Methane Adsorption Research Articles

Investigations on Supercritical Methane Adsorption and Storage in the Lower Longmaxi Shale of Nanchuan Area, Southeast Sichuan Basin

A series of high-pressure methane adsorption measurements were performed at various temperatures on whole shale and kerogen samples collected from the Lower Longmaxi shale in the Nanchuan area, southeast Sichuan Basin, to investigate supercritical methane adsorption properties and evaluate in-place methane storage capacity as a function of burial depth. The results show that the supercritical Dubinin–Radushkevich (SDR) model fits the excess adsorption isotherms marginally better than the supercritical Langmuir model. However, the fitted adsorbed methane density of kerogens obtained from the SDR model may be greater than the liquid methane density at the atmospheric boiling point (0.423 g/cm3). The proposed multiple regression fitting carried out in this work illustrates that approximately 57.59% (34.51–85.45%) and 37.60% (10.74–59.52%) of the methane adsorption capacity at 333.15 K can be attributed to organic matter (OM) and clay minerals (CMs), respectively, for whole shales investigated. According to thermodynamic analyses, the significant contribution of OM to the methane adsorption capacity can be attributed to the stronger affinity between kerogens and methane molecules in contrast to that between CMs and whole shales. The methane storage capacity estimated as a function of burial depth showed that the adsorbed gas storage capacity declines with increasing burial depth between 2000 and 5000 m, while the free gas storage capacity shows the opposite trends. Gas accumulation pressure primarily exerts a significant effect on the free gas storage capacity rather than adsorbed gas storage capacity, and adsorbed gas storage capacity begins to exceed free gas storage capacity at shallow burial depths for normally pressured gas accumulations. Normally pressured shale gas accumulations at shallow burial depths, which are widely distributed in the residual syncline of the study area, should be given more attention due to their relatively low development costs and relatively high storage capacity for adsorbed gas.

EXPERIMENTAL STUDY ON PRESSURIZED ADSORPTION OF CARBON DIOXIDE AND METHANE FROM COMPLEX GAS MIXTURE OF BIOGAS IN ZEOLITE 13X

The majority of research on biogas adsorption does not use biogas gas but by mixing CO2 and CH4 gas or (binary gas) or with additional other gases, such as N2 or H2S. In real application, the adsorption method of biogas purification is conducted by using its complex mixture of biogas to obtain the purer methane gas. Accordingly, in case of biogas purification, adsorption capacity of the adsorbent towards both CH4 and CO2 gases from a complex gas mixture of biogas is indispensable to be studied thoroughly for improving the existing purification method, such as the pressure swing adsorption (PSA) method. The objective of this experiment is to compare the adsorption of carbon-dioxide and methane from complex mixture of biogas by Zeolite 13X under pressurized condition using experimental data. The experiment was conducted using a specially designed experimental setup, and the data obtained was evaluated and analyzed using the Freundlich Isotherm Model. The results show that experimental study on the adsorption of CO2 and CH4 gas from complex mixture of biogas in Zeolite 13X was distinguishable by their values of Freundlich coefficient. CO2 and CH4 gas adsorption in zeolite vary directly with pressure raised to the power 1/n, where its value for CH4 adsorption was higher than CO2. However, within the range of applicable pressure, the equilibrium adsorption of CO2 in Zeolite 13X was still higher than that of CH4.

Fractal Dimension and Nuclear Magnetic Resonance Characteristics of Surfactants for Coal Gas Desorption

In this paper, the fractal dimension of coal surfaces was calculated using the fractal theory, and the influence of different surfactants on the fractal dimension of coal surface was studied. Six kinds of sustainable and traditional surfactants used in coal gas desorption processes were compared and analyzed. We used mineral gas fertilizer coal from Huainan Liuzhuang, China, as the research object and studied sodium dodecyl benzene sulfonate (SDBS), cohol diethanolamide (CDEA), nonylphenol polyoxyethylene ether (NP-10), tea saponin, sucrose ester and rhamnolipid surfactants used to modify coal. The methane adsorption capacity of coal before and after surfactant modification was measured by low field nuclear magnetic resonance methane adsorption, and Langmuir volume and Langmuir pressure were obtained according to the Langmuir fitting equation. The results showed that from the perspective of fractal dimensions, the best surfactant in the context of sustainability (in order) is rhamnolipid, CDEA, tea saponin, sucrose ester. According to the two important parameters VL and PL in the Langmuir equation, the coal sample modified by sucrose ester had the strongest gas adsorption capacity. According to the numerical analysis of the surface fractal dimension DS of the coal modified by surfactants, the soluble organic matter in the raw coal samples dissolved, and the micropore morphology evolved to become mesoporous or macroporous, which is more favorable for desorption. The coal samples modified by rhamnolipid and SDBS had the strongest gas desorption ability.

A DFT study on the selective adsorption and separation of CO2/CH4 on the Mg-decorated 2-D covalent organic framework (COF-5)

Covalent organic frameworks (COFs), an emerging class of crystalline polymeric materials, have garnered growing interest due to their ideal chemical and thermal stability and ordered microporous architectures, which make them effective agents for selective CH4/CO2 separation. In this work, adsorption and separation of methane and carbon dioxide molecules on the two-dimensional pristine and Mg-decorated COF-5 (MgCOF-5) was investigated using density functional theory, employing B3LYP. Both CH4 and CO2 molecules were found to weakly adsorbed through van der Waals interactions to the bare sheet via physisorption, releasing energies ranging from -3.8 to -5.6 and -8.7 to 12.8, respectively and the sheet's electrical characteristics don't alter all that much. To overcome this weak selectivity/sensitivity, multiple Mg atoms were decorated atop aromatic rings of COF-5. Our results show that up to four CO2 molecules can be adsorbed on each Mg atom exothermically, whereas Ead of CH4 is near zero so the theoretical CO2 capacity of a full Mg-covered sheet is 0.51 gCO2/g MgCOF-5. Also, the decorating of Mg atoms on the surface of COF-5 induces certain changes in the sheet's electrical characteristics and that the sheet's Eg changes up to 80% following the adsorption of several CO2 molecules, making it a potential candidate for CO2 detection.

The Characteristic Development of Micropores in Deep Coal and Its Relationship with Adsorption Capacity on the Eastern Margin of the Ordos Basin, China

The accurate description of micro-/nanopores in deep coal reservoirs plays an important role in evaluating the reservoir properties and gas production capacity of coalbed methane (CBM). This work studies nine continuous samples of high–rank coal from the Daning–Jixian area of the Ordos Basin. Maceral analysis, proximate analysis, field emission scanning electron microscopy (FE-SEM), low-pressure CO2 adsorption (LPA), low-temperature N2 adsorption (LTA) and high-pressure methane adsorption (HPMA) experiments were conducted for each sample. The fractal dimension (D) of the LPA data was calculated by using the micropore fractal model. The characteristics of the deep coal reservoir pore structure, proximate analysis, relationship between maceral and fractal dimensions, and gas adsorption capacity of the micropores are discussed. The results showed that the combination of LPA with nonlocalized density functional theory (NLDFT) models and LTA with NLDFT models can more accurately determine the pore size distribution of the micropores. The pore volume (PV) and specific surface area (SSA) of the coals were distributed in the ranges of 0.059~0.086 cm3/g and 204.38~282.42 m2/g, respectively. Although the degree of micropore development varies greatly among different coal samples, the pore distribution characteristics are basically the same, and the PV and SSA are the most developed in the pore size range of 0.4–0.7 nm. Ash content (Ad) and mineral composition are two major factors affecting micropore structure, but they have different impacts on the fractal dimension. The higher the vitrinite content, moisture content (Mad) and Ad are, the larger the micropore fractal dimension (D) and the stronger the heterogeneity of the pore structure. Micropores account for 99% of the total SSA in coal, and most methane can be adsorbed in micropores. The fractal dimension of micropores can be used to evaluate the pore structure characteristics. The larger the fractal dimension, the smaller the micro-SSA and micro-PV of the coal sample. Fractal analysis is helpful to better understand the pore structure and adsorption capacity of CBM reservoirs.

Thermodynamic characteristics of methane adsorption on coals from China with selected metamorphism degrees: Considering the influence of temperature, moisture content, and in situ modification

A better understanding of the thermodynamic characteristics of methane (CH4) adsorption on coal surfaces is needed for the high-efficiency coalbed methane (CBM) preextraction or prevention of coal and gas outbursts. In this study, atomistic representations of selected coal samples with different degrees of metamorphism, such as long flame coal, coking coal, and anthracite coal obtained from China were created; CH4 adsorption isotherms considering the temperature, moisture content, and microwave in situ modification for CBM preextraction were simulated and analysed. The coal molecular structural results showed that as the degree of coal metamorphism increased from long flame coal to coking coal and anthracite coal, the functional groups in the molecular structure of the coal reduced, while the degree of graphite increased. In situ modification of coal facilitated this process. The saturation adsorption capacity of CH4 decreased and then increased with increasing coal metamorphism degree and decreased linearly with increasing temperature. When water molecules were present, the adsorbed CH4 showed different degrees of decreasing trends with increasing moisture content. The isosteric heat of CH4 adsorption followed the order of coking coal > anthracite coal > long flame coal. The isosteric heat gradually decreased with increasing methane adsorption, and the presence of water molecules had a limited effect on the isosteric heat. In situ modification disrupted the self-conjugated hydrogen bonds, reduced the oxygen-containing functional groups, and decomposed some associated minerals in the coal samples. After in situ modification, the amount of methane adsorption decreased due to a greater contribution from the functional group change than that from the pore volume change, and the modification effect was more evident for the low-rank coal samples than for the middle and high metamorphism degree coal samples. In situ modification applied in the coal seams could contributed to designs for CBM exploration, and the results of this experiment and simulation could provide a novel theoretical basis for in situ modification technology.

Promotion effect of different lanthanide doping on Co/Al2O3 catalyst for dry reforming of methane

In this paper, a series of cobalt catalysts modified by different lanthanide metals were synthesized via co-impregnation method using inexpensive industrial-grade alumina as a support for dry reforming of methane. The effect of lanthanide metals as accelerators of cobalt-based catalysts on catalytic performance and anti-coking properties was mainly investigated. The textural relationships between the catalytic performance and physicochemical properties of cobalt-based catalysts doped with different lanthanide metals were further investigated. Different characterization techniques demonstrate the positive effect of lanthanide metals on the physicochemical properties of catalysts. The results show that the electron transfer between cobalt species and lanthanide metal oxides is significantly enhanced due to the introduction of lanthanide elements. The process generates more active sites, which is favorable for the adsorption and activation of methane. In addition, the abundant medium basic sites and oxygen vacancies on the surface of cobalt-based catalysts with the effect of lanthanides promoted the adsorption and activation of carbon dioxide and the gasification of carbon accumulation, which greatly improved the anti-carbon accumulation performance of the catalysts. Therefore, the prepared cobalt-lanthanum-based catalysts showed the best catalytic effect and have great potential for application.

Efficient adsorption of carbon dioxide and methane on activated carbon prepared from glycerol with potassium acetate

In the context of global warming and the energy crisis, emissions to the atmosphere of greenhouse gases such as carbon dioxide (CO2) and methane (CH4) should be reduced, and biomethane from landfill biogas should be recycled. For this, there is a need for affordable technologies to capture carbon dioxide, such as adsorption of biogas on activated carbon produced from industrial wastes. Here we converted glycerol, a largely available by-product from biodiesel production, into activated carbon with the first use of potassium acetate as an activating agent. We studied adsorption of CO2 and CH4 on activated carbon. The results show that activated carbon adsorb CO2 up to 20% activated carbon weight at 250 kPa, and 9% at atmospheric pressure. This is explained by high specific surface areas up to 1115 m2g−1. Moreover, selectivity values up to 10.6 are observed for the separation of CO2/CH4. We also found that the equivalent CO2 emissions from activated carbon synthesis are easily neutralized by their use, even in a small biogas production unit.

Obtaining carbon materials for the adsorption of greenhouse gases

Coffee-based carbon adsorbents are promising adsorbents for greenhouse gases, in particular methane, due to the possibility of creating a precision porous structure. Microporous and micromesoporous samples with a narrow pore size distribution up to 7 nm have been obtained. A study was made of methane adsorption in carbon adsorbents obtained by chemical activation at different ratios of KOH to coffee precursor. The highest adsorption of the greenhouse gas methane, equal to ~18 mmol/g at 100 bar and a temperature of 298 K, is achieved on a sample with a ratio of activating agent to carbonized precursor of 6:1 (6AKP)

Effect of Different Placement Sequences of Water on the Methane Adsorption Properties of Coal.

After the coal seam is injected with water, the moisture content in the coal body increases, which affects the output capacity of coalbed methane (CBM). In order to improve the effect of CBM mining, the classical anthracite molecular model has been selected. To analyze the influence of different placement orders of water and methane on the characteristics of coal-adsorbing methane from the micro point of view, a molecular simulation method is used for comprehensive consideration in the study. The results show that H2O does not change the mechanism of CH4 adsorption by anthracite, but it inhibits the adsorption of methane by anthracite. When water enters the system afterward, there arises an equilibrium pressure point where water plays the most significant role in inhibiting methane adsorption by anthracite coals, which increases with increasing moisture content. When water enters the system first, no equilibrium pressure point occurs. The excess adsorption of methane by anthracite when water enters second is higher. The reason is that H2O can replace CH4 at the higher energy adsorption sites of the anthracite structure, while CH4 can only be adsorbed at the lower energy sites, and some of CH4 is not adsorbed. For the coal samples with a low-moisture content system, the equivalent heat of adsorption of CH4 increases first rapidly and then slowly with the increase of pressure. However, it decreases with pressure in the high-moisture content system. The variation of the equivalent heat of adsorption further explains the variation of the magnitude of methane adsorption under different conditions.

Grand canonical Monte Carlo simulation of the adsorption and separation of carbon dioxide and methane using functionalized Mg-MOF-74

Grand canonical Monte Carlo (GCMC) simulations were used to analyse the effect of -O-Li, -NH2, -SH, -F, -COOH, and -NO2 functional groups on the adsorption and separation of pure CO2 and a mixture of CO2 and CH4. The metal–organic framework (MOF) skeleton was structurally optimized using the Forcite and Dmol 3 modules. First, the GCMC method was employed to simulate the adsorption of pure CO2 by functionalized Mg-MOF-74 at 298 K and 10–3000 kPa. The results illustrated that -O-Li, -NH2, and -SH groups increased the CO2 adsorption below 101 kPa and followed the order Li-O-Mg-MOF-74 > NH2-Mg-MOF-74 > SH-Mg-MOF-74. When the pressure was >101 kPa, the adsorption capacity of Mg-MOF-74 was higher than that of functionalized Mg-MOF-74. Then, the adsorption capacity and selectivity of functionalized Mg-MOF-74 in the CO2/CH4 mixture were investigated at 298 K and 10–3000 kPa. The results showed that the introduction of -O-Li, -NH2, and -SH groups increased the CO2 selectivity of Mg-MOF-74 within the range of 10–1440 kPa and followed the order Li-O-Mg-MOF-74 > NH2-Mg-MOF-74 > SH-Mg-MOF-74.

Molecular Dynamics Simulation of Methane Adsorption and Diffusion: A Case Study of Low-Rank Coal in Fukang Area, Southern Junggar Basin

Adsorption and diffusion are the key factors affecting coalbed methane (CBM) accumulation, resource assessment and production prediction. To study the adsorption and diffusion mechanism of Fukang low-rank coal at the microscopic level, samples of Fukang low-rank coal were collected, and the elemental composition, carbon type distribution and functional group type of the Fukang low-rank coal structure were determined by elemental analysis (Ea), Fourier-transform interferometric radiometer (FTIR), X-ray photoelectron spectroscopy (XPS) and 13C nuclear magnetic resonance (13C NMR) experiments to construct a 2D molecular structure of the coal and a 3D macromolecular structure model. The adsorption and diffusion characteristics of methane were researched by giant regular Monte Carlo (GCMC) and molecular dynamics (MD) simulation methods. The results showed that the excess adsorption amount of methane increased and then decreased with the increase in pressure. The diffusion of methane showed two stages with increasing pressure: a sharp decrease in the diffusion coefficient from 0.5 to 5.0 MPa and a slow decrease in the diffusion coefficient from 5.0 to 15.0 MPa. The lower the pressure, the larger the effective radius of the CH4 and C atoms, and the higher the temperature, the more pronounced the diffusion and the larger the effective radius.

Microporous MOF-5@AC and Cu-BDC@AC Composite Materials for Methane Storage in ANG Technology

Novel composites (MOF-5 and Cu-BDC) based on economically activated carbon have been developed to investigate methane adsorption capacity for ANG applications. The composites were synthesized by adding MOFs precursor in two different weight percent (10% and 40%) to commercial activated carbon under solvothermal conditions (110-120°C). The synthesized adsorbents were characterized by FT-IR, XRD, SEM, EDS, and BET techniques to gather information about their crystallinity, morphology, and specific surface area. A methane uptake measurement system based on the volumetric method was made to obtain methane adsorption capacity on each composite. Then, the amount of methane adsorption for each one was calculated, and the experimental data were compared with different isotherm adsorption models appropriate for gas adsorption, including Langmuir, Freundlich, and Dubinin-Radushkevich. This comparison showed that the best fitting belonged to the Langmuir isotherm model. Also, stability and kinetic studies were done for two MOF-540% @AC and Cu-BDC40% @AC composites. In the kinetics study, experimental data were compared and analyzed in terms of pseudo-first order, pseudo-second order, and intraparticle diffusion models. The kinetics study showed that methane adsorption happens very fast on the synthesized adsorbents. The amount of methane adsorption at 35 bar and room temperature for pure activated carbon was specified as 4.32 mmol/g. The 10% and 40% of Cu-BDC with activated carbon are 5.59 mmol/g and 6.85 mmol/g, respectively. The capacity of MOF-510% @AC and MOF-540% @AC composites were obtained at 5.9 mmol/g and 7.3 mmol/g, respectively. Increasing methane uptake (70%) was obtained by adding 40 wt.% of MOF-5 to commercial activated carbon.

Perspectives of Gas Adsorption and Storage in Kerogens and Shales

Shale gas from unconventional resources will contribute to meeting the energy demand during the transition to a net-zero carbon economy. In this minireview, the current status of understanding methane adsorption on kerogens and shales is discussed in relation to methane storage capacity. Standard subcritical adsorption studies provide characterization data (micropore volumes, total pore volumes, surface areas, and pore size distributions) for the porous structures of shales and kerogens. However, supercritical methane adsorption measurements under simulated geological conditions are necessary to assess realistic methane adsorption storage capacities. Supercritical methane adsorption on shale and shale components (kerogens and clays) under high pressure and temperature conditions that simulated geological conditions is compared. Kerogen structural characteristics are discussed in relation to supercritical methane isotherms and isobars. The contribution of adsorbed methane gas relative to “free” or compressed gas to the total gas stored in shale is considered. The importance of kerogens in both storage of the adsorbed phase and as the source of methane is highlighted, and the areas where knowledge and understanding are deficient are identified, in particular, the relationship of kerogen type and maturity with supercritical methane adsorption under simulated geological conditions. The competitive adsorption of water on methane capacity is also an area where more detailed studies are necessary. These are challenges to address gaps in the current knowledge and understanding, which require future research.

Adsorption of methane onto mudstones under supercritical conditions: Mechanisms, physical properties and thermodynamic parameters

Since the mechanisms of methane-mudstone interactions are important for estimating shale gas reserves, methane adsorption under supercritical conditions of 30 MPa pressure and 303.15, 333.15, 363.15 K temperatures was studied to measure the excess methane adsorption in two mudstone samples from Yanchang Formation, Ordos Basin. Excess adsorption features inflection points where the amount of adsorbed gas changes from increasing to decreasing concentrations. Three methods (fixed, slope, and freely fitted density) were applied to calculate the adsorbed-phase density ( ρ ad ), which was then used to fit the measured excess adsorption. Two criteria, the goodness-of-fit and whether the fitting can obtain reasonable absolute adsorption, were applied to determine the most accurate model. Results indicated that the supercritical Dubinin-Radushkevich ( SDR ) model with freely fitted ρ ad was the most reasonable model. The volume of adsorbed methane at 363.15 K is close to the micropore ( d < 2 nm) volume of the corresponding mudstone. Considering the actual geological conditions, the adsorbed gas should be predominantly stored in micropores. Thermodynamic parameters reveal that the methane adsorption on mudstone is a physisorption process that is jointly controlled by the heterogeneity of, and interaction forces between the methane molecule and, the rock surface.

Adsorption of Methane onto Microporous Activated Carbon in a Volumetric Storage System

Adsorption of Methane onto Microporous Activated Carbon in a Volumetric Storage System

Interaction between slick water and gas shale and its impact on methane desorption: a case study of Longmaxi member shale formation in the northeast of Chongqing, China

Well shut-in time significantly affects the production performance of shale-gas-well. However, interaction between shale powders and fracking fluid on methane desorption has been rarely reported. In this work, based on the volume method following Boyle’s law under higher pressure, the experimental setup was conducted to obtain the adsorption and desorption isotherms to explore the effect of different shut-in times (including 0, 1, 3, 5, 10, and 30 days) on methane desorption. We fitted the methane adsorption and desorption isotherms by the Freundlich model, and the results show that the interaction can obviously impact desorption isotherm, desorption efficiency and adsorbed phase methane content. The inflection points of the constant k and n reduction curves, desorption efficiency reduction curve and adsorbed gas content reduction curve all occur when the interaction time is to 10 days, indicating that 10 days is the best value for the interaction between slick water and gas shale. The results provide an essential supplement that can help elucidate the impact of shut-in time on gas-shale-well production performance experimentally.

Molecular Simulation Study on Methane Adsorption in Amorphous Shale Structure

Gas adsorption in the porous shale matrix is critical for gas-in-place (GIP) evaluation and exploration. Adsorption investigations benefit significantly from the use of molecular simulation. However, modelling adsorption in a realistic shale topology remains a constraint, and there is a need to study the adsorption behaviour using molecular models containing both organic and inorganic nanopores. Most simulations use a single component, either kerogen (organic composition) and quartz or clay (inorganic composition), to represent the shale surface. In this work, the molecular dynamic (MD) and grand conical Monte Carlo (GCMC) simulations were utilised to provide insight into methane adsorption behaviour. Amorphous shale structures composed of kerogen and quartz were constructed. The kerogen content was varied to replicate the shale with 2 wt.% and 5 wt.% Total Organic Carbon (TOC) content with 5 nm pore size. The simulated densities of the shale structures showed consistent values with actual shale from the Montney, Antrim, and Eagle Ford formations, with 2.52 g/cm3 and 2.44 g/cm3, respectively. The Average Error Analysis (ARE) was used to assess the applicability of the proposed amorphous shale model to replicate the laboratory adsorption isotherm measurements of actual shale. The ARE function showed that the amorphous shale shows good agreement with experimental measurements of all Barnett shale samples with an average of 5.0% error and slightly higher for the Haynesville samples with 8.0% error. The differences between the experimental adsorption measurement and simulation resulted from the amorphous packing, and actual shales have more minerals than the simulated model.

Porosity Engineering of Hyper-Cross-Linked Polymers Based on Fine-Tuned Rigidity in Building Blocks and High-Pressure Methane Storage Applications

Exploring the effect of the structural rigidity of selected building blocks on the resultant porosity of the desired polymers is crucial for the bottom-up design of hyper-cross-linked polymers. Herein, several novel polymers, based on two series building blocks with stepwise fine-tuned rigidity, were constructed by the low-cost solvent knitting method. Significantly, the porosity of these polymers is highly consistent with the structural rigidity of the basic building blocks, dramatically enhanced from a poor porous state to a micropore-rich framework, with an increase in BET surface areas from 248 to 1276 m2 g–1 for the HCPs based on monomers containing double benzene rings and from 37 to 2368 m2 g–1 for tetraphenyl-like monomer-based HCPs. The best performances, especially concerning methane adsorption capacity, are reached for the rigid 9,9′-spirobifluorene (SBF)-based HCP-SBF framework and flexible tetraphenylmethane (TPM)-based HCP-TPM, showing a 5–100 bar working capacity of 206 cm3 (STP: 273 K, 1 atm) cm–3 (0.296 g g–1) and 199 cm3 (STP) cm–3 (0.112 g g–1) at 273 K, respectively. The bottom-up-designed HCPs with engineered porosity are expected to become novel candidates for onboard methane storage.

Prediction of methane adsorption isotherms in metal–organic frameworks by neural network synergistic with classical density functional theory

A rapid method for predicting the unary gas adsorption isotherms of metal–organic frameworks (MOFs) is of great significance for the engineering design of both gas storage and gas separation. Here, we proposed a framework based on neural network (NN) synergistic with classical density functional theory (cDFT) that can be used to accurately predict methane adsorption isotherms of MOFs on a large scale. First, 17,644 candidate MOFs with orthorhombic unit cells were chosen from 324,426 hypothetical structures, and their methane adsorption isotherms were calculated by cDFT. Furthermore, we obtained the isotherm parameters for each MOF by fitting the isotherms with Langmuir equation. Second, the geometrical and chemical properties of all candidates were then calculated to construct the fingerprint descriptors of MOFs. These descriptors and isotherm parameters were used as inputs and targets, respectively, to train a deep neural network model. The trained neural network model can rapidly predict the isotherm parameters and further calculate the methane adsorption isotherms of the MOFs. During the model training, we proposed a physical constraint method embedded in the loss function to make the model better approximate the target isotherm parameters. Finally, we discussed several strategies to improve the prediction accuracy of the neural network.