Anomalous Isosteric Enthalpy of Adsorption of Methane on Zeolite-Templated Carbon

Thermodynamically and Kinetically Enhanced Benzene Vapor Sensor Based on the Cu-TCPP-Cu MOF with Extremely Low Limit of Detection

As a carcinogenic and highly neurotoxic hazardous gas, benzene vapor is particularly difficult to be distinguished in BTEX (benzene, toluene, ethylbenzene, xylene) atmosphere and be detected in low concentrations due to its chemical inertness. Herein, we develop a depth-related pore structure in Cu-TCPP-Cu to thermodynamically and kinetically enhance the adsorption of benzene vapor and realize the detection of ultralow-temperature benzene gas. We find that the in-plane π electronic nature and proper pore sizes in Cu-TCPP-Cu can selectively induce the adsorption and diffusion of BTEX. Interestingly, the theoretical calculations (including density functional theory (DFT) and grand canonical Monte Carlo (GCMC) simulations) exhibit that benzene molecules are preferred to adsorb and array as a consecutive arrangement mode in the Cu-TCPP-Cu pore, while the TEX (toluene, ethylbenzene, xylene) dominate the jumping arrangement model. The differences in distribution behaviors can allow adsorption and diffusion of more benzene molecules within limited room. Furthermore, the optimal pore-depth range (60-65 nm) of Cu-TCPP-Cu allows more exposure of active sites and hinders the gas-blocking process. The optimized sensor exhibits ultrahigh sensitivity to benzene vapor (155 Hz/μg@1 ppm), fast response time (less than 10 s), extremely low limit of detection (65 ppb), and excellent selectivity (83%). Our research thus provides a fundamental understanding to design and optimize two-dimensional metal-organic framework (MOF)-based gas sensors.

Diversity in Atomic Structures of Zeolite-Templated Carbons and the Consequences for Macroscopic Properties

Zeolite-templated carbons (ZTCs) are a family of ordered microporous carbons with extralarge surface areas and micropore volumes, which are synthesized by carbon deposition within the confined spaces of zeolite micropores. There has been great controversy regarding the atomic structures of ZTCs, which encompass two extremes: (1) three-dimensionally connected curved open-blade-type carbon moieties and (2) ideal tubular structures (commonly referred to as "Schwarzites"). In this study, through a combination of experimental analyses and theoretical calculations, we demonstrate that the atomic structure of ZTCs is difficult to define as a single entity, and it widely varies depending on their synthesis conditions. Carbon deposition using a large organic precursor and low-temperature framework densification generates ZTCs predominantly composed of open-blade-type moieties, characterized by low surface curvature and abundant H-terminated edge sites. Meanwhile, synthesis using a small precursor with high-temperature densification produces ZTCs with an increased portion of closed-strut carbon moieties (or closed-fullerene-like nodes), exhibiting large surface curvature and diminished edge sites. The variations in the atomic structure of ZTCs result in significant differences in their macroscopic properties, such as N2/CO2 adsorption, oxidative stability, work function, and electrocatalytic properties, despite the presence of comparable pore structures. Therefore, ZTCs demonstrate the potential to synthesize ordered nanoporous carbons with tunable physicochemical properties.

Bottom-up synthesis of two-dimensional carbon with vertically aligned ordered micropores for ultrafast nanofiltration

Two-dimensional (2D) carbon materials perforated with uniform micropores are considered ideal building blocks to fabricate advanced membranes for molecular separation and energy storage devices with high rate capabilities. However, creating high-density uniform micropores in 2D carbon using conventional perforation methods remains a formidable challenge. Here, we report a zeolite-templated bottom-up synthesis of ordered microporous 2D carbon. Through rational analysis of 255 zeolite structures, we find that the IWV zeolite having large 2D microporous channels and aluminosilicate compositions can serve as an ideal template for carbon replication. The resulting carbon is made of an extremely thin polyaromatic backbone and contains well-defined vertically aligned micropores (0.69 nm in diameter). Its areal pore density (0.70 nm^-2) is considerably greater than that of porous graphene (<0.05 nm^-2) prepared using top-down perforation methods. The isoporous membrane fabricated by assembling the exfoliated 2D carbon nanosheets exhibits outstanding permeance and molecular sieving properties in organic solvent nanofiltration.

Synergy of developed micropores and electronic structure defects in carbon-doped boron nitride for CO2 capture

With the aim of relieving the serious environmental and climate issues arising from excessive emission of anthropogenic CO₂, extensive solid absorbents have been developed for CO₂ capture. Among them, porous boron nitride (BN) is considered an ideal candidate due to its high specific surface area, abundant structural defects, low density, and outstanding chemical inertness. Herein, BN absorbents were synthesized from pyrolysis of melamine-boric acid precursors, and the effect of pyrolysis temperature (900, 1000, 1050 and 1100 °C) on the properties and performances was investigated. Various characterizations were performed to evaluate the physicochemical properties and CO₂ uptake capacities of BN absorbents. The result demonstrated that a carbon-doped BN structure was achieved instead of a pure BN material, and the carbonization degree was enhanced with the increase of pyrolysis temperatures. BN absorbent pyrolyzed at 1100 °C exhibited the highest CO₂ adsorption capacity of 3.71 mmol/g (273 K). The reason should be that the doping of carbon in the framework of BN contributed to the formation of abundant micropores, which enhanced the physical adsorption by offering more adsorption sites. At the same time, more negative charges on BN were induced by structural defects, which favored the chemical adsorption of CO₂ by invoking charge-induced chemisorption interaction. This study clarified the role of pore structure and electronic structure defects in CO₂ adsorption capacity of carbon-doped BN, which would open up more spacious avenues for the development of promising BN-based absorbents, or even catalysts.

Absolute adsorption and adsorbed volume modeling for supercritical methane adsorption on shale

Adsorbed methane significantly affects shale gas reservoir estimates and shale gas transport in shale formations. Hence, a practical model for accurately representing methane adsorption behavior at high-pressure and high-temperature in shale is imperative. In this study, a reliable mathematical framework that estimates the absolute adsorption directly from low-pressure excess adsorption data is applied to describe the excess methane adsorption data in literature. This method provides detailed information on the volume and density of adsorbed methane. The obtained results indicate that the extensively used supercritical Dubinin-Radushkevich model with constant adsorbed phase density underestimates absolute adsorption at high pressure. The adsorbed methane volume increases both the pressure and expands with the temperature. The adsorbed methane density reduces above 10 MPa, and approaches a steady value at high pressure. This study provides a novel method for estimating adsorbed shale gas, which is expected improve the prediction of shale gas in place and gas production.

Materials Design, Sensing Performance and Mechanism of Anhydrous Hydrogen Fluoride Gas Sensor Based on Amino-Functionalized MIL-101(Cr) for New Energy Vehicles

To guarantee the security of new energy vehicles (NEV), which include energy storage devices such as batteries, a quartz crystal microbalance (QCM) sensor was designed to detect online the HF gas produced from the leakage of electrolyte in the power system. Based on the chemical properties of HF gas, an amino-functionalized metal–organic framework NH2-MIL-101 (Cr) was synthesized as a sensing material of a QCM transducer to detect HF gas for NEV safeguard. The sensing materials are designed based on the hydrogen bond interaction between the amino group and HF molecular and were characterized by powder X-ray diffraction, Brunauer–Emmett–Teller (BET) surface area analysis, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA), etc. The performance of this sensor showed high sensitivity, with a limit of detection at 500 ppb, short response/recovery time and good reproducibility for anhydrous hydrogen fluoride (AHF) detection. Additionally, the sensing mechanism of NH2-MIL-101(Cr) QCM resonator to AHF is revealed to be reversible chemical adsorption by Gaussian 09. It is well-matched with a result of experimental determination through temperature-varying microgravimetric experiments. Therefore, the amino-functionalized MIL-101(Cr) QCM resonator may be a good candidate for an NEV safety monitor due to its rapid response to HF leaked from the decomposition of the electrolyte.

ZrBDC-Based Functional Adsorbents for Small-Scale Methane Storage Systems

Metal-organic frameworks (MOF), potentially porous coordination structures, are envisioned for adsorption-based natural gas (ANG) storage, including mobile applications. The factors affecting the performance of the ANG system with a zirconium-based MOF with benzene dicarboxylic acid as a linker (ZrBDC) as an adsorbent were considered: textural properties of the adsorbent and thermal effect arising upon adsorption. The high-density ZrBDC-based pellets were prepared by mechanical compaction of the as-synthesized MOF powder at different pressures from 30 to 240 MPa at 298 K without a binder and mixed with polymer binders: polyvinyl alcohol (PVA) and carboxyl methylcellulose (CMC). The structural investigations revealed that the compaction of ZrBDC with PVA under 30 MPa was optimal to produce the ZrBDC-PVA adsorbent with more than a twofold increase in the packing density and the lowest degradation of the porous structure. The specific total and deliverable volumetric methane storage capacities of the ZrBDC-based adsorbents were evaluated from the experimental data on methane adsorption measured up to 10 MPa and within a temperature range from 253 to 333 K. It was measured experimentally that at 253 K, an 100 mL adsorption tank loaded with the ZrBDC-PVA pellets exhibited the deliverable methane storage capacity of 172 m3(NTP)/m3 when the pressure dropped from 10 to 0.1 MPa. The methane adsorption data for the ZrBDC powder and ZrBDC-PVA pellets were used to calculate the important thermodynamic characteristic of the ZrBDC/CH4 adsorption system—the differential molar isosteric heat of adsorption, which was used to evaluate the state thermodynamic functions: entropy, enthalpy, and heat capacity. The initial heats of methane adsorption in powdered ZrBDC evaluated from the experimental adsorption isosteres were found to be ~19.3 kJ/mol, and then these values in the ZrBDC/CH4 system decreased at different rates during adsorption. In contrast, the heat of methane adsorption onto the ZrBDC-PVA pellets increased from 19.4 kJ/mol to a maximum with a magnitude, width, and position depended on temperature, and then it fell. The behaviors of the thermodynamic state functions of the ZrBDC/CH4 adsorption system were interpreted as a variation in the state of adsorbed molecules determined by a ratio of CH4-CH4 and CH4-ZrBDC interactions. The heat of adsorption was used to calculate the temperature changes of the ANG systems loaded with ZrBDC powder and ZrBDC pellets during methane adsorption under adiabatic conditions; the maximum integrated heat of adsorption was found at 273 K. The maximum temperature changes of the ANG system with the ZrBDC materials during the adsorption (charging) process did not exceed 14 K that are much lower than those reported for the systems loaded with activated carbons. The results obtained are of direct relevance for designing the adsorption-based methane storage systems for the automotive industry, developing new gas-power robotics systems and uncrewed aerial vehicles.

Methane Adsorption on Heteroatom-Modified Maquettes of Porous Carbon Surfaces

Experimental and theoretical studies disagree on the energetics of methane adsorption on carbon materials. However, this information is critical for the rational design and optimization of the structure and composition of adsorbents for natural gas storage. The delicate nature of dispersion interactions, polarization of both the adsorbent and the adsorbate, interplay between H-bonding and tetrel bonding, and induced dipole/Coulomb interactions inherent to methane physisorption require computational treatment at the highest possible level of theory. In this study, we employed the smallest reasonable computational model, a maquette of porous carbon surfaces with a central site for substitution and methane binding. The most accurate predictions of methane adsorption energetics were achieved by electron-correlated molecular orbital theory CCSD(T) and hybrid density functional theory MN15 calculations employing a saturated, all-electron basis set. The characteristic geometry of methane adsorption on a carbon surface ("lander approach") arises due to bonding interactions of the adsorbent π-system with the proximal H-C bonds of methane, in addition to tetrel bonding between the antibonding orbital of the distal C-H bond and the central atom of the maquette (C, B, or N). The polarization of the electron density, structural deformations, and the comprehensive energetic analysis clearly indicate a ∼3 kJ mol^-1 preference for methane binding on the N-substituted maquette. The B-substituted maquette showed a comparable or lower binding energy than the unsubstituted, pure C model, depending on the level of theory employed. The calculated thermodynamic results indicate a strategy for incorporating electron-enriched substitutions (e.g., N) into carbon materials as a way to increase methane storage capacity over electron-deficient (e.g., B) modifications. The thermochemical analysis was revised for establishing a conceptual agreement between the experimental isosteric heat of adsorption and the binding enthalpies from statistical thermodynamics principles.

Revival of Zeolite-Templated Nanocarbon Materials: Recent Advances in Energy Storage and Conversion

Nanocarbon materials represent one of the hottest topics in physics, chemistry, and materials science. Preparation of nanocarbon materials by zeolite templates has been developing for more than 20 years. In recent years, novel structures and properties of zeolite-templated nanocarbons have been evolving and new applications are emerging in the realm of energy storage and conversion. Here, recent progress of zeolite-templated nanocarbons in advanced synthetic techniques, emerging properties, and novel applications is summarized: i) thanks to the diversity of zeolites, the structures of the corresponding nanocarbons are multitudinous; ii) by various synthetic techniques, novel properties of zeolite-templated nanocarbons can be achieved, such as hierarchical porosity, heteroatom doping, and nanoparticle loading capacity; iii) the applications of zeolite-templated nanocarbons are also evolving from traditional gas/vapor adsorption to advanced energy storage techniques including Li-ion batteries, Li-S batteries, fuel cells, metal-O2 batteries, etc. Finally, a perspective is provided to forecast the future development of zeolite-templated nanocarbon materials.

Microporous 3D Graphene-like Zeolite-Templated Carbons for Preferential Adsorption of Ethane

Microporous 3D graphene-like carbons were synthesized in Faujasite (FAU)-, EMT-, and beta-zeolite templates using the recently developed Ca²⁺ ion-catalyzed synthesis method. The microporous carbons liberated from these large-pore zeolites (0.7-0.9 nm) retain the structural regularity of zeolite. FAU-, EMT-, and beta zeolite-templated carbons (ZTCs) with faithfully constructed pore diameters of 1.2, 1.1, and 0.9 nm, respectively, and very large Brunauer-Emmet-Teller areas (2700-3200 m² g^-1) were obtained. We have discovered that these schwarzite-like carbons exhibit preferential adsorption of ethane over ethylene at pressures in the range of 1-10 bar. The curved graphene structure, consisting of a diverse range of carbon polygons with a narrow pore size of ∼1 nm, provides abundant adsorption sites in micropores and retains its ethane selectivity at pressures up to 10 bar. After varying the oxygen content in the beta ZTC, the ethane and ethylene adsorption isotherms show that the separation ability is not significantly affected by surface oxygen groups. Based on these adsorption results, a breakthrough separation procedure using a C₂H₄/C₂H₆ gas mixture (9:1 molar ratio) is demonstrated to produce ethylene with a purity of 99.9%.

Structural Properties of Kerogens with Different Maturities

The thermogenic transformation of kerogen into hydrocarbons accompanies the development of a pore network within the kerogen that serves as gas storage locations both in pore space and surface area for adsorbed gas within the source rock. Therefore, the successful recovery of gas from these rocks depends on the accessible surface area, surface properties, and interconnectivity of the pore system. These parameters can be difficult to determine because of the nanoscale of the structures within the rock. This study seeks to investigate the pore structure, surface heterogeneity, and composition of recovered kerogens isolated from source rocks with progressively increasing thermogenic maturities. Prompt gamma-ray activation analysis (PGAA), nitrogen and methane volumetric gas sorption, and small-angle neutron scattering (SANS) are combined to explore the relationship between the chemical composition, pore structure, surface roughness, surface heterogeneity, and maturity. PGAA results indicate that higher mature kerogens have lower hydrogen/carbon ratio. Nitrogen gas adsorption indicates that the pore volume and accessible specific surface area are higher for more mature kerogens. The methane isosteric heat at different methane uptake in the kerogens is determined by methane isotherms and shows that approximately two types of binding sites are present in low mature kerogens while the binding sites are relatively homogeneous in the most mature kerogen. The hysteresis effect of the structure during the adsorption and desorption process at different CD4 gas pressures are studied. An extended generalized Porod's scattering law method (GPSLM) is further developed here to analyze kerogens with fractal surfaces. This extended GPSLM quantifies the surface heterogeneity of the kerogens with a fractal surface and shows that kerogen with high maturity is chemically more homogeneous, consistent with the results from methane isosteric heat. SANS analysis also suggests a pronounced surface roughness in the more mature kerogens. A microporous region circling around the nanopores, which contributes to high surface roughness and methane storage, is shown to develop with maturity.

Scaling-Up Simulations of Diffusion in Microporous Materials

We introduce and demonstrate the coarse-graining of static and dynamical properties of host-guest systems constituted by methane in two different microporous materials. The reference systems are mapped to occupancy-based pore-scale lattice models. Each coarse-grained model is equipped with an appropriate coarse-grained potential and a local dynamical operator, which represents the probability of interpore molecular jumps between different cages. Coarse-grained thermodynamics and dynamics are both defined based on small-scale atomistic simulations of the reference systems. We considered two host materials: the widely studied ITQ-29 zeolite and the LTA-zeolite-templated carbon, which was recently theorized. Our method allows for representing with satisfactory accuracy and a considerably reduced computational effort the reference systems while providing new interesting physical insights in terms of static and diffusive properties.

Langmuir's Theory of Adsorption: A Centennial Review

The 100th anniversary of Langmuir's theory of adsorption is a significant landmark for the physical chemistry and chemical engineering communities. Despite its simplicity, the Langmuir adsorption model captures the key physics of molecular interactions at interfaces and laid the foundation for further progress in understanding interfacial phenomena, developing new adsorbent materials, and designing engineering processes. The Langmuir model has had an exceptional impact on diverse fields within the chemical sciences (ranging from chemical biology to materials science), an impact that became clearer with the development of modified adsorption theories and continues to be relevant today.

High-Pressure Hydrogen Adsorption on a Porous Electron-Rich Covalent Organonitridic Framework

We report that a porous, electron-rich, covalent, organonitridic framework (PECONF-4) exhibits an unusually high hydrogen uptake at 77 K, relative to its specific surface area. Chahine's rule, a widely cited heuristic for hydrogen adsorption, sets a maximum adsorptive uptake of 1 wt % hydrogen at 77 K per 500 m² of the adsorbent surface area. High-pressure hydrogen adsorption measurements in a Sieverts apparatus showed that PECONF-4 exceeds Chahine's rule by 50%. The Brunauer-Emmett-Teller (BET) specific surface area of PECONF-4 was measured redundantly with nitrogen, argon, and carbon dioxide and found to be between 569 ± 2 and 676 ± 13 m² g^-1. Furthermore, hydrogen on PECONF-4 has a high heat of adsorption, in excess of 9 kJ mol^-1.

Structure-Function Relations for Gravimetric and Volumetric Methane Storage Capacities in Activated Carbon

The complex structure of activated carbon can be described as a three-dimensional network of graphene layers oriented in random directions. In this work, we propose a new model of the microporous structure, taking into account the degree of activation. We derive a structural relation between porosity, skeletal density, specific surface area, and the number of graphitic blocks per unit volume. In addition, we present a new approach to evaluate the interdependency between porosity and specific surface area by combining high-resolution scanning transmission electron microscopy and subcritical nitrogen adsorption. Finally, we propose a structural metric that predicts the relation between the volumetric storage capacity and the gravimetric storage capacity of supercritical methane at room temperature.

Porous carbon-based adsorption systems for natural gas (methane) storage

The use of gas fuel has considerable environmental advantages over traditional types of fuel based on petroleum products or fossil coal. The adsorption technology for methane (natural gas) uptake, storage and transportation can serve as a connecting link in gas supply to customers. The review considers characteristics of adsorption systems for methane storage. The key methods used for the synthesis of microporous carbon adsorbents based on various organic and inorganic carbon-containing compounds are described. Methods for increasing the efficiency of methane storage systems based on carbon adsorbents are analyzed. Theoretical approaches to optimization of the properties of methane – carbon adsorbent systems are discussed.

The bibliography includes 174 references.

Zeolite-templated carbons - three-dimensional microporous graphene frameworks

Zeolite-templated carbons (ZTCs) are ordered microporous carbons synthesized by using zeolite as a sacrificial template. Unlike well-known ordered mesoporous carbons obtained by using mesoporous silica templates, ZTCs consist of curved and single-layer graphene frameworks, thereby affording uniform micropore size (ca. 1.2 nm), developed microporosity (∼1.7 cm3 g-1), very high surface area (∼4000 m2 g-1), good compatibility with chemical modification, and remarkable softness/elasticity. Thus, ZTCs have been used in many applications such as hydrogen storage, methane storage, CO2 capture, liquid-phase adsorption, catalysts, electrochemical capacitors, batteries, and fuel cells. Herein, the relevant research studies are summarized, and the properties as well as the performances of ZTCs are compared with those of other materials including metal-organic frameworks, to elucidate the intrinsic advantages of ZTCs and their future development.

Heat of adsorption, adsorption stress, and optimal storage of methane in slit and cylindrical carbon pores predicted by classical density functional theory

Temperature, pressure and pore-size dependences of the heat of adsorption, adsorption stress, and adsorption capacity of methane in simple models of slit and cylindrical carbon pores are studied using classical density functional theory (CDFT) and grand-canonical Monte-Carlo (MC) simulation. Studied properties depend nontrivially on the bulk pressure and the size of the pores. Heat of adsorption increases with loading, but only for sufficiently narrow pores. While the increase is advantageous for gas storage applications, it is less significant for cylindrical pores than for slits. Adsorption stress and the average adsorbed fluid density show oscillatory dependence on the pore size and increase with bulk pressure. Slit pores exhibit larger amplitude of oscillations of the normal adsorption stress with pore size increase than cylindrical pores. However, the increase of the magnitude of the adsorption stress with bulk pressure increase is more significant for cylindrical than for slit pores. Adsorption stress appears to be negative for a wide range of pore sizes and external conditions. The pore size dependence of the average delivered density of the gas is analyzed and the optimal pore sizes for storage applications are estimated. The optimal width of slit pore appears to be almost independent of storage pressure at room temperature and pressures above 10 bar. Similarly to the case of slit pores, the optimal radius of cylindrical pores does not exhibit much dependence on the storage pressure above 15 bar. Both optimal width and optimal radii of slit and cylindrical pores increase as the temperature decreases. A comparison of the results of CDFT theory and MC simulations reveals subtle but important differences in the underlying fluid models employed by the approaches. The differences in the high-pressure behaviour between the hard-sphere 2-Yukawa and Lennard-Jones models of methane, employed by the CDFT and MC approaches, respectively, result in an overestimation of the heat of adsorption by the CDFT theory at higher loadings. However, both adsorption stress and adsorption capacity appear to be much less sensitive to the differences between the models and demonstrate excellent agreement between the theory and the computer experiment.

Zeolite-Templated Carbon as an Ordered Microporous Electrode for Aluminum Batteries

High surface area porous carbon frameworks exhibit potential advantages over crystalline graphite as an electrochemical energy storage material owing to the possibility of faster ion transport and up to double the ion capacity, assuming a surface-based mechanism of storage. When detrimental surface-related effects such as irreversible capacity loss due to interphase formation (known as solid-electrolyte interphase, SEI) can be mitigated or altogether avoided, the greatest advantage can be achieved by maximizing the gravimetric and volumetric surface area and by tailoring the porosity to accommodate the relevant ion species. We investigate this concept by employing zeolite-templated carbon (ZTC) as the cathode in an aluminum battery based on a chloroaluminate ionic liquid electrolyte. Its ultrahigh surface area and dense, conductive network of homogeneous channels (12 Å in width) render ZTC suitable for the fast, dense storage of AlCl₄^- ions (6 Å in ionic diameter). With aluminum as the anode, full cells were prepared which simultaneously exhibited both high specific energy (up to 64 Wh kg^-1, 30 Wh L^-1) and specific power (up to 290 W kg^-1, 93 W L^-1), highly stable cycling performance, and complete reversibility within the potential range of 0.01-2.20 V.

Postextraction Separation, On-Board Storage, and Catalytic Conversion of Methane in Natural Gas: A Review

In today's perspective, natural gas has gained considerable attention, due to its low emission, indigenous availability, and improvement in the extraction technology. Upon extraction, it undergoes several purification protocols including dehydration, sweetening, and inert rejection. Although purification is a commercially established technology, several drawbacks of the current process provide an essential impetus for developing newer separation protocols, most importantly, adsorption and membrane separation. This Review summarizes the needs of natural gas separation, gives an overview of the current technology, and provides a detailed discussion of the progress in research on separation and purification of natural gas including the benefits and drawbacks of each of the processes. The transportation sector is another growing sector of natural gas utilization, and it requires an efficient and safe on-board storage system. Compressed natural gas (CNG) and liquefied natural gas (LNG) are the most common forms in which natural gas can be stored. Adsorbed natural gas (ANG) is an alternate storage system of natural gas, which is advantageous as compared to CNG and LNG in terms of safety and also in terms of temperature and pressure requirements. This Review provides a detailed discussion on ANG along with computation predictions. The catalytic conversion of methane to different useful chemicals including syngas, methanol, formaldehyde, dimethyl ether, heavier hydrocarbons, aromatics, and hydrogen is also reviewed. Finally, direct utilization of methane onto fuel cells is also discussed.

Krypton Adsorption on Zeolite-Templated Carbon and Anomalous Surface Thermodynamics

Krypton adsorption was measured at eight temperatures between 253 and 433 K on a zeolite-templated carbon and two commercial carbons. The data were fitted using a generalized Langmuir isotherm model and thermodynamic properties were extracted. Differing from that on commercial carbons, krypton adsorption on the zeolite-templated carbon is accompanied by an increasing isosteric enthalpy of adsorption, rising by up to 1.4 kJ mol(-1) as a function of coverage. This increase is a result of enhanced adsorbate-adsorbate interactions promoted by the ordered, nanostructured surface of the adsorbent. An assessment of the strength and nature of these adsorbate-adsorbate interactions is made by comparing the measured isosteric enthalpies of adsorption (and other thermodynamic quantities) to fundamental metrics of intermolecular interactions of krypton and other common gases.

Enhanced gas-sorption properties of a high surface area, ultramicroporous magnesium formate

The gas-sorption properties of a high surface area α-magnesium formate with an expanded unit cell are reported. The material is stable in NH₃ and shows very high CH₄/N₂ (5.2) selectivity.

Ultimate H2 and CH4 adsorption in slit-like carbon nanopores at 298 K: a molecular dynamics study

Molecular dynamics calculations of gas adsorption in ideal carbon slit pores provide new insights into the physical limits of nanocarbons for hydrogen and methane storage at very high pressures and room temperature.