CH4 Adsorption Capacity Research Articles

The structural versus textural control on the methane sorption capacity of clay minerals

In the natural, high-pressure environments of sediments and sedimentary rocks, clay minerals, along with organic matter, contribute to a large portion of the available surface area and microporosity in which methane (CH4) can be adsorbed. However, most of the questions concerning the location of adsorption sites, e.g. interlayer accessibility for CH4, remain unknown. Here, we have separately investigated the textural and structural control on CH4 high-pressure adsorption on pure clay minerals by combining high- and low-pressure gas adsorption techniques, transmission electron microscopy, and thermogravimetric and X-ray diffraction analyses on various cationic forms of montmorillonite, beidellite, and two illites, with different contents of adsorbed water. The results show that CH4 adsorption capacity is controlled by N2-accesible micropore volume. CH4 adsorption sites are located mainly outside of the interlayer galleries unless they are open wide enough (e.g. pillared by organic cations or incompletely dried divalent cations). However, the structure-independent factors like the crystallite planar dimensions and the way that they assemble are the main control on CH4 adsorption capacity. This might be the reason for the inconsistencies in CH4 adsorption reported for clay minerals in the literature. CO2 adsorption measurements, assumed to provide a good proxy for the estimation of CH4 adsorption capacity in natural mudrocks, may overestimate the CH4 adsorption potential in geomaterials containing a significant amount of exchangeable divalent cations due to higher penetrability of CO2 than CH4 in the interlayers of expandable clay minerals.

High C2 hydrocarbons capture and selective C2/C1 separation in A Tb(III)-organic framework

By employing a tripod rigid ligand with six coordination sites, 4,4’,4”-(pyridine-2,4,6-triyl)tribenzoic acid (H6PTA), a microporous terbium(III)-organic framework, [(Me)2NH2]1.5[Tb1.5(PTA)]·9H2O (1) has been synthesized under the solvothermal condition. Structural analysis demonstrates that 1 is a 3D anionic framework based on two kinds of Tb(III) units, which presents a rare framework constructed from ternary secondary building units (SBUs) and shows a new (4,5,6)-connected topology. Gas adsorption measurements reveal that 1 exhibits the significant C2H2 and C2H4 adsorption capacity but negligible uptake of CH4, which makes 1 as a promising adsorbent for C2H2/CH4 and C2H4/CH4 separation.

Measurement and Modeling of the Adsorption/Desorption Behavior of Light Hydrocarbons on Shale

Understanding the adsorption/desorption behavior, as the primary phenomenon in shale reservoirs, is crucial for shale resource production, which is necessary in approximating the gas-in-place estimation. CH4 and C2H6 in shale gas are two common dominating gas components. We first measure the adsorption/desorption isotherms of CH4 and C2H6 at temperatures of 313.15–333.15 K. The maximum operating pressures for CH4 and C2H6 are 50 and 30 bar, respectively. Relationships of the physical properties of core samples with adsorption capacities of CH4 and C2H6 are analyzed. In addition, the accuracy of four popular adsorption models, i.e., Langmuir, Brunauer–Emmett–Teller (BET), Dubinin–Astakhov (D–A), and Dubinin–Radushkevich (D–R), is quantitatively evaluated by matching with the measured data. Test results show that C2H6 shows more obvious adsorption/desorption hysteresis compared to CH4. In addition, the measured adsorption capacity of C2H6 is much stronger than that of CH4. This indicates that C2H6 exhibits more affinity on the organic-rich shale. It is observed that the total organic carbon (TOC) content correlates linearly with the gas adsorption capacities. In comparison to the TOC content, the BET surface area shows less effect on adsorption capacity. In addition, we found that the D–A model shows the most accuracy among the four popular adsorption models in describing CH4 and C2H6 adsorption. However, Langmuir adsorption is not suitable in reproducing the adsorption of heavier hydrocarbons, i.e., C2H6.

Molecular simulation of gas adsorption characteristics and diffusion in micropores of lignite

In order to study the adsorption characteristics of single component, binary and ternary mixed gases in lignite, the microscopic processes of CO2 and N2 injection for CH4 desorption was revealed. In this paper, the molecular models of Shendong lignite (C197H146N2O31) at 273.15, 283.15, 293.15 and 313.15 K were established. Based on the theory of molecular mechanics and dynamics, the adsorption characteristics of lignite were simulated by means of grand canonical Monte Carlo and molecular dynamic methods. The adsorption capacities and configurations of CH4, CO2, N2 and H2O in lignite were obtained, and their corresponding adsorption isosteric heats and diffusion coefficients were calculated. The results show that the adsorption isotherm of a single component gas corresponds well to the Langmuir equation. For multi-component gas adsorption, the competitive adsorption advantage of CO2 is obvious, and adsorption capacity of CO2 is minimally affected by other factors. However, the adsorption capacities of CH4 and N2 respectively are seriously affected by their molar ratios in the mixtures and the moisture content of lignite. The adsorption isosteric heats of CH4, CO2, H2O and N2 decrease with increasing temperature, following the order of H2O > CO2 > CH4 > N2.

The Effect of Mg, Fe(II), and Al Doping on CH4: Adsorption and Diffusion on the Surface of Na-Kaolinite (001) by Molecular Simulations.

Because kaolinite includes a large range of defect elements, the effects of Mg, Fe(II), and Al doping on the CH4 adsorption and diffusion on the surface of Na-kaolinite (001) were investigated by molecular simulations. The simulation results illustrate that ion doping can significantly reduce the amount of CH4 adsorbed by kaolinite, but the type of doped ions has little effect on the amount of adsorption. The specific surface area of kaolinite and the interaction energy between CH4 and the kaolinite’s surface are two key factors that can determine CH4 adsorption capacity. The first peak value of the radial distribution functions (RDFs) between CH4 and the pure kaolinite is larger than that between Mg-, Fe(II)-, and Al-doped kaolinite, which indicates that ion doping can reduce the strength of the interactions between CH4 and the kaolinite’s surface. Besides hydrogen and oxygen atoms, interlayer sodium ions are also strong adsorption sites for CH4 and lead to a weakened interaction between CH4 and the kaolinite’s surface, as well as a decrease in CH4 adsorption. Contrary to the adsorption results, ion doping facilitates the diffusion of CH4, which is beneficial for actual shale gas extraction.

Superior performance of modified pitch-based adsorbents for cyclic methane storage

As an alternative approach for natural gas storage at relatively low pressure and ambient temperature, Adsorbed Natural Gas (ANG) has aroused tremendous interest in recent years. However, still, there is a great challenge to find a suitable adsorbent with a high capacity for gas storage. Here in this study, we reported how to prepare an activated carbon with high methane (CH4) uptake using a low cost and abundant precursor such as coal tar pitch (CTP). The effect of two-stage treatment (acidification and carbonization) of CTP on its surface and structural properties, as well as methane adsorption capacity of the final activated carbon products, were explored. Experimental results revealed that the carbon yield of the precursor, porous textural properties, and CH4 adsorption capacity of the adsorbent were efficiently improved via optimization of the pre-treatment conditions. The AC600CTP adsorbent, as an optimum sample, shows the largest capacity of CH4 adsorption on a volumetric basis (184 V(STP)/V) at 25 °C and 40 bar. Based on the authors’ knowledge, the volumetric CH4 capacity of AC600CTP is comparable with the high values reported in the literature among some different classes of the adsorbent. Finally, multiple cyclic operations on AC600CTP at 25 °C and pressure of 40 bar showed the excellent performance of the adsorbent over the dynamic cycle test.

Adsorption equilibrium isotherms and thermodynamic analysis of CH4, CO2, CO, N2 and H2 on NaY Zeolite

Adsorption capacities of CH4, CO2, CO, N2 and H2 on NaY zeolite were measured at 298 K, 318 K, 338 K and 358 K with pressure ranged from 0 to 10 bar. The order of adsorption capacity was CO2 ≫ CH4 > CO > N2 ≫ H2. The experiment data were fitted by the Langmuir, Toth and Sips equations. The fitting relativity of above models were also compared. Moreover, the isosteric heat of adsorption were calculated by the Clausius–Clapeyron equation, the results showed that the adsorption heat of CO2 is the largest (41.89764 kJ/mol with adsorption loading of 5.8 mmol/g) and that of H2 is the smallest. Finally, the selectivity of binary mixture was predicted according to the IAS theory.

An experimental study on the effect of the acid and heavy metal treatments on the adsorption of CH4 by sepiolite.

This study investigated methane (CH4) adsorption by natural sepiolite-obtained from Eskisehir in Turkey-and its Ag-, Cu-, Fe-, and H-exchanged forms by using a volumetric gas adsorption method. Sepiolite was modified with 1 M AgNO3, 1 M Cu(NO3)2∙3H2O, 1 M Fe(NO3)3∙9H2O, and 1 M HCl solutions at 80°C for 6h, respectively. The natural and modified sepiolite samples were characterized by using X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TG-DTG), differential thermal analysis (DTA), and the nitrogen adsorption method. Quantitative XRD analysis showed that the sample consisted primarily of sepiolite clay mineral and dolomite as an impurity in small amounts. It was found that acid and heavy metal treatments caused apparent changes in the structure and microporosity of the sepiolite samples. CH4 adsorption isotherms of clay samples were examined at temperatures of 0°C and 25°C and pressures up to 100kPa. It was determined that the CH4 adsorption capacities of sepiolite samples increased at both temperatures according to the following sequence: CuS < AgS < HS < S < FeS. CH4 adsorption values of sepiolite samples varied between 0.084mmol/g and 0.299mmol/g. It was observed that the CH4 adsorption capacities of heavy metal cation-exchange clay samples were related to the surface area.

Methane adsorption by porous graphene derived from rice husk ashes under various stabilization temperatures

The present work focused on the determination of texture, morphology, crystallinity, and gas adsorption characteristics of porous graphene prepared from rice husks ashes at different stabilization temperature. The stabilization temperature applied in this work is 100 °C, 200 °C, 300 °C, and 400 °C to convert rice husk into rice husk ashes (RHA). Chemical activation was adopted at temperature 800 °C using potassium hydroxide (KOH) as dehydrating agent at (1:5) impregnation ratio to convert RHA into rice husk ashes-derived graphene (GRHA). The resultant GRHA were characterized in terms of their morphological changes, SSA, crystallinity, and functional group with TEM, the BET method, Raman spectroscopy, and XRD analysis, respectively. Results from this study showed that the SSA of the GRHA at stabilization temperature 200 °C (1556.3 m2/g) is the highest compared to the other stabilization temperature. Raman spectroscopy analysis revealed that all GRHA samples possess D, G, and 2D bands, which confirm the successful synthesis of the rice husks into porous graphene-like materials, known as GRHA. Appearance of diffraction peak in XRD at 44.7° indicating the graphitic structure of all the GRHA samples. Meanwhile, the TEM images of GRHA200 exhibited wrinkled structures due to the intercalation of oxygen and a few layers of graphene flakes. These wrinkled structures and graphene layers are the other factors that lead to the highest SSA of GRHA200 compared to other prepared samples GRHA. Furthermore, the adsorption capacity of CH4 for GRHA200 is up to 43 cm3/g at 35 bar and ambient temperature, almost double the adsorption capacity performance of GRHA400 at the same operating pressure and temperature.

Sustainable Biomass Glucose-Derived Porous Carbon Spheres with High Nitrogen Doping: As a Promising Adsorbent for CO2/CH4/N2 Adsorptive Separation.

Separation of CO2/CH4/N2 is significantly important from the view of environmental protection and energy utilization. In this work, we reported nitrogen (N)-doped porous carbon spheres prepared from sustainable biomass glucose via hydrothermal carbonization, CO2 activation, and urea treatment. The optimal carbon sample exhibited a high CO2 and CH4 capacity, as well as a low N2 uptake, under ambient conditions. The excellent selectivities toward CO2/N2, CO2/CH4, and CH4/N2 binary mixtures were predicted by ideal adsorbed solution theory (IAST) via correlating pure component adsorption isotherms with the Langmuir−Freundlich model. At 25 °C and 1 bar, the adsorption capacities for CO2 and CH4 were 3.03 and 1.3 mmol g−1, respectively, and the IAST predicated selectivities for CO2/N2 (15/85), CO2/CH4 (10/90), and CH4/N2 (30/70) reached 16.48, 7.49, and 3.76, respectively. These results should be attributed to the synergistic effect between suitable microporous structure and desirable N content. This report introduces a simple pathway to obtain N-doped porous carbon spheres to meet the flue gas and energy gas adsorptive separation requirements.

The Adsorption and Desorption Behavior of CH4 on Jincheng Anthracite Modified in Fe3+ and Cu2+ Ion Electrolytes

The anthracite was electrochemically treated in Fe2(SO4)3 and CuSO4 electrolytes, and the adsorption capacity and desorption ratio of CH4 on the anthracite were investigated using adsorption and de...

Study of carbon dioxide and methane adsorption on carbon molecular sieves, raw and modified by waste engine oil

In this study, a carbon molecular sieve (CMS) was synthesized from walnut shells, followed by physical activation of the carbon content of the CMS. Adsorption of CO2 and CH4 onto raw and acid treated adsorbents were investigated using two sizes, 300?600 and 600?1180 ?m. The adsorbents were impregnated with two solvent mixtures of waste engine oil with kerosene and with thinner at a proportion of 1:1 at 25?C. The highest adsorption for CO2 and CH4 was obtained at the suitable size of a group of CMS(A) adsorbents, with acid treated adsorbents being more efficient than the raw adsorbents. The acid treated CMS(A-3) sample adsorbed 0.925 mol CO2 g-1 and 0.353 mol CH4 g-1. The results indicated that by decreasing the granulation size of group CMS(R) adsorbents, the adsorption capacities for CO2 and CH4 were reduced while increasing the granulation size of group CMS(A) adsorbents resulted in an enhancement in the adsorption capacity for CO2 and CH4. Moreover, acid treated adsorbents achieved enhanced adsorption capacity for CO2 and CH4. Further modifications reduced the adsorption capacity for CO2 and CH4 in impregnated adsorbents, due to a decrease in surface area, pore volume and pore size of the adsorbent.

Adsorption simulation of open-ended single-walled carbon nanotubes for various gases

In order to study the adsorption capacity of open-ended single-walled carbon nanotubes for various gases, the grand canonical Monte Carlo method is used to simulate the adsorption capacities of methane, nitrogen, water, carbon dioxide, and carbon monoxide in different types of open-ended single-walled carbon nanotubes at temperatures of 273.15 K and 298.15 K and pressures of 1 Pa–101.325 kPa. Gas adsorption isotherms under various conditions were obtained. The effects of temperature and diameter of open-ended single-walled carbon nanotubes on gas adsorption capacity were discussed. The results showed that the open-ended single-walled carbon nanotubes had a certain adsorption capacity for five kinds of gases under low pressure conditions. For a given temperature, as the diameter of the tube increased, the adsorption capacities of various gases were enhanced. Each gas exhibited different growth gradients; specifically, the growth gradients of methane and nitrogen were relatively small, while the growth gradients of water, carbon dioxide, and carbon monoxide were relatively large. With an increase in the temperature, the adsorption capacities of CH4, N2, H2O, and CO2 exhibited a downward trend, while the adsorption capacity of CO was not affected by temperature, keeping a stable value. The open-ended single-walled carbon nanotube with a diameter of 10.85 Å exhibited a high adsorption capacity for CO, and it could be used as a porous material for storing or separating CO.

New insights into the CH4 adsorption capacity of coal based on microscopic pore properties

The objective of this study is to quantitatively describe the CH4 adsorption capacity of coal through microscopic pore properties. In this work, the micropore volume distributions (MPVDs) of granular coal samples from six collieries were obtained by low-pressure CO2 adsorption (LPGA-CO2), and the external specific surface areas (SSAs) were calculated using low-pressure N2 adsorption (LPGA-N2). Based on micropore filling and monolayer coverage theories, the micropores were assumed to be cylindrical to obtain the distribution of CH4 in pore structures with different scales. For the coal samples used in this study, micropores were common, whose SSAs accounted for most of the total SSAs (90.39–99.58%), and the micropore volumes accounted for 75.61–96.55% of total pore volumes. The quantity of CH4 adsorbed in the form of micropore filling account for 74–99% of the total amount adsorbed, while the amount of CH4 adsorbed by micropores in the size range of 0.38–0.76 nm was 38–55% of the total amount adsorbed and accounted for the largest proportion in the nine adsorption areas partitioned according to the number of CH4 molecules occupying micropores with different scales. Based on a combination of the high-pressure CH4 adsorption (HPGA-CH4) results, the estimated Langmuir volumes are in close agreement with the measured Langmuir volumes, which demonstrates that the CH4 adsorption capacity of the coal is determined by both the accessible MPVD and external SSAs. The results of this study may be significant for understanding the pore networks and the CH4 adsorption mechanism in coal under in situ conditions.

Molecular Investigation of CO2/CH4 Competitive Adsorption and Confinement in Realistic Shale Kerogen.

The adsorption behavior and the mechanism of a CO2/CH4 mixture in shale organic matter play significant roles to predict the carbon dioxide sequestration with enhanced gas recovery (CS-EGR) in shale reservoirs. In the present work, the adsorption performance and the mechanism of a CO2/CH4 binary mixture in realistic shale kerogen were explored by employing grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. Specifically, the effects of shale organic type and maturity, temperature, pressure, and moisture content on pure CH4 and the competitive adsorption performance of a CO2/CH4 mixture were investigated. It was found that pressure and temperature have a significant influence on both the adsorption capacity and the selectivity of CO2/CH4. The simulated results also show that the adsorption capacities of CO2/CH4 increase with the maturity level of kerogen. Type II-D kerogen exhibits an obvious superiority in the adsorption capacity of CH4 and CO2 compared with other type II kerogen. In addition, the adsorption capacities of CO2 and CH4 are significantly suppressed in moist kerogen due to the strong adsorption strength of H2O molecules on the kerogen surface. Furthermore, to characterize realistic kerogen pore structure, a slit-like kerogen nanopore was constructed. It was observed that the kerogen nanopore plays an important role in determining the potential of CO2 subsurface sequestration in shale reservoirs. With the increase in nanopore size, a transition of the dominated gas adsorption mechanism from micropore filling to monolayer adsorption on the surface due to confinement effects was found. The results obtained in this study could be helpful to estimate original gas-in-place and evaluate carbon dioxide sequestration capacity in a shale matrix.

Molecular simulations of competitive adsorption behavior between CH4-C2H6 in K-illite clay at supercritical conditions

Methane (CH4) and ethane (C2H6) are dominating compositions in natural gas produced from shale, approximately 80~90 percent. For efficient development and utilization of shale gas, the competitive adsorption behavior between CH4 and C2H6 is considerable significance to make sure the storage and transportation mechanisms in the pore structure of shale. The adsorption behavior of CH4-C2H6 in K-illite slits is studied with wide range of aperture (1.5~5.5 nm), pressure (≤50 MPa) and temperature (320~380 K) by using Grand Canonical Monte Carlo (GCMC) simulations and molecular dynamics (MD) simulations. The adsorption isotherms, isosteric heats, density distribution and absorbed site are used to analyze the pure and binary adsorption behavior considering the effects of temperature, pressure and contents. The results indicate that the pressure has a large influence on the adsorption capacity of C2H6 and CH4. At the low pressure, the adsorption capacity of C2H6 is stronger than that of CH4. With the increasing pressure, CH4 molecule shows the stronger increasing adsorption behavior than C2H6. From the results of adsorption isotherms of pure gas, excess adsorption amounts of pure CH4 and C2H6 are decreased with broader apertures in unit volume of K-illite slits. C2H6 molecule is easier to full in K-illite slits and alkanes absorb on the site of Al-O-Si bond bridge in K-illite. The adsorption selectivity of C2H6/CH4 is more than unity. The content of CH4 suppresses the first and second adsorption peak of C2H6. This work can give some understandings about single and binary gas adsorption behavior in K-illite shales.

Effect of CO2 injection on adsorption of methane on shale from the Sichuan Basin in China

In order to understand the change of adsorption capacity of methane (CH4) after carbon dioxide (CO2) injection into shale at high pressure condition. The pore structure character and adsorption capacity of CH4 were analysed via low-pressure N2 adsorption and isothermal adsorption measurements for original and supercritical CO2 (ScCO2) treated shale samples from Jiaoshiba area in the Sichuan Basin. The results show that the ScCO2 treated samples have lower specific surface areas, less micropore and mesopore, and more macropore compare to original one. For ScCO2 treated shale samples, specific surface area and micropore decrease with increasing temperature. Furthermore, the absolute adsorption capacity of CH4 in original shale is higher than that in ScCO2 treated ones, indicating that micropore specific surface area is probably the main factor controlling adsorption capacity of CH4 on shale. For all samples, the absolute adsorption capacity of CH4 increase with increasing pressure from 0 MPa to 43 MPa and then tended to be stable.

Improve in CO2 and CH4 Adsorption Capacity on Carbon Microfibers Synthesized by Electrospinning of PAN

Carbon microfibers (CMF) has been used as an adsorbent material for CO2 and CH4 capture. The gas adsorption capacity depends on the chemical and morphological structure of CMF. The CMF physicochemical properties change according to the applied stabilization and carbonization temperatures. With the aim of studying the effect of stabilization temperature on the structural properties of the carbon microfibers and their CO2 and CH4 adsorption capacity, four different stabilization temperatures (250, 270, 280, and 300 °C) were explored, maintaining a constant carbonization temperature (900 °C). In materials stabilized at 250 and 270 °C, the cyclization was incomplete, in that, the nitrile groups (triple-bond structure, e.g., C≡N) were not converted to a double-bond structure (e.g., C=N), to form a six-membered cyclic pyridine ring, as a consequence the material stabilized at 300 °C resulting in fragile microfibers; therefore, the most appropriate stabilization temperature was 280 °C. Finally, to corroborate that the specific surface area (microporosity) is not the determining factor that influences the adsorption capacity of the materials, carbonization of polyacrylonitrile microfibers (PANMFs) at five different temperatures (600, 700, 800, 900, and 1000 °C) is carried, maintaining a constant temperature of 280 °C for the stabilization process. As a result, the CMF chemical composition directly affects the CO2 and CH4 adsorption capacity, even more directly than the specific surface area. Thus, the chemical variety can be useful to develop carbon microfibers with a high adsorption capacity and selectivity in materials with a low specific surface area. The amount adsorbed at 25 °C and 1.0 bar oscillate between 2.0 and 2.9 mmol/g adsorbent for CO2 and between 0.8 and 2.0 mmol/g adsorbent for CH4, depending on the calcination treatment applicated; these values are comparable with other material adsorbents of greenhouse gases.

Preparation of PEBAX-1074/modified ZIF-8 nanoparticles mixed matrix membranes for CO2 removal from natural gas

In this work, as synthesized and modified ZIF-8 nanoparticles were used as the filler particles for mixed matrix membranes (MMMs) preparation for natural gas CO2 removal. Characterization of the prepared MMMs using SEM, XRD and FTIR were performed provided essential insights to the MMMs structure and revealed no defect in the MMMs due to incorporation of the ZIF-8 nanoparticles within the polymer matrix. The nanoparticles were also loaded by ethylenediamine (ED) amine loaded and incorporated within the PEBAX1074 matrix up to 20 wt% without agglomeration. After modification of the nanoparticles with ED, the ZIF-8 nanoparticles loading in the MMMs were extended up to 30 wt% without any agglomeration. The MMMs CO2 and CH4 adsorption and permeation rate were evaluated at the room temperature and different transmembrane pressures. The unmodified ZIF-8 nanoparticles loaded MMMs adsorption capacities for CH4 and CO2 were found as 6.28, 27.07 cm3 STP/cm3, respectively, compared with those of the modified ZIF-8 nanoparticles loaded MMMs were found as 6.88 and 30.46 cm3 STP/cm3, respectively. CH4 and CO2 permeabilities through the unmodified ZIF-8 nanoparticles loaded MMMs were found as ~9.39 and 134 Barrer, respectively, while for the modified MMMs, CH4 and CO2 permeation were measured as ~14.2 and 344 Barrer, respectively. The results showed significant improvement in ideal and real CO2/CH4 selectivity (71% and 40%) at 30 wt% of the ZIF-8 loading.

Effective CH4 enrichment from N2 by SIM-1 via a strong adsorption potential SOD cage

Methane enrichment from nitrogen is a necessary means for low-quality unconventional natural gas (coal mine methane) extraction, where adsorption-separation technology has become a research hotspot due to its low energy consumption and cost-effectiveness. In this work, three SOD-type ZIFs (ZIF-8, ZIF-90 and SIM-1, the latter also known as ZIF-94) are taken as methane sorbents for CH4/N2 separation. The experimental results show that SIM-1 (ZIF-94) has the highest CH4 adsorption capacity (1.5 mmol/g, 298 K and 1 bar) and adsorption heat (23.9 kJ/mol), although its surface area is the lowest (597 m2/g). No other known ZIF material has a higher CH4 adsorption capacity than SIM-1(ZIF-94), although some rare MOF and other porous materials can achieve such a high value. By comparing its CH4 adsorption capacity and BET surface with ZIF-93 (RHO type), which has the same units as Zn-almeIm, SIM-1(ZIF-94) has a high adsorption capacity of CH4 due to its suitable SOD cage size (0.84 nm) acting as a strong adsorption potential. Indeed, excellent enrichment–separation of the CH4/N2 mixture (30:70 and 50:50, v/v) with a high adsorption selectivity of 7.0 (IAST) rarely occurs for sorbents at room temperature and ambient pressure. Both the experimental and simulated data of the gas mixtures indicate that SIM-1 (ZIF-94) has excellent capability for enriching and removing nitrogen from methane, and it shows extraordinary industrial value.