Search

Porous materials with d3 electronic configuration open metal sites have been proved to be effective adsorbents for N2 capture and N2/O2 separation. However, the reported materials remain challenging to address the trade‐off between adsorption capacity and selectivity. Herein, we report a robust MOF, MIL‐102Cr, that features two binding sites, can synergistically afford strong interactions for N2 capture. The synergistic adsorption site exhibits a benchmark Qst of 45.0 kJ mol−1 for N2 among the Cr‐based MOFs, a record‐high volumetric N2 uptake (31.38 cm3 cm−3), and highest N2/O2 selectivity (13.11) at 298 K and 1.0 bar. Breakthrough experiments reveal that MIL‐102Cr can efficiently capture N2 from a 79/21 N2/O2 mixture, providing a record 99.99 % pure O2 productivity of 0.75 mmol g−1. In situ infrared spectroscopy and computational modelling studies revealed that a synergistic adsorption effect by open Cr(III) and fluorine sites was accountable for the strong interactions between the MOF and N2. [ABSTRACT FROM AUTHOR]

A robust aluminum‐based metal–organic framework (Al‐MOF) MIL‐120Al with 1D rhombic ultra‐microporous was reported. The nonpolar porous walls composed of para‐benzene rings with a comparable pore size to the kinetic diameter of methane allow it to exhibit a novel thermodynamic‐kinetic synergistic separation of CH4/N2 mixtures. The CH4 adsorption capacity was as high as 33.7 cm3/g (298 K, 1 bar), which is the highest uptake value among the Al‐MOFs reported to date. The diffusion rates of CH4 were faster than N2 in this structure as confirmed by time‐dependent kinetic adsorption profiles. Breakthrough experiments confirm that this MOF can completely separate the CH4/N2 mixture and the separation performance is not affected in the presence of H2O. Theoretical calculations reveal that pore centers with more energetically‐favorable binding sites for CH4 than N2. The results of pressure swing adsorption (PSA) simulations indicate that MIL‐120Al is a potential candidate for selective capture coal‐mine methane. [ABSTRACT FROM AUTHOR]

Various adsorbents for CH4/N2 separation were developed to enrich low‐concentration coal‐mine methane. Most are hydrophilic and cannot treat moist coal‐mine methane. We report for the first time a microporous zeolitic imidazolate framework Co(dcIm)2 (TUT‐100) with superhydrophobic properties for CH4/N2 separation. The CH4 adsorption capacity and CH4/N2 selectivity were as high as 45.29 cm3/cm3 and 6.3 (298 K, 1 bar), respectively, which results from the suitable SOD cage size (0.80 nm). The H2O adsorption was lower than 6.3 cm3/g at 298 K and near saturated pressure due to the hydrophobic group Cl. Breakthrough experiments were carried out to indicate the significant potential for CH4/N2 adsorption separation in a humid environment. The adsorption behavior of the gas mixture on the TUT‐100 was investigated by the Grand Canonical Monte Carlo method and coupled with the experimental data. [ABSTRACT FROM AUTHOR]

Methane (CH4) enrichment and purification is of great significance for increasing the heating value of unconventional natural gas sources and curtailing its effect on global warming. For a long time, commercial adsorbents for CH4 separation have been hampered by low adsorption capacities, sub‐optimal adsorption selectivities, or slow diffusion rates, which have significantly restricted separation productivity. Herein, we report a facile and green seed‐passaging method to fabricate donut‐like macro–meso–micro hierarchical zeolite K‐Chabazite nanocrystal aggregates. This consecutive seed‐inducing method requires no organic template. By utilizing this unique nanocrystallization technique, the CH4 adsorption capacity, gas diffusion rate, and separation productivity of the resultant material are dramatically increased compared with those of commercially available adsorbents, thus setting a new benchmark in CH4/N2 separation. More importantly, production of this adsorbent can be easily scaled‐up to the order of 100 kg using readily available raw materials in this environmentally friendly synthetic route, enabling potential industrial implementation. [ABSTRACT FROM AUTHOR]

Introduction of pore partition agents into hexagonal channels of MIL‐88 type (acs topology) endows materials with high tunability in gas sorption. Here, we report a strategy to partition acs framework into pacs (partitioned acs) crystalline porous materials (CPM). This strategy is based on insertion of in situ synthesized 4,4′‐dipyridylsulfide (dps) ligands. One third of open metal sites in the acs net are retained in pacs MOFs; two thirds are used for pore‐space partition. The Co2V‐pacs MOFs exhibit near or at record high uptake capacities for C2H2, C2H4, C2H6, and CO2 among MOFs. The storage capacity of C2H2 is 234 cm3 g−1 (298 K) and 330 cm3 g−1 (273 K) at 1 atm for CPM‐733‐dps (the Co2V‐BDC form, BDC=1,4‐benzenedicarboxylate). These high uptake capacities are accomplished with low heat of adsorption, a feature desirable for low‐energy‐cost adsorbent regeneration. CPM‐733‐dps is stable and shows no loss of C2H2 adsorption capacity following multiple adsorption–desorption cycles. [ABSTRACT FROM AUTHOR]

Introduction of pore partition agents into hexagonal channels of MIL‐88 type (acs topology) endows materials with high tunability in gas sorption. Here, we report a strategy to partition acs framework into pacs (partitioned acs) crystalline porous materials (CPM). This strategy is based on insertion of in situ synthesized 4,4′‐dipyridylsulfide (dps) ligands. One third of open metal sites in the acs net are retained in pacs MOFs; two thirds are used for pore‐space partition. The Co2V‐pacs MOFs exhibit near or at record high uptake capacities for C2H2, C2H4, C2H6, and CO2 among MOFs. The storage capacity of C2H2 is 234 cm3 g−1 (298 K) and 330 cm3 g−1 (273 K) at 1 atm for CPM‐733‐dps (the Co2V‐BDC form, BDC=1,4‐benzenedicarboxylate). These high uptake capacities are accomplished with low heat of adsorption, a feature desirable for low‐energy‐cost adsorbent regeneration. CPM‐733‐dps is stable and shows no loss of C2H2 adsorption capacity following multiple adsorption–desorption cycles. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The disposal of dredged sediment (DS) is a challenge because of its output and ecotoxicity. Highly toxic Pb(II) enriched in aquatic environment has become a severe global issue. In this study, we developed a new type of ceramsite by co-utilizing of DS and rice husk (RH) to remove Pb(II) from aquatic environments from the viewpoint of "using waste to treat waste." Optimized ceramsite (D9R1-C) sintered at 1120 ℃ with 10% RH additive, exhibited excellent adsorption potential and environmental friendliness. RH addition was an essential component in obtaining ceramsite with richer pore structures, higher polymerization degree and more zeolite serials contents. D9R1-C had selective adsorption to Pb(II), with a maximum adsorption capacity of 18.53 mg/g. The incorporation of adsorption kinetics, isotherms, and thermodynamics, it indicated that adsorption behavior of D9R1-C was codetermined by physisorption and chemisorption. Between the two, physisorption was uppermost. The detailed adsorption mechanism was summarized as follows: (1) physisorption occurred in the intersurface and pore structure of the sorbent; (2) Si-O-T or -OH bond from gismondine or gismondine-like phases combined with Pb(II) to form a stable Si–O–Pb bond; (3) Pb(II) disintegrated the skeleton structure of zeolite serials and then reacted with decomposed units to form Pb-containing minerals such as alamosite. [Display omitted] • Co-utilization of dredged sediment and rice husk for ceramsite production is feasible. • Ceramsite possessed excellent and selective adsorption capacity for lead. • Superior lead adsorption of ceramsite was mainly achieved by the pore structure. • Chemisorption also worked by the interaction between lead and zeolite serials. [ABSTRACT FROM AUTHOR]

In this work, natural biopolymer stemming from lignocellulosic peanut hull biomass was used as a green and low-cost adsorbent to eliminate anionic Congo red (CR) and Cr(VI) ions from aqueous sample. In order to enhance the removal performance, the lignocellulosic biopolymer was subjected to amino-modification by the graft copolymerization of (3-acrylamidopropyl) trimethylammonium chloride and N , N ′-methylenebisacrylamide. The property of the prepared amino-functionalized biopolymer (AFB) was examined through FTIR, TG, SEM, particle size analysis, zeta potential determination and XPS. The adsorption efficacy of AFB for CR and Cr(VI) was tested at different pH, contact time and initial concentration. The kinetic, isotherm and thermodynamics investigations revealed that the uptakes of CR and Cr(VI) were the combination processes of chemical and physical interactions, and both endothermic in nature. The AFB exhibited good reusability without significant loss in adsorption capacity after five consecutive cycles. Mechanistic analysis indicated that the quaternary ammonium groups in AFB contributed a lot to the binding of anionic compounds through electrostatic attraction. In addition, n-π and hydrogen bonding while reduction and coordination were also responsible for the removal of CR and Cr(VI), respectively. The present study provides a favorable strategy for the removal of anionic contaminates in water by using green and sustainable lignocellulosic wastes. • Lignocellulosic biopolymer was amino-modified by graft copolymerization. • The biopolymer exhibited good removal performance for anionic Congo red and Cr(VI). • Chemical and physical interactions were both responsible for the adsorption. • Excellent reusability was observed after five repeated uses. [ABSTRACT FROM AUTHOR]

[Display omitted] • Precise sieving of N 2 and CH 4 was achieved by controlling Si/Al. • The diffusion capacity of NaK-PHI@GI was significantly enhanced. • NaK-PHI@GI showed excellent regeneration ability, and its regeneration could be realized by vacuuming at room temperature. The separation of nitrogen and methane via molecular sieving is often accompanied by mass transfer limitations. Here, we report a NaK-PHI zeolite that not only achieves the precise sieving of nitrogen and methane, but also significantly enhances the diffusion rate of nitrogen. By adjusting the framework composition of the zeolite, the metal cation in the NaK-PHI channel allows smaller nitrogen molecules to enter the channel but blocks methane entry, achieving precise N 2 /CH 4 sieving. A growth inhibitor (GI) was introduced to reduce the crystal size of the NaK-PHI@GI zeolite, and the adsorption kinetics were optimized, resulting in a diffusion rate enhancement of approximately three times; NaK-PHI@GI also exhibited an enhanced nitrogen adsorption capacity (10.5 cm3 g−1) as well as a higher nitrogen/methane uptake ratio (20.9). After multiple cycle-breakthrough tests and regeneration processes involving evacuation and depressurization, NaK-PHI@GI maintained a stable separation capacity, confirming its good recyclability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pure-phase K-MER with controllable Si/Al ratios were synthesized. • The control of the Si/Al ratio enabled precise regulation of the pore size on the sub-angstrom scale. • K-MER-2.7 showed a hindering effect on CH 4 and exhibited outstanding N 2 /CH 4 selectivity. • Breakthrough experiments confirmed the practical feasibility of zeolite separation of N 2 /CH 4 mixtures for the first time. The separation of nitrogen (N 2) and methane (CH 4) is a difficult challenge in the field of natural gas purification, especially the removal of small amounts of N 2. Here, we have successfully developed a series of pure-phase MER zeolites with controllable Si/Al ratios, showing different N 2 trapping effects through an oxalic acid-assisted synergistic fast dynamic crystallization strategy. Among them, K-MER-2.7 showed the most remarkable result, with an N 2 adsorption capacity of up to 0.48 mmol g−1 at 273 K, and an N 2 /CH 4 uptake ratio greater than 10. This was attributed to a narrowing of the pores to form ultra-micropores that limited the uptake of larger sized CH 4 , leading to excellent N 2 /CH 4 selectivity (85.6). Adsorption kinetic experiments and molecular dynamics simulations corroborated the severe hindering effect towards CH 4. Breakthrough experiments with a variety of feed gas compositions at different flow rates confirmed the practical feasibility of applying K-MER-2.7 to separate N 2 /CH 4 gas mixtures. [ABSTRACT FROM AUTHOR]

Three samples with different silica-alumina ratios (40, 500 and 1500) were synthesized to reveal the effect of high silica-alumina ratios on the selectivity of C 2 H 6 /C 2 H 4. The results show that C 2 H 6 /C 2 H 4 selectivity increase as the silica-alumina ratios increases. Both experimental and simulation studies showed that pure silica zeolite (SiO 2 /Al 2 O 3 = 1500) exhibited excellent separation performance for C 2 H 6 /C 2 H 4. It remains unaffected even in the presence of H 2 O, making it a highly promising adsorbent for selective ethane adsorption. [Display omitted] • C 2 H 6 and C 2 H 4 adsorption was investigated on samples with different silica-alumina ratios. • The selectivity of C 2 H 6 /C 2 H 4 increase as the silica-alumina ratios increases. • Pure silica sample exhibits excellent C 2 H 6 /C 2 H 4 separation performance. • The separation performance remains unaffected even in the presence of H 2 O. The economically efficient separation of ethane (C 2 H 6)/ethylene (C 2 H 4) 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 (SiO 2 /Al 2 O 3 = 40, 500, and 1500) of high silica zeolites ZSM-11 on the C 2 H 6 /C 2 H 4 separation performance to develop efficient C 2 H 6 selective adsorbents. The results show that the C 2 H 6 adsorption capacity and C 2 H 6 /C 2 H 4 selectivity of ZSM-11 increase as the silica-alumina ratios increases. The pure silica zeolite (ZSM-11(1500)) exhibits the highest adsorption capacity for C 2 H 6 (59.19 cm3/g) and the highest selectivity for C 2 H 6 /C 2 H 4 (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 C 2 H 6 /C 2 H 4 separation ability. The PSA simulation calculated data demonstrating promising potential for industrial applications. Importantly, this separation performance remains unaffected even in the presence of H 2 O. [ABSTRACT FROM AUTHOR]

Introduction of pore partition agents into hexagonal channels of MIL‐88 type (acs topology) endows materials with high tunability in gas sorption. Here, we report a strategy to partition acs framework into pacs (partitioned acs) crystalline porous materials (CPM). This strategy is based on insertion of in situ synthesized 4,4′‐dipyridylsulfide (dps) ligands. One third of open metal sites in the acs net are retained in pacs MOFs; two thirds are used for pore‐space partition. The Co2V‐pacs MOFs exhibit near or at record high uptake capacities for C2H2, C2H4, C2H6, and CO2 among MOFs. The storage capacity of C2H2 is 234 cm3 g−1 (298 K) and 330 cm3 g−1 (273 K) at 1 atm for CPM‐733‐dps (the Co2V‐BDC form, BDC=1,4‐benzenedicarboxylate). These high uptake capacities are accomplished with low heat of adsorption, a feature desirable for low‐energy‐cost adsorbent regeneration. CPM‐733‐dps is stable and shows no loss of C2H2 adsorption capacity following multiple adsorption–desorption cycles. [ABSTRACT FROM AUTHOR]

Introduction of pore partition agents into hexagonal channels of MIL‐88 type (acs topology) endows materials with high tunability in gas sorption. Here, we report a strategy to partition acs framework into pacs (partitioned acs) crystalline porous materials (CPM). This strategy is based on insertion of in situ synthesized 4,4′‐dipyridylsulfide (dps) ligands. One third of open metal sites in the acs net are retained in pacs MOFs; two thirds are used for pore‐space partition. The Co2V‐pacs MOFs exhibit near or at record high uptake capacities for C2H2, C2H4, C2H6, and CO2 among MOFs. The storage capacity of C2H2 is 234 cm3 g−1 (298 K) and 330 cm3 g−1 (273 K) at 1 atm for CPM‐733‐dps (the Co2V‐BDC form, BDC=1,4‐benzenedicarboxylate). These high uptake capacities are accomplished with low heat of adsorption, a feature desirable for low‐energy‐cost adsorbent regeneration. CPM‐733‐dps is stable and shows no loss of C2H2 adsorption capacity following multiple adsorption–desorption cycles. [ABSTRACT FROM AUTHOR]

Excessive phosphate and tetracycline (TC) contaminants pose a serious risk to human health and the ecological environment. As such exploring the simultaneous adsorption of phosphate and TC is garnering increasing attention. In this study, an efficient lanthanum ferrate magnetic biochar (FLBC) was synthesised from crab shells using an ultrasound-assisted sol–gel method to study its performance and mechanisms for phosphate and TC adsorption in aqueous solutions in mono/bis systems. According to the Langmuir model, the developed exhibited a maximum adsorption capacity of 65.62 mg/g for phosphate and 234.1 mg/g for TC (pH:7.0 ± 0.1, and 25 °C). Further, it exhibited high resistance to interference and pH suitability. In practical swine wastewater applications, whereby the concentrations of phosphate and TC are 37 and 19.97 mg/L, respectively, the proposed material demonstrated excellent performance. In addition, electrostatic adsorption, chemical precipitation and ligand exchange were noted to be the main mechanisms for phosphate adsorption by FLBC, whereas hydrogen bonding and π-π interaction were the main adsorption mechanisms for TC adsorption. Therefore, this study successfully prepared a novel and efficient adsorbent for phosphate and TC. [Display omitted] • Preparation of magnetic biochar by ultrasound-assisted sol-gel method. • Simultaneous adsorption of phosphate and tetracycline (TC). • FLBC could effectively remove P and TC from swine wastewater. [ABSTRACT FROM AUTHOR]

The subtle differences between the xylene isomers make the separation of p-xylene/m-xylene/o-xylene mixtures one of the most challenging tasks in the petrochemical industry. In this study, CAU-1 was used as a platform compound to construct functionalized pore environment with high stability for selective PX adsorption and separation. Single-component adsorption tests and liquid-phase multicomponent adsorption experiments showed that a series of functionalized scaffolds exhibited PX selective adsorption compared to the other two isomers, among them functional groups optimized CAU-1-OH ([Al 8 (OH) 4 (OCH 3) 8 (BDC-OH) 6 ])(BDC = 1,4-benzenedicarboxylate) showed ultra-high PX adsorption capacity (460 mg/g), superior to most reported MOFs. And the PX/MX selectivity of functionalized CAU-1-OH was improved by 18% compared to the original CAU-1. Furthermore, vapor breakthrough experiments on CAU-1-OH showed that it can effectively extract PX from ternary PX/MX/OX mixtures. The fundamental PX selective adsorption mechanism was also visually illustrated using grand canonical Monte Carlo simulation. In addition, the stability of the adsorbent was investigated under different conditions (RH = 40% and 80%, pH = 1–11, different solvents, and high temperatures), and the unchanged PXRD and BET curves indicate that the adsorbent has excellent structural stability. As thus, the large PX adsorption capacity, ultra-high structural stability, and excellent isomer separation performance make these materials good candidates for industrial PX purification from xylene isomers mixture. CAU-1-OH has been prepared on the basis of the ligand functionalization strategy. CAU-1-OH has an ultra-high adsorption capacity, which is higher than most previously reported adsorbents. It can selectively adsorb PX in ternary xylene isomer mixtures, thus achieving selective adsorption separation of PX. It also has excellent stability and is a potential material for industrial separation and purification of PX. [Display omitted] • CAU-1-OH was synthesized by ligand functionalization strategy. • Functional modification strategy significantly improves the adsorption capacity and separation selectivity. • The PX adsorption capacity of CAU-1-OH is superior to most reported MOFs and zeolites. • CAU-1-OH can selectively adsorb PX in dynamic breakthrough experiments. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorbent demonstrates high adsorption capacity and stability at 3–10 pH. • The adsorbent showed selectivity for phosphate. • Iron modified crab shells for phosphate adsorption. • A potential phosphate fertilizer for plant growth. It is important to address the issues of fishery waste treatment and integrated pollutant removal in environmental remediation. In this study, FeSO 4 ·7H 2 O was used for the first time to combine with fishery waste crab shells for the preparation of magnetic biochar in a practical and effective manner (FBC 600) for the selective adsorption of phosphate. FBC 600 was prepared by the one-pot dipping method and the features of its phosphate adsorption were studied. The outcomes demonstrate that pseudo-second-order kinetics and the Langmuir model effectively describe the adsorption process. The maximum adsorption capacity was 149.27 P mg/g. The adsorption capacity of FBC 600 at equilibrium was 2.13 times higher than that of unmodified biochar BC. FBC 600 is pH-adaptable from 3 to 10 and has excellent anti-interference capabilities. FTIR and XPS investigations revealed that electrostatic adsorption, ion exchange, ligand exchange, and chemical precipitation are the primary processes of FBC 600 phosphate adsorption. The P-loaded FBC 600 promoted the germination index (GI: 290.17%-314.51%) and root growth (root length: 1.54 cm-2.27 cm) of maize seeds better than other liquid substrates (20 p mg/L, 100 p mg/L). Therefore, P-loaded FBC 600 is anticipated to have agricultural use as a phosphate fertilizer for plant growth. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanosized IM-5 zeolite is prepared by decreasing the amount of Al source of the precursors. • Nano-IM-5 zeolite has good CH 4 /N 2 adsorption and separation properties. • The presence of mesopores significantly enhances the mass-transfer rate. Reduction of zeolite crystal size from the micron scale to the nanoscale leads to a significant increase in specific surface area, favoring mass-transfer pathways. Here, we have prepared nanoscale (ca. 30–80 nm) IM-5@100 zeolite (IMF type) by a facile strategy of regulating the amount of Al source in the starting gel, and have investigated its CH 4 /N 2 adsorption and separation properties. We found that on decreasing the amount of Al source, the crystal size of the product changed significantly, decreasing from strips of length about 1 μm to irregular nanocrystals. Compared with micron-sized IM-5@50, the mesopore volume of IM-5@100 was increased fourfold from 0.12 cm3/g to 0.49 cm3/g, its external surface area was increased from 38 m2/g to 118 m2/g, and its DFT pore size distribution based on N 2 adsorption/desorption showed a mesopore distribution in the range 5–10 nm. Adsorption kinetics tests showed that nano-IM-5@100 can achieve adsorption equilibrium more swiftly and exhibits better mass-transfer performance. Moreover, IM-5@100 showed good adsorption capacity for CH 4 (17.8 cm3/g) and high IAST selectivity (4.7) for CH 4 /N 2 (50:50, v/v). Breakthrough experiments have indicated that IM-5@100 permits efficient practical separation of CH 4 /N 2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of silver-loaded silicalite-1 adsorbent via in situ silver modification. • Sixteen times greater ethylene adsorption capacity under very low pressure. • Excellent capture trace ethylene ability resistance to water vapor and carbon dioxide. • Effective ethylene removal in actual fruit preservation. The removal of trace C 2 H 4 at high relative humidity has significant importance for the preservation of fruit; however, owing to the severe storage environment and competitive adsorption of high humidity water vapor and carbon dioxide, few suitable adsorbent materials are currently available for this application. Herein, silver-loaded silicalite-1 sorbent (S-1@Ag) was synthesized via an in-situ silver modification method to enhance its interaction with ethylene. By adjusting the amount of silver source to 0.94 wt%, the ethylene uptake of S-1@Ag at P/P 0 of 0.01 was sixteen times greater than unmodified silicalite-1. S-1@Ag prepared using the in-situ method exhibits a uniform distribution of Ag+ that enhances the recognition of ethylene, resulting in an excellent ability to capture ethylene at low pressures. Crucially, S-1@Ag(0.94 %) was unaffected by the presence of water vapor and carbon dioxide in its application environment, and exhibits the best preferential adsorption of ethylene under low pressures. Dynamic breakthrough tests under humid conditions demonstrated that S-1@Ag(0.94 %) captures trace ethylene four times more effectively than S-1@Ag, even under different gas mixtures (C 2 H 4 /N 2 , 0.1/99.9, v/v; C 2 H 4 /CO 2 /N 2 , 0.1/0.1/99.8 and 0.1/1/98.9, v/v/v). Furthermore, banana storage experiments show that S-1@Ag(0.94 %) slows the decay time of the fruit and improves its storage life. [ABSTRACT FROM AUTHOR]

[Display omitted] • Inverse CO 2 /C 2 H 2 separation was achieved via an ultramicroporous MOF (Y-bptc). • Y-bptc exhibits thermodynamic and kinetic selectivity for CO 2 over C 2 H 2. • The µ 3 -OH− anions provide adsorption sites for CO 2 by forming hydrogen bonds. • High-purity C 2 H 2 was directly obtained from CO 2 /C 2 H 2 mixtures in one-step separation. • The modest adsorption heats, great stability and recyclability added suitability. The selective removal of carbon dioxide (CO 2) from acetylene (C 2 H 2) is an important separation process in the petrochemical industry, but is challenging due to the similar physicochemical properties of the two gases. Using CO 2 -selective adsorbents that have preferential affinity for CO 2 over C 2 H 2 in pressure swing adsorption was deemed a promising separation method for the separation of CO 2 /C 2 H 2 mixtures. Herein, we report an ultramicroporous metal-organic framework, Y-bptc, to achieve efficient separation of CO 2 /C 2 H 2 through thermodynamic and kinetic synergetic effects. The unique cage-type structure interconnected by small windows exhibits high adsorption capacity for CO 2 while efficiently impeding adsorption diffusion of C 2 H 2 , which was proved by the single-component equilibrium and kinetic adsorption curves. Grand canonical Monte Carlo (GCMC) molecular calculations further show that the µ 3 -OH− of the framework have a stronger adsorption affinity for CO 2 through forming hydrogen bonds. Breakthrough experiments using Y-bptc as a CO 2 -selective adsorbent proved that high-purity C 2 H 2 (>99%) could be directly produced from one-step separation of CO 2 /C 2 H 2 (1/1, v/v) mixtures, which greatly reduced the separation process and energy consumption. In addition, the structure of Y-bptc due to the high charge density of the Y6 cluster has high stability under humid and high-temperature conditions adding to the application possibility in industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pristine Ca-rich biochar was prepared by pyrolysis of solid digestate of food waste. • The biochar exhibited an extraordinary adsorption capacity for As (69.03 mg/g). • As removal was notably impacted by the pH, and coexisting ions revealed inhibition. • The mechanisms involved oxidation, precipitation, electrostatic attraction, and complexation. Arsenic (As) contamination in water is an international environmental issue. Biochar adsorption is often considered a promising way for removing As from contaminated water due to its low-cost and environmental friendliness. However, the poor adsorption capacity limits the application of pristine biochar, and various modification methods are proposed to improve this shortcoming, which inevitably brings some new environmental problems. Herein, a pristine Ca-rich biochar with excellent As adsorption performance was prepared through one-step pyrolysis of food waste digestate. The results demonstrated that the biochar obtained at 800 °C (CDBC8) exhibited higher specific surface area and absorption capacity of As than biochars prepared at other temperatures, with the maximum As adsorption capacity of 69.03 mg/g, which was much higher than most previously reported pristine biochars and even some modified biochars. This is attributed to the considerable portions of CaO and carbon in CDBC8. The adsorption process was best modeled by Langmuir model and the pseudo-second-order kinetic model. Furthermore, the removal mechanism of As was discussed in-depth. The complexation, precipitation, oxidation, and electrostatic attraction participated in the adsorption, and their contributions were significantly impacted by the pH of the solution. This work presents the great potential of this Ca-rich biochar for wastewater remediation, and also provides a feasible way for the rational utilization of food waste digestate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu(BDC)(DMF) using BDC as a cheap ligand was prepared using a simple and easy-to-scale up method. • Cu(BDC) simultaneously meets the requirements of high C 2 H 6 uptake and excellent ethane/ethylene separation selectivity. • Cu(BDC) exhibits excellent thermal stability and could be stored at room temperature for>1 year. • Cu(BDC) shows excellent separation ability with superior regeneration capability. Separating ethane (C 2 H 6) from ethylene (C 2 H 4) using ethane-selective adsorbents to replace energy-intensive cryogenic distillation technology is an important energy-saving method in the petrochemical industry to obtain high purity C 2 H 4. Limited to the low separation efficiency in current commercial materials, it is very urgent and promising to fabricate such alkane selective adsorbents using cheap ligands and simple synthesis methods, which have characteristics such as stable structure, high C 2 H 6 uptake, and adsorption selectivity. In this work, we have used one of the cheapest ligands (terephthalic acid, H 2 BDC) to prepare Cu(BDC)(DMF) via a simple and easy-to-scale up solvothermal method. The activated Cu(BDC) exposed diamond-shaped one-dimensional pores form a stronger affinity with C 2 H 6 than C 2 H 4 through the double function of C-H∙∙∙π interactions and C-H∙∙∙O hydrogen bonds. Benefiting from the difference in these interactions, Cu(BDC) exhibited a higher adsorption capacity of C 2 H 6 (51.5 cm3/g) compared to C 2 H 4 (45.1 cm3/g) at 1 bar and 298 K, which resulted in high adsorption selectivity (2.0) for the C 2 H 6 /C 2 H 4 mixture (50/50, v/v). Breakthrough experiments indicated that Cu(BDC) successfully achieved the removal of C 2 H 6 from C 2 H 6 /C 2 H 4 (50/50 and 10/90, v/v) mixtures to obtain high purity C 2 H 4 (> 99.99%) using a one-step separation process. When compared with the benchmark materials, Fe 2 (O 2)(dobdc) and NIIC-20, Cu(BDC) had the advantages of much lower preparation cost and enhanced structural stability. These comprehensive properties indicated that Cu(BDC) with a commercially viable price and synthesis process, could be potentially used for the C 2 H 6 removal step during the production of high purity C 2 H 4. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel strategy to prepare zeolite monolith. • Unaltered Al/Si ratio. • Higher specific surface area and pore volume than conventional zeolite pellet. • Enhanced adsorption capacity and separation performance. The Si/Al ratio in zeolite will be altered and the porous structure will be diluted by the traditional silica/aluminum-based binder in the granulation process. Here, a novel zeolite/activated carbon monolith (Z/AC) was prepared by adding coal-tar pitch in silicalite-1 (Si/Al greater than 400), where the pure silica characteristic is well maintained and the coal-tar pitch transforms to porous carbon with a uniform pore structure, in comparison, the aluminum-based bonded silicalite-1 pellet (ABSP) shows a much lower Si/Al ratio of 4.1. As a result, the Z/AC-600 monolith demonstrates a competitive CH 4 adsorption capacity of 23.45 cm3/g, outperforming silicalite-1 powder and ABSP pellet, and the CH 4 /N 2 selectivity is higher than 4.0 at 298 K and 1 bar. The gas-mixture breakthrough experiments demonstrated that Z/AC-600 can effectively separate the CH 4 /N 2 mixtures (20/80 and 50/50; v/v) with dynamic selectivity of 4.2 and 3.9, respectively. Pressure swing adsorption (PSA) simulations further indicate that, by one step enrichment, pristine 50% methane can be enriched to 80% with a recovery of 85%. [ABSTRACT FROM AUTHOR]

• Construction saturated coordination Ti-MOF for alkanes-selective adsorption. • C 2 H 6 and C 2 H 2 can be selective adsorbed simultaneously on the adsorbents. • One-step separate C 2 H 4 from ternary C 2 H 6 /C 2 H 2 /C 2 H 4 mixture. • The synthesized Ti-MOFs show good structural stability for C 2 H 4 purification. The slight differences between ternary components of C 2 hydrocarbons make the separation of C 2 H 2 /C 2 H 6 /C 2 H 4 mixtures one of the most challenging tasks in the petrochemical industry. In this study, a family of saturated coordination titanium-based metal–organic frameworks with high stability is constructed for one-step C 2 H 4 purification. Single component adsorption measurements along with dynamic breakthrough experiments illustrated that these MOFs clearly exhibited large adsorption for C 2 H 2 and C 2 H 6 compared to C 2 H 4 , and could efficiently extract low concentrations of C 2 H 6 and C 2 H 2 from ternary C 2 H 2 /C 2 H 6 /C 2 H 4 mixtures simultaneously. Grand canonical Monte Carlo simulations revealed the stronger affinity of the MOFs toward C 2 H 6 and C 2 H 2 compared to C 2 H 4. Furthermore, the mostly intact structure of these MOFs after various examinations revealed their distinctive stability. The reasonably high C 2 H 6 and C 2 H 2 adsorption capacity, ultrahigh structural stability, and excellent separation performance rendered these materials good candidates for C 2 H 4 purification from C 2 H 2 /C 2 H 6 /C 2 H 4 mixtures in industry. [ABSTRACT FROM AUTHOR]

The development of ethane (C 2 H 6)-selective adsorbents displaying high uptake and selectivity to purify ethylene (C 2 H 4) to obtain polymer-grade raw materials is a meaningful, but challenging process. Tailoring the pore chemistry of a metal-organic framework is an effective strategy used to construct high performance adsorbents. Herein, BUT-10 with a tailored pore environment for tuning the C 2 H 6 adsorption ability has been synthesized via introducing functional sites into UiO-67. The single component gas adsorption capacity, adsorption heat and adsorption selectivity of BUT-10 have been proven to be effectively increased after modifying the pore environment. Computational studies have revealed that the stronger adsorption affinity for C 2 H 6 was achieved via multiple adsorbate-framework interactions in the appropriate pore environment. Breakthrough experiments using BUT-10 as a C 2 H 6 -selective adsorbent have shown that polymer grade C 2 H 4 was directly produced from C 2 H 6 /C 2 H 4 (1/15 v/v) mixtures using a single separation process under ambient conditions. [Display omitted] • The functionalization of UiO-67 has been achieved for efficient ethylene separation. • BUT-10 exhibited a stronger adsorption affinity toward ethane over ethylene. • BUT-10 simultaneously improved the adsorption capacity and C 2 H 6 /C 2 H 4 selectivity. • Polymer-grade ethylene was produced from C 2 H 6 /C 2 H 4 mixtures by one step separation. [ABSTRACT FROM AUTHOR]

• Efficient strategy to down-size zeolite crystal to 50–100 nm. • Higher specific surface area and pore volume than conventional zeolite. • Enhanced adsorption capacity and separation performance. • Boosted diffusion and mass transfer rate. Down-sizing zeolite crystals to achieve enhanced gas adsorption and separation performances is largely unexplored and underestimated. Nano-sized zeolite can expose more adsorption sites and shorten the diffusion path compared to micro-sized counterparts; however, the synthesis of Nano-sized zeolite is still very challenging. Herein, nano-sized ZK-5 is successfully prepared for the first time via the regulation effects of β-cyclodextrin. The crystal size of ZK-5 can be reduced from micron-size (3 μm) to nano-size (50–100 nm), thus the nano-ZK-5 exhibits a superior surface area (370 cm2 g−1) and pore volume (0.22 cm3 g−1) than the micron-sized sample (149 cm2 g−1 and 0.07 cm3 g−1), which may be due to the reduction in crystal size, which in turn leads to more micropores being detected. The CH 4 adsorption capacity on nano-sized sample increased by 64% compared to that of micron-sized ZK-5. Notably, the record-high CH 4 adsorption capacity of 1.34 mmol g−1 at 298 K is obtained on the nano-ZK-5 among the commercial zeolites. The equilibrium adsorption selectivity of CH 4 /N 2 (20/80, v/v) mixed gas is as high as 4.2 (IAST method) at 1 bar and 298 K. The adsorption kinetics experiments have illustrated the boosted gas diffusion and mass transfer rate. Furthermore, the breakthrough experiments have confirmed the practical feasibility of separating various gas-mixtures, such as CH 4 /N 2 (20/80, v/v). [ABSTRACT FROM AUTHOR]

• Extremely simple and fast for the preparation of Ni 2 (BTEC)(bipy) 3 and highly yield. • Exhibits particular two-step adsorption of C 2 H 2 with enhanced adsorption sites. • Ni 2 (BTEC)(bipy) 3 has good regeneration properties and high air stability. • Exhibits very high C 2 H 2 /CO 2 and C 2 H 2 /C 2 H 4 uptake ratio and separation selectivity. Ethylene and acetylene are both important starting materials for the production of polyethylene, vinyl chloride, but-2-yne-1,4-diol, etc. To remove trace acetylene effectively from ethylene and the separation of acetylene from carbon dioxide are particularly challenging in the petrochemical industry. Although catalytic hydrogenation or cryogenic distillation for the separation of such light hydrocarbons is a very mature operation in the current petrochemical industry, it still requires huge capital and energy consumptions. Herein, a metal-organic framework (MOF), [Ni 2 (BTEC)(bipy) 3 ] (H 4 BTEC = 1,2,4,5-benzene tetracarboxylic acid, bipy = 4,4′-bipyridine), has been developed for efficient adsorptive separation of C 2 H 2 from C 2 H 2 /C 2 H 4 or C 2 H 2 /CO 2 mixtures. Ni 2 (BTEC)(bipy) 3 exhibited extraordinary two-step adsorption for C 2 H 2 with the adsorption capacity of 76.8 cm3/g at 298 K and 1 bar, significantly discriminating from C 2 H 4 (7.9 cm3/g) and CO 2 (13.0 cm3/g) in the same condition. The huge adsorption difference of Ni 2 (BTEC)(bipy) 3 between C 2 H 2 and C 2 H 4 /CO 2 resulted in the record high uptake ratio for C 2 H 2 /C 2 H 4 (9.7), C 2 H 2 /CO 2 (5.9) and very high ideal adsorption solution selectivity (104, 33.5) in robust MOFs at 298 K and 1 atm. The excellent separation performance was verified by breakthrough experiments; this material could effectively separate C 2 H 2 /C 2 H 4 or C 2 H 2 /CO 2 mixtures directly to obtain high purity of C 2 H 4 (>99.999%) and CO 2 (>99.99%) in one separation cycle. Furthermore, this material could be easily scaled up to be synthesized at room temperature under mild conditions, indicating the great potential in actual industrial applications. [ABSTRACT FROM AUTHOR]

• Gate-opening pressure difference is used to separate twin-like gases CO 2 and N 2 O. • The performance of flexible MOFs ELM-11, ELM-12 and MIL-53Al for N 2 O-CO 2 separation is researched systematically. • Efficient separation of CO 2 -N 2 O (50%/50%) in the mixture breakthrough at high pressure is carried. • MIL-53Al has great potential to separate N 2 O and CO 2 at 8 bar. N 2 O and CO 2 are two linear molecules, which have almost the same molecular size and similar physical properties (polarizability and quadrupole moment). Therefore, the separation of CO 2 and N 2 O is extremely challenging. Flexible metal organic frameworks exhibit a gate-opening phenomenon for one type of gas molecule, but not for another, thus enabling excellent selectivity for twin-like molecules. In this study, the separation of CO 2 /N 2 O by flexible metal organic frameworks with different structures was studied systematically using a combination of adsorption and breakthrough tests. The results show that the gate-opening pressure of CO 2 is lower than that of N 2 O on Cu(bpy) 2 (BF 4) 2 (ELM-11) and Cu(bpy) 2 (OTf) 2 (ELM-12), which are two-dimensional layered flexible MOFs, whereas N 2 O has a lower gate-opening pressure than CO 2 on MIL-53Al, a three-dimensional breathing structure with an adsorption capacity of up to 8 mmol/g was observed at 298 K and ~5 bar, indicating its good separation properties for N 2 O from CO 2 under high pressure. Breakthrough experiments for N 2 O/CO 2 mixtures confirmed that MIL-53Al is capable of separating N 2 O and CO 2 under the optimized conditions (8 bar), making it a promising material for industrial application. [ABSTRACT FROM AUTHOR]

• SOD-type ZIFs (ZIF-8, ZIF-90 and SIM-1(ZIF-94)) are taken as methane sorbents for CH 4 /N 2 separation. • SIM-1 has the highest CH 4 adsorption capacity and selectivity vs N 2 around reported ZIFs. • The high capacity due to its suitable SOD cage size (0.84 nm) acting as a strong adsorption potential. • Experimental and simulated data of the breakthrough indicate that SIM-1 shows extraordinary industrial value. Methane enrichment from nitrogen is a necessary means for low-quality unconventional natural gas (coal mine methane) extraction, where adsorption-separation technology has become a research hotspot due to its low energy consumption and cost-effectiveness. In this work, three SOD-type ZIFs (ZIF-8, ZIF-90 and SIM-1, the latter also known as ZIF-94) are taken as methane sorbents for CH 4 /N 2 separation. The experimental results show that SIM-1 (ZIF-94) has the highest CH 4 adsorption capacity (1.5 mmol/g, 298 K and 1 bar) and adsorption heat (23.9 kJ/mol), although its surface area is the lowest (597 m2/g). No other known ZIF material has a higher CH 4 adsorption capacity than SIM-1(ZIF-94), although some rare MOF and other porous materials can achieve such a high value. By comparing its CH 4 adsorption capacity and BET surface with ZIF-93 (RHO type), which has the same units as Zn-almeIm, SIM-1(ZIF-94) has a high adsorption capacity of CH 4 due to its suitable SOD cage size (0.84 nm) acting as a strong adsorption potential. Indeed, excellent enrichment–separation of the CH 4 /N 2 mixture (30:70 and 50:50, v/v) with a high adsorption selectivity of 7.0 (IAST) rarely occurs for sorbents at room temperature and ambient pressure. Both the experimental and simulated data of the gas mixtures indicate that SIM-1 (ZIF-94) has excellent capability for enriching and removing nitrogen from methane, and it shows extraordinary industrial value. [ABSTRACT FROM AUTHOR]