scholarly journals Gas adsorption mechanism in MOF materials: Role of interaction between adsorbed gas molecules

2020 ◽  
Author(s):  
Rodion Belosludov
Keyword(s):  
Adsorption Mechanism ◽  
Gas Adsorption ◽  
Adsorbed Gas ◽  
Gas Molecules

scholarly journals Monolayer Gas Adsorption on Graphene-Based Materials: Surface Density of Adsorption Sites and Adsorption Capacity

Surfaces ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 423-432
Author(s):  
Olga Jakšić ◽  
Marko Spasenović ◽  
Zoran Jakšić ◽  
Dana Vasiljević-Radović
Keyword(s):  
Surface Density ◽  
Gas Adsorption ◽  
Simple Expression ◽  
Pristine Graphene ◽  
Adsorption Sites ◽  
Adsorbed Gas ◽  
Gas Molecules ◽  
Application Specific ◽  
Analytical Expressions ◽  
Basic Input

Surface density of adsorption sites on an adsorbent (including affinity-based sensors) is one of the basic input parameters in modeling of process kinetics in adsorption based devices. Yet, there is no simple expression suitable for fast calculations in current multiscale models. The published experimental data are often application-specific and related to the equilibrium surface density of adsorbate molecules. Based on the known density of adsorbed gas molecules and the surface coverage, both of these in equilibrium, we obtained an equation for the surface density of adsorption sites. We applied our analysis to the case of pristine graphene and thus estimated molecular dynamics of adsorption on it. The monolayer coverage was determined for various pressures and temperatures. The results are verified by comparison with literature data. The results may be applicable to modeling of the surface density of adsorption sites for gas adsorption on other homogeneous crystallographic surfaces. In addition to it, the obtained analytical expressions are suitable for training artificial neural networks determining the surface density of adsorption sites on a graphene surface based on the known binding energy, temperature, mass of adsorbate molecules and their affinity towards graphene. The latter is of interest for multiscale modelling.

Enhanced Catalytic Activity of α-Fe2O3 with the Adsorption of Gases for Ammonia Synthesis

2016 ◽  
Vol 880 ◽  
pp. 15-18 ◽  
Author(s):  
Saima Qureshi ◽  
Noorhana Yahya ◽  
Chong Fai Kait ◽  
Bilal Alqasem ◽  
Zia ur Rehman ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Density Functional ◽  
Ammonia Synthesis ◽  
Synthesis Method ◽  
Functional Theory ◽  
Adsorbed Gas ◽  
Kjeldahl Method ◽  
Adsorption Of Gases ◽  
Gas Molecules

Ab initio density functional theory employed to study the adsorption of hydrogen and nitrogen gas molecule on the α-Fe2O3 (111) surface for ammonia synthesis. The calculated adsorption energy is-4.70kcal/mol, -4.60kcal/mol,-4.38kcal/mol and-3.77kcal/mol for different orientations of adsorbed gas molecules and shows that system is stable and gas molecules have adsorbed. It can also be seen with adsorption of gas molecules the net spin of hematite enhanced from 0 to 2 hence confirms the activity of hematite surface. Hematite nanowires synthesized by oxidation method. Raman spectrum analyses demonstrates that the nanowires are single-crystalline. Field Emission Scanning Electron Microscopy (FESEM) reveals that the nanowires have lengths of 10-25 μm. The magnetic saturation of the nanowires is 15.6 emu/g investigated by vibrating sample magnetometer (VSM). Ammonia was synthesized by magnetic induction method using the hematite nanowires as catlyst and quantified by Kjeldahl method. It is found that the role of gases adsorption was able to enhance catalytic activity of hematite nanowires for the ammonia synthesis. This green synthesis method could be a contender to the Haber-Bosch process currently used by the industry.

Dependence of gas permeation and adsorption on temperature in vacuum insulation panels (VIPs) containing getter materials

2021 ◽  
pp. 174425912110171
Author(s):  
Hideya Yamamoto ◽  
Daisuke Ogura
Keyword(s):  
Glass Fiber ◽  
Adsorption Mechanism ◽  
Gas Adsorption ◽  
Gas Permeation ◽  
Fiber Core ◽  
Vacuum Insulation ◽  
Calculation Results ◽  
Long Term Performance ◽  
Term Performance

Vacuum insulation panels (VIPs) with a glass-fiber core has been considered to be difficult to operate for a long period of time, such as for building applications, because the thermal conductivity rises rapidly as the pressure increases. However, glass-fiber-core VIPs contain a material called a getter that continuously adsorbs permeated gas, and a theoretical model that considers the properties of the getter has not yet been developed. In this paper, the gas-adsorption mechanism by getters was investigated and a long-term-performance prediction model that considers the temperature dependence was proposed. Some gases were not adsorbed by the getter in the VIPs; however, a model was proposed that takes into account the non-absorbed gases by applying partial pressure to the adsorption isotherm in advance. The long-term performance of VIPs with different areas and volumes was compared with the measured values, and the validity of the calculation results was confirmed. These results show that the long-term performance of VIPs of different sizes can be accurately predicted when the getter performance is well understood.

Competitive adsorption mechanism of thiophene with benzene in FAU zeolite: The role of displacement

2017 ◽  
Vol 328 ◽  
pp. 172-185 ◽  
Author(s):  
Shanqing Dang ◽  
Liang Zhao ◽  
Qing Yang ◽  
Meng Zheng ◽  
Jingjing Zhang ◽  
...  
Keyword(s):  
Adsorption Mechanism ◽  
Competitive Adsorption ◽  
Fau Zeolite

Assessment of surface energetic heterogeneity of synthetic Na- saponites. The role of layer charge

Clay Minerals ◽  
2002 ◽  
Vol 37 (1) ◽  
pp. 39-57 ◽  
Author(s):  
L. J. Michot ◽  
F. Villiéras
Keyword(s):  
Aspect Ratio ◽  
Gas Adsorption ◽  
High Energy ◽  
Layer Charge ◽  
Adsorption Mechanisms ◽  
Energetic Heterogeneity ◽  
Complex Adsorption ◽  
Adsorption Energy Distribution ◽  
Synthetic Saponite

AbstractHigh-resolution gas adsorption techniques were used to analyse the evolution of the aspect ratio and adsorption energy distribution on synthetic saponite samples with increasing layer charge. Using Ar as a gaseous probe, the aspect ratio of the saponite particles can be determined easily by decomposing the derivative adsorption isotherms and taking into account high-energy sites which can be assigned to talc-like ditrigonal cavities. Changes in the shape of the elementary particles are observed for layer charges above 1.30, i.e. when all the ditrigonal cavities contain at least one Al atom substituting for Si. When N2 is used as a probe, high-energy sites that could be wrongly interpreted as micropores on the basis of classical t-plot treatments are observed whatever the layer charge. Using the information obtained from both Ar and N2, schemes for describing adsorption can be proposed for all layer charges and suggest complex adsorption mechanisms for charged clay minerals.

scholarly journals The binary gas sorption in the bituminous coal of the Huaibei Coalfield in China

2018 ◽  
Vol 36 (9-10) ◽  
pp. 1612-1628 ◽  
Author(s):  
Lei Zhang ◽  
Zhiwei Ye ◽  
Mingxue Li ◽  
Cun Zhang ◽  
Qingsheng Bai ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Sorption Capacity ◽  
Bituminous Coal ◽  
Gas Adsorption ◽  
Langmuir Equation ◽  
Separation Coefficient ◽  
Gas Sorption ◽  
Langmuir Adsorption ◽  
Gas Molecules ◽  
Huaibei Coalfield

Knowledge of the gas sorption characteristics of a coal not only helps to explain the mechanism of enhanced coalbed methane recovery but also provides an important basis for simultaneous coal and gas extraction. In consequence, the pure and binary gas excess sorption capacity of methane, carbon dioxide, and nitrogen of bituminous coal samples derived from the Xutuan Coal Mine in Huaibei coalfield, in Anhui Province in China, was measured using the volumetric method. The fitting analysis of the pure gas Langmuir adsorption model was carried out. The binary gas excess sorption measurement showed that the final sorption capacity of bituminous samples was the same no matter what the gas adsorption order of competitive adsorption and displacement adsorption. Hence, coal gas adsorption is physical adsorption, i.e. the different adsorption and desorption process of gas molecules does not affect the final adsorption amount of coal to each component of gas. Using the fitting parameters obtained by the Langmuir equation, the extended Langmuir equation was used to predict the adsorption capacity for each component of the binary gas. The comparison between predicted adsorption capacity and measured adsorption capacity showed that the extended Langmuir equation can better describe the trend of the adsorption isotherm curves of a binary gas under different pressures. The separation coefficient and displacement coefficient were defined from Langmuir adsorption theory. The separation coefficient involves the proportion of each component in the free phase and the proportion of each component in the adsorption phase. The displacement coefficient involves the displacement ability of gas molecules at adsorption sites by free gas molecules.

A Theoretical Study of H2S Toxic Gas Adsorption on Pristine and Doped Monolayer (AlN)21 Using Density Functional Theory

2020 ◽  
Vol 12 (02) ◽  
pp. 99-111
Author(s):  
Jamal A. Shlaka ◽  
◽  
Abbas H. Abo Nasria
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Theoretical Study ◽  
Gas Adsorption ◽  
Aluminium Nitride ◽  
Functional Theory ◽  
Adsorption Sites ◽  
Gas Molecules ◽  
Toxic Gas ◽  
Center Ring

Been studying the interactions between graphene - like aluminium nitride P(AlN)21 nano ribbons doped and defect (AlN)21Sheet, Molecules and small toxic gas molecules ( H2S), were built for two different adsorption sites on graphene like aluminium nitride P(AlN)21. this was done by employing B3LYP density functional theory (DFT) with 6-31G*(d,p) using Gaussian 09 program, Gaussian viw5.0 package of programs and Nanotube Modeller program 2018. the adsorptions of H2S on P(AlN)21, (C) atoms-doped P(AL-N)20 sheet, D-P(AL-N)20 and D-(C)atoms-doped P(AL-N)19 (on atom) with (Ead) (-0.468eV),(-0.473 eV), (-0.457 eV), (-0.4478 eV) and (-0.454 eV), respectively, (Ead) of H2S on the center ring of the P(AL-N)21, (C) atoms-doped P(AL-N)20 sheet, D-P(AL-N)20 and D-(C,B)atoms-doped P(AL-N)19 sheet are (-0.280 eV),(-0.465 eV), (-0.405 eV), (-0.468 eV) and -0.282 eV), respectively, are weak physisorption . However, the adsorptions of H2S, on the ((AlN)20 -B and D- (AlN)19 -B), (on atom N and center ring the sheet) are a strong chemisorption because of the (Ead) larger than -0.5 eV, due to the strong interaction, the ((AlN)20-B and D-(AlN)19-B), could catalyst or activate, through the results that we obtained, which are the improvement of the sheet P(AlN)21 by doping and per forming a defect in, it that can be used to design sensors. DOI: http://dx.doi.org/10.31257/2018/JKP/2020/120210

Critical role of water stability in metal–organic frameworks and advanced modification strategies for the extension of their applicability

2020 ◽  
Vol 7 (5) ◽  
pp. 1319-1347 ◽  
Author(s):  
Botao Liu ◽  
Kumar Vikrant ◽  
Ki-Hyun Kim ◽  
Vanish Kumar ◽  
Suresh Kumar Kailasa
Keyword(s):  
Drug Delivery ◽  
Water Purification ◽  
Gas Adsorption ◽  
Critical Role ◽  
Metal Organic Frameworks ◽  
Water Stability ◽  
Metal Organic

Metal–organic frameworks (MOFs) are well known for their versatile applications in diverse fields (e.g., gas adsorption, water purification, sensing, drug delivery, and catalysis).

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