Статті в журналах: "Gas adsorption and selectivity"

1

Jiang, Weile, Yong Xia, Aifei Pan, Yunyun Luo, Yaqiong Su, Sikai Zhao, Tao Wang, and Libo Zhao. "Facet-Dependent Gas Adsorption Selectivity on ZnO: A DFT Study." Chemosensors 10, no. 10 (October 21, 2022): 436. http://dx.doi.org/10.3390/chemosensors10100436.

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Semiconductor-based gas sensors are of great interest in both industrial and research settings, but poor selectivity has hindered their further development. Current efforts including doping, surface modifications and facet controlling have been proved effective. However, the “methods-selectivity” correlation is ambiguous because of uncontrollable defects and surface states during the experiments. Here, as a case study, using a DFT method, we studied the adsorption features of commonly tested gases—CH2O, H2, C2H5OH, CH3COCH3, and NH3—on facets of ZnO(0001¯), ZnO(101¯0) and ZnO(101¯1). The adsorption energies and charge transfers were calculated, and adsorption selectivity was analyzed. The results show ZnO(0001¯) has obvious CH2O adsorption selectivity; ZnO(101¯0) has a slight selectivity to C2H5OH and NH3; and ZnO(101¯1) has a slight selectivity to H2, which agrees with the experimental results. The mechanism of the selective adsorption features was studied in terms of polarity, geometric matching and electronic structure matching. The results show the adsorption selectivity is attributed to a joint effort of electronic structure matching and geometric matching: the former allows for specific gas/slab interactions, the latter decides the strength of the interactions. As the sensing mechanism is probably dominated by gas–lattice interactions, this work is envisioned to be helpful in designing new sensing material with high selectivity.

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2

Chan Wai, Hoong, Mohd Noor Mazlee, Zainal Arifin Ahmad, Shamsul Baharin Jamaludin, Mohd Azlan Mohd Ishak, and Muhammad Shahar Jusoh. "Sustainable Porous Materials for Gas Adsorption Applications; A Concise Review." Advanced Materials Research 795 (September 2013): 96–101. http://dx.doi.org/10.4028/www.scientific.net/amr.795.96.

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Many new sustainable porous materials were developed for gas adsorption applications. Common materials such as activated carbon, clay materials and metal organic framework (MOF) that utilized as potential porous adsorption materials were studied. The article was also discussed on the fabrication methods of porous materials. Adsorptions of flue gas using porous materials were reviewed. It was found that the adsorption properties of porous materials were highly dependent on surface area, selectivity and impregnation. Low cost porous adsorbents such as clay and fly ash were also reviewed as potential and cost effective materials to be used in industries.

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3

He, Jiating, and Xu Li. "Metal–Organic Framework for Selective Gas Scavenging." Journal of Molecular and Engineering Materials 04, no. 04 (December 2016): 1640014. http://dx.doi.org/10.1142/s2251237316400141.

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Selective gas adsorption plays an important role in adsorptive separation of gases and scavenging unfavorable or hazardous gases. The use of cost-effective and environmentally friendly materials for selective gas adsorption has become one of the most pressing needs today. The development of new adsorbents is essential but difficult due to the selectivity and efficiency requirements for practical application. As potential scavengers, metal–organic frameworks (MOFs) have drawn great attention. In this review, the current progress of science and technology development of MOFs on selective gas scavenging will be highlighted. Future perspectives for exploring MOFs for practical application will also be put forward.

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4

Parinyakit, Supatsorn, and Patcharin Worathanakul. "Static and Dynamic Simulation of Single and Binary Component Adsorption of CO2 and CH4 on Fixed Bed Using Molecular Sieve of Zeolite 4A." Processes 9, no. 7 (July 20, 2021): 1250. http://dx.doi.org/10.3390/pr9071250.

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The simulation of carbon dioxide (CO2)-methane (CH4) mixed gas adsorption and the selectivity on zeolite 4A using Aspen Adsorption were studied. The influence of temperature ranging from 273 to 343 K, pressure up to 10 bar and various compositions of CO2 in the binary system were simulated. The findings of the study demonstrate that the models are accurate. In addition, the effects of various key parameters such as temperature, pressure, and various compositions of binary gases were investigated. The highest CO2 and CH4 adsorption are found at 273 K and 10 bar in the Langmuir isotherm model with 5.86 and 2.88 mmol/g, respectively. The amount of CO2 adsorbed and the selectivity of the binary mixture gas depends on the composition of CO2. The kinetics of adsorption for pure components of CO2 at high temperatures can reach saturation faster than CH4. The influence of the physical properties of zeolite 4A on kinetic adsorption were also studied, and it was observed that small adsorbent particles, large pore diameter, and large pore volume would enter saturation quickly. The prediction of CO2-CH4 mixed gas adsorption and selectivity on zeolite 4A were developed for further use for commercial gas separation.

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5

Wu, Chin-Wen, and Shivaji Sircar. "Comments on binary and ternary gas adsorption selectivity." Separation and Purification Technology 170 (October 2016): 453–61. http://dx.doi.org/10.1016/j.seppur.2016.06.053.

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6

Dutta, Sujeet, Ronan Lefort, Denis Morineau, Ramona Mhanna, Odile Merdrignac-Conanec, Arnaud Saint-Jalmes, and Théo Leclercq. "Thermodynamics of binary gas adsorption in nanopores." Physical Chemistry Chemical Physics 18, no. 35 (2016): 24361–69. http://dx.doi.org/10.1039/c6cp01587e.

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7

Dubskikh, Vadim A., Konstantin A. Kovalenko, Anton S. Nizovtsev, Anna A. Lysova, Denis G. Samsonenko, Danil N. Dybtsev, and Vladimir P. Fedin. "Enhanced Adsorption Selectivity of Carbon Dioxide and Ethane on Porous Metal–Organic Framework Functionalized by a Sulfur-Rich Heterocycle." Nanomaterials 12, no. 23 (December 1, 2022): 4281. http://dx.doi.org/10.3390/nano12234281.

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Porous metal–organic framework [Zn2(ttdc)2(bpy)] (1) based on thieno[3,2‑b]thiophenedicarboxylate (ttdc) was synthesized and characterized. The structure contains intersected zig-zag channels with an average aperture of 4 × 6 Å and a 49% (v/v) guest-accessible pore volume. Gas adsorption studies confirmed the microporous nature of 1 with a specific surface area (BET model) of 952 m2·g–1 and a pore volume of 0.37 cm3·g–1. Extensive CO2, N2, O2, CO, CH4, C2H2, C2H4 and C2H6 gas adsorption experiments at 273 K and 298 K were carried out, which revealed the great adsorption selectivity of C2H6 over CH4 (IAST selectivity factor 14.8 at 298 K). The sulfur-rich ligands and double framework interpenetration in 1 result in a dense decoration of the inner surface by thiophene heterocyclic moieties, which are known to be effective secondary adsorption sites for carbon dioxide. As a result, remarkable CO2 adsorption selectivities were obtained for CO2/CH4 (11.7) and CO2/N2 (27.2 for CO2:N2 = 1:1, 56.4 for CO2:N2 = 15:85 gas mixtures). The computational DFT calculations revealed the decisive role of the sulfur-containing heterocycle moieties in the adsorption of CO2 and C2H6. High CO2 adsorption selectivity values and a relatively low isosteric heat of CO2 adsorption (31.4 kJ·mol–1) make the porous material 1 a promising candidate for practical separation of biogas as well as for CO2 sequestration from flue gas or natural gas.

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8

Ismail, Marhaina, Mohamad Azmi Bustam, Nor Ernie Fatriyah Kari, and Yin Fong Yeong. "Ideal Adsorbed Solution Theory (IAST) of Carbon Dioxide and Methane Adsorption Using Magnesium Gallate Metal-Organic Framework (Mg-gallate)." Molecules 28, no. 7 (March 28, 2023): 3016. http://dx.doi.org/10.3390/molecules28073016.

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Ideal Adsorbed Solution Theory (IAST) is a predictive model that does not require any mixture data. In gas purification and separation processes, IAST is used to predict multicomponent adsorption equilibrium and selectivity based solely on experimental single-component adsorption isotherms. In this work, the mixed gas adsorption isotherms were predicted using IAST calculations with the Python package (pyIAST). The experimental CO2 and CH4 single-component adsorption isotherms of Mg-gallate were first fitted to isotherm models in which the experimental data best fit the Langmuir model. The presence of CH4 in the gas mixture contributed to a lower predicted amount of adsorbed CO2 due to the competitive adsorption among the different components. Nevertheless, CO2 adsorption was more favorable and resulted in a higher predicted adsorbed amount than CH4. Mg-gallate showed a stronger affinity for CO2 molecules and hence contributed to a higher CO2 adsorption capacity even with the coexistence of a CO2/CH4 mixture. Very high IAST selectivity values for CO2/CH4 were obtained which increased as the gas phase mole fraction of CO2 approached unity. Therefore, IAST calculations suggest that Mg-gallate can act as a potential adsorbent for the separation of CO2/CH4 mixed gas.

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9

Zhang, Xiaoxing, Rongxing Fang, Dachang Chen та Guozhi Zhang. "Using Pd-Doped γ-Graphyne to Detect Dissolved Gases in Transformer Oil: A Density Functional Theory Investigation". Nanomaterials 9, № 10 (19 жовтня 2019): 1490. http://dx.doi.org/10.3390/nano9101490.

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To realize a high response and high selectivity gas sensor for the detection dissolved gases in transformer oil, in this study, the adsorption of four kinds of gases (H2, CO, C2H2, and CH4) on Pd-graphyne was investigated, and the gas sensing properties were evaluated. The energetically-favorable structure of Pd-Doped γ-graphyne was first studied, including through a comparison of different adsorption sites and a discussion of the electronic properties. Then, the adsorption of these four molecules on Pd-graphyne was explored. The adsorption structure, adsorption energy, electron transfer, electron density distribution, band structure, and density of states were calculated and analyzed. The results show that Pd prefers to be adsorbed on the middle of three C≡C bonds, and that the band gap of γ-graphyne becomes smaller after adsorption. The CO adsorption exhibits the largest adsorption energy and electron transfer, and effects an obvious change to the structure and electronic properties to Pd-graphyne. Because of the conductance decrease after adsorption of CO and the acceptable recovery time at high temperatures, Pd-graphyne is a promising gas sensing material with which to detect CO with high selectivity. This work offers theoretical support for the design of a nanomaterial-based gas sensor using a novel structure for industrial applications.

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10

Pan, Sudip, Ranajit Saha, Subhajit Mandal, Sukanta Mondal, Ashutosh Gupta, María A. Fernández-Herrera, Gabriel Merino, and Pratim K. Chattaraj. "Selectivity in Gas Adsorption by Molecular Cucurbit[6]uril." Journal of Physical Chemistry C 120, no. 26 (June 28, 2016): 13911–21. http://dx.doi.org/10.1021/acs.jpcc.6b02545.

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11

Verma, Pankaj, Udai P. Singh, and Ray J. Butcher. "Luminescent metal organic frameworks for sensing and gas adsorption studies." CrystEngComm 21, no. 36 (2019): 5470–81. http://dx.doi.org/10.1039/c9ce00732f.

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Two three-dimensional metal organic frameworks (LZn and LCd) were synthesized solvothermally for sensing of nitro phenolic explosives and gas adsorption studies. LZn showed selectivity towards N₂ gas at 77 K.

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12

He, Xiaodong, Jiamei Zhu, Hongmin Wang, Min Zhou, and Shuangquan Zhang. "Surface Functionalization of Activated Carbon with Phosphonium Ionic Liquid for CO2 Adsorption." Coatings 9, no. 9 (September 18, 2019): 590. http://dx.doi.org/10.3390/coatings9090590.

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Immobilization of phosphonium ionic liquid (IL) onto activated carbon (AC) was synthesized via grafting and impregnated methods, and the modified materials were analyzed via Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, thermal gravity analysis, scanning electron microscope, pore structure and CO2/N2 adsorption selectivity. The effect of the gas flow rate (100–500 mL/min) and adsorption pressure (0.2–0.6 MPa) on the dynamic adsorption behavior of mixture gas containing 15 vol.% CO2 and 85 vol.% N2 was explained using a breakthrough method. By analyzing the breakthrough curves, the adsorption capacity was determined. The results show that surface functionalization of activated carbon with phosphonium ionic liquid is conducive to improving CO2/N2 selectivity, especially ionic liquid-impregnated film. The different adsorption behaviors of impregnated and grafted adsorbents are observed under various conditions. The grafted AC had better CO2 adsorption and mass transfer due to a lower blockage of pores by ionic liquid.

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13

Kandagal, Vinay S., Jennifer M. Pringle, Maria Forsyth, and Fangfang Chen. "Predicting gas selectivity in organic ionic plastic crystals by free energy calculations." RSC Advances 11, no. 32 (2021): 19623–29. http://dx.doi.org/10.1039/d1ra01844b.

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The free energy calculation shows the different free energy changes of the adsorption and absorption of gas molecules into an organic ionic plastic crystal, successfully predicting the gas selectivity of this new type of gas separation material.

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14

DENİZ, Celal Utku. "A Computational Study of the Adsorptive Separation of Methane and Hydrogen in Zeolite Templated Carbons." Gazi University Journal of Science Part A: Engineering and Innovation 9, no. 4 (December 31, 2022): 545–53. http://dx.doi.org/10.54287/gujsa.1205356.

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Combustion of conventional energy sources produces pollutants such as SOx, NOx, and CO; the use of hydrogen and methane can eliminate these harmful emissions. In fuel cell technology and other uses, hydrogen must be refined by extracting methane from the methane/hydrogen combination, produced via dry or steam reforming. This study investigates the adsorption and separation capabilities of recently discovered zeolite-templated carbons (ZTCs) for binary mixtures consisting of hydrogen and methane. To assess the adsorption and separation performances of these carbon-based nanostructures, grand canonical Monte Carlo (GCMC) simulations were used. The simulation results revealed that AFY (|(C6H15N)3(H2O)7|[Co3Al5P8O32]) and RWY (|(C6H18N4)16| [Ga32Ge16S96]) structures could be viable alternatives for applications involving adsorptive gas separation based on selectivity and the CH4 uptake capacity. The selectivity of AFY was calculated to be 176, while its capacity to uptake CH4 was found to be 2.57 mmol/g, the selectivity of RWY was calculated to be 132, and its CH4 uptake was 3.49 mmol/g.

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15

DeWitt, Stephen J. A., Anshuman Sinha, Jayashree Kalyanaraman, Fengyi Zhang, Matthew J. Realff, and Ryan P. Lively. "Critical Comparison of Structured Contactors for Adsorption-Based Gas Separations." Annual Review of Chemical and Biomolecular Engineering 9, no. 1 (June 7, 2018): 129–52. http://dx.doi.org/10.1146/annurev-chembioeng-060817-084120.

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Recent advances in adsorptive gas separations have focused on the development of porous materials with high operating capacity and selectivity, useful parameters that provide early guidance during the development of new materials. Although this material-focused work is necessary to advance the state of the art in adsorption science and engineering, a substantial problem remains: how to integrate these materials into a fixed bed to efficiently utilize the separation. Structured sorbent contactors can help manage kinetic and engineering factors associated with the separation, including pressure drop, sorption enthalpy effects, and external heat integration (for temperature swing adsorption, or TSA). In this review, we discuss monoliths and fiber sorbents as the two main classes of structured sorbent contactors; recent developments in their manufacture; advantages and disadvantages of each structure relative to each other and to pellet packed beds; recent developments in system modeling; and finally, critical needs in this area of research.

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16

Sotelo, Jorge, Scott McKellar, Stephen Moggach, John Mowat, Anna Warren, Mark Warren, and Paul Wright. "In-situ Gas Adsorption SC-XRD Study: Understanding Gas Uptake in a Sc-based MOF." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1261. http://dx.doi.org/10.1107/s2053273314087385.

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In recent years the development of new methods of storing, trapping or separating light gases, such as CO2, CH4 and CO has become of utmost importance from an environmental and energetic point of view. Porous materials such as zeolites and porous organic polymers have long been considered good candidates for this purpose. More recently, the ample spectrum of existing metal organic frameworks (MOFs) together with their functional and mechanical properties have attracted even further interest. The porous channels found in these materials are ideal for the uptake of guests of different shapes and sizes, and with careful design they can show high selectivity. Adsorption properties of MOFs have been thoroughly studied, however obtaining in depth structural insight into the adsorption/desorption mechanism of these materials is challenging. For example, out of the hundreds of MOF structures published to date, there are less than 20 entries currently in the CSD in which the CO2 molecule can be located. Here we present our novel findings using the high-pressure gas cell at the Diamond Light Source on beamline I19, where we have studied the inclusion of CO2, CH4 and CO on the microporous scandium framework, Sc2BDC3 (BDC = benzene-1,4-dicarboxylate) and its amino-functionalised derivative, Sc2(BDC-NH2)3. Here, the different adsorption sites for CO2, CH4 and CO in both frameworks have been determined as a function of increasing gas pressure. These structures, coupled with Density Functional Theory calculations, have helped to elucidate the host-guest interactions governing the different levels of selectivity shown by both Sc2BDC3 and Sc2(BDC-NH2)3. Additionally, gas mixtures have also been studied; in particular CO2/CH4 mixtures of different compositions, explaining the selectivity of the frameworks for CO2 over other gases and showing the great potential of in situ structural experiments for investigation of the potential applications of MOFs.

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17

Ding, Jijun, Yuwen Bu, Mingya Yang, Jialong Feng, Rongguo Wu, and Haixia Chen. "I-V characteristics and adsorption properties of ZnO/rGO/ZnO for gas sensing detection." Journal of Physics: Conference Series 2548, no. 1 (July 1, 2023): 012001. http://dx.doi.org/10.1088/1742-6596/2548/1/012001.

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Abstract The heterostructure consisting of zinc oxide and reduced graphene oxide (ZnO/rGO/ZnO) is prepared on cotton fabric by repeated immersion and magnetron sputtering. In addition, the gas selectivity of the sample is analyzed based on I-V characteristics under different gas atmospheres (air, methanal, ethanol, acetone and toluene). Compare with that in air atmosphere, the I-V characteristic curve under toluene gas atmosphere changes significantly, and the current decreased significantly. The experimental results show that the samples exhibit high selectivity. In order to study the intrinsic physical characteristics of the heterostructure after gas adsorption, the band structures, density of states (DOS), adsorption energy (Ead) and charge density difference (CDD) are calculated based on density function theory (DFT). The existence of rGO results in a high electrical conductivity, which is consistent with the experimental results. Meanwhile, toluene has the highest Ead (-0.85 eV) and charge transfer (0.67 e). The charge transfer results prove that a large number of electrons are transferred from the surface of the heterostructure to the vicinity of toluene molecules, which leads to a change in the electrical conductivity of the heterostructure. Based on the excellent gas selectivity, the application of cotton-based ZnO/rGO/ZnO structure in gas sensing field is promoted.

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18

Wang, Dongmei, Tingting Zhao, Yu Cao, Shuo Yao, Guanghua Li, Qisheng Huo, and Yunling Liu. "High performance gas adsorption and separation of natural gas in two microporous metal–organic frameworks with ternary building units." Chem. Commun. 50, no. 63 (2014): 8648–50. http://dx.doi.org/10.1039/c4cc03729d.

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19

Pillai, Renjith S., Moisés L. Pinto, João Pires, Miguel Jorge, and José R. B. Gomes. "Understanding Gas Adsorption Selectivity in IRMOF-8 Using Molecular Simulation." ACS Applied Materials & Interfaces 7, no. 1 (January 6, 2015): 624–37. http://dx.doi.org/10.1021/am506793b.

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20

Cui, Di, Xuesong Ding, Wei Xie, Guangjuan Xu, Zhongmin Su, Yanhong Xu, and Yuzhong Xie. "A tetraphenylethylene-based covalent organic framework for waste gas adsorption and highly selective detection of Fe3+." CrystEngComm 23, no. 33 (2021): 5569–74. http://dx.doi.org/10.1039/d1ce00870f.

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21

Liang, Jie, Wei Xia, Junliang Sun, Jie Su, Maofeng Dou, Ruqiang Zou, Fuhui Liao, Yingxia Wang, and Jianhua Lin. "A multi-dimensional quasi-zeolite with 12 × 10 × 7-ring channels demonstrates high thermal stability and good gas adsorption selectivity." Chemical Science 7, no. 5 (2016): 3025–30. http://dx.doi.org/10.1039/c5sc04916d.

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22

Luan, Daniel, Victor Zhou, Nianjun Zhou, and Binquan Luan. "Improving CO₂ capture in porous 3D-graphene by cationic nitrogen doping." Journal of Applied Physics 132, no. 21 (December 7, 2022): 214901. http://dx.doi.org/10.1063/5.0129554.

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The highly porous three-dimensional (3D) graphene is a promising solid sorbent for carbon capture and storage. However, generally, the selectivity of a carbon-based sorbent for [Formula: see text] in a gas mixture (such as the post-combustion flue gas in a power plant) is only moderate ([Formula: see text]10–20), which limits its applications. Here, using the Grand Canonical Monte Carlo (GCMC) simulation, we investigate a new type of nitrogen doping (N-doping) in graphene that contains cationic nitrogen sites for [Formula: see text] adsorption. We found that due to the favorable electrostatic interaction both [Formula: see text] adsorption and selectivity are improved substantially for the porous 3D graphene with the cationic N-doping and are at least an order of magnitude higher than those for the ones without N-doping or with neutral N-doping (such as graphitic, pyridinic, and pyrrolic ones). Our results highlight the possibility for this modified porous 3D graphene to possess both high selectivity and large adsorption for carbon capture, enhancing its commercial viability.

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23

Yaqub, Sana, Nurhayati Mellon, and Azmi Mohamad Shariff. "A Review on Robustness of Covalent Organic Polymers for CO₂ Capture." Applied Mechanics and Materials 625 (September 2014): 237–40. http://dx.doi.org/10.4028/www.scientific.net/amm.625.237.

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The presence of carbon dioxide (CO2) in natural gas stream is a critical problem; besides causing corrosion it also reduces the energy contents and heating value of natural gas. Various separation techniques are available to separate CO2from natural gas, such as metal organic framework (MOF), covalent organic framework (COF) and Covalent Organic Polymer (COP) adsorbents. The criteria of adsorbent selection that need to be fulfilled include high adsorption capacity, high selectivity of CO2and hydrothermal stability at operating conditions. COPs are crystalline porous materials having high CO2capacity and selectivity in the presence of water vapors. However, the research on COP material development is new and scarce information is available in literature. In this prospect, the paper highlights the different types of COPs, their basic constituents and the adsorption capacities.

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24

Ahn, Ho Sang, Byung Kwon Jung, Jin Chul Joo, and Jae Ro Park. "Characterization of Graphene Oxide Thin Film According to Heat Treatment Condition for the Selective VOCs Sensing." Applied Mechanics and Materials 627 (September 2014): 40–45. http://dx.doi.org/10.4028/www.scientific.net/amm.627.40.

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Graphene oxide (GO) thin films were fabricated into thin film sensor for the selective VOCs detection. Different concentrations of GO aqueous solutions (6.2g/L and 5.0 g/L) were tested and thermally treated to obtain the appropriate sensing layer in terms of specific surface area and functional group. For the selectivity, it was assumed that different numbers and types of attached functional group of GO could induce the difference in gas adsorption, which may consequently derive to the selective VOCs detection. FE-SEM, XRD, and FTIR were utilized to characterize crystalline phase and functional group change by heat treatment condition and resistance measurements were followed. We suggest that thermally treated GO thin film sensor can be the alternative approach to achieve the improved selectivity in multiple gas detection by controlling the degree of gas adsorption.

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25

Grancha, Thais, Marta Mon, Jesús Ferrando-Soria, Jorge Gascon, Beatriz Seoane, Enrique V. Ramos-Fernandez, Donatella Armentano, and Emilio Pardo. "Tuning the selectivity of light hydrocarbons in natural gas in a family of isoreticular MOFs." Journal of Materials Chemistry A 5, no. 22 (2017): 11032–39. http://dx.doi.org/10.1039/c7ta01179b.

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26

Wang, Zengyao, Hao Wu, Qingyun Wu, Yi-Ming Zhao та Lei Shen. "Magnetic ε-Phosphorene for Sensing Greenhouse Gas Molecules". Molecules 28, № 14 (14 липня 2023): 5402. http://dx.doi.org/10.3390/molecules28145402.

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It is critical for gas sensors that sense greenhouse gas molecules to have both good sensitivity and selectivity for water molecules in the ambient environment. Here, we study the charge transfer, IV curves, and electric field tuning of vanadium-doped monolayer ϵ-phosphorene as a sensor for NO, NO2, and H2O gas molecules via first-principle and transport calculations. We find that the paramagnetic toxic molecules of NO and NO2 have a high adsorption energy on V-ϵ-phosphorene, which originates from a large amount of charge transfer driven by the hybridisation of the localised spin states of the host with the molecular frontier orbital. Using the non-equilibrium Green’s function, we investigate the IV responses with respect to the adsorption of different molecules to study the performance of gas molecule sensors. Our IV curves show a larger amount of changes in resistance of the paramagnetic NO and NO2 than nonmagnetic H2O gas molecules, suggesting both sensitivity and selectivity. Moreover, our calculations show that an applied external electric field (gate voltage) can effectively tune the amount of charge transfer. More charge transfer makes the sensor more sensitive to the molecule, while less charge transfer can reduce the adsorption energy and remove the adsorbed molecules, allowing for the repeated use of the sensor.

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27

Aghaseyedi, Maryam, Alireza Salehi, Shayan Valijam, and Mostafa Shooshtari. "Gas Selectivity Enhancement Using Serpentine Microchannel Shaped with Optimum Dimensions in Microfluidic-Based Gas Sensor." Micromachines 13, no. 9 (September 10, 2022): 1504. http://dx.doi.org/10.3390/mi13091504.

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A microfluidic-based gas sensor was chosen as an alternative method to gas chromatography and mass spectroscopy systems because of its small size, high accuracy, low cost, etc. Generally, there are some parameters, such as microchannel geometry, that affect the gas response and selectivity of the microfluidic-based gas sensors. In this study, we simulated and compared 3D numerical models in both simple and serpentine forms using COMSOL Multiphysics 5.6 to investigate the effects of microchannel geometry on the performance of microfluidic-based gas sensors using multiphysics modeling of diffusion, surface adsorption/desorption and surface reactions. These investigations showed the simple channel has about 50% more response but less selectivity than the serpentine channel. In addition, we showed that increasing the length of the channel and decreasing its height improves the selectivity of the microfluidic-based gas sensor. According to the simulated models, a serpentine microchannel with the dimensions W = 3 mm, H = 80 µm and L = 22.5 mm is the optimal geometry with high selectivity and gas response. Further, for fabrication feasibility, a polydimethylsiloxane serpentine microfluidic channel was fabricated by a 3D printing mold and tested according to the simulation results.

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28

Zagorevskaya, E. V., N. V. Ishchenko, A. V. Kiselev, and N. V. Kovaleva. "Studies of adsorption of polychlorocarbons on carbon blacks by gas chromatography." Adsorption Science & Technology 2, no. 4 (December 1985): 219–28. http://dx.doi.org/10.1177/026361748500200402.

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Adsorption properties of carbon black before and after modification to polyhalogenohydrocarbons, including polyorganochlorine pesticides, have been investigated. It has been shown that graphitised thermal carbon blacks and carbochroms possess high adsorption capacity relative to the above compounds and can be used as supporting adsorbents to analyse these airborne chemicals. Modification raises the selectivity of adsorbents to the compounds being investigated and lowers retention volumes and heats of adsorption, which makes it possible to carry out thermal desorption of the accumulated species at lower temperatures.

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Pham, Khang D., Tran Huu Ly, Tuan V. Vu, Luong L. Hai, Hong T. T. Nguyen, P. T. T. Le, and O. Y. Khyzhun. "Gas adsorption properties (N2, H2, O2, NO, NO2, CO, CO2, and SO2) on a Sc2CO2 monolayer: a first-principles study." New Journal of Chemistry 44, no. 43 (2020): 18763–69. http://dx.doi.org/10.1039/d0nj03545a.

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30

Toda, Masaya, Takahito Ono, and Jun Okubo. "Metal-Multilayered Nanomechanical Cantilever Sensor for Detection of Molecular Adsorption." Biosensors 13, no. 6 (May 23, 2023): 573. http://dx.doi.org/10.3390/bios13060573.

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A metal-multilayered nanomechanical cantilever sensor was proposed to reduce the temperature effect for highly sensitive gas molecular detection. The multilayer structure of the sensor reduces the bimetallic effect, allowing for the detection of differences in molecular adsorption properties on various metal surfaces with higher sensitivity. Our results indicate that the sensor exhibits higher sensitivity to molecules with greater polarity under mixed conditions with nitrogen gas. We demonstrate that stress changes caused by differences in molecular adsorption on different metal surfaces can be detected and that this approach could be used to develop a gas sensor with selectivity for specific gas species.

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31

Chaudhary, V. A., I. S. Mulla, and K. Vijayamohanan. "Selective gas-sensing properties of surface ruthenated tin oxide." Journal of Materials Research 14, no. 1 (January 1999): 185–88. http://dx.doi.org/10.1557/jmr.1999.0027.

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Gas-sensing properties of a novel surface functionalized tin oxide material have been studied to demonstrate the possibility of selectivity control by surface state formation. Covalent anchoring of ruthenium oxide on the tin oxide surface (ruthenated tin oxide) is found to give considerable enhancement in sensitivity (320) as well as selectivity to 1000 ppm of liquified petroleum gas (LPG) at 300 °C compared to the sensitivity (4) of pure tin oxide samples. The amount and distribution of grafted ruthenium oxide on the surface of tin oxide seems to be the most important parameter controlling the change in electrical transport with LPG gas adsorption.

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Faghihian, H., and M. Pirouzi. "Nitrogen separation from natural gas by modified clinoptilolite." Clay Minerals 44, no. 3 (September 2009): 289–92. http://dx.doi.org/10.1180/claymin.2009.044.3.289.

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AbstractSeparation of nitrogen, the major impurity of natural gas, is necessary for quality improvement of the gas. In this study, purified and some ion-exchanged forms of clinoptilolite were used to separate N2 from natural gas. Competitive adsorption of mixtures of N2, CH4 and C2H6 by Cu2+ (Cu-Cp)-, Zn2+ (Zn-Cp)-, Ni2+ (Ni-Cp)- and Mn2+ (Mn-Cp)-exchanged samples was studied at different pressures and ambient temperature. Among the cations studied, Cu2+ has the lowest selectivity towards N2. Samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, BET N2 adsorption and wet chemical analysis techniques.

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33

Cheng, Wei-Ying, Huei-Ru Fuh, and Ching-Ray Chang. "First-Principles Study for Gas Sensing of Defective SnSe2 Monolayers." Applied Sciences 10, no. 5 (February 29, 2020): 1623. http://dx.doi.org/10.3390/app10051623.

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We report the interaction between gas molecules (NO2 and NH3) and the SnSe2 monolayers with vacancy and dopants (O and N) for potential applications as gas sensors. Compared with the gas molecular adsorbed on pristine SnSe2 monolayer, the Se-vacancy SnSe2 monolayer obviously enhances sensitivity to NO2 adsorption. The O-doped SnSe2 monolayer shows similar sensitivity to the pristine SnSe2 monolayer when adsorbing NO2 molecule. However, only the N-doped SnSe2 monolayer represents a visible enhancement for NO2 and NH3 adsorption. This work reveals that the selectivity and sensitivity of SnSe2-based gas sensors could be improved by introducing the vacancy or dopants.

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34

Mohlala, Lesego M., Tien Chien Jen, and Peter Apata Olubambi. "Effect of Ni Doping and Vacancy Defects on the Sensing Characteristics of Graphene for NO<sub>2</sub> and CO Detection: A DFT Study." Key Engineering Materials 917 (April 13, 2022): 170–81. http://dx.doi.org/10.4028/p-x28800.

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The sensing characteristics of pristine, Ni-doped, and C-vacancy graphene towards CO and NO2 gas molecules were studied using density functional theory (DFT). The adsorption energies, electronic properties, charge transfer, and stable geometries were calculated to evaluate the gas-surface interaction mechanisms. Both pristine and vacancy graphene have smaller CO and NO2 adsorption energies and charge transfer than the Ni-doped graphene, whereas the adsorption energy on Ni-doped vacancy graphene is higher than that of Ni-doped graphene. The results indicate that both CO and NO2 gas molecules only attach to pristine graphene through weak physical adsorption. Stronger chemisorption occurs when the gas molecules adsorb on the surface of vacancy, Ni-doped, and Ni-doped vacancy graphene. Additionally, the results demonstrated that Ni-doped vacancy graphene has higher sensitivity and selectivity towards the NO2.

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35

Pan, Z. J., S. G. Chen, J. Tang, and R. T. Yang. "Pore Structure Alteration of a Carbon Molecular Sieve for the Separation of Hydrogen Sulfide from Methane by Adsorption." Adsorption Science & Technology 10, no. 1-4 (March 1993): 193–201. http://dx.doi.org/10.1177/0263617499010001-418.

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The equilibrium adsorption of H2S is substantially stronger than that of CH4 on carbons, including carbon molecular sieve (CMS). A carbon molecular sieve with a proper pore structure can provide a kinetic selectivity for H2S over CH4, thus further enhancing the overall selectivity (equilibrium plus kinetic) for H2S and providing the basis of natural gas desulfurization by adsorption. Kinetic selectivity requires a unique pore structure due to the small difference in the molecular dimensions of H2S and CH4 (~0.2 Å). Equilibrium and diffusion rate data for CH4 and H2S at 25°C have been measured in three commercial carbon molecular sieves: Bergbau Forschung CMS, Takeda CMS 3A and Takeda CMS 5A. The pores are either too small (in the two former carbons) or too large (in CMS 5A) for H2S/CH4 separation. Alterations to the pore structure either by controlled oxidation or carbon deposition by pyrolysis have been studied. Optimal results were obtained by pyrolysis of propylene on CMS 5A under the following conditions: 0.05 atm, 700°C, 5 min, weight gain of 0.67%. The resulting carbon molecular sieve retained the high equilibrium adsorption capacities while yielding a diffusion time constant ratio for H2S/CH4 of 8.2. This carbon is suitable for natural gas desulfurization by adsorption processes such as pressure swing adsorption. Temperature was the most important variable in pore structure alteration by carbon deposition. Under the optimal pyrolysis conditions, carbon was only deposited near the pore entrances.

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Wang, Li Min, Ying Hua Li, and Wei Wei. "A Double Imprinted Organic-Inorganic Hybrid Sorbent for Selective Separation of Lead from Aqueous Solution." Advanced Materials Research 311-313 (August 2011): 1491–95. http://dx.doi.org/10.4028/www.scientific.net/amr.311-313.1491.

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A novel ion-imprinted organic-inorganic hybrid sorbent was synthesized and characterized by FT-IR and nitrogen gas adsorption-desorption. The adsorption property and selective recognition ability of the imprinted sorbents for the lead ion were studied. Results showed that the uptake capacities and selectivity coefficients of the double imprinted sorbent were much higher than that of the non-imprinted sorbent. The adsorption capacity of the double imprinted sorbent is 545.6 mg•g-1. The largest relative selectivity coefficient between Pb (II) and Cd (II) was 192. This results suggested that the new sorbent can be used as effective solid-phase material for the selective preconcentration and separation of Pb (II) in environmental water samples.

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37

Wang, Dakai, Lingzhi Ma, Guoliang Zhao, Zhenan Tang, Philip C. H. Chan, Johnny K. O. Sin, and Lie-yi Sheng. "Gas chromatographic study on adsorption selectivity of tin dioxide gas sensor to organic vapors." Sensors and Actuators B: Chemical 66, no. 1-3 (July 2000): 156–58. http://dx.doi.org/10.1016/s0925-4005(00)00318-x.

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38

Haidry, Azhar Ali, Qawareer Fatima, Ahmar Mehmood, Asim Shahzad, Yinwen Ji, and Bilge Saruhan. "Adsorption Kinetics of NO2 Gas on Pt/Cr-TiO2/Pt-Based Sensors." Chemosensors 10, no. 1 (December 27, 2021): 11. http://dx.doi.org/10.3390/chemosensors10010011.

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Metal oxides are excellent candidates for the detection of various gases; however, the issues such as the limited operating temperature and selectivity are the most important ones requiring the comprehensive understanding of gas adsorption kinetics on the sensing layer surfaces. To this context, the present study focuses mainly on the fabrication of a Pt/Cr-TiO2/Pt type sensor structure that is highly suitable in reducing the operating temperature (from 400 to 200 °C), extending the lower limit NO2 gas concentration (below 10 ppm) with fast response (37 s) and recovery (24 s) times. This illustrates that the sensor performance is not only solely dependent on the nature of sensing material, but also, it is significantly enhanced by using such a new kind of electrode geometry. Moreover, Cr doping into TiO2 culminates in altering the sensor response from n- to p-type and thus contributes to sensor performance enhancement by detecting low NO2 concentrations selectively at reduced operating temperatures. In addition, the NO2 surface adsorption kinetics are studied by fitting the obtained sensor response curves with Elovich, inter-particle diffusion, and pseudo first-order and pseudo second-order adsorption models. It is found that a pseudo first-order reaction model describes the best NO2 adsorption kinetics toward 7–170 ppm NO2 gas at 200 °C. Finally, the sensing mechanism is discussed on the basis of the obtained results.

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39

Su, Yiru, Siyao Liu, and Xuechao Gao. "Impact of Impure Gas on CO2 Capture from Flue Gas Using Carbon Nanotubes: A Molecular Simulation Study." Molecules 27, no. 5 (March 1, 2022): 1627. http://dx.doi.org/10.3390/molecules27051627.

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We used a grand canonical Monte Carlo simulation to study the influence of impurities including water vapor, SO2, and O2 in the flue gas on the adsorption of CO2/N2 mixture in carbon nanotubes (CNTs) and carboxyl doped CNT arrays. In the presence of single impure gas, SO2 yielded the most inhibitions on CO2 adsorption, while the influence of water only occurred at low pressure limit (0.1 bar), where a one-dimensional chain of hydrogen-bonded molecules was formed. Further, O2 was found to hardly affect the adsorption and separation of CO2. With three impurities in flue gas, SO2 still played a major role to suppress the adsorption of CO2 by reducing the adsorption amount significantly. This was mainly because SO2 had a stronger interaction with carbon walls in comparison with CO2. The presence of three impurities in flue gas enhanced the adsorption complexity due to the interactions between different species. Modified by hydrophilic carboxyl groups, a large amount of H2O occupied the adsorption space outside the tube in the carbon nanotube arrays, and SO2 produced competitive adsorption for CO2 in the tube. Both of the two effects inhibited the adsorption of CO2, but improved the selectivity of CO2/N2, and the competition between the two determined the adsorption distribution of CO2 inside and outside the tube. In addition, it was found that (7, 7) CNT always maintained the best CO2/N2 adsorption and separation performance in the presence of impurity gas, for both the cases of single CNT and CNT array.

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40

Chen, Zilu, Xianlin Liu, Anfu Wu, Yuning Liang, Xinyu Wang, and Fupei Liang. "Synthesis, structure and properties of an octahedral dinuclear-based Cu12 nanocage of trimesoyltri(l-alanine)." RSC Advances 6, no. 12 (2016): 9911–15. http://dx.doi.org/10.1039/c5ra26357c.

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We report here a Mo₆C1₈⁴⁺-like dinuclear-based octahedral nanocage, presenting antiferromagnetic interactions between the Cu(ii) ions and nice selectivity on gas adsorption.

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41

Zhang, Haihui, Nabi Ullah, Mudassar Abbas, Sumaira Naeem, Mirza Nadeem Ahmad, Shahid Hussain, Naseem Akhtar, Awais Ahmad, Muhammad Sufyan Javed, and Omar Riaz. "NiCo2O4 Nanosheets for High Performances Formaldehyde Gas Sensing Performances." Journal of Nanoelectronics and Optoelectronics 16, no. 2 (February 1, 2021): 288–92. http://dx.doi.org/10.1166/jno.2021.2950.

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The advancements in gas sensors application with maximum performances in selectivity, response, accuracy in resistance measurements and inexpensive fabrication cost has led researcher to develop and new outstand nanomaterials for environmental safety. In this study, we followed a simple hydrothermal route to synthesize ultrathin NiCo2O4 nanosheets used in gas sensing applications. The wide surface area of nanosheets provides plenty of surface area for the adsorption of HCHO gas molecules. The nanostructures are testified using XRD, XPS, SEM and TEM, respectively. The nanosheets are tested for diverse gases at assorted effective temperature ranges, and shows high response and selectivity towards formaldehyde gas. The outstanding gas-sensing properties of ultrathin NiCo2O4 nanosheets based sensor make it a potential candidate in industrial applications.

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42

Babaei, Majideh, Mansoor Anbia, and Maryam Kazemipour. "Synthesis of zeolite/carbon nanotube composite for gas separation." Canadian Journal of Chemistry 95, no. 2 (February 2017): 162–68. http://dx.doi.org/10.1139/cjc-2016-0305.

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A hybrid composite of NaY zeolite and amine modified multi-walled carbon nanotube (MWCNT) has been synthesized by hydrothermal method. The obtained NaY/CNT composite (NC composite) was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and BET analysis. CO2, CH4 and N2 adsorption at two different temperatures and P < 5 bar on the composite was investigated by the volumetric method. The selectivity of the NC composite for CO2/CH4 and CO2/N2 has been studied and compared with pure NaY zeolite. Crystal structures of NC composite were similar to those of pure NaY zeolite, but the surface area and pore volume of the NC composite are enhanced. Incorporation of MWCNTs into NaY zeolite increases nucleation sites for the formation of NaY zeolite crystals, resulting in the smaller size of NaY zeolite crystals. Gas adsorption capacity and selectivity of NC composite increased because of enhancement of micropore volume. The results confirm that NC composite is a promising material for the separation and purification of gases.

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43

Yuan, Shan, Hong-Ze Gang, Yi-Fan Liu, Lei Zhou, Muhammad Irfan, Shi-Zhong Yang, and Bo-Zhong Mu. "Adsorption and Diffusion Behaviors of CO2 and CH4 Mixtures in Different Types of Kerogens and Their Roles in Enhanced Energy Recovery." Sustainability 14, no. 22 (November 11, 2022): 14949. http://dx.doi.org/10.3390/su142214949.

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CO2 geological sequestration in subsurface shale formations is a promising strategy to store CO2 and to increase shale gas production. The understanding of gas adsorption and diffusion mechanisms in microporous media is critical for CO2 storage-enhanced gas recovery (CS-EGR). The type of kerogens is one of the important factors that influence the adsorption and diffusion behaviors of gases. In this work, the Grand Canonical Monte Carlo and Molecular Dynamics simulations were utilized to develop kerogen models and further investigate gas and water adsorption and diffusion behavior on the type IA, IIA, and IIIA kerogen models. The results indicated that the adsorption and diffusion capacities of CO2 are larger than those of CH4. The adsorption and diffusion capacity decreased with increasing water content. However, the CO2/CH4 adsorption selectivity increased with the increase in water content. Type IIIA demonstrated the best potential for adsorption and diffusion. This study provides insights into the role of the adsorption and diffusion behavior of CO2 and CH4 mixtures on kerogens of different types under different water contents at a microscopic scale, and can facilitate further understanding of the processes involved in CO2 storage coupled with enhanced energy recovery.

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44

Guo, Rui, Lalita Bharadwaj, and Lee D. Wilson. "Adsorption Studies of Waterborne Trihalomethanes Using Modified Polysaccharide Adsorbents." Molecules 26, no. 5 (March 6, 2021): 1431. http://dx.doi.org/10.3390/molecules26051431.

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The adsorptive removal of trihalomethanes (THMs) from spiked water samples was evaluated with a series of modified polysaccharide adsorbents that contain β-cylodextrin or chitosan. The uptake properties of these biodegradable polymer adsorbents were evaluated with a mixture of THMs in aqueous solution. Gas chromatography employing a direct aqueous injection (DAI) method with electrolytic conductivity detection enabled quantification of THMs in water at 295 K and at pH 6.5. The adsorption isotherms for the polymer-THMs was evaluated using the Sips model, where the monolayer adsorption capacities ranged between 0.04 and 1.07 mmol THMs/g for respective component THMs. Unique adsorption characteristics were observed that vary according to the polymer structure, composition, and surface chemical properties. The modified polysaccharide adsorbents display variable molecular recognition and selectivity toward component THMs in the mixed systems according to the molecular size and polarizability of the adsorbates.

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45

Montes, E., and U. Schwingenschlögl. "Superior selectivity and sensitivity of blue phosphorus nanotubes in gas sensing applications." Journal of Materials Chemistry C 5, no. 22 (2017): 5365–71. http://dx.doi.org/10.1039/c6tc05094h.

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46

Trisunaryanti, Wega. "Selectivity of an Active Natural Zeolite in Catalytic Conversion Process of Bangkirai, Kruing and Kamper Woods Biofuel to Gasoline Fraction." Indonesian Journal of Chemistry 1, no. 1 (June 1, 2010): 35–42. http://dx.doi.org/10.22146/ijc.21959.

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The selectivity of an active natural zeolite (ZAAH) in catalytic conversion process of Bangkirai, Kruing and Kamper woods biofuels has been studied. The ZAAH catalyst was prepared from a natural zeolite (ZA) treated with acids solution (1% HF and 6M HCI) and hydrothermal then calcined at 500 °C and oxidized at 400 °C under nitrogen and oxygen gas stream, respectively. Characterizations of the catalysts including Si/Al ratio and acidity were determined by atomic adsorption spectroscopy (AAS) and ammonia gas adsorption method, respectively. The conversion process was carried out in a flow reactor system at 400 °C, under N2 stream (20 mL/min). The biofuel was vaporized from the pyrolysis zone to the catalytic reactor. A liquid product was covered and analyzed by gas chromatograph (GC) and that connected with mass spectroscopy (GC-MS). The characterization results showed that the Si/AI ratio and acidity of the ZAAH were higher than that of the ZA catalyst. The GC-MS data showed that the highest product selectivity was 2,4-dimethyl heptane and 1,2-dimethyl benzene. The total product selectivity using the ZAAH catalyst (bangkirai = 68.10%; kruing = 54.76%; kamper = 50.72%) was higher than that of the ZA catalyst (bangkirai = 39.24%; kruing = 44.38%; kamper = 46.11%).

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47

Han, Xiwei, Xiaoxian Yang, Chuan Yu, Shuyan Lu, Ehsan Sadeghi Pouya, Peng Bai, Jiafei Lyu, and Xianghai Guo. "Fine-tuning the pore structure of metal–organic frameworks by linker substitution for enhanced hydrogen storage and gas separation." CrystEngComm 23, no. 16 (2021): 3026–32. http://dx.doi.org/10.1039/d1ce00087j.

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48

Andrić, Stevan, Ivana Jokić, Jelena Stevanović, Marko Spasenović, and Miloš Frantlović. "Noise Spectrum as a Source of Information in Gas Sensors Based on Liquid-Phase Exfoliated Graphene." Chemosensors 10, no. 6 (June 14, 2022): 224. http://dx.doi.org/10.3390/chemosensors10060224.

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Surfaces of adsorption-based gas sensors are often heterogeneous, with adsorption sites that differ in their affinities for gas particle binding. Knowing adsorption/desorption energies, surface densities and the relative abundance of sites of different types is important, because these parameters impact sensor sensitivity and selectivity, and are relevant for revealing the response-generating mechanisms. We show that the analysis of the noise of adsorption-based sensors can be used to study gas adsorption on heterogeneous sensing surfaces, which is applicable to industrially important liquid-phase exfoliated (LPE) graphene. Our results for CO2 adsorption on an LPE graphene surface, with different types of adsorption sites on graphene flake edges and basal planes, show that the noise spectrum data can be used to characterize such surfaces in terms of parameters that determine the sensing properties of the adsorbing material. Notably, the spectrum characteristic frequencies are an unambiguous indicator of the relative abundance of different types of adsorption sites on the sensing surface and their surface densities. We also demonstrate that spectrum features indicate the fraction of the binding sites that are already occupied by another gas species. The presented study can be applied to the design and production of graphene and other sensing surfaces with an optimal sensing performance.

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49

Xue, Zhen-Zhen, Di Zhang, Jie Pan, Song-De Han, Jin-Hua Li, and Guo-Ming Wang. "A porous copper–organic framework with intersecting channels and gas adsorption properties." Dalton Trans. 46, no. 40 (2017): 13952–56. http://dx.doi.org/10.1039/c7dt03339g.

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Integration of [CuI2I₂] and [CuII2(COO)₄(H₂O)₂] clusters produces a porous copper–organic framework, exhibiting high H₂ uptake capacity and excellent adsorption selectivity for CO₂ over N₂ and CH₄.

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50

Aryanpour, Masoud, Nassim Rafiefard, Seyed Hossein Hosseini-Shokouh, Somayeh Fardindoost, and Azam Iraji zad. "Computational investigation of gas detection and selectivity on TiS3 nanoflakes supported by experimental evidence." Physical Chemistry Chemical Physics 20, no. 39 (2018): 25458–66. http://dx.doi.org/10.1039/c8cp05026k.

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