Separation Of Ethane Research Articles

Preparation of highly graphitized porous carbon and its ethane/ethylene separation performance

The efficient separation of ethane (C2H6) and ethylene (C2H4) is crucial for the preparation of polymer-grade C2H4, necessitating the development of highly selective and stable C2H6/C2H4 adsorbents. Highly graphitized porous carbon, denoted GC-800, was synthesized by polymerization at room temperature followed by carbonization at 800 °C using phenolic resin as the precursor and FeCl3 as the iron source. Vienna Ab-initio Simulation Package (VASP) calculations confirmed a higher binding energy between C2H6 molecules and graphitized porous carbon surfaces, so that a high degree of graphitization increased the adsorption capacity of porous carbon for C2H6. However, catalytic graphitization using Fe at high temperatures disrupted the microporous structure of the carbon, thereby reducing its ability to separate C2H6/C2H4. By controlling the carbonization temperature, the degree of graphitization and pore structure of the porous carbon could be changed. Raman spectra and XPS spectra showed that the GC-800 had a high degree of graphitization, with a sp2 C content as high as 73%. Low-temperature N2 physical adsorption measurements estimated the specific surface area of GC-800 to be as high as 574 m2·g−1. At 298 K and 1 bar, it had an equilibrium adsorption capacity of 2.16 mmol·g−1 for C2H6, with the C2H6/C2H4 (1:1 and 1:9, v/v) ideal adsorbed solution theory selectivity respectively reaching 2.4 and 3.8, significantly higher than the values of most reported high-performance C2H6 selective adsorbents. Dynamic breakthrough experiments showed that GC-800 could produce high-purity C2H4 in a single step from a mixture of C2H6 and C2H4. Dynamic cycling tests confirmed its good cyclic stability, and that it could efficiently separate C2H6/C2H4 even under humid conditions.

Catalytic engineering of transition metal (TM: Ni, Pd, Pt)-coordinated Ge-doped graphitic carbon nitride (Ge@g-c3n4) nanostructures for petroleum hydrocarbon separation: An outlook from theoretical calculations

The extraction, processing, and utilization of petroleum often results in the release of diverse hydrocarbon pollutants into the environment, leading to severe ecological and health implications. Herein, the adsorption and separation of ethane (EAN), ethene (EEN), ethyne (EYN), and benzene (BZN) fractions of paraffin, olefin, acetylene, and aromatic petroleum hydrocarbons were investigated via the catalytically engineered nickel group transition metals; nickel (Ni), palladium (Pd), and platinum (Pt). These transition metals were coordinated on Germanium-doped graphitic carbon nitride (Ge@g-C3N4) nanostructures, and the behavior of the systems was studied through Kohn–Sham density functional theory (KS-DFT) with the B3LYP–D3(BJ)/Def2-SVP computational method. The adsorption of petroleum hydrocarbons decreased in the order Ge_Ni@C3N4 > Ge_Pd@C3N4 > Ge_Pt@C3N4>Ge_Pt@C3N4. These results showed that the coordination of Ni, Pd, and Pt within Ge@C3N4 improved the separation of petroleum hydrocarbons.

The Procedure of Extracting Natural Gas liquids in Cryosift Method

The extraction of Natural Gas Liquids (NGLs) plays a pivotal role in the modern energy landscape, serving as both a significant economic driver and a critical component of energy supply chains. This project investigates the comprehensive processes involved in NGL extraction, which includes the separation of ethane, propane, butanes, and natural gasoline from natural gas and crude oil. Key techniques such as cryogenic distillation, absorption, and fractionation are explored in depth, highlighting their operational principles, efficiency, and technological advancements. In addition to the technical aspects, this project examines the environmental impacts of NGL extraction and the strategies employed to mitigate these effects. Innovations in technology and process optimization are discussed, emphasizing their role in reducing carbon footprints and enhancing sustainability. The economic dimension of NGL extraction is also analyzed, with a focus on market trends, supply chain logistics, and the factors influencing global demand and pricing. Case studies from leading NGL extraction facilities are used to illustrate best practices, challenges, and the implementation of cutting-edge technologies. Through a multi-faceted approach, this project aims to provide a detailed understanding of the NGL extraction industry. It underscores the importance of NGLs in the global energy market, the technological advancements driving the industry forward, and the economic and environmental considerations that shape its future. The findings offer valuable insights for stakeholders, policymakers, and industry professionals seeking to navigate the complexities of NGL extraction and leverage its benefits for sustainable development. Key Words: Cryogenic Distillation, Absorption, Fractionation

Solvent-Driven Dynamics: Crafting Tailored Transformations of Cu(II)-Based MOFs.

Metal-organic frameworks (MOFs), a sort of crystalline porous coordination polymers composed of metal ions and organic linkers, have been intensively studied for their ability to take up nonpolar gas-phase molecules such as ethane and ethylene. In this context, interpenetrated MOFs, where multiple framework nets are entwined, have been considered promising materials for capturing nonpolar molecules due to their relatively higher stability and smaller micropores. This study explores a solvent-assisted reversible strategy to interpenetrate and deinterpenetrate a Cu(II)-based MOF, namely, MOF-143 (noninterpenetrated form) and MOF-14 (doubly interpenetrated forms). Interpenetration was achieved using protic solvents with small molecular sizes such as water, methanol, and ethanol, while deinterpenetration was accomplished with a Lewis-basic solvent, pyridine. Additionally, this study investigates the adsorptive separation of ethane and ethylene, which is a significant application in the chemical industry. The results showed that interpenetrated MOF-14 exhibited higher ethane and ethylene uptakes compared to the noninterpenetrated MOF-143 due to narrower micropores. Furthermore, we demonstrate that pristine MOF-14 displayed higher ethane selectivity than transformed MOF-14 from MOF-143 by identifying the "fraction of micropore volume" as a key factor influencing ethane uptake. These findings highlight the potential of controlled transformations between interpenetrated and noninterpenetrated MOFs, anticipating that larger MOF crystals with narrower micropores and higher crystallinity will be more suitable for selective gas capture and separation applications.

Adjusting the Si/Al ratio of high silica zeolites for efficient ethane and ethylene separation

The economically efficient separation of ethane (C2H6)/ethylene (C2H4) presents challenges in the petrochemical industry, and the use of traditional adsorbents zeolite provides a reliable guarantee for maintaining the economic viability of adsorption separation technology. In this study, we investigate the impact of different silica-alumina ratios (SiO2/Al2O3 = 40, 500, and 1500) of high silica zeolites ZSM-11 on the C2H6/C2H4 separation performance to develop efficient C2H6 selective adsorbents. The results show that the C2H6 adsorption capacity and C2H6/C2H4 selectivity of ZSM-11 increase as the silica-alumina ratios increases. The pure silica zeolite (ZSM-11(1500)) exhibits the highest adsorption capacity for C2H6 (59.19 cm3/g) and the highest selectivity for C2H6/C2H4 (2.04), which were superior to ultra-high silica sample (ZSM-11(500)) (55.06 cm3/g and 1.62, respectively) and high silica sample (ZSM-11(40)) (47.28 cm3/g and 1.23, respectively), at 273 K and 1 bar. The mixed gas breakthrough experiments results show that pure silica sample has outstanding C2H6/C2H4 separation ability. The PSA simulation calculated data demonstrating promising potential for industrial applications. Importantly, this separation performance remains unaffected even in the presence of H2O.

Energy, exergy, and economic analyses and optimization of a deethanizer tower of a petrochemical plant

Abstract The distillation tower’s reboiler is one of the largest energy consumers in petrochemical facilities, and reducing its energy consumption is a crucial issue. This study proposes two optimal methods, namely Direct Vapor Recompression (DVR) and External Vapor Recompression (EVR), to reduce the consumption of cold and hot utilities in a petrochemical deethanizer tower. The Pars petrochemical in Iran is taken as a case study, and the proposed methods are compared with the base case using energy, exergy, and economic approaches, simulated through Aspen HYSYS software in the steady-state design conditions. Exergy analysis reveals that the EVR and DVR methods reduce the exergy destruction of the deethanizer tower by about 70.06 % and 67.29 %, respectively, compared to the base case. Moreover, the EVR method allows for complete recycling of low-pressure vapor, reducing the total exergy destruction rate from 0.871 to 0.261 GJ/tethane. The feed separation cost for the base case, DVR, and EVR are estimated to be around 28 $/kgfeed, 21.57 $/kgfeed, and 21.14 $/kgfeed, respectively. The EVR method results in reduced utility and ethane separation cost rates from 5.153 to 3.274 $/tethane and 17.64 to 15.78 $/year. Overall, the findings suggest that both DVR and EVR methods are effective in reducing the energy consumption and costs associated with deethanizer tower operations. Moreover, real-time optimization techniques can be developed to monitor and adjust the deethanizer tower’s operating parameters, such as feed flow rate, reboiler duty, and reflux ratio.

A Route to Understanding the Ethane Adsorption Selectivity of the Zeolitic Imidazolate Framework-8 in Ethane-Ethylene Mixtures.

Ethylene production has a negative environmental impact, with its separation step being one of the major contributors of pollution. This has encouraged the search for energy-efficient alternatives, among which the adsorptive separation of ethane and ethylene stands out. ZIF-8 is a molecular sieve that is potentially useful for this purpose. It is selective to ethane, an exceptional property that remains unexplained. Furthermore, the adsorption of ethane and ethylene above room temperature, such as at steam cracking process outlet temperatures, has not been addressed either. This work aims to fill this knowledge gap by combining experiments at very low volumetric fillings with density-functional theory modelling methods. Adsorption isotherms of ethane and ethylene on ZIF-8 at pressures below 0.3 bar and 311 K, 333 K, and 363 K were measured using zero-length column chromatography. The low-pressure domain of the isotherms contains information on the interactions between the adsorbate molecules and the adsorbent. This favors the understanding of their macroscopic behavior from simulations at the atomic level. The isosteric enthalpy of adsorption of ethane remained constant at approximately -10 kJ/mol. In contrast, the isosteric enthalpy of adsorption of ethylene decreased from -4 kJ/mol to values akin to those of ethane as temperature increased. ZIF-8 selectivity to ethane, estimated from ideal adsorbed solution theory, decreased from 2.8 to 2.0 with increasing pressure up to 0.19 bar. Quantum mechanical modelling suggested that ethylene had minimal interactions with ZIF-8, while ethane formed hydrogen bonds with nitrogen atoms within its structure. The findings of this research are a platform for designing new systems for the adsorptive separation of ethane and ethylene and thus, reducing the environmental impact of ethylene production.

Stable and Efficient Cu‐Based Zeolitic Octahedral Metal Oxides for Ethylene and Ethane Separation at High Temperature and Humidity

Zeolitic octahedral metal oxides based on vanadotungstate have shown great potential in gas separation. The microporosity of these materials is highly dependent on their structure and composition, allowing for precise tuning of their separation performance. In this study, zeolitic vanadotungstate is utilized for the separation of ethylene and ethane. The choice of cation is found to significantly impact the separation performance of the material. Specifically, the material with only Cu as the cation exhibits differentiated adsorption performance for ethylene and ethane, with high theoretical selectivity. Breakthrough experiments demonstrate that the Cu‐based material is able to effectively separate ethylene and ethane even at high temperature and humidity levels. Furthermore, the material exhibits excellent stability and is able to be reused without any loss in separation performance.

A robust perylene diimide-based zirconium metal–organic framework for preferential adsorption of ethane over ethylene

Adsorptive separation of ethane (C2H6)/ ethylene (C2H4) mixtures based on C2H6-selective adsorbents through one-step separation unit has attracted great attention in view of its enormous potential to reduce energy consumption in the petrochemical industry. To achieve this, it is highly demanded to develop C2H6-selective adsorbents. However, it is challenging to construct C2H6-selective adsorbents due to the difficulty in building suitable interaction between C2H6 molecules and adsorption active sites. Here, we constructed a robust perylene diimide-based zirconium metal–organic framework (MOF, denoted as Zr-Me-PDI) of superior stability under aqueous solution of different pH values (1.0 ∼ 10.0), for effectively separation of C2H6 from C2H4. Zr-Me-PDI displayed C2H6-selective adsorption behavior at both 298 and 273 K. High C2H6 adsorption capacity 3.9 mmol·g−1 and C2H6/C2H4 selectivity (1.5) was achieved for Zr-Me-PDI at 1 bar and 298 K, comparable to most of the high-performance C2H6-selective MOFs. Calculation results of Grand Canonical Monte Carlo (GCMC) simulation show that the interpenetrated structure of Zr-Me-PDI exhibit multiple C-H···Cl and C-H···O interactions with C2H6 and preferentially binds to C2H6 over C2H4. Therefore, the results demonstrated in this project may provide valuable guidance for the design and synthesis of C2H6-selective adsorbents.

Simulation and technical, economic, and environmental analyses of natural gas liquefaction cycle using different configurations

This paper aims to improve the performance of the simple C3MR natural gas liquefaction cycle from the thermodynamic, economic, and environmental aspects. Four processes are proposed where the first system uses heat recovery with the ORC cycle and boil-off gas cooling, and the second proposed plant uses the first plant with a distillation tower added for the separation of ethane plus and simultaneous production of NGL/LNG. The third scenario adds a Proton Exchange Membrane, gas turbine cycle, steam turbine, and electrolyzer to the second scenario. And the fourth scenario is in which a Rankine ammonia cycle is added to the structure of the second scenario to recover more wasted heat. Regarding exergy analysis, the third scenario represents 64.32% exergetic efficiency, while the base, 1st, 2nd, and 4th scenarios have 35.4, 47.35, 12.64%, and 17.1% exergetic efficiency, respectively. The LNG production requires 260.76, 941, 469, and 893 kWh/ tonLNG energy for the 1st, 2nd, 3rd, and 4th scenarios. According to the economic analysis, the first scenario with 0.0034 $/kg total cost rate of products has the best economic performance compared to 0.0037, 0.042, 0.059 $/kg, and 0.055 total cost rate of products for the base, 2nd, 3rd, and 4th scenarios, respectively. The environmental assessment results reveal that the first scenario with 72,567 kgCO2/h has the minimum CO2 emission. The overall results indicate that the first scenario is the best, but considering the trigeneration, the third scenario is a proper system.

Design and Screening of Metal-Organic Frameworks for Ethane/Ethylene Separation.

Separation of ethane and ethylene is considered to be industrially important for various chemical processes, but their similarities make the process expensive. In this study, we integrated computational screening with machine learning to find optimal metal-organic frameworks (MOFs) with high ethane/ethylene selectivity. Using our algorithm, a hypothetical MOF structure with an ideal adsorption solution theory selectivity of 3.6 at 298 K and 1 bar was discovered. Furthermore, structural analysis was implemented, and the full adsorption isotherm of some of the top structures was obtained.

Regulation of the nature and sites of copper species in CuNaY zeolites for ethylene and ethane separation

Relationship between the states of Cu species and ethylene adsorption capacity.

Enhancing Ethane/Ethylene Separation Performance in Two Dynamic MOFs by Regulating Temperature-Controlled Structural Interpenetration.

The separation of ethane from ethylene is an important but challenging process in the chemical industry because of their similar physicochemical properties. Generally, the adsorbents for C2H6/C2H4 separation require an appropriate and relatively small aperture. Herein, we report two dynamic pillar-layered metal-organic frameworks (MOFs) BUT-111 and BUT-112 with isomorphic frameworks but different degrees of interpenetration for efficient C2H4 purification. The dynamic behavior makes both the activated MOFs exhibit ultramicropores and reversed order adsorption behavior for C2H6 and C2H4, which could obtain highly purified C2H4 in one step from the C2H6/C2H4 mixture. BUT-111 and BUT-112 could work in a wide temperature range, and with the decrease in temperature, the C2H6/C2H4 selectivity would increase. Moreover, the degree of interpenetration could be well controlled by the synthetic temperature, and the increase in the interpenetration degree of BUT-112 enhanced the C2H4 purification effectively.

A novel process of low-temperature fractionation combined with extractive distillation for H2S removal from natural gas

H2S is a common component of natural gas. In order to meet the quality standards for U.S. commodity natural gas that contains less than 5.7 mg/m3 of H2S, it is necessary to process the natural gas to remove H2S. Since H2S will form azeotropes with ethane and propane in natural gas, it is impossible to achieve complete separation of H2S by ordinary distillation columns. Therefore, a novel low-temperature fractionation combined with extractive distillation process is proposed and designed, which can achieve the removal of H2S from sulfur-containing natural gas and obtain sweet gas(almost pure methane), ethane product and H2S gas. The process consists of three steps: demethanization with low temperature, deethanization with extractive distillation and H2S recovery. Extensive simulation and analysis have confirmed that extractive distillation using high molecular weight, high boiling point benzene homologs (toluene, o-Xylene, p-Xylene, m-Xylene) as extractant is a good method to separate ethane-H2S azeotrope. Furthermore, the effects of parameters such as the number of column stages, the reflux ratio, the location of feed stream inlet stage, the type of extractants, the inlet stage location of extractant, the molar flow rate of extractant on the product purity and the column duty have been studied, and the optimal applicable ranges of different parameters are finally determined. The simulation results show that o-Xylene is the best extractant for the separation of ethane and H2S. Under the economic optimization, the minimum total annual cost for the demethanizer is $952,611 per year and the minimum total annual cost for the deethanizer is $2,026,364 per year.

An ethane-trapping Zn (II) cluster-based metal-organic framework with suitable pockets for efficient ethane/ethylene separation

Efficient separation of ethane (C2H6) from ethylene (C2H4) using C2H6-selective adsorbents is more efficient but challenging due to their similar physical and chemical properties. Herein, we report a Zn (II) cluster-based metal-organic framework, Zn4O(NTB)2, with suitable cavity pockets and favorable adsorption sites for the reverse capture of C2H6 from C2H6/C2H4 mixtures. Both high C2H6 uptake (2.83 mmol g−1) and C2H6/C2H4 selectivity (2.06) at 273 K and 1 bar was achieved, outperforming many top-ranking C2H6-selective adsorbents. Moreover, dispersion-corrected density functional theory (DFT) and grand canonical Monte Carlo (GCMC) simulation revealed that CH···O and CH···π interactions are formed with C2H6 in the suitable pockets with saturated Zn clusters and nonpolar pore surfaces. Dynamic breakthrough experiments demonstrated its practical separation performances with various gas-mixture compositions and those containing water vapor.

Interpretable machine learning for accelerating the discovery of metal-organic frameworks for ethane/ethylene separation

Interpretable machine learning (ML) is applied to accelerate the discovery of promising metal–organic frameworks (MOFs) for the selective separation of ethane (C2H6) and ethylene (C2H4). Based on molecular simulation data, ML models are first trained and tested to classify MOFs into C2H4-selective and C2H6-selective categories using different types of material descriptors and fingerprints as input. It turns out that the model developed with the force-field inspired descriptors shows a higher classification accuracy. However, the PubChem fingerprint-based model is more interpretable because its binary variables directly indicate the existence or nonexistence of various substructures. Adopting this interpretable ML model, insightful structural characteristics are obtained and applied for efficient MOF screening to identify C2H6-selective candidates by means of substructure matching. Based on molecular simulation, 93.8% of the identified candidates are verified to be C2H6-selective with the best MOF presenting a high C2H6/C2H4 selectivity of 6.46. This work demonstrates the great potential of interpretable ML in accelerating the discovery of high-performance MOFs.

A robust ethane-selective metal-organic framework with nonpolar pore surface for efficient C2H6/C2H4 separation

A robust chiral chain-based microporous MOF with nonpolar pore surface and suitable cavity space was designed and synthesized for C 2 H 6 /C 2 H 4 separation. The MOF shows simultaneously high C 2 H 6 uptake and inverse C 2 H 6 /C 2 H 4 selectivity, affording the one-step purification of C 2 H 4 from C 2 H 6 -C 2 H 4 mixture under ambient condition. • Adopting the methyl-modified ligands afforded a Zn-MOF with nonpolar channels. • The MOF shows excellent stability and uncommon preferential adsorption for C 2 H 6 . • The methyl groups in MOF are crucial for the separation of C 2 H 6 over C 2 H 4 . • The MOF achieves effective one-step purification of C 2 H 4 from C 2 H 6 -C 2 H 4 mixture. Due to similar physical and chemical properties, the separation of ethane (C 2 H 6 ) and ethylene (C 2 H 4 ) is an indispensable and extremely challenging task in petrochemical process. Although traditional C 2 H 4 -selective porous materials realize the separation of C 2 H 6 -C 2 H 4 mixture, but subsequent multiple separation operations are required to produce high-purity C 2 H 4 . Herein, we designed a hydrophobic methyl group-modified metal-organic framework (MOF) for one-step efficient purification of C 2 H 4 from C 2 H 6 -C 2 H 4 mixture. The as-synthesized MOF constructed from inexpensive carboxylic acid and pyrazole mixed linkers shows high thermal stability and chemical stability (water resistance). Cooperative study on the pure-component sorption isotherm, Ideal Adsorbed Solution Theory method, adsorption heat calculation and grand canonical Monte Carlo (GCMC) simulation supports the unique C 2 H 6 -selective feature of the MOF. Breakthrough experiments revealed the one-step C 2 H 4 purification from C 2 H 6 -C 2 H 4 (1/1, 1/10 and 1/15) mixtures through the MOF around room temperature condition with nice recyclability.

Recent advances in adsorptive separation of ethane and ethylene by C2H6-selective MOFs and other adsorbents

• The recent developments of C 2 H 6 -selective adsorbents are overviewed. • The method for boosting adsorption uptake, selectivity and stability is discussed. • The mechanism underlying the preferential adsorption of C 2 H 6 over C 2 H 4 is briefed. • Balancing the trade-off between adsorption uptake and selectivity is challenging. • Lowering cost and enhancing stability of MOF are future research directions. C 2 H 4 is the most important and demanded chemical raw materials. Separating C 2 H 6 from C 2 H 4 using C 2 H 6 -trapping adsorbents to lower the energy consumption in the petrochemical industry is important but challenging. This review summarizes the research progresses on the development of C 2 H 6 -selective metal–organic frameworks (MOFs), covalent-organic frameworks (COFs), hydrogen-bonded organic frameworks (HOFs), porous organic cages (POCs), carbon-based materials, and zeolites for C 2 H 6 /C 2 H 4 separation. The C 2 H 6 uptakes, C 2 H 6 /C 2 H 4 selectivities, stability, cost, scale-up synthesis, regeneration performance and shaping of C 2 H 6 -selective MOFs are overviewed. The strategies for enhancing C 2 H 6 uptakes, C 2 H 6 /C 2 H 4 selectivities and moisture stability on MOFs are summarized. The mechanism underlying the preferential adsorption of C 2 H 6 over C 2 H 4 on different adsorbents is also highlighted. Additionally, challenges and future developments of various C 2 H 6 -selective adsorbents are discussed.

Preferential Adsorption Performance of Ethane in a Robust Nickel-Based Metal–Organic Framework for Separating Ethane from Ethylene

Development of an ethane-selective adsorbent to separate ethane from ethylene is a challenging issue with great significance for ethylene purification. The adsorptive separation technique based on physical adsorption holds a great promise to address this issue. Herein, we report a robust ethane-selective metal–organic framework, Ni(BODC)(TED), and investigate its separation performance on C2H6/C2H4. The as-synthesized Ni(BODC)(TED) exhibits excellent water vapor stability and high capacity of C2H6 molecules with an uptake of 3.36 mmol/g at 298 K and 100 kPa, higher than those of many adsorbents reported in recent years. Its C2H6/C2H4 selectivity predicted by the ideal adsorbed solution theory (IAST) model reaches 1.79. A molecular simulation is applied to unveil the preferential adsorption mechanism of ethane. Calculation shows that five strong C–H···H interactions are formed between C2H6 and the framework of Ni(BODC)(TED), and the isosteric heat of ethane on Ni(BODC)(TED) is 27.02 kJ/mol, higher than that of ethylene, resulting in preferential adsorption of ethane. Ni(BODC)(TED) would become a promising member of the family of ethane-selective materials for the industrial separation of ethane from ethylene.

A Microporous Metal-Organic Framework with Channels Constructed from Nonpolar Aromatic Rings for the Selective Separation of Ethane/Ethylene Mixtures.

The separation of ethane and ethylene is an important segment in the purification of chemical raw materials in industrial production. However, due to their similar physical and chemical properties, the separation of C2 H6 /C2 H4 is challenging. Herein, we report the selective adsorption of ethane over ethylene by a microporous metal-organic framework with nonpolar aromatic rings constructed channels, [Co1.5 (TATB)(H2 O)0.5 ] ⋅ 5DMA ⋅ 3H2 O (Co-TATB, H3 TATB=4,4',4''-(s-triazine-2,4,6-triyl) tribenzoic acid). This compound showed a higher ethane capacity than that of ethylene, and a low adsorption enthalpy of ethane only of 19.4 kJ mol-1 . Further, the dynamic breakthrough experimental confirmed that Co-TATB can selectively adsorb ethane from ethane/ethylene separation.