Absorption Properties Of Gases Research Articles

High-precision concentration detection of CO2 in flue gas based on BO-LSTM and variational mode decomposition

In order to improve the detection accuracy of CO2 and other gases in the flue gas emitted from thermal power plants, a CO2 concentration detection model based on tunable semiconductor laser absorption spectroscopy was proposed. First, a variational mode decomposition model was used to filter the harmonic signal after removing the outliers to reduce the influence of noise on the detection results. Suitable absorption lines and concentration characteristics were then selected according to the gas absorption properties and correlation theory. Finally, the CO2 concentration inversion was completed using long short-term memory networks, and a Bayesian optimization algorithm was introduced to optimize the hyperparameters of the network. The experimental results showed that the R 2 and RMSE of the test set were 0.998 84 and 0.116 08, respectively, in the concentration range of 1%–12%. In addition, the Allan analysis of variance revealed that the maximum measurement error of CO2 was only 0.005 619% when the integration time was 38 s. Compared to the traditional CO2 detection schemes, the detection accuracy and stability are significantly improved, which provides a feasible scheme for flue gas detection in thermal power plants.

Precise Modulation of Surface Layer Dynamics for Tunable Flowability and Gas Absorption Properties of Molecular Porous Liquids

AbstractPorous liquids (PLs) have improved the understanding of the porous properties of matter; however, rational tuning of the viscosities and gas absorption properties of PLs lag far behind the explosive growth of PL applications. Herein, neat molecular PLs are constructed by grafting polymers onto the surface of 2 nm molecular nanocages with precisely tuned graft densities and molecular weights Mws. The flowability of the PLs showed a non‐monotonic dependence on the Mw of the polymers due to the interplay between the surface confinement effect and polymer chain entanglements, enabling optimization of their viscosities, similar to those of conventional liquids. The surface layer dynamics and gas absorption kinetics are quantified, correlation between the two properties is confirmed, and gas permeation process is regulated by surface layer dynamics. From the understanding of the structure–property relationship, the surface layer grafting densities are tuned to promote surface layer dynamics to achieve improved gas sorption performance.

Pore Accessibility in Amorphous Solid Water

The porous nature of amorphous solid water (ASW) can significantly effect the chemical evolution of any planetary or astrophysical surface it forms on due to its ability to trap and retain volatiles. The amount of volatiles that can enter an ASW grain or mantle is limited by how interconnected the pores are to each other and to the exterior surface. Previous laboratory studies examined the interconnectivity of ASW pores in thin ASW films relevant to ice mantles on interstellar grains. Here, we investigate to what extent the interconnectivity of pores and subsequent gas absorption properties of ASW change as one moves toward thicker samples (up to ∼1019 H2O cm−2 or ∼4 μm) more representative of icy material found in the outer solar system. We find that for all film thicknesses studied, the internal pores are accessible from the sample’s surface, and the amount of gas needed to fill the pores increases linearly with the ASW column density. This linear relation supports that the interconnectivity to the surface will persist in ices that are much thicker than those we were able to study, suggesting that the amount of contaminant gas trapped within ASW can significantly alter the chemical evolution of a variety of ASW-rich surfaces in the outer solar system.

Understanding Relationships between Free Volume and Oxygen Absorption in Ionic Liquids.

Understanding the factors that govern gas absorption in ionic liquids is critical to the development of high-capacity solvents for catalysis, electrochemistry, and gas separations. Here, we report experimental probes of liquid structure that provide insights into how free volume impacts the O2 absorption properties of ionic liquids. Specifically, we establish that isothermal compressibility─measured rapidly and accurately through small-angle X-ray scattering─reports on the size distribution of transient voids within a representative series of ionic liquids and is correlated with O2 absorption capacity. Additionally, O2 absorption capacities are correlated with thermal expansion coefficients, reflecting the beneficial effect of weak intermolecular interactions in ionic liquids on free volume and gas absorption capacity. Molecular dynamics simulations show that the void size distribution─in particular, the probability of forming larger voids within an ionic liquid─has a greater impact on O2 absorption than the total free volume. These results establish relationships between the ionic liquid structure and gas absorption properties that offer design strategies for ionic liquids with high gas solubilities.

Synthesis, Structures, and Sorption Properties of Two New Metal-Organic Frameworks Constructed by the Polycarboxylate Ligand Derived from Cyclotriphosphazene.

Solvothermal reactions of hexakis(4-carboxyphenoxy)cyclotriphospazene (H6L1) with copper ions in DMF/H2O produced one complex, {[Cu6(L1)2(OH)(H2O)3]·guest}n (1), but with copper ions and auxiliary rigid 4,4-bipyridine (bpy) produced another new complex, namely, {[Cu3(L1)(bpy)(H2O)6]·guest}n (2). These complexes had been characterized by IR spectroscopy, elemental analysis, and X-ray structural determination. 1 exhibits a 3D anionic structure with the binodal 4,8-connected network with Schläfli symbol {46}2{49·618·8}, consisting of Cu6 clusters and L1 ligands. In contrast, complex 2 possesses a different 3D network with trinodal 3,4,6-c topology with Schläfli symbol {4·62}2{42·66·85·102}{64·8·10}. In these two complexes, the semirigid hexacarboxylate ligands adopt distinct conformations to connect metal ions/clusters, which must be ascribed to the addition of the auxiliary rigid ligand in reaction systems. In addition, gas absorption properties of 1 and 2 including CO2 and N2 were further investigated.

Technology for Improving Technical, Economic and Ecological Efficiency of Boiler Plants Using Physico-Chemical Correction of the Water-Fuel Emulsions Composition

The aim of this work is to substantiate the possibility of increasing the technical, economic and environmental efficiency, as well as the efficiency of boilers (in terms of the intensity of corrosion processes) when burning water-fuel emulsions with the increased water and salt contents. To achieve these goals complex experimental studies were performed on the combustion of fuel oil and emulsions based on it, as well as the corrosion processes with a water content in the range from 2 to 30%, and a salt content ranging from 17 to 490 mg/dm3 hydrodynamic homogenizer. A significant result of the studies carried out is that with a water content of ~30% in the fuel gases composition, an NO2:NO ratio of 0,33 was achieved. That increased the absorption properties of gases and allowed passivation of carbon steel in sulfuric acid condensate. It also decreased the intensity of the low-temperature corrosion in the range of metal temperature of 130...70°C. All these made it possible to use condensation surfaces and to reduce the flue gases temperatures, to increase the efficiency of boilers, to ensure the economy of pure fuel, to increase the depth of utilization of the exhaust gases heat, and to reduce the concentration of toxic gases. The results obtained differed from those known. The significance of the results obtained lies in the fact that a technology was developed for the integrated use of the electrodialysis water resources, the waste and oil-containing waters, ensuring the operability of boilers, with a water content of emulsions of ~30% and a salt content of up to 450 mg/dm3.

The Industrial Production of Water Dedicated to Absorption of Gases

The paper presents a flow plasma reactor permitting modification of the properties of water/aqueous solutions by stochastic resonance amplification of vibrations of selected chemical species in water with electromagnetic noise generated during a plasma discharge. The main parameters characterizing the quality for super-pure water, tap water and water from the intake in Besko (Poland) before and after the process in the plasma reactor were presented for comparison. In addition, the 17O NMR (the full width at half maximum) and electrospray ionization mass spectrometry (ESI MS) methods were used to determine differences in physicochemical parameters between the untreated and plasma-treated water. It has been established that the water subjected to plasma treatment shows much different gas absorption properties than the untreated water samples, as a function of temperature and pressure, in this paper we report exemplary data for CO2, oxygen and acetylene. The improved gas absorption properties of the plasma-treated water make it attractive for the use in industrial processes. It is worth pointing to a great capacity of the new reactor (4000 l/h), and low energy consumption (20 MJ/h) for the treatment of the above mentioned volume flow rate of water.

Catadioptric Stereo Optical Gas Imaging System for Scene Flow Computation of Gas Structures

The need for reducing greenhouse gas emissions from industrial facilities has motivated the development of new and more reliable techniques for gas leak localization and quantification. Optical gas imaging (OGI) systems offer a fast and intuitive approach by exploiting the absorption properties of gases, such as methane, in the infrared range. Based on this, several efforts have been made in the recent years for gaining additional quantitative information from the measurement data, e.g. gas concentration or gas velocity. In this work, a catadioptric stereo OGI system based on four planar mirrors and an OGI camera is proposed for computing spatio-temporal (also referred to as scene flow) information from stereo gas images. The proposed system represents a way to reduce the effects of temporal and radiometric differences and the cost and size of two-camera-based stereo OGI systems and leads to more reliable results under the tested conditions.

Radiation heat transfer in ablating boundary layer combustion theory used for hybrid rocket motor analysis

Marxman theory is often used for developing correlations of fuel regression rate for hybrid rocket motor analysis. Effects of radiation are accounted for in this theory as a perturbation to the non-radiating blowing limit allowing for the leading order effects of blowing blockage from radiation heat transfer to influence convective heat flux. The theory does not, however, account for the non-linear changes in radiative gas absorption properties to allow for tightly coupled descriptions of heat transfer and surface blowing. In this study, Marxman theory is expanded in a new fully coupled approach, employing Schvab-Zeldovich coupling functions, unsteady heat transfer response of the fuel, and solution of the gas-phase radiation heat transfer. To develop this theory, Marxman’s theory is generalized to allow for expanded functional forms of friction coefficient and account for changes in gas properties. To validate the modeling approach, measurements from a simplified slab burner experiment are conducted. Paraffin wax is used as the fuel and relatively low oxidizer fluxes are employed so the dominate effects of radiation heat transfer can be understood. Measurements of temperature, soot volume fraction, and fuel radiative heat flux rely on two-color pyrometry analyses using high-speed camera color images. Comparisons of model predictions to data indicate the new tightly coupled approach provides good predictions of regression rate, temperature, and radiative heat flux to the fuel surface over the range of oxidizer flow rates considered. Model sensitivity studies reveal commonly used one-way coupling strategies may result in significant over prediction in fuel regression rate that are most likely compensated for by errors in simplified treatments of radiation heat transfer.

Synthesis and characterization of silica mesoporous material produced by hydrothermal continues pH adjusting path way

Mesoporous silica molecular sieves MCM-41 were synthesized under hydrothermal conditions. For this purpose, a solution with a molar coefficient of water, cetyltri-methyl ammonium bromide surfactants as template and sodium silicate as the source of SiO2 are used. Phase formation, morphology and gas absorption properties were investigated by XRD and BET analysis, respectively. The results showed that silica mesoporous material has been successfully synthesized. A favorable special surface and porosity volume together with regular arrangement of nano metric-hexagonal porosities were obtained from this synthesis. Thickness of the wall and average diameter of the pores are 0.8nm and 4nm, respectively.

Probing the cool interstellar and circumgalactic gas of three massive lensing galaxies atz= 0.4–0.7

We present multi-sightline absorption spectroscopy of cool gas around three lensing galaxies at z=0.4-0.7. These lenses have half-light radii r_e=2.6-8 kpc and stellar masses of log M*/Ms=10.9-11.4, and therefore resemble nearby passive elliptical galaxies. The lensed QSO sightlines presented here occur at projected distances of d=3-15 kpc (or d~1-2 r_e) from the lensing galaxies, providing for the first time an opportunity to probe both interstellar gas at r~r_e and circumgalactic gas at larger radii r>>re of these distant quiescent galaxies. We observe distinct gas absorption properties among different lenses and among sightlines of individual lenses. Specifically, while the quadruple lens for HE0435-1223 shows no absorption features to very sensitive limits along all four sightlines, strong Mg II, Fe II, Mg I, and Ca II absorption transitions are detected along both sightlines near the double lens for HE0047-1756, and in one of the two sightlines near the double lens for HE1104-1805. The absorbers are resolved into 8-15 individual components with a line-of-sight velocity spread of dv~300-600 km/s. The large ionic column densities, log N>14, observed in two components suggest that these may be Lyman limit or damped Lya absorbers with a significant neutral hydrogen fraction. The majority of the absorbing components exhibit a uniform super solar Fe/Mg ratio with a scatter of <0.1 dex across the full dv range. Given a predominantly old stellar population in these lensing galaxies, we argue that the observed large velocity width and Fe-rich abundance pattern can be explained by SNe Ia enriched gas at radius r~r_e. We show that additional spatial constraints in line-of-sight velocity and relative abundance ratios afforded by a multi-sightline approach provide a powerful tool to resolve the origin of chemically-enriched cool gas in massive halos.

イオン液体のガス吸収特性とガス分離技術への応用

イオン液体のガス吸収特性とガス分離技術への応用

Improvements in the CO2 permeation selectivities of amino acid ionic liquid-based facilitated transport membranes by controlling their gas absorption properties

A series of amino acid ionic liquids (AAILs) composed of different cations of different sizes, including trihexyl(tetradecyl)phosphonium glycinate, tetrabutylphosphonium glycinate and triethyl(pentyl)phosphonium glycinate have been synthesized for the carrier of CO2 facilitated transport membrane. Their physical properties, including their viscosity, density, molar volume and N2 absorption amount were investigated. The amount of N2 absorption decreased as the size of the cation of the AAIL decreased. Facilitated transport membranes containing these AAILs were prepared, and their CO2 and N2 permeabilities were measured. The N2 permeabilities were systematically investigated both experimentally and theoretically with the aim of improving the selectivity of the CO2 permeation of the AAIL-based facilitated transport membrane. As expected, the CO2 permselectivity was improved using triethyl(pentyl)phosphonium glycinate, which contained the smallest cation of the AAILs investigated in this study. We have proposed a methodology for improving the CO2 selectivity of AAIL-based facilitated transport membranes based on reducing their N2 permeabilities.

Enhanced Gas Absorption in the Ionic Liquid 1-n-Hexyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)amide ([hmim][Tf2N]) Confined in Silica Slit Pores: A Molecular Simulation Study

Two-dimensional NPxyT and isostress-osmotic (N2PxyTf1) Monte Carlo simulations were used to compute the density and gas absorption properties of the ionic liquid (IL) 1-n-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([hmim][Tf2N]) confined in silica slit pores (25-45 Å). Self-diffusivity values for both gas and IL were calculated from NVE molecular dynamics simulations using both smooth and atomistic potential models for silica. The simulations showed that the molar volume of [hmim][Tf2N] confined in 25-45-Å silica slit pores is 12-31% larger than that of the bulk IL at 313-573 K and 1 bar. The amounts of CO2, H2, and N2 absorbed in the confined IL are 1.1-3 times larger than those in the bulk IL because of the larger molar volume of the confined IL compared to the bulk IL. The CO2, N2, and H2 molecules are generally absorbed close to the silica wall where the IL density is very low. This arrangement causes the self-diffusivities of these gases in the confined IL to be 2-8 times larger than those in the bulk IL at 298-573 K. The solubilities of water in the confined and bulk ILs are similar, which is likely due to strong water interactions with [hmim][Tf2N] through hydrogen bonding, so that the molar volume of the confined IL plays a less important role in determining the H2O solubility. Water molecules are largely absorbed in the IL-rich region rather than close to the silica wall. The self-diffusivities of water correlate with those of the confined IL. The confined IL exhibits self-diffusivities larger than those of the bulk IL at lower temperatures, but smaller than those of the bulk IL at higher temperatures. The findings from our simulations are consistent with available experimental data for similar confined IL systems.

Galaxy morphology – halo gas connections

We studied a sample of 38 intermediate redshift MgII absorption-selected galaxies using (1) Keck/HIRES and VLT/UVES quasar spectra to measure the halo gas kinematics from MgII absorption profiles and (2) HST/WFPC-2 images to study the absorbing galaxy morphologies. We have searched for correlations between quantified gas absorption properties, and host galaxy impact parameters, inclinations, position angles, and quantified morphological parameters. We report a 3.2-sigma correlation between asymmetric perturbations in the host galaxy morphology and the MgII absorption equivalent width. We suggest that this correlation may indicate a connection between past merging and/or interaction events in MgII absorption-selected galaxies and the velocity dispersion and quantity of gas surrounding these galaxies.

Absorption of radiation by gases from low to high pressures. I. Empirical line-by-line and narrow-band statistical models

We present new models which provide satisfactory and low cost modeling of infrared absorption spectra of gases from low to high pressures. The first is a line-by-line approach based on simple and empirical corrections of the lorentzian shape which account for the effects of line-mixing and finite duration of collisions. It leads to satisfactory agreement with experimental infrared spectra in a wide density range. It is degraded for the deduction of a Generalized Narrow-Band Statistical Model (GNBSM) which enables very rapid computation of medium resolution radiative properties. The latter is an extension of the low density (i.e., when lines are much narrower than the considered spectral resolution) approach developed by Goody [1] ; it is based on a random representation of line-positions and statistical description of line integrated-intensities and leads to a very simple expression of spectrally averaged absorption properties of gases. It is consistent with previous low density models and requires computer times several orders of magnitude shorter than line-by-line calculations. Comparisons between degraded approaches, line-by-line models, and experimental results demonstrate the accuracy of the present models in cases where previously proposed approaches are very inaccurate.

Quantitative analysis of photoacoustic IR spectra

Photoacoustic spectroscopy is a method for directly measuring the absorption properties of gases and condensed matter. We have developed a photoacoustic gas cell for a rapid-scan Fourier spectrometer. With this cell we can extend the spectral range down to 180 cm−1; more than one octave lower than previously reported useful broadband measurements. The photoacoustic spectrum of a microscope cover glass was measured from 180 ... 200 cm−1 and normalized with respect to the spectrum of carbon black as a reference material. Starting from the one-dimensional equation of heat conduction we derived an expression for the surface temperature of single and double-layer samples. We calculated the surface temperature of the glass lamella and divided it by the corresponding values for carbon black using the thermal conductivity of carbon black as a fitting parameter. We show that the one-dimensional model calculation reproduces the experimental spectrum over the whole spectral range.

Optics in the Oil Industry*

The employment of optical principles and equipment is vitally important in many operations of the petroleum industry. At the present time the greatest concentration of optical applications is in spectroscopy. Emission spectroscopy is widely used in almost all operations for rapid reliable analyses of materials for metallic or inorganic elements. These applications range from the measurement of metallic elements present in crude oil to the solving of customer complaints where there is a relation between poor performance and the presence of impurities.The techniques of infrared and ultraviolet absorption spectroscopy are quite widely used to solve many analytical and molecular structure problems encountered in hydrocarbon chemistry. Infrared absorption is particularly valuable for distinguishing between close boiling isomers, and the ultraviolet technique is very extensively used in the analysis for various kinds of aromatics. A specialized branch of infrared absorption wherein the selective absorption properties of gases are utilized is becoming of great importance for the continuous monitoring and automatic control of refining processes.An indirect but extremely important application of optics is in the utilization of thermodynamic quantities derived from spectroscopic data. Fairly complete data from this source are available on about 210 hydrocarbons, and today research on any refining process is seldom undertaken until a preliminary study is made of the thermodynamic data. Various aspects of photochemistry and optical activity are important in the oil business. It has been found practical and convenient to utilize ultraviolet light in accelerated stability tests of products subject to deterioration with age. At present it is known that a hydrocarbon of phenomenal octane number may be prepared by photochemical synthesis. In the study of compounds isolated from petroleum it has been discovered that some of them are optically active. At least one of these has been isolated and studied.Aerial photography occupies a very important place in the mapping work involved in exploration and pipe-line surveys. Stereograms are used for contouring purposes to yield satisfactory topographic maps. Many significant surface geological features may be delineated from stereograms and photomosaics. A field allied to mapping and employing the concepts, if not the equipment, of optics is in radiolocation wherein either direct interferometric techniques or time measurements of wave propagation are employed. Other sciences utilizing common optical concepts are x-ray diffraction, electron diffraction, electron microscopy, and mass spectrometry. All of these are essential to the modern research laboratory of the petroleum industry.