A comparative evaluation of coal specific surface area by CO2 and N2 adsorption and its influence on CH4 adsorption capacity at different pore sizes

Zhao, Jiaxin; Xu, Hao; Tang, Dazhen; Mathews, Jonathan P.; Tao, Shu

doi:10.1016/j.fuel.2016.06.076

Cited by 219 publications

(127 citation statements)

References 69 publications

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“…At a P/P 0 of 0.99, the total pore volume of the studied sample was calculated by converting the total volume of the adsorbed gas into the volume of a liquid. At P/P 0 values of 0.05-0.35, the measured adsorption volumes were in good agreement with Brunauer-Emmett-Teller (BET) equation [24], which was utilized for the determination of specific surface areas [25]. Micropore volumes and external surface areas (including those of mesopores and macropores) were estimated from the corresponding t-plots [26], and the specific surface areas of micropores were obtained by subtracting the related external surface areas.…”

Section: Low-pressure Nitrogen Gas Adsorption Studiesmentioning

confidence: 59%

Experimental Study of CO2-Water-Mineral Interactions and Their Influence on the Permeability of Coking Coal and Implications for CO2-ECBM

Guo

Wang

et al. 2018

Minerals

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Abstract:Coal permeability is one of the most critical parameters affecting gas flow behavior during coalbed methane (CBM) production. However, little research has been conducted on how permeability evolves after CO 2 injection in coking coal. Hence, examining possible chemical interactions between coal minerals, water, and injected CO 2 can be very helpful to better characterize coking coal. In this study, coking coal specimens obtained from the Malan and Tunlan mines located in the Gujiao block of the Qinshui basin were treated with water and CO 2 to achieve a better understanding of their dissolution kinetics, pore structure, and permeability. It was found that the relative carbonate mineral content decreases with time, while the relative clay mineral content increases after the reaction with CO 2 and water. Scanning electron microscopy (SEM) confirmed these mineral alteration phenomena. Carbonate minerals (calcite, dolomite) dissolve faster than clay minerals (montmorillonite, illite and kaolinite). In particular, the dissolution rates of Ca 2+ in carbonate minerals increases with decreasing temperature (25-45 • C) and pH (4.3-6.3), and the dissolution rate of Ca 2+ ions in the calcite reaction solution is higher than that in the dolomite solution. In addition, the results of low-pressure nitrogen adsorption analysis showed that CO 2 injection can enlarge smaller size pores into larger size pores and change the overall pore size distribution. Therefore, CO 2 injection can increase the porosity of coal beds and ultimately their permeability, which in turn facilitates CBM production.

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Section: Low-pressure Nitrogen Gas Adsorption Studiesmentioning

confidence: 59%

Experimental Study of CO2-Water-Mineral Interactions and Their Influence on the Permeability of Coking Coal and Implications for CO2-ECBM

Guo

Wang

et al. 2018

Minerals

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“…Based on the IUPAC and Hodot pore classification, the pores can be divided by diameter into supermicropores (<2 nm), micropores (2–10 nm), transition pores (10–100 nm), and mesopores (100–1000 nm) . Pore structure parameters obtained from CO 2 adsorption and NMRC, respectively, are shown in Tables and .…”

Section: Resultsmentioning

confidence: 99%

“…D‐R model: in a single adsorbate system, taking characteristic adsorption energy as E, the adsorbed volume by adsorbate is derived as follows:…”

Section: Methodsmentioning

confidence: 99%

Methane adsorption constrained by pore structure in high‐rank coals using FESEM, CO₂ adsorption, and NMRC techniques

Liu

Cai

Zhou

2019

Energy Science & Engineering

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To evaluate the impacts of nanopores of high‐rank coals on coalbed methane adsorption and storage, 12 anthracite and semianthracite coal samples from Yangquan and Shouyang blocks in the Qinshui Basin were investigated. Field emission scanning electron microscopy (FESEM) and CO2 adsorption combined with nuclear magnetic resonance cryoporometry (NMRC) experiments were used to evaluate the pore structure with diameters ranging from 0 to 500 nm and their impact on adsorption capacity based on qualitative and quantitative analysis. The results show that a coalification jump from semianthracite to anthracite occurred in the study area due to the magmatic intrusion. In the process, the volume of supermicropores and micropores largely increased while the volume of transition pores and mesopores decreased slightly. Additionally, vitrinite gets purified and enriched during the rapid maturation of coal reservoir, which is beneficial to the microporous structure development. The pore size distribution (PSD) of anthracite is mainly divided into two types, which are in serrated and decreasing forms, respectively. Higher vitrinite content can promote the formation of decreasing type (type II), which corresponds to a lower degree of complexity. The fractal dimensions indicate that the heterogeneity of coal samples is increasing with the decrease in pore size. Accordingly, the increase in pore heterogeneity corresponds to the lower adsorption capacity. The main pore sizes that contribute to CBM adsorption include two parts: 25‐30 nm and 50‐60 nm. For the supermicropores with large specific surface areas, the pore system detected by CO2 molecules is not conducive to CBM adsorption, while the increase in pore volume can improve the adsorption rate and capacity of CO2. These findings are vital for a precisely understanding of nanoscale pores as well as future CBM exploitation.

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“…36 It was reported that CO 2 permeance through the silica membrane was improved as the temperature reduced, while for N 2 and CH 4 permeances were enhanced very slightly as CO 2 has higher adsorption capability on the silica surface compared with N 2 or CH 4 . 37,38 Porous silica membranes in dry environments are relatively stable, and in moist conditions, silica membrane is considered stable on a silica-zirconia sub-layer. 39 Another study found that by increasing the temperature, the separation factors were decreased, which was due to the fewer porous penetrants having higher activation energy.…”

Section: Introductionmentioning

confidence: 99%

High‐temperature CO₂ removal from CH₄ using silica membrane: experimental and neural network modeling

et al. 2019

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Inorganic membranes can operate under harsh conditions. However, successful synthesis of inorganic membranes is still challenging, and its performance depends on many factors. This work reports the effect of dip‐coating duration, inlet pressure, and inlet flow rate on the flux, permeability, and selectivity of silica membranes. A silica membrane was prepared by the deposition of silica sol onto porous alumina support. The permeability test was conducted at 100 °C using a single gas of CO2 and CH4. The highest flux was observed at the maximum inlet pressure and inlet flow rate for the membrane prepared at the minimum dip‐coating duration. The neural network modeling of the membrane predicted permeabilities showed a considerably high validity regression (R ≈ 0.99) of the predicted data linked to the experimental sets. The separation factor (α) was the highest at the maximum dip‐coating duration. The synthesized silica membrane has potential for CO2/CH4 separation under harsh operating conditions. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

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A comparative evaluation of coal specific surface area by CO2 and N2 adsorption and its influence on CH4 adsorption capacity at different pore sizes

Cited by 219 publications

References 69 publications

Experimental Study of CO2-Water-Mineral Interactions and Their Influence on the Permeability of Coking Coal and Implications for CO2-ECBM

Experimental Study of CO2-Water-Mineral Interactions and Their Influence on the Permeability of Coking Coal and Implications for CO2-ECBM

Methane adsorption constrained by pore structure in high‐rank coals using FESEM, CO₂ adsorption, and NMRC techniques

High‐temperature CO₂ removal from CH₄ using silica membrane: experimental and neural network modeling

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A comparative evaluation of coal specific surface area by CO2 and N2 adsorption and its influence on CH4 adsorption capacity at different pore sizes

Cited by 219 publications

References 69 publications

Experimental Study of CO2-Water-Mineral Interactions and Their Influence on the Permeability of Coking Coal and Implications for CO2-ECBM

Experimental Study of CO2-Water-Mineral Interactions and Their Influence on the Permeability of Coking Coal and Implications for CO2-ECBM

Methane adsorption constrained by pore structure in high‐rank coals using FESEM, CO2 adsorption, and NMRC techniques

High‐temperature CO2 removal from CH4 using silica membrane: experimental and neural network modeling

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Methane adsorption constrained by pore structure in high‐rank coals using FESEM, CO₂ adsorption, and NMRC techniques

High‐temperature CO₂ removal from CH₄ using silica membrane: experimental and neural network modeling