Adsorption Separation Research Articles

Adsorption characteristics and separation behavior of binder and binderless zeolite LiX Pellets: O2, N2, and CO2

In adsorptive gas separation process design, optimal adsorbent selection acts as a critical factor in process efficiency. This study investigated the adsorption equilibria and kinetics of O2, N2, and CO2 (weak, medium and strong affinity, respectively) and the breakthrough performance of four commercial zeolite LiX pellets (one binderless and three binder zeolite LiX pellets) because the performance of pelletized zeolites becomes different by adding binders and pelletizing methods. The adsorption isotherms at 293–323 K and up to 100 kPa were correlated with the dual-site Langmuir and Sips models. For all adsorbents, the order of adsorption amount and isosteric heat of adsorption was CO2 ≫ N2 > O2. However, differences among the four zeolite pellets were also observed, showing the highest values of the binderless zeolite LiX pellet. Furthermore, the adsorption capacity was 20–25 % smaller for CO2 and 40–50 % smaller of N2 and O2 at 100 kPa compared to pure zeolite LiX powder. According to kinetic analysis using a non-isothermal diffusion model, the adsorption rate of N2 was faster than that of CO2 for all adsorbents, showing the order difference in the low-pressure range. The kinetic difference among the zeolite pellets resulted from the effects of heat of adsorption, heat dissipation, and thermal resistance. The breakthrough performance using N2 and O2 was mainly controlled by the adsorption capacity, showing almost constant breakthrough pattern regardless of the samples. This study suggests that detailed evaluation of pelletized adsorbent is essential before designing adsorptive processes because performance of adsorbent powder would lead to under-design of the process. (255 words)

Preparation of Guanidine-Grafted NH2-MIL-101(Fe)/Polyvinylidene Fluoride Mixed Matrix Membranes for Adsorption of Pb2+ for Isopropanol Purification.

Electronic-grade isopropyl alcohol is widely utilized in the cleaning of semiconductors and microelectronic components. Removing ions like Pb2+ is crucial since the presence of impurities may cause degradation of electronics, increased failure rates, and short circuits. Membrane materials offer a number of advantages in the field of adsorption separation; however, the lack of adsorption sites results in limited adsorption capacity. In the current work, guanidino-grafted NH2-MIL-101(Fe) was incorporated into polyvinylidene fluoride (PVDF) to prepare MOF/PVDF mixed matrix membranes (NM/PVDF) for the removal of Pb2+ from isopropanol. Benefiting from the larger specific surface area and more lone electron pairs in the guanidine group, the Pb2+ adsorption capacity of the as-prepared NM/PVDF membrane was 29.4458 mg/g, which was higher than that of the NH2-MIL-101(Fe)/PVDF membrane (20.9306 mg/g) and the pure PVDF membrane (6.7324 mg/g). The NM/PVDF membrane was able to reduce the concentration of Pb2+ from 500 to 86.73 ppb. This work highlights the potential of guanidine-grafted Fe-based MOFs/PVDF membranes as adsorbents for acquisition of electronic-grade solvents.

Construction of a Methoxy-Functionalized Pillar-Layer Metal-Organic framework for low-concentration SO2 uptake and adsorption separation

We report the synthesis and structural characterization of a novel methoxy (–OCH3) −functionalized pillar-layer metal–organic framework (MOF), denoted as DZU-17 (DZU=Dezhou University), which is isoreticular to Co6-MOF-3. DZU-17 is constructed by integrating a –OCH3 modified bipyridine ligand, 1,4-dipyridine-2,5-dimethoxybenzene (BPB-OCH3), into the framework of Co6-MOF-3. Single-crystal X-ray diffraction analysis confirms that the introduction of the –OCH3 groups effectively partitions the spacious channels of Co6-MOF-3 into more confined spaces within DZU-17. This structural modification results in a significant enhancement in SO2 uptake at low −pressure (P=0.1 bar, 112.7 cm3 g−1) and improved separation capacity for SO2/CO2/N2 mixture under ambient conditions. Our findings underscore the potential of functional group engineering on MOF linkers to modulate pore dimensions and chemical environments, thereby enhancing the frameworks’ performance in gas adsorption and separation processes.

Aromatic pore engineering in microporous metal–organic frameworks for high-production one-step methane purification from ternary alkanes mixtures

The exploitation of competent isolation and purification technology of methane (CH4) is an imperative and challenging task for full utilization of clean natural gas in petrochemical industry. Compared to traditional energy-intensive low-temperature distillation, adsorptive separation using porous metal–organic framework (MOF) materials provides an alternative technique with low energy consumption and high efficiency. In this situation, an aromatic pore engineering strategy in a series of pillar-layered Zn-based MOFs by introducing organic linkers with different degrees of aromatic units was investigated to tune pore size and pore environment for simultaneously removing propane (C3H8) and ethane (C2H6) from C3H8/C2H6/CH4 mixtures. Compared to the other two analogues, i.e. Zn(BDC)(TED)0.5 and Zn(ADC)(TED)0.5, obtained Zn(NDC)(TED)0.5 showed high adsorption capacity for C3H8 (5.18 mmol/g) and C2H6 (5.04 mmol/g) and selectivity for C3H8/CH4 and C2H6/CH4 at 298 K and 1.0 bar. Breakthrough tests proved the three MOFs can effectively separate ternary C3H8/C2H6/CH4 mixtures, and Zn(NDC)(TED)0.5 especially exhibited excellent high-purity CH4 yield of 10.07 mmol/g. Computational simulations showed that suitable pore space and surface aromatic environment in Zn(NDC)(TED)0.5 created beneficial interactions with C3H8 and C2H6 molecules, which ultimately contributed to its favourable adsorption and separation property. This system work provides insights for the development of pore control method in MOF materials for natural gas purification.

Efficient adsorptive separation of Cu(II) from Ph by ZIF-8 constructed with sodium alginate polymer backbone

With the rapid development of industrialization, the removal of heavy metal ions and small organic molecules from wastewater has triggered a hot debate. ZIF-8 was grown on a sodium alginate backbone using an in situ growth technique, the core-shell P-SMG@ZIF-8 was synthesized. It was also characterized by FTIR, XRD, SEM, UV–Vis and XPS, and the optimal conditions and mechanism of adsorption were explored. At pH 2.0, a contact time of 200 min, and 298 K, removal of Cu(II) and Ph up to 80.2 %, 65.6 % by P-SMG@ZIF-8, adsorption behavior consistent with Langmuir model for pseudo-secondary rates, the saturated adsorption of Cu(II) and Ph could reach up to 83.5812 mg/g and 78.1779 mg/g, respectively. And the adsorbed P-SMG@ZIF-8 is easy to separate and reusable, which is a cost-effective and efficient natural product-based adsorption material.

Separation of C6 hydrocarbons on sodium dithionite reduced graphene oxide aerogels

The ability of reduced graphene oxide aerogels (rGOAs) for challenging gas-phase separation was investigated with hexane isomers and benzene (C6 hydrocarbons) using inverse gas chromatography (IGC). For the first, rGOAs were synthesized with sodium dithionite (DTN) as a reductant. Experiments revealed that the most optimal DTN to graphene oxide mass ratio was 2:1, resulting in the highest specific surface area of 432.3 m2 g−1 and the highest degree of graphitization among analyzed samples. C6 hydrocarbon adsorption tests demonstrated the dominant role of the kinetic effect for the adsorption of branched and cyclic hexane isomers - the partition coefficient decreased as the molecule kinetic diameter increased. The contribution of thermodynamic effects was distinguished for molecules with uneven charge distribution. A comparison of the partition coefficient ratios for different pairs of hydrocarbons demonstrated the potential of rGOAs in separating various C6 hydrocarbons. The selectivity, calculated from binary-component adsorption tests of benzene (Bz)/cC6 equimolar mixture, was 13.7, 8.5 and 2.8 for DTN4, DTN2, and DTN1. The research indicates that rGOAs may have potential as adsorbents for the selective separation of hydrocarbons, however, the competitive adsorption and performance at high surface coverages of adsorbates have to be accounted for in further research to assess the applicability of rGOAs reliably.

Integration of deep eutectic solvent with adsorption and membrane-based processes for CO2 capture: An innovative approach

CO2 capture strategies have been implemented to address climate change by reducing CO2 emissions from large-scale sources such as fossil fuel power plants and natural gas upgrading. Deep eutectic solvents (DESs) are a new class of green solvents with good CO2 affinity, simple synthesis steps, inexpensive raw materials, non-toxic and non-volatile properties. For these reasons, they are a promising platform for CO2 capture applications and have tremendous untapped potential to enhance the performance of the adsorption and membrane-based separation processes. Unlike existing reviews which have focused on the functionalities of DESs, as well as the physicochemical and CO2 solubility properties of DESs, this mini-review discusses the integration of DESs with adsorption and membrane processes to evaluate their CO2 separation performance. Moreover, simulation and computational studies on DES-based systems, including confinement in porous solids and membranes, are discussed. Finally, perspectives on developing DES-based adsorbents and DES-based membranes for the CO2 separation field are presented. This review provides insight into the potential of integrating DESs with CO2 capture technologies to enhance the performance of hybrid systems in relation to standalone approaches.

Adsorption of haem by magnetic chitosan microspheres: Optimal conditions, adsorption mechanisms and density functional theory analyses

Magnetic chitosan microspheres (Al@CTS@Fe3O4) were prepared for haem separation via chemical cross-linking of chitosan, Fe3O4 and AlCl3·6H2O. The properties of the Al@CTS@Fe3O4 microspheres were investigated through techniques including XRD, TEM, FTIR, BET analysis, SEM, TG, VSM, XPS and pHpzc analysis. The haem adsorption of Al@CTS@Fe3O4 was optimized via a Box–Behnken design (BBD) with three operating factors: Fe3O4 dose (0.5–1.3 g), AlCl3·6H2O concentration (0.25–1.25 mol/L) and glutaraldehyde dose (2–6 mL). The optimal haem adsorption effect was achieved with 1.1 g of Fe3O4, 0.75 mol/L AlCl3·6H2O, and 3 mL of glutaraldehyde. The adsorption kinetics and isotherms demonstrated that haem adsorption by the Al@CTS@Fe3O4 microspheres was best described by the pseudo-second-order model. The maximum adsorption capacity is 33.875 mg/g at pH 6. After six adsorption–desorption cycles, the removal of haem still reached 53.83 %. The surface adsorption mechanism of haem on Al@CTS@Fe3O4 can be attributed to electrostatic, hydrogen bonding, and n-π interactions. Thermodynamic calculations indicated that the adsorption process is spontaneous, with the microspheres preferentially accepting electrons and haem preferentially providing electrons. Consequently, the Al@CTS@Fe3O4 microspheres exhibit considerable potential as adsorbents for haem separation.

Understanding pore features of pillar-layered MOFs on one-step C2H4 purification from C2H6/C2H4 mixtures

Purification of ethylene from ethane through adsorption separation is a key industrial process in present chemical field, since the similar physical properties of both C2H4 and C2H6 that makes them difficult to separate. Therefore, constructing C2H6-selective adsorbents and clarifying its structure–activity relationship is a very difficult undertaking. In this study, 3D pillar-layered metal organic frameworks (MMOF-kgm (M = Zn, Co, Ni) and NiMOF-sql) with different topologies, kagome and square lattice, were constructed by using the cheap ligands (1,4-benzenedicarboxylic acid and triethylenediamine). The effect of pore features on C2H6/C2H4 separation performance and the separation mechanism were systematically investigated by the above two isomeric MOFs. In particular, NiMOF-kgm with kagome topology provides narrower triangular pore shows notably adsorption of C2H6 over C2H4, which is validated by gas adsorption, IAST selectivity and breakthrough measurements. The selective adsorption mechanisms of MOF with kagome topology were further revealed through DFT calculations. This study provides in-depth insights into optimizing the pore structure of MOFs to enhance C2H6/C2H4 separation performance, offering new design strategies for developing efficient materials for ethane-selective adsorbent for one-step ethylene purification.

Alginate functionalized sugarcane cellulose-based beads to improve methylene blue adsorption from aqueous solution

The study was carried out with the goal of synthesizing composite bead of cellulose, chitosan functionalized by sodium alginate using as an efficient and applicable adsorbent for methylene blue removal. Fabricating parameters of the material synthesis process like cellulose mass, sodium hydroxide concentration, immersing time and sodium alginate concentration were assessed in detail. The dye adsorption performance in water under the influence of pH, contact time, dye initial concentration, the material mass, shaking speed, temperature was also thoroughly evaluated. The results of advanced analyses showed that the beads were successfully synthesized with a rough surface and mesoporous structure. The adsorption isotherm and adsorption kinetics of dye adsorption process exhibited that the process was consistent with the Freundlich adsorption isotherm and the pseudo-second-order kinetic model, indicating a favorable physical adsorption process with multilayer of the dye on the adsorbent surface. The intra-particle diffusion model showed the strong dye adsorption by the beads occurred during the first two and half hours. The adsorbent could maintain its adsorption performance of 86 % for three times of regeneration. Finally, this study provided a recyclable and effective adsorbent for dyes separation from water.

Adsorptive membrane separation for eco-friendly decontamination of chlorpyrifos via biochar-impregnated cellulose acetate mixed matrix membrane.

In this work, the phase inversion approach is used to synthesize a blended mixed matrix membrane from cellulose acetate polymer and sugarcane bagasse biochar. The experiments were carried out to estimate the extent of chlorpyrifos (CPS) pesticide removal. The results showed that the removal rate was more than 99% in making the filtered water suitable enough for domestic use. The physical and functional characteristics of the membranes, such as permeability, and contact angle were identified. The changes in the membrane characteristics were observed using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction both before and after the experimental trials. Experiments were conducted to assess not only the rejection characteristics of CPS, as a function feed concentration, but also the effect co-ions on the rejection used to analyze the composition both before and after filtration. The effects of initial CPS concentration, biochar loading, and co-ions on the membrane were investigated. The membranes showed contact angles between 70° and 97° and a permeability between 0.25 × 1010 m Pa-1 s-1 and 0.31 × 1010 m Pa-1 s-1. The effective removal of CPS from the contaminated aqueous stream was attributed to a combination of adsorptive uptake and membrane-based separation. CPS was found to get adsorbed onto the membrane matrix through an intraparticle diffusion mechanism along with an irreversible monolayer adsorption. The membrane-solute adsorptive interaction was represented by Langmuir isotherm and intraparticle diffusion models with a maximum adsorption capacity of 192.3 mg g-1. The findings indicated the efficacy of biochar-cellulose acetate mixed matrix membrane for sustainable and eco-friendly treatment of chlorpyrifoscontaminated water.

Noble metal-free plasmonic Cu/WO3-x@ZNC bi-functional composite for ciprofloxacin photocatalytic degradation and photothermal water evaporation via visible-infrared exposure

Herein, coupling of noble metal-free plasmonic copper nanoparticles with tungsten suboxide and supporting on zeolite nanoclay (Cu/WO3-x@ZNC) composite will be introduced for bi-functional photocatalytic ciprofloxacin (CIP) degradation and water photothermal evaporation under visible/infrared (Vis/IR) exposure. Reduced band-gap of WO3-x via oxygen vacancies creation and localized surface plasmon resonance (LSPR) formation by Cu nanoparticles contributed significantly the extension and intensification of composite's photo-absorption range. Furthermore, small mesoporous structure of ZNC enhanced CIP adsorption and charge carriers separation where the reported photocatalytic efficiencies were 88.3 and 81.7% upon IR and Vis light exposure respectively. It was evidenced that plasmonic hot electrons (e−.s) and hydroxyl radicals (OH•-) performed the basic functions of the photocatalytic process. At the other side, oxygen vacancies existence, plasmonic effect, and confining thermal characteristics of WO3-x, Cu, and ZNC correspondingly induced water photothermal evaporation with efficiencies up to 97.5 and 72.8% under IR and Vis illumination respectively. This work introduces synthesis of a novel bi-functional photocatalytic-photothermal composite by metal sub-oxide and non-noble metal plasmonic coupling and supporting on naturally-derived carrier for water restoration under broad spectral exposure.

Plant-wide modeling and techno-economic optimization of a low-pressure microwave-assisted ammonia synthesis process with adsorption separation

Ammonia production has traditionally been done by using the Haber-Bosch process, that operates at extremely high pressure (200–300 bar), has a large carbon footprint, and requires significant energy. For ammonia to be used as a hydrogen carrier, it is desired that it is produced by using modular technologies under benign conditions, yet the economics remain commercially viable. This paper investigates a novel technology for ammonia synthesis by using a microwave-assisted low-pressure reactor. Microwave reactors are compact and can be readily modularized and started/shutdown thus making them ideal to be integrated with the electric grid or with regional/local renewable-based electric generation facilities. For separation of unreacted reactants from the product ammonia, if the traditional condensation separation technology used in the high-pressure Haber-Bosch process is used, then the separation process needs to be operated under cryogenic condition thus adversely affecting the economics. A solid sorbent based separation technology is investigated in this paper. A kinetic model for the microwave-catalytic synthesis process is used. An isotherm model is developed for MgCl2–Si adsorbent and used for modeling the dynamic adsorption-desorption cycle. A plant-wide model with heat and mass integration is developed. An economic model is developed and used for economic optimization by using an equation-oriented approach. Since the adsorption-desorption process is dynamic, for techno-economic optimization, a reduced order model for the key performance measures of the adsorption-desorption process as a function of its input and decision variable is developed under cyclic steady-state conditions. For the optimized MW-assisted process, the levelized cost of ammonia is $772/mt as opposed to $808/mt for the conventional Haber-Bosch process for a hydrogen price of $2.07/kg. The MW-assisted process is found to be economically viable in the US market if the hydrogen price is below $4/kg.

Efficient water disinfection against antibiotic-resistant bacteria by visible-light heterogeneous photo-Fenton-like process with atomically dispersed Cu on graphitic carbon nitride as the catalyst

Waterborne microbial contamination poses significant environmental and health risks. Photocatalytic heterogeneous Fenton and Fenton-like processes can offer efficient pathogen removal, with benefits in recycling, solid–liquid separation, and byproduct avoidance. However, their low reaction efficiency and slow kinetics for low-valence metal regeneration are limitations. This study addresses these challenges by incorporating atomically dispersed Cu onto graphitic carbon nitride (g-CN) as a single-atom catalyst (SAC). The Cu atoms are stabilized by pyridinic N atoms through coordination, forming Cu-N4 catalytic sites that enhance photogenerated charge carrier transfer. This leads to a more efficient synergistic photocatalytic-Fenton-like reaction, generating more hydroxyl radicals and achieving effective water disinfection. Results show a 7-log bacterial inactivation of antibiotic-resistant Acinetobacter baumannii within 8 min, surpassing prior photocatalytic-Fenton-like disinfection systems. Density functional theory calculations confirm improved hydrogen peroxide adsorption, electron transport, and electron-hole separation in the Cu-N4 structure. The catalyst’s durability and stability were demonstrated through extensive cycling experiments, ion interference tests, and disinfection trials in various water matrices. Additionally, the Cu-SAC@CN catalyst, loaded onto a polytetrafluoroethylene membrane, achieved a 99% bacterial eradication rate within 20 min. This study provides valuable insights into the potential applications of heterogeneous photocatalytic-Fenton-like systems for efficient eradication of waterborne bacteria.

Ultramicroporous zinc-aminotriazole MOF with customized alkaline pore environments for highly efficient capture of CO2 from flue gas

CO2 capture from natural gas and N2-rich flue gas is essential for improving the utilization of natural resource gases reducing CO2 emission, thereby alleviating the greenhouse effect. However, achieving effective Adsorptive separation of CO2 from CH4, N2, and O2 based on molecular sieving is still challenging and rarely reported, but selectively capturing CO2 places high desires on maximizing separation efficiency. Here, we report a zinc-aminotriazole ultramicroporous metal–organic framework (ZnATZoxH2O), constructed from zinc carbonate, 3-amino-1,2,4-triazole (ATZ), and oxalic acid with water as the only solvent. ZnATZoxH2O features NH2-functionalized and pore channels around 3.6 Å, which preferentially adsorb CO2. This material exhibits high CO2 uptake of 61.9 cm3 g−1 at 298 K and 1 bar and significantly high IAST selectivity for CO2/N2 (>103) and CO2/CH4 (>105) and CO2/O2 (>104). Theoretical GCMC simulations reveal that negatively charged amino groups decorated on the pore channel surface and carboxylic acid in the pore environment enhance the binding affinity over CO2 through electrostatic interactions for preferential capture of CO2. Single-component adsorption experiments and dynamic breakthrough experiments mutually validated the superior separation performance of this material and dynamic column breakthrough tests to produce high dynamic CO2 separation productivity of 2.017 mmol g−1 and 3.4 mmol g−1 for CO2/N2 (15/85), CO2/CH4 (50/50), and 2.26mmol g−1 CO2/N2/O2 (15/80/5). Non-hazardous water as a synthetic solvent to assemble highly stable and efficient CO2-selective materials makes it promising for practical industrial applications.

Fabrication of Cross‐Linked Polyimide Hollow Microspheres With Lightweight, Thermal Resistance and Controllable Size

AbstractPolyimide (PI) hollow microspheres possess lightweight and excellent thermal resistance, which are widely used in microreactors, catalysis, adsorption separation, high‐temperature insulation, and so on. In this manuscript, PI hollow microspheres are fabricated by constructing a crosslinked structure combined with gradient heating. The formation of PI hollow microspheres includes gas nucleation, expansion, and imidization. The PI hollow microspheres size is controlled by adjusting polyester ammonium salts size, and microspheres size is distributed in 309–956 µm. PI hollow microspheres have lightweight, excellent heat resistance and carbonization performance, bulk density, initial decomposition temperature, and weight residue at 800 °C is 87.3–178.6 kg m−3, 533.6 °C and 59.8%. The PI hollow microspheres have potential applications in high‐temperature resistant and multifunctional composite materials preparation. Moreover, this method is simple, efficient, and highly operable, which can be used for large‐scale production of PI hollow microspheres.

Preparation of ultra-light, highly compressible, and biodegradable chitosan porous materials for heavy metal adsorption, dye adsorption and oil-water separation

Chitosan materials are much important in adsorption, separation and water treatment due to their hydrophilicity, biodegradability and easy functionalization. However, they were difficult to form structural materials, which limited its application in engineering. In this paper, a new type of chitosan porous materials was prepared with two-step strategy involving the freezing crosslinking of chitosan with glutaraldehyde to form cryogels, and their subsequent reduction with NaBH4 to transform CN bonds into CN bonds, resulting in remarkable improvement of mechanical property. That is, the strength remained almost unchanged after 80 % deformation. The abundant -NH2 and -OH on the surface of materials, as well as the unique pore structure from cryogels, gave relatively high adsorption capacity for metals and dyes (88.73 ± 4.25 mg·g−1 for Cu(II) and 3261.05 ± 36.10 mg·g−1 for Congo red). The surface hydrophilicity of materials made it possible for selective water permeation with over 95 % separation efficiency for oil-water mixtures. In addition, simple hydrophobic modification using bromotetradecane achieved selective oil permeation with over 96 % separation efficiency for oil-water mixtures. This study not only provides a new strategy to endow chitosan materials with excellent mechanical property, large adsorption capacity and good oil-water separation performance, but also offers environmentally friendly materials for sewage treatment applications.

The Chemistry of Metal-Organic Frameworks for Multicomponent Gas Separation.

Adsorbents-based gas separation technologies are regarded as the potential energy-efficient alternatives towards current thermal-driven methods, and the study on multi-component gas separation is essential to deepen our understanding of the adsorbents for practical use. Relative to the ideal two-component mixtures, both the adsorption behavior and separation mechanisms are obviously more complex in multiple gas mixtures due to their close or even overlapped sizes and properties. The emergence of metal-organic frameworks with controllable pore size and pore chemistry provides the platform for the tailor-made pore structure to satisfy the harsh requirements of multi-component gas separation. This minireview highlights the recent advance of multi-component gas separation using metal-organic frameworks, including multiple impurities removal and selective molecular capture. Combining with the typical cases of hydrocarbon separations (C2, C4, and C8), the detailed discussion about the developed strategies (e.g. self-adaptive binding sites, multiple binding spaces, synergistic binding sites, synergistic sorbent separation technology, gate-opening effect, size and thermodynamic combine effect) that are adaptive to different scenarios would be provided. The review will conclude with our perspective on the existing barriers and the future direction of this topic.

Mind the Gap: The Role of Mass Transfer in Shaped Nanoporous Adsorbents for Carbon Dioxide Capture.

Adsorptive separations by nanoporous materials are major industrial processes. The industrial importance of solid adsorbents is only expected to grow due to the increased focus on carbon dioxide capture technology and energy-efficient separations. To evaluate the performance of an adsorbent and design a separation process, the adsorption thermodynamics and kinetics must be known. However, although diffusion kinetics determine the maximum production rate in any adsorption-based separation, this aspect has received less attention due to the challenges associated with conducting diffusion measurements. These challenges are exacerbated in the study of shaped adsorbents due to the presence of porosity at different length scales. As a result, adsorbent selection typically relies mainly on adsorption properties at equilibrium, i.e., uptake capacity, selectivity and adsorption enthalpy. In this Perspective, based on an extensive literature review on mass transfer of CO2 in nanoporous adsorbents, we discuss the importance and limitations of measuring diffusion in nanoporous materials, from the powder form to the adsorption bed, considering the nature of the process, i.e., equilibrium-based or kinetic-based separations. By highlighting the lack of and discrepancies between published diffusivity data in the context of CO2 capture, we discuss future challenges and opportunities in studying mass transfer across scales in adsorption-based separations.

Techno-Economic Analysis of Ethylene Adsorptive Separation Using Zeolite 13X in Oxidative Coupling of Methane Integrated Process

Techno-Economic Analysis of Ethylene Adsorptive Separation Using Zeolite 13X in Oxidative Coupling of Methane Integrated Process