Recalculation of excess adsorption into absolute adsorption from adsorption isosteres

1993 ◽  
Vol 42 (6) ◽  
pp. 1108-1109
Author(s):  
V. V. Serpinskii ◽  
A. A. Pribylov ◽  
T. S. Yakubov
Keyword(s):  
Excess Adsorption ◽  
Absolute Adsorption ◽  
Adsorption Isosteres

Absolute Adsorption of CH4 on Shale with the Simplified Local-Density Theory

SPE Journal ◽  
2019 ◽  
Vol 25 (01) ◽  
pp. 212-225 ◽  
Author(s):  
Yueliang Liu ◽  
Jian Hou ◽  
Chen Wang
Keyword(s):  
Local Density ◽  
Molecular Simulations ◽  
Pore Wall ◽  
Excess Adsorption ◽  
Adsorbed Phase ◽  
Absolute Adsorption ◽  
Ch4 Adsorption ◽  
The Absolute ◽  
Two Parameters ◽  
Organic Pores

Summary Using a thermogravimetric (TGA) method, the excess methane (CH4) adsorption of four organic shale samples is measured at temperatures of 303.15 to 383.15 K and pressures of 0 to 15.0 MPa. Simplified-local-density (SLD) theory is used to calculate the density distribution of CH4 in nanopores, which is then used to obtain the adsorbed CH4 density on four shale samples. Such density is applied to obtain the absolute CH4 adsorption by correcting the measured excess CH4 adsorption. SLD theory shows that the adsorbed CH4 density is strongly affected by temperature and pressure, as well as the pore size, which is in line with the previous findings from molecular simulations. SLD theory captures the density of the adsorbed phase of CH4 in the presence of CH4/pore-wall interactions. However, the SLD theory is more efficient than molecular simulation methods in determining the adsorbed CH4 density considering that only two parameters in the SLD model are adjusted to match the excess adsorption of CH4 on shale. It is observed that the corresponding absolute adsorption of CH4 is higher than the excess adsorption; this suggests that it is not reasonable to use the measured excess adsorption to estimate the storage of CH4 on shale. This study applies the SLD theory to investigate the adsorption behavior of CH4 in organic pores at different pressure/temperature conditions, and, more importantly, it yields a more-efficient approach (i.e., SLD theory) in determining the absolute adsorption than the sophisticated molecular simulations tools.

scholarly journals The Total Content Adsorption of Binary Liquid Mixtures on NaX Zeolite

1998 ◽  
Vol 16 (7) ◽  
pp. 547-556 ◽  
Author(s):  
E.S. Jakubov ◽  
O.G. Larionov
Keyword(s):  
Adsorption Isotherms ◽  
Thermodynamic Characteristics ◽  
Total Content ◽  
Liquid Mixtures ◽  
Binary Liquid Mixtures ◽  
Excess Adsorption ◽  
Nax Zeolite ◽  
Binary Liquid ◽  
Absolute Adsorption ◽  
The Individual

The total content of tetradecene-1/n-dodecane solutions adsorbed in NaX zeolite has been measured gravimetrically at 303.15, 333.15 and 363.15 K. The total content data together with the excess adsorption values have been used for the calculation of the individual (absolute) adsorption isotherms and the basic thermodynamic characteristics of the system.

Effect of adsorbed phase density on the correction of methane excess adsorption to absolute adsorption in shale

2020 ◽  
pp. 127678
Author(s):  
Lei Chen ◽  
Keyu Liu ◽  
Shu Jiang ◽  
Hexin Huang ◽  
Jingqiang Tan ◽  
...  
Keyword(s):  
Excess Adsorption ◽  
Phase Density ◽  
Adsorbed Phase ◽  
Absolute Adsorption

On the Negative Excess Isotherms for Methane Adsorption at High Pressure: Modeling and Experiment

SPE Journal ◽  
2019 ◽  
Vol 24 (06) ◽  
pp. 2504-2525 ◽  
Author(s):  
Jing Li ◽  
Keliu Wu ◽  
Zhangxin Chen ◽  
Kun Wang ◽  
Jia Luo ◽  
...  
Keyword(s):  
High Pressure ◽  
Mass Balance ◽  
High Pressures ◽  
Pore Wall ◽  
Void Volume ◽  
Excess Adsorption ◽  
Experimental Conditions ◽  
Accessible Volume ◽  
Adsorbed Phase

Summary An excess adsorption amount obtained in experiments is always determined by mass balance with a void volume measured by helium (He) –expansion tests. However, He, with a small kinetic diameter, can penetrate into narrow pores in porous media that are inaccessible to adsorbate gases [e.g., methane (CH4)]. Thus, the actual accessible volume for a specific adsorbate is always overestimated by an He–based void volume; such overestimation directly leads to errors in the determination of excess isotherms in the laboratory, such as “negative isotherms” for gas adsorption at high pressures, which further affects an accurate description of total gas in place (GIP) for shale–gas reservoirs. In this work, the mass balance for determining the adsorbed amount is rewritten, and two particular concepts, an “apparent excess adsorption” and an “actual excess adsorption,” are considered. Apparent adsorption is directly determined by an He–based volume, corresponding to the traditional treatment in experimental conditions, whereas actual adsorption is determined by an adsorbate–accessible volume, where pore–wall potential is always nonpositive (i.e., an attractive molecule/pore–wall interaction). Results show the following: The apparent excess isotherm determined by the He–based volume gradually becomes negative at high pressures, but the actual one determined by the adsorbate–accessible volume always remains positive.The negative adsorption phenomenon in the apparent excess isotherm is a result of the overestimation in the adsorbate–accessible volume, and a larger overestimation leads to an earlier appearance of this negative adsorption.The positive amount in the actual excess isotherm indicates that the adsorbed phase is always denser than the bulk gas because of the molecule/pore–wall attraction aiding the compression of the adsorbed molecules. Practically, an overestimation in pore volume (PV) is only 3.74% for our studied sample, but it leads to an underestimation reaching up to 22.1% in the actual excess amount at geologic conditions (i.e., approximately 47 MPa and approximately 384 K). Such an overestimation in PV also underestimates the proportions of the adsorbed–gas amount to the free–gas amount and to the total GIP. Therefore, our present work underlines the importance of a void volume in the determination of adsorption isotherms; moreover, we establish a path for a more–accurate evaluation of gas storage in geologic shale reservoirs with high pressure.

scholarly journals Local Pressure of Supercritical Adsorbed Hydrogen in Nanopores

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2235 ◽  
Author(s):  
Jimmy Romanos ◽  
Sara Abou Dargham ◽  
Roy Roukos ◽  
Peter Pfeifer
Keyword(s):  
Binding Energy ◽  
Hydrogen Storage ◽  
Lattice Gas ◽  
Adsorbed Hydrogen ◽  
Local Pressure ◽  
Average Binding Energy ◽  
Adsorbed Phase ◽  
Absolute Adsorption ◽  
Sorbent Materials ◽  
Low Coverage

An overview is given of the development of sorbent materials for hydrogen storage. Understanding the surface properties of the adsorbed film is crucial to optimize hydrogen storage capacities. In this work, the lattice gas model (Ono-Kondo) is used to determine the properties of the adsorbed hydrogen film from a single supercritical hydrogen isotherm at 77 K. In addition, this method does not require a conversion between gravimetric excess adsorption and absolute adsorption. The overall average binding energy of hydrogen is 4.4 kJ/mol and the binding energy at low coverage is 9.2 kJ/mol. The hydrogen film density at saturation is 0.10 g/mL corresponding to a local pressure of 1500 bar in the adsorbed phase.

scholarly journals Experimental studies on equilibrium adsorption isosteres and determination of the thermodynamic quantities of polar media on alumina Al2O3

2017 ◽  
Vol 4 (1) ◽  
pp. 34-45 ◽  
Author(s):  
Albena Yonova
Keyword(s):  
Active Sites ◽  
Adsorption Process ◽  
Surface Acidity ◽  
Experimental Studies ◽  
Isosteric Heat ◽  
Heat Of Adsorption ◽  
Equilibrium Adsorption ◽  
Thermodynamic Quantities ◽  
Isosteric Heat Of Adsorption ◽  
Adsorption Isosteres

Abstract The present work is a revieif of theoretical and experimental study on the adsorption performance of the adsorbent Alumina (Al2O3) used in the adsorption system. An experimental investigation on the equilibrium adsorption isosteres at low pressure (< 1 atm) of working pairs Al2O3/H2O and Al2O3/C2H6O2 is carried out. The isovolume measurement method is adopted in the test setup to directly measure the saturated vapor pressures of working pairs at vapor-liquid equilibrium (dG=0 and dμi=0). Quantity adsorbed is determined from pressure, volume and temperature using gas law. The isosteric heat of adsorption is calculated from the slope of the plot of lnP versus 1/T different amounts of adsorbate onto adsorbent as follows: 0,01 vol% Al2O3/H2O; 0,03 vol% Al2O3/H2O; 0,1 vol% Al2O3/H2O; 0,01 vol% Al2O3/C2H6O2; 0,03 vol% Al2O3/C2H6O2; 0,1 vol% Al2O3/C2H6O2. This study shows that adsorption working pair Al2O3 C2H6O2 has better adsorption performances than those of the A2O3/H2O. Surface acidity! is a most important property! far both adsorption and catalysis and therefore is examined structure of active sites of alumina surface. Thermodynamic parameters such as isosteric heat of adsorption, isosteric enthalpy and entropy of adsorption are critical design variables in estimating the performance and predicting the mechanism of an adsorption process and are also one of the basic requirements for the characterization and optimization of an adsorption process

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