventional flow microreactor system at 15 bar at 250–350°C. Three independent competing reactions: Reverse gas-water shift (RGWS), Fischer-Tropsch (FT) and methanol synthesis were observed.

---

CO₂ : Fe/MgO, Ni/Ti, Cr/Zn . 15 250–350°C. : RGWS, F.T. .

     

Theoretical models for activation of CO2 towards hydration (CO2 + H2O → H2CO3) by cationic binding sites

Theoretical models are studied which illustrate how the hydration reaction CO₂ + H₂O → H₂CO₃ can be catalysed by one or two cationic binding sites (NH₄⁺). In the latter, the arrangement of the two bindings sites is held during the course of the reaction, simulating a rigid molecular receptor. Two different arrangements of the binding sites are studied, and their relative abilities to lower the activation energy of the hydration reaction are studied.     

Valence-shell photoabsorption by CO2 and its connections with electron-CO2 scattering

Photoabsorption cross sections and photoelectron asymmetry parameters, calculated with the multiple-scattering model (MSM), are reported for the 4σ_g, 3σ_u, 1π_u and 1π_g valence levels of CO₂. The results are discussed in the context of photoabsorption and electron energy-loss measurements and other theoretical calculations. Further comparisons are made with previously reported MSM calculations of elastic electron-CO₂ scattering. The close connection between the sets of shape resonances in the electron-scattering and photoabsorption by CO₂ is emphasized with plots of continuum eigenchannel wavefunctions for shape-resonant and non-resonant eigenchannels of σ_u symmetry.     

CO2 fixation by hydrogenation over coprecipitated Co/Al2O3

CO₂ fixation by hydrogenation over coprecipitated 36 wt.% Co/Al₂O₃ has been studied under a range of reaction conditions to clarify the effects of reaction variables and to determine the kinetics and mechanism of the reaction. A comparison of the results with those reported for CO hydrogenation on the same catalyst indicates that, although product distributions of CO₂ and CO hydrogenation differ, the kinetics and mechanism are similar.     

Gas hydrate equilibria for CO2-N2 and CO2-CH4 gas mixtures—Experimental studies and thermodynamic modelling

In this paper, a set of experimental data on the phase equilibrium of gas hydrates in the presence of binary gas mixtures comprising CO₂ is presented. The procedure established allows for the determination of both the composition of the gas phase as well as the hydrate phase without the need to sample the hydrate. The experimental results obtained in these measurements have been described by means of the classical model of van der Waals and Platteeuw. The values of internal parameters of the reference state and the Kihara parameters have been re-discussed and their interdependency is pointed. Finally the new set of parameters is validated against experimental data from other sources available in the literature, or invalidated against other sources. Finally, we conclude on the difference of experimental data between laboratories. The differences are not on the classical (pressure, temperature, gas composition) data which appear equivalent between laboratories. The difference stands on the measurement composition of the hydrate phase.     

Atomic-level insights into surface engineering of semiconductors for photocatalytic CO2 reduction

Photocatalytic conversion of CO₂ into solar fuels provides a bright route for the green and sustainable development of human society.However,the realization of efficient photocatalytic CO₂reduction reaction (CO₂RR) is still challenging owing to the sluggish kinetics or unfavorable thermodynamics for basic chemical processes of CO₂RR,such as adsorption,activation,conversion and product desorption.To overcome these shortcomings,recent works have demonstr...     

TiO_2纳米带光催化二氧化碳甲烷化

研究了在常温常压下TiO2纳米带光催化CO2催化加氢气反应。在紫外光照射下,二氧化碳的加氢还原产物为甲烷。利用高分辨TEM,XRD,UV-Vis DRS,低温氮吸附-脱附,TG等考察了催化剂与甲烷产率的构效关系。结果表明,在600℃焙烧时得到的双晶材料具有最佳的光催化活性。优异的光催化活性主要得益于TiO2双晶脱水纳米带(DNR Bicrystalline dehydratednanoribbon)。上面形成的纳米晶界能够提高催化剂在紫外区的光吸收能力,TiO2(B)和锐钛矿独特的双晶间隔结构也提高了界面电荷分离的效率。担载贵金属Pt显著地提高了反应速率。     

PLASMA POLYMERIZATION OF ACETYLENE/CO_2/H_2

A study has been made on the plasma polymerization of acetylene/CO_2/H_2 in a capacitively coupled RF plasma. The monomer mixture yielded a crosslinked film with light brown color. A kinetic study is reported for the plasma polymer ization of acetylene/CO_2/H_2. The effects of discharge power level and reactor geometry on the rate of polymer formation are reported. The structure of the plasma polymer is investigated by IR study.     

低阶煤半焦利用热重在O2/CO2、O2/N2和O2/Ar气氛下燃烧特性研究

利用热重研究了两种中国西北典型低阶煤半焦的燃烧特性。探究了不同气氛（O₂/CO₂、O₂/N₂和O₂/Ar）和不同氧气浓度对其燃烧特性的影响。实验结果表明,无论是反应气氛还是氧气浓度都会对低阶煤半焦的燃烧产生影响。相比于N₂和Ar,CO₂明显有利于燃烧反应进行：当反应气氛由O₂/CO₂变为O₂/Ar时,两种不同低阶煤半焦的燃尽温度分别升高了63.7和68.8℃;而当反应气氛由O₂/CO₂变为O₂/N₂时,两种不同低阶煤半焦的燃尽温度分别升高了135.9和129.6℃。在研究范围内,氧气浓度的提高也能明显提高半焦的燃烧性能。与此同时,半焦燃烧特性的动力学分析表明,随着氧气浓度提高,两种半焦燃烧反应的表观活化能E和指前因子A均呈增大趋势。通过对E和A两者关系的分析结果表明,半焦富氧燃烧的活化能和指前因子存在动力学补偿效应。     

CO2的光电催化还原

CO2为温室气体的主要成分,同时也是潜在的碳能源。本文主要介绍了近年来利用光催化、电催化以及光电催化3种不同催化方法还原CO2的研究现状。文章综述了催化剂材料和催化反应体系对CO2还原效果的影响。从催化效率,光、电转化效率,选择性和能耗等不同角度进行了比较和评价。细致地讨论分析了各种催化还原方法的反应机理,并对催化还原CO2研究的发展方向和应用前景进行了展望。     

Hydrocondensation of CO2: Reaction of CO2(CO)/H2 on CuO/ZnO contact masses

The hydrocondensation of CO₂ and CO with and without added MeOH, HCHO and (CH₃)₂CHOH has been studied on CuO/ZnO contact masses in a static reactor at different pressures and reaction times.

---

CO₂ CO MeOH, HCHO (CH₃)₂CHOH CuO/ZnO .

     

Metastable anions of CO2

Long-lived metastable negative ions of CO₂ have been observed in the gas phase as direct products of electron and cesium collisions with organic molecules which contain “bent” CO₂ as a basic unit. The long autodetachment life-times are attributed to two related factors - first, the potential energy curve of CO⁻₂(²A₁) lies below that of CO₂(¹A₁) at 134°, and, second, an unfavorable Franck-Condon overlap exists between the bent ion (134°) and the linear neutral parent.     

CO/H2 and CO2/H2 reactions with amorphous carbon-metal catalysts

By metal impregnation of selected naturally occurring organic materials followed by controlled carbonization, metal semicoke catalysts can be readily prepared. These catalysts have been tested in the synthesis of hydrocarbons and alcohols from CO/H₂ and CO₂/H₂ mixtures. Fe and Co preparations have been used. Relatively high temperatures are required when using these catalysts, which are quite active for synthesis using CO₂ and H₂. The pressure (5150 kPa) is very favorable both for the synthesis of liquid hydrocarbons (C₅–C₃₀) and alcohols (C₁–C₅).

---

. CO/H₂ CO₂/H₂. Fe Co. , CO₂ H₂. 5150 ) (C₅–C₃₀) (C₁–C₅).

     

Vibrational relaxation of CO2(0001) in pure CO2

The rate constant for collisional deactivation of CO₂(00⁰1) in pure CO₂ has been measured at room temperature using the laser fluorescence technique. The relaxation rate has been found to be (1.0 ± 0.2) × 10^?14 cm³ s^?1 which is in favorable agreement with previously published values.