Adsorption Of Ethylene Research Articles

Ethane Triggered Gate‐Opening in a Flexible−Robust Metal−Organic Framework for Ultra‐high Purity Ethylene Purification

Priority recognition separation of inert and larger ethane molecules from high‐concentration ethylene mixtures instead of traditional thermodynamic or size sieving strategy is a fundamental challenge. Herein, we report the ethane triggered gate‐opening in the flexible‐robust metal−organic framework Zn(ad)(min), the 3‐methylisonicotinic acid ligand can spin as a flexible gate when adsorbing the cross‐section well‐matched ethane molecule, thus achieving the unprecedent ethane adsorption capacity (62.6 cm3 g‐1) and ethane/ethylene uptake ratio (3.34) under low‐pressure region (0.1 bar and 298 K). The ethane‐induced structural transition behavior is uncovered by a collaboration of single‐crystal X‐ray diffraction, in‐situ variable pressure X‐ray diffraction and theoretical calculations, elucidating the synergetic mechanism of cross‐section matching and multiple supramolecular interactions within the tailor‐made pore channels. Dynamic breakthrough experiments revealed the outstanding separation performance of Zn(ad)(min) in the production of ultra‐high purity ethylene (> 99.995%) with a productivity of up to 39.2 L/kg under ambient conditions.

Ethane Triggered Gate-Opening in a Flexible-Robust Metal-Organic Framework for Ultra-high Purity Ethylene Purification.

Priority recognition separation of inert and larger ethane molecules from high-concentration ethylene mixtures instead of traditional thermodynamic or size sieving strategy is a fundamental challenge. Herein, we report the ethane triggered gate-opening in the flexible-robust metal-organic framework Zn(ad)(min), the 3-methylisonicotinic acid ligand can spin as a flexible gate when adsorbing the cross-section well-matched ethane molecule, thus achieving the unprecedent ethane adsorption capacity (62.6cm3 g-1) and ethane/ethylene uptake ratio (3.34) under low-pressure region (0.1 bar and 298 K). The ethane-induced structural transition behavior is uncovered by a collaboration of single-crystal X-ray diffraction, in-situ variable pressure X-ray diffraction and theoretical calculations, elucidating the synergetic mechanism of cross-section matching and multiple supramolecular interactions within the tailor-made pore channels. Dynamic breakthrough experiments revealed the outstanding separation performance of Zn(ad)(min) in the production of ultra-high purity ethylene (> 99.995%) with a productivity of up to 39.2 L/kg under ambient conditions.

Finely Pore‐Engineered Ultra‐Stable Cluster–Cluster‐type Metal–Organic Frameworks with Shifting One‐Step Ethylene Purification

AbstractOne‐step ethylene (C2H4) purification from multicomponent mixtures to obtain polymerized grade C2H4 is vital in industry but still difficult to achieve. Herein untramicropore engineering is demonstrated in unique cluster–cluster‐type metal–organic framework (CCMOF) adsorbents (SNNU‐107‐X, X = OH/Cl/F) with shifting one‐step ethylene purification from the ternary mixture. Triangular prismic [Cd8(TAZ)9] and hollow hexagonal prismic [Cd42(TAZ)42] clusters (TAZ = tetrazolate) connect each other directly without inter‐cluster linkers to generate SNNU‐107‐X CCMOFs with fixed hexagonal large pore and alterable quadrilateral small pore. It is curious that these unique CCMOFs can keep their 3D porous frameworks in aqueous solution with pH = 2–13 for 30 days and even in boiling water for 15 days. Regulated by terminal coordinated anions (OH/Cl/F) located in quadrilateral pores, SNNU‐107‐X exhibits controllable and shifting ethylene adsorption and separation performance. In particular, SNNU‐107‐F can separate 99.999% C2H4 from C2H2/CO2/C2H4 ternary mixture with a productivity of 274.4 L kg−1 by one‐step process superior to almost all advanced materials. The time‐dependent kinetic adsorption, in situ FT‐IR spectra, DFT, and GCMC calculations indicate that the shifting ethylene separation of SNNU‐107‐X is ascribed to a thermodynamic and dynamic coupling effect modulated by single terminal anions in the ultramicropore space.

Creation of Composite Aerogels Consisting of Activated Carbon and Nanocellulose Blended with Cross-Linked Biopolymers: Application as Ethylene Scavengers.

This study involved producing aerogels using activated carbon (AC) and nanocellulose (NC). Two distinct structured composites, AC composite aerogel (ACCA) and NC composite aerogel (NCCA), were developed by separately mixing AC and NC with identical proportions of cross-linked biopolymers: hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), and chitosan (C). These aerogels were evaluated for their capability to adsorb ethylene gas through batch experiments, while the physical and chemical characteristics were thoroughly examined to determine their feasibility of removing ethylene. The resulting ACCA and NCCA aerogels exhibited low densities of 0.094 g cm-3 and 0.077 g cm-3, respectively, coupled with high porosity ranging between 95 and 96%. During the ethylene adsorption test, NCCA exhibited superior ethylene removal rates (~14.88-16.77 mL kg-1) compared to ACCA (~13.57-14.97 mL kg-1). Specifically, NCCA achieved a removal efficiency of 83.86% compared to 74.64% for ACCA. Kinetic model fitting yielded high R2 values ranging from 0.97 to 0.98 with the Lagergren kinetic model. These findings suggest the potential of composite aerogels to be incorporated into food packaging materials for dynamic ethylene capture, independent of environmental conditions, thereby providing promising routes for further development.

Hydrophilic Chain Length for Octylphenol Polyoxyethylene Ether Adsorption at the n-Hexadecane-Water Interface: Theoretical and Experimental Study.

With the advancement of technologies for developing tight and shale reservoirs, nonionic surfactants have garnered significant attention due to their remarkable properties. The structure of these surfactants plays a crucial role in determining the characteristics of the oil-water interface, particularly influencing emulsification behavior and crude oil recovery. This study investigates the effect of varying the number of hydrophilic polar groups (n = 10, 20, 30, 50) in octylphenol polyoxyethylene ether (OP-n) on its adsorption behavior at the n-hexadecane-water interface using molecular dynamics simulation. The impact of these variations on interfacial properties was further analyzed through measurements of interfacial tension and observations of emulsion droplet morphology. The study results indicate that variations in the number of hydrophilic polar groups significantly affect interfacial properties. Increasing the number of hydrophilic polar groups led to a notable increase in the thickness of the n-hexadecane or water phase, as well as the thickness of the water or oil layer and the surfactant layer. Moreover, when the number of hydrophilic polar groups reached 20, the OP-n molecules exhibited a more curled conformation at the interface, enhancing their ability to encapsulate water and resulting in a decrease in the diffusion coefficient of the molecules in each phase. Additionally, interfacial tension was found to be positively correlated with the number of hydrophilic polar groups and remained unchanged beyond a certain emulsion diameter. This study provides a theoretical basis and reference data for optimizing surfactant structures to improve crude oil recovery.

Interface engineering to construct heterostructured MoO3/SmMn2O5 for chemical looping oxidative dehydrogenation of ethane

Electronic structure and lattice oxygen in metal oxides play important roles in the chemical looping oxidative dehydrogenation of ethane. Herein, an interface strategy is proposed to tailor electronic structure and activate lattice oxygen of mullite SmMn2O5 via the interface fabrication with MoO3 for enhancing the reactivity of the sample. The optimized 2MoO3/SmMn2O5 oxygen carrier exhibited 50 % ethane conversion and 83.9 % ethylene selectivity higher than that of pure SmMn2O5 and pure MoO3. Density functional theory simulations and characterization results revealed that the interface of MoO3/SmMn2O5 regulated the d-band center, which tailored the adsorption of ethane. Besides, the interface of MoO3/SmMn2O5 also caused the charge transfer from Mn atoms in SmMn2O5 to O atoms in MoO3 and SmMn2O5, leading to a reduction of the Mn-O bond strength and an enhancement in the activity of the lattice oxygen and Oads. This study provides useful insights to regulate electronic structure and activate lattice oxygen of oxygen carrier through interfacial engineering for the practical application of ethane chemical looping oxidative dehydrogenation.

Surface Molding Hydrogel Film Initiated by ZIF-8 with Ethylene Adsorption Performance for Preserving Perishable Fruits.

The quality deterioration of postharvest fruits is greatly influenced by ethylene, leading to food wastage worldwide. Therefore, it is urgent to develop an efficient packaging strategy to reduce ethylene concentration and prolong the shelf life of perishable fruits. In this work, a surface-molding hydrogel film was created using ZIF-8 in combination with carboxymethyl starch (CMS) and carboxymethyl chitosan (CMCS). Specifically, ZIF-8 is first anchored on CMS and then rapidly cross-linked in situ with CMCS, forming ZIF-8@CC on the fruit surface (within 10 s). The perfect tight-fitting effects of ZIF-8@CC were observed on various fruit surfaces with different roughness (Ra: ranges from 102 to 308 nm). ZIF-8@CC could absorb 57.3% endogenous ethylene from bananas, and the interaction mechanism between ethylene and ZIF-8 was studied by molecular dynamics simulations, providing insights into the ethylene adsorption capacity of ZIF-8@CC. Moreover, ZIF-8@CC presented excellent antibacterial properties and achieved satisfactory ultralong preservation effects on both nonclimatic and climatic fruits (12 days for strawberries and 14 days for bananas) at room temperature. Importantly, ZIF-8@CC is easily removed, washed, and degradable. These findings offer an efficient and potential food packing material with multifunctional properties for preserving perishable fruits.

Revving Up a Designed Copper Catecholate Porous Organic Polymer for Its Potent Ethylene Adsorption than Ethane.

The potential to produce high-purity C2H4 has made ethylene-selective adsorbents for ethane (C2H6)/ethylene (C2H4) gas mixture separation appealing as viable substitutes for traditional cryogenic distillation. In this aspect, porous organic polymers (POPs) are anticipated to become the next-generation potential adsorbent due to their easily customizable functions and functional sites suitable for gas separation. This article reports the selective C2H4 adsorption over C2H6 using microporous copper(I)-coordinated POP (Cu@Di-POP) via fine-tuning of the π complexation and pore size. The specially designed adsorbent has the ideal pore size and coordinated Cu(I) ions to form π-complexation with C2H4 molecules, which enabled it to adsorb C2H4 (at 1 bar, 24.9, 18.9, and 13.4 cm3 g-1 at 273, 298, and 323 K, respectively) while significantly reducing C2H6 adsorption (at 1 bar, 16.9, 12.7, and 8.8 cm3 g-1 at 273, 298, and 323 K, respectively). At 1 bar, Cu@Di-POP exhibited IAST selectivities of 6.09, 5.60, and 4.13 for C2H4/C2H6 at 273, 298, and 323 K, respectively, suggesting its C2H4 selective behavior, which was further confirmed from the experimental breakthrough measurement. Furthermore, the computational studies carried out with density functional theory highlighted an enhanced charge distribution leading to dπ-pπ conjugation between C2H4 π-electrons and Cu d-electrons, thereby showing a relatively higher interaction energy of -37.23 kcal/mol with C2H4 as compared to -16.06 kcal/mol with C2H6 gas molecules.

Self-Modification of Dynamic Network Valence Bonds in ZeinNFs via Post-Heat Treatment: Preparation of an Efficient and Environmentally Friendly Ethylene Adsorbent

Self-Modification of Dynamic Network Valence Bonds in ZeinNFs via Post-Heat Treatment: Preparation of an Efficient and Environmentally Friendly Ethylene Adsorbent

Adsorption of ethylene and 1-methylcyclopropene (1-MCP) on Al-doped graphene structure: A DFT study for gas sensing application

Ethylene is the ripening hormone of fruits and vegetables. 1-Methylcyclopropene (1-MCP) is used as the inhibitor of the ethylene actions for extending the postharvest shelf life of the plants. To control the ripening and extending the shelf life of the plants, the adsorption characteristics of ethylene and 1-MCP on Al-doped graphene structure (AlG) were investigated as a gas sensing application by density functional theory (DFT) calculations. The geometric structures were optimized, HOMO and LUMO, energy gap, adsorption energies, the density of states (DOS), electrostatic potential (ESP) and the global reactivities were calculated for different distances between the adsorbed ethylene or 1-MCP and the adsorbent AlG. Chemisorption and physisorption interactions were analyzed. For the chemisorption process of ethylene and 1-MCP on AlG, the adsorption energies were 19.34 kJ/mol and 56.53 kJ/mol, respectively. Whereas for the physisorption process, the adsorption energies of ethylene and 1-MCP were -60.16 kJ/mol and -7.32 kJ/mol, respectively. As a result, it was presented that the AlG structure has sufficient characteristics to be a good adsorbent and a gas sensor of ethylene and 1-MCP.

Enhancement of zein-based films for mango preservation using high-intensity ultrasound and castor oil plasticization

Zein-based films exhibit high efficiency in ethylene adsorption. However, its brittleness limits the practical applications. To address this issue, this study synergizes the plasticizing effects of high-intensity ultrasound (HIU) and castor oil (CO) to reduce the brittleness of zein-based films. The plasticizing mechanism was demonstrated through the formation of new intermolecular hydrogen bonds and electrostatic interactions, as evidenced by fourier transform infrared spectroscopy (FTIR) and zeta potential measurements. The tensile strength of 6 % CO-zein film increased eightfold. Additionally, the freshness of mangoes stored with 6 % CO-zein film significantly improved, extending their shelf life from 5 days to 15 days. Therefore, this study investigated the synergistic plasticization of zein-based films through the addition of CO, based on HIU. It also provides a theoretical basis for fruit packaging.

Molecular simulation on competitive adsorption of ethanol, acetaldehyde and acetic acid on zeolites in humid conditions

Adsorption is a key technique for purifying volatile organic compounds (VOCs) from indoor air. Due to the complexity of multi-component VOCs and humid environment, the competitive adsorption among VOCs under the influence of water vapor remains unclear, which limits adsorbent selection and performance prediction. In this work, adsorption characteristics of typical indoor VOCs (ethanol, acetaldehyde, and acetic acid) on commercial zeolites (BETA-25 and ZSM5-300) under varying humidity were studied through molecular simulation. The simulation based on charge-corrected molecular structures and force field was validated by experiments. The unary, binary and ternary adsorption isotherms of three VOCs were obtained. At both dry and wet conditions, the VOCs with higher polarity shows greater adsorption capacity: acetic acid > ethanol > acetaldehyde. BETA-25 exhibits stronger adsorption on all three gases under dry conditions, while under wet conditions ZSM5-300 shows greater adsorption capacity of ethanol and acetaldehyde with lower polarity as compared to BETA-25. Simulation of adsorption energy and adsorbate density distribution in ternary equilibrium demonstrates the presence of water vapor alters the sorbate-sorbent interaction, particularly for ethanol and acetaldehyde showing stronger adsorption on BETA-25 than on ZSM5-300 at dry conditions but reversely at wet conditions. The lower-silica zeolite favors the adsorption of highly-polar VOC regardless of water, and the higher-silica counterpart with greater hydrophobicity facilitates adsorption of less-polar compounds in competing with water. The findings in this work can provide methodological reference for adsorbent screening and data basis for real VOCs purification applications.

Selective hydrogenation of acetylene over Pd/β-Mo2C catalyst: Experimental and theoretical studies

Molybdenum carbide is a promising support to tune the metal reactivity, which originates from the interaction between metal and support. In this work, Pd/β-Mo2C was prepared using a deposition-precipitation method for selective hydrogenation of acetylene. The high temperature calcination is employed to modulate the interaction between Pd and β-Mo2C. The Pd/β-Mo2C catalyst calcined at 600 °C exhibits significant promotion in selective hydrogenation, which shows 100 % acetylene conversion and 81.4 % ethylene selectivity at 160 °C. The activity promotion originates from the enhanced electronic metal-support interaction, which induces a shift of Pd 3d to higher binding energy. Besides, the Pd species become atomically dispersed after calcination. The changes in geometric and electronic structure suppress the formation of Pd hydrides, which consequently inhibits the excessive hydrogenation capacity of Pd. The structure variation also affects the adsorption of ethylene. No strong adsorbed ethylene (di-σ bonded ethylene) can be identified, which is conducive to the improvement of ethylene selectivity. Density functional theoretical (DFT) calculations confirm that Pd on β-Mo2C is positively charged. The desorption energy of C2H4* (0.78 eV) is significantly lower than that of further hydrogenation (1.45 eV), which explains the improved ethylene selectivity of the calcinated catalyst. The present study indicates calcination is an effective method to tune the activity of Pd/β-Mo2C for reactions beyond selective hydrogenation of acetylene.

Methane Storage and Purification of Natural Gas in Metal-Organic Frameworks.

Natural gas, primarily composed of methane (CH4), represent an excellent choice for a potentially sustainable renewable energy transition. However, the process of compressing and liquefying CH4 for transport and storage typically results in significant energy losses. In addition, in order to optimize its efficacy as a fuel, the CH4 content of natural gas needs to be increased to a level of at least 97 % to ensure its quality and efficiency in various applications. Metal-organic frameworks (MOFs) represent a novel category of porous materials that possess exceptional capability in modifying pore size and chemical environment, making them ideally suited for the storage of CH4 and the adsorption of propane (C3H8), ethane (C2H6), carbon dioxide (CO2), nitrogen (N2), and hydrogen sulfide (H2S) to facilitate the purification process of CH4 from natural gas. In this paper, we systematically summarize the mechanism by which MOF materials facilitate the storage of CH4 and the purification of CH4 from natural gas, leveraging the structural characteristics inherent to MOF materials. The focus of further research should also be directed towards the investigation of CH4 storage by flexible MOFs, the resolution of the trade-off dilemma, and the commercial application of MOFs.

Molecular simulations and deep neural networks‐based interpretable machine learning modelling of reverse adsorptive MOFs for ethane/ethylene separation

AbstractThe thermal decomposition of ethane (C2H6) and the steam cracking of fossil fuels are the main sources of ethylene (C2H4). However, it usually contains 5%–9% of C2H6 residue, which must be reduced to ensure its utilization during polymerization. C2H6 and C2H4 have comparable kinetic diameters and boiling points (C2H6: 4.44, 184.55 K; C2H4: 4.16, 169.42 K), which makes the separation process very difficult. This contribution employs a methodology that integrates machine learning (ML) with Monte Carlo simulations to evaluate the ddmof database to develop a predictive model for separating ethane (C2H6) and ethylene (C2H4). The ML model's input is the metal–organic frameworks (MOFs) chemical and structural descriptors. The grand canonical Monte Carlo (GCMC) simulations in RASPA software were carried out to calculate the equilibrium adsorption of ethane and ethylene. Different ML models such as random forest, decision tree, and deep neural network models have been tested to estimate the selectivity and ethane uptake from the MOF data being generated. Interpretable ML model using SHapley Additive exPlanations (SHAP) is developed for the better understanding of the impact of the parameters on selectivity and ethane uptake. A user‐friendly graphical user interface (GUI) is presented, allowing users to predict the ethane uptake and selectivity of MOFs simply by entering the values of chemical and structural descriptors.

Monte Carlo Calculation of the Thermodynamic Characteristics of Methane and Ethane Adsorption on Graphite

Monte Carlo Calculation of the Thermodynamic Characteristics of Methane and Ethane Adsorption on Graphite

Reversible oxidation of ethylene on ferroelectric BaTiO3(001): An X-ray photoelectron spectroscopy study

Adsorption and desorption of ethylene on BaO-terminated (001) barium titanate are investigated by X-ray photoelectron spectroscopy. Carbon is found in an oxidized state, at a binding energy similar to that resulting from CO adsorption on BaTiO3(001). The amount of carbon adsorbed on the surface is also similar to the case of CO/BaTiO3(001). Upon heating the substrate up to the loss of its ferroelectric polarization, the C 1s signal from the oxidized spectral region vanishes. At the same time, there was no noticeable oxygen depletion of the surface after repeated C2H4 adsorption and desorption. The substrate remains stable after repeated oxidative adsorption and desorption of ethylene. Desorption occurs at different temperatures, depending on the adsorption temperature, which suggests different adsorption geometries: non-dissociated adsorption at high temperature with ethylene bond on two surface oxygen atoms, and locally dissociated adsorption at lower temperatures, in “formaldehyde-like” local configurations.

Acetylene and Ethylene Adsorption during Floating Fe Catalyst Formation at the Onset of Carbon Nanotube Growth and the Effect of Sulfur Poisoning: a DFT Study.

Here, we investigated the adsorption of acetylene and ethylene on iron clusters and nanoparticles, which is a crucial aspect in the nascent phase of carbon nanotube growth by floating catalyst chemical vapor deposition (FCCVD). The effect of sulfur on adsorption was also studied due to its indispensable role in the process and its commonly known impact on metal catalyst poisoning. We performed systematic density functional theory (DFT) computations, considering numerous adsorption configurations and iron particles of various sizes (Fen, n = 3-10, 13, 55). We found that acetylene binds significantly more strongly than ethylene and prefers different adsorption sites. The presence of sulfur decreased the adsorption strength only in the immediate proximity of the adsorbate, suggesting that the effect of sulfur is mainly of steric origin while electronic effects play only a minor role. Higher sulfur coverage of the catalyst surface significantly weakened the binding of acetylene or ethylene. To further investigate this interaction, Bader's atoms in molecules (AIM) analysis and charge density difference (CDD) were used, which showed electron transfer from iron clusters or nanoparticles to the adsorbate molecules. The charge transfer exhibited a decreasing trend as sulfur coverage increased. These results can also contribute to the understanding of other iron-based catalytic processes involving hydrocarbons and sulfur, such as the Fischer-Tropsch synthesis.

Effect analysis on the hydrocarbon adsorption performance enhancement of the different zeolite molecular sieves in the gasoline engine under the cold start process

In this work, the adsorption performance of ZSM-5, Beta-A, and NON zeolites on hydrocarbons emitted from the engine is investigated for selecting the best suited zeolite molecular sieves for hydrocarbon traps during the cold-start phase of the engine. Based on the giant canonical Monte Carlo (MC) method for adsorption simulation, the single-component, multi-component maximum adsorption, adsorption isotherms, adsorption sites of different hydrocarbon molecules on ZSM-5, Beta-A, and NON molecular sieves were investigated by using C2H2, C2H4, C3H6, and C7H8 molecules as probe molecules. The single-component adsorption results showed that for the macromolecular hydrocarbon toluene (C7H8) Beta-A zeolite had the best adsorption effect, followed by ZSM-5 zeolite, and NON had the worst adsorption effect. The adsorption of propylene (C3H6) on ZSM-5 and Beta-A is close to each other, and the adsorption of ethylene (C2H4) and acetylene (C2H2) are much different relative to C3H6 and C7H8. This is due to the fact that the adsorption properties of zeolites are determined by the molecular diameter of the hydrocarbons. The results of multicomponent adsorption showed that the adsorption amounts of multicomponent competitive adsorption were reduced relative to single-component adsorption, but were affected by other components in different ways, from small to large C7H8<C3H6<C2H4<C2H2.

Effect analysis on hydrocarbon adsorption performance of transition metal modified zeolites in the gasoline engine during cold start process using Monte Carlo method

Zeolite molecular sieves are commonly used for adsorption of hydrocarbons(HCs) during cold start phase of gasoline engines. In this work, the adsorption properties of three zeolites modified with three transition metal ions(Fe2+, Cu2+ and Zn2+) were investigated for the HCs adsorption using the Monte Carlo method. Adsorption simulations were carried out with ethylene and propylene as probe molecules or with a mixture of five hydrocarbon and water molecules. The introduction of transition metal cations enhances the local positive electric field within the molecular sieve, enabling it to engage in stronger adsorption interactions with adsorbate molecules, which significantly improves the adsorption performance of the molecular sieve. For single-component adsorption, Zn2+-MFI with a Si/Al ratio of 7 showed the best adsorption of ethylene, with a high adsorption capacity of 149.19 molecules per cell at 298 K, which was 1.47 times higher than that of pure silicon. The enhanced hydrophilicity of the modified zeolite resulted in a substantial increase in the adsorption of water molecules during multicomponent adsorption. The limited adsorption sites and intermolecular competition for adsorption resulted in the occupation of adsorption sites by large hydrocarbons and a decrease in the adsorption of the remaining small molecules.