Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 99
Filtrar
Más filtros

Bases de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
BMC Public Health ; 24(1): 2368, 2024 Aug 31.
Artículo en Inglés | MEDLINE | ID: mdl-39217314

RESUMEN

BACKGROUND: The built environment, as a critical factor influencing residents' cardiovascular health, has a significant potential impact on the incidence of cardiovascular diseases (CVDs). METHODS: Taking Xixiangtang District in Nanning City, Guangxi Zhuang Autonomous Region of China as a case study, we utilized the geographic location information of CVD patients, detailed road network data, and urban points of interest (POI) data. Kernel density estimation (KDE) and spatial autocorrelation analysis were specifically employed to identify the spatial distribution patterns, spatial clustering, and spatial correlations of built environment elements and diseases. The GeoDetector method (GDM) was used to assess the impact of environmental factors on diseases, and geographically weighted regression (GWR) analysis was adopted to reveal the spatial heterogeneity effect of environmental factors on CVD risk. RESULTS: The results indicate that the built environment elements and CVDs samples exhibit significant clustering characteristics in their spatial distribution, with a positive correlation between the distribution density of environmental elements and the incidence of CVDs (Moran's I > 0, p < 0.01). Further factor detection revealed that the distribution of healthcare facilities had the most significant impact on CVDs (q = 0.532, p < 0.01), followed by shopping and consumption (q = 0.493, p < 0.01), dining (q = 0.433, p < 0.01), and transportation facilities (q = 0.423, p < 0.01), while the impact of parks and squares (q = 0.174, p < 0.01) and road networks (q = 0.159, p < 0.01) was relatively smaller. Additionally, the interaction between different built environment elements exhibited a bi-factor enhancement effect on CVDs. In the local analysis, the spatial heterogeneity of different built environment elements on CVDs further revealed the regional differences and complexities. CONCLUSIONS: The spatial distribution of built environment elements is significantly correlated with CVDs to varying degrees and impacts differently across regions, underscoring the importance of the built environment on cardiovascular health. When planning and improving urban environments, elements and areas that have a more significant impact on CVDs should be given priority consideration.


Asunto(s)
Entorno Construido , Enfermedades Cardiovasculares , Análisis Espacial , Humanos , Enfermedades Cardiovasculares/epidemiología , China/epidemiología , Entorno Construido/estadística & datos numéricos , Masculino , Femenino , Persona de Mediana Edad , Anciano , Incidencia , Ciudades , Adulto
2.
Small ; 19(30): e2300417, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37026664

RESUMEN

Post-combustion flue gas (mainly containing 5-40% CO2 balanced by N2 ) accounts for about 60% global CO2 emission. Rational conversion of flue gas into value-added chemicals is still a formidable challenge. Herein, this work reports a ß-Bi2 O3 -derived bismuth (OD-Bi) catalyst with surface coordinated oxygen for efficient electroreduction of pure CO2 , N2, and flue gas. During pure CO2 electroreduction, the maximum Faradaic efficiency (FE) of formate reaches 98.0% and stays above 90% in a broad potential of 600 mV with a long-term stability of 50 h. Additionally, OD-Bi achieves an ammonia (NH3 ) FE of 18.53% and yield rate of 11.5 µg h-1 mgcat -1 in pure N2 atmosphere. Noticeably, in simulated flue gas (15% CO2 balanced by N2 with trace impurities), a maximum formate FE of 97.3% is delivered within a flow cell, meanwhile above 90% formate FEs are obtained in a wide potential range of 700 mV. In-situ Raman combined with theory calculations reveals that the surface coordinated oxygen species in OD-Bi can drastically activate CO2 and N2 molecules by selectively favors the adsorption of *OCHO and *NNH intermediates, respectively. This work provides a surface oxygen modulation strategy to develop efficient bismuth-based electrocatalysts for directly reducing commercially relevant flue gas into valuable chemicals.

3.
Angew Chem Int Ed Engl ; 61(34): e202205453, 2022 08 22.
Artículo en Inglés | MEDLINE | ID: mdl-35700334

RESUMEN

One pot synthesis of 2,5-dimethylfuran (2,5-DMF) from saccharides under mild conditions is of importance for the production of biofuel and fine chemicals. However, the synthesis requires a multitude of active sites and suffers from slow kinetics due to poor diffusion in most composite catalysts. Herein, a metal-acid functionalized 2D metal-organic framework (MOF; Pd/NUS-SO3 H), as an ultrathin nanosheet of 3-4 nm with Lewis acid, Brønsted acid, and metal active sites, was prepared based on the diazo method for acid modification and subsequent metal loading. This new composite catalyst gives substantially higher yields of DMF than all reported catalysts for different saccharides (fructose, glucose, cellobiose, sucrose, and inulins). Characterization suggests that a cascade of reactions including polysaccharide hydrolysis, isomerization, dehydration, and hydrodeoxygenation takes place with rapid molecular interactions.


Asunto(s)
Furanos , Estructuras Metalorgánicas , Catálisis , Dominio Catalítico , Furanos/química , Ácidos de Lewis
4.
J Am Chem Soc ; 143(50): 21294-21301, 2021 Dec 22.
Artículo en Inglés | MEDLINE | ID: mdl-34874721

RESUMEN

Hydrogen (H2) is widely used as a reductant for many hydrogenation reactions; however, it has not been recognized as a catalyst for the acid transformation of active sites on solid surface. Here, we report the H2-promoted hydration of alkenes (such as styrenes and cyclic alkenes) and epoxy alkanes over single-atom Co-dispersed nitrogen-doped carbon (Co-NC) via a transformation mechanism of acid-base sites. Specifically, the specific catalytic activity and selectivity of Co-NC are superior to those of classical solid acids (acidic zeolites and resins) per micromole of acid, whereas the hydration catalysis does not take place under a nitrogen atmosphere. Detailed investigations indicate that H2 can be heterolyzed on the Co-N bond to form Hδ--Co-N-Hδ+ and then be converted into OHδ--Co-N-Hδ+ accompanied by H2 generation via a H2O-mediated path, which significantly reduces the activation energy for hydration reactions. This work not only provides a novel catalytic method for hydration reactions but also removes the conceptual barriers between hydrogenation and acid catalysis.

5.
J Enzyme Inhib Med Chem ; 36(1): 248-256, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33327795

RESUMEN

A novel lipase, SCNL, was isolated from Staphylococcus caprae NCU S6 strain in the study. The lipase was purified to homogeneity with a yield of 6.13% and specific activity of 502.76 U/mg, and its molecular weight was determined to be approximately 87 kDa. SCNL maintained above 80% of its initial activity at a wide range of temperatures (20-50 °C) and pH values (6-11), with an optimal temperature at 40 °C and optimal pH at 9.0 with p-nitrophenyl palmitate as a substrate. SCNL exhibited a higher residual activity than the other staphylococcal lipases in the presence of common enzyme inhibitors and commercial detergents. The lipase activity was enhanced by organic solvents (isooctane, glycerol, DMSO and methanol) and metal ions (Na+, Ba2+, Ca2+, and Mn2+). The Km and Vmax values of SCNL were 0.695 mM and 262.66 s-1 mM-1, respectively. The enzyme showed a preference for p-NP stearate, tributyrin and canola oil. These biochemical features of SCNL suggested that it may be an excellent novel lipase candidate for industrial and biotechnological applications.


Asunto(s)
Lipasa , Staphylococcus/enzimología , Concentración de Iones de Hidrógeno , Lipasa/biosíntesis , Lipasa/aislamiento & purificación , Lipasa/metabolismo , Filogenia , Temperatura
6.
J Am Chem Soc ; 142(21): 9744-9751, 2020 05 27.
Artículo en Inglés | MEDLINE | ID: mdl-32406682

RESUMEN

Isoreticular principle has been employed to realize a flexible-robust metal-organic framework (MOF) with extended pore structure for the adsorptive removal of trace acetylene from ethylene under ambient conditions. The substitution from zinc(II) to copper(II) of high coordination distortion leads to elongated Cu-F bonds that expand the closed pore cavities in the prototypical MOF from 3.5 × 3.9 × 4.1 to 3.6 × 4.3 × 4.2 Å3. The optimal cavity size together with strong binding sites thus endows the new Cu analogue to possess open pore space accessible for trace C2H2 within a substantial low-pressure range while excluding C2H4 molecules, as validated by gas isotherms and single-crystal structure of its partially C2H2-loading phase. In contrast to the Zn prototype, at 298 K and 1.0 bar, the guest-free Cu analogue shows significant C2H2 uptake increase with a total capacity of 4.57 mmol g-1, and gains an over two orders of magnitude jump in IAST selectivity for C2H2/C2H4 (1/99, v/v). These results are higher than the benchmark MOFs for molecular sieving of C2H2/C2H4, leading a high C2H4 productivity of 14.9 mmol g-1. Crystallography studies, molecular modeling, selectivity evaluation, and breakthrough experiments have comprehensively demonstrated this flexible-robust MOF as an efficient adsorbent for C2H2/C2H4 separation.

7.
Molecules ; 23(6)2018 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-29914123

RESUMEN

High-throughput technology has generated large-scale protein interaction data, which is crucial in our understanding of biological organisms. Many complex identification algorithms have been developed to determine protein complexes. However, these methods are only suitable for dense protein interaction networks, because their capabilities decrease rapidly when applied to sparse protein⁻protein interaction (PPI) networks. In this study, based on penalized matrix decomposition (PMD), a novel method of penalized matrix decomposition for the identification of protein complexes (i.e., PMDpc) was developed to detect protein complexes in the human protein interaction network. This method mainly consists of three steps. First, the adjacent matrix of the protein interaction network is normalized. Second, the normalized matrix is decomposed into three factor matrices. The PMDpc method can detect protein complexes in sparse PPI networks by imposing appropriate constraints on factor matrices. Finally, the results of our method are compared with those of other methods in human PPI network. Experimental results show that our method can not only outperform classical algorithms, such as CFinder, ClusterONE, RRW, HC-PIN, and PCE-FR, but can also achieve an ideal overall performance in terms of a composite score consisting of F-measure, accuracy (ACC), and the maximum matching ratio (MMR).


Asunto(s)
Biología Computacional/métodos , Mapeo de Interacción de Proteínas/métodos , Algoritmos , Redes Reguladoras de Genes , Humanos
8.
Langmuir ; 31(36): 9845-52, 2015 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-26258871

RESUMEN

Oxygen-doped microporous carbons were synthesized by chemical activation of polyfuran with KOH or ZnCl2 at 600 and 800 °C. It was found that KOH preserves and ZnCl2 eliminates the O-C functional groups in the activation process. The O-doped carbon activated with KOH at 800 °C exhibited a high CO2 capacity (4.96 mmol g(-1), 273 K, 1 bar) and CH4 adsorption capacity (2.27 mmol g(-1), 273 K, 1 bar). At 298 K and 1 bar, a very high selectivity for separating CO2/N2 (41.7) and CO2/CH4 (6.8) gas mixture pairs was obtained on the O-doped carbon activated with KOH at 600 °C. The excellent separation ability of the O-doped carbons was demonstrated in transient breakthrough simulations of CO2/CH4/N2 mixtures in a fixed bed adsorber. The isosteric adsorption heats of the O-doped carbons were also significantly lower than those of MOF-74 and NaX zeolite. The O-doped microporous carbon adsorbents appear to be a very promising adsorbent for CO2 capture from flue gas, biogas upgrading, and CH4 storage.

9.
Environ Sci Technol ; 49(15): 9364-73, 2015 Aug 04.
Artículo en Inglés | MEDLINE | ID: mdl-26114815

RESUMEN

Hydroquinone and quinone functional groups were grafted onto a hierarchical porous carbon framework via the Friedel-Crafts reaction to develop more efficient adsorbents for the selective capture and removal of carbon dioxide from flue gases and natural gas. The oxygen-doped porous carbons were characterized with scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. CO2, CH4, and N2 adsorption isotherms were measured and correlated with the Langmuir model. An ideal adsorbed solution theory (IAST) selectivity for the CO2/N2 separation of 26.5 (298 K, 1 atm) was obtained on the hydroquinone-grafted carbon, which is 58.7% higher than that of the pristine porous carbon, and a CO2/CH4 selectivity value of 4.6 (298 K, 1 atm) was obtained on the quinone-grafted carbon (OAC-2), which represents a 28.4% improvement over the pristine porous carbon. The highest CO2 adsorption capacity on the oxygen-doped carbon adsorbents is 3.46 mmol g(-1) at 298 K and 1 atm. In addition, transient breakthrough simulations for CO2/CH4/N2 mixture separation were conducted to demonstrate the good separation performance of the oxygen-doped carbons in fixed bed adsorbers. Combining excellent adsorption separation properties and low heats of adsorption, the oxygen-doped carbons developed in this work appear to be very promising for flue gas treatment and natural gas upgrading.


Asunto(s)
Dióxido de Carbono/química , Carbono/química , Hidroquinonas/química , Gas Natural/análisis , Quinonas/química , Adsorción , Difusión , Cinética , Metano/química , Microscopía Electrónica de Rastreo , Nitrógeno/química , Porosidad , Espectroscopía Infrarroja por Transformada de Fourier , Espectrometría Raman , Temperatura , Termodinámica , Factores de Tiempo
10.
ACS Appl Mater Interfaces ; 16(22): 28655-28663, 2024 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-38776450

RESUMEN

Amorphous metal-organic frameworks (aMOFs) are highly attractive for electrocatalytic applications due to their exceptional conductivity and abundant defect sites, but harsh preparation conditions of "top-down" strategy have hindered their widespread use. Herein, the scalable production of aMIL-68(In)-NH2 was successfully achieved through a facile "bottom-up" strategy involving ligand competition with 2-methylimidazole. Multiple in situ and ex situ characterizations reveal that aMIL-68(In)-NH2 evolutes into In/In2O3-x as the genuine active sites during the CO2 electrocatalytic reduction (CO2RR) process. Moreover, the retained amino groups could enhance the CO2 adsorption. As expected, the reconstructed catalyst demonstrates high formate Faradaic efficiency values (>90%) over a wide potential range of 800 mV in a flow cell, surpassing most top-ranking electrocatalysts. Density functional theory calculations reveal that the abundant oxygen vacancies in aMIL-68(In)-NH2 induce more local charges around electroactive sites, thereby promoting the formation of HCOO* intermediates. Furthermore, 16 g of samples can be readily prepared in one batch and exhibit almost identical CO2RR performances. This work offers a feasible batch-scale strategy to design amorphous MOFs for the highly efficient electrolytic CO2RR.

11.
PLoS One ; 19(7): e0306344, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38995906

RESUMEN

As urbanization speeds up, the concept of healthy cities is receiving more focus. This article compares Chongzuo and Nanning in Guangxi with Beijing to assess the development gaps in cities in Guangxi. An indicator system for healthy cities was designed from six dimensions-healthy economy, healthy population, healthy healthcare, healthy environment, healthy facilities, and healthy transportation-and 26 secondary indicators, which were selected from 2005 to 2022, and an improved factor analysis was used to synthesize a healthy city index (HCI). The number of factors was determined by combining characteristic roots and the variance contribution rate, and the HCI was weighted using the entropy-weighted Topsis method. A comprehensive evaluation of the urban health status of these cities was conducted. The results showed that extracting six common factors had the greatest effect, with a cumulative variance contribution rate of 93.83%. Chongzuo city scored higher in the field of healthcare. The healthy environment score of Nanning was relatively high, which may be related to continuous increases in green measures. In terms of the healthy economy dimension, Beijing was far ahead. However, in recent years, the healthy economy level in Chongzuo has increased, and the GDP growth rate has ranked among the highest in Guangxi. In addition, the growth rate of healthy facilities in Nanning was relatively fast and has been greater than that in Chongzuo in recent years, which indicates that the Nanning Municipal Government believes urban construction and municipal supporting facilities are highly important. In terms of healthy transportation, Chongzuo and Nanning scored higher than Beijing. This may be because the transportation in these two cities is convenient and the traffic density is more balanced than that in Beijing, thereby reducing traffic congestion. Chongzuo had the highest score for a healthy population, and a steadily growing population provides the city with stable human resources, which helps promote urban economic and social development. Finally, relevant policy recommendations were put forwards to enhance the health level of the cities.


Asunto(s)
Ciudades , China , Humanos , Análisis Factorial , Urbanización , Transportes , Salud Urbana , Beijing
12.
Adv Mater ; 36(41): e2408681, 2024 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-39155581

RESUMEN

Direct production of high-purity ethylene from acetylene using renewable energy through electrocatalytic semi-hydrogenation presents a promising alternative to traditional thermocatalytic processes. However, the low conversion of acetylene results in a significant amount of acetylene impurities in the product, necessitating additional purification steps. Herein, a tandem electrocatalytic system that integrates acetylene electrolyzer and zinc-acetylene battery units for high-purity ethylene production is designed. The ultrathin CuO nanoribbons with enriched oxygen vacancies (CuO1-x NRs) as electrocatalysts achieve a remarkable 93.2% Faradaic efficiency of ethylene at an ampere-level current density of 1.0 A cm-2 in an acetylene electrolyzer, and the power density reaches 3.8 mW cm-2 in a zinc-acetylene battery under acetylene stream. Moreover, the tandem electrocatalysis system delivers a single-pass acetylene conversion of 99.998% and ethylene selectivity of 96.1% at a high current of 1.4 A. Experimental data and calculations demonstrate that the presence of oxygen vacancies accelerates water dissociation to produce active hydrogen atoms while preventing the over-hydrogenation of ethylene. Furthermore, techno-economic analysis reveals that the tandem system can dramatically reduce the overall ethylene production cost compared to the conventional thermocatalytic processes. A novel strategy for complete acetylene-to-ethylene conversion under mild conditions, establishing a non-petroleum route for the production of ethylene is reported.

13.
Environ Sci Pollut Res Int ; 31(27): 39208-39216, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38814558

RESUMEN

This study presents a theoretical analysis of the adsorption process of pharmaceutical pollutants, specifically acetaminophen (ATP) and diclofenac (DFC), onto activated carbon (AC) derived from avocado biomass waste. The adsorption isotherms of ATP and DFC were analyzed using a multilayer model, which revealed the formation of two to four adsorption layers depending on the temperature of the aqueous solution. The saturation adsorption capacities for ATP and DFC were 52.71 and 116.53 mg/g, respectively. A steric analysis suggested that the adsorption mechanisms of ATP and DFC involved a multi-molecular process. The calculated adsorption energies (ΔE1 and ΔE2) varied between 12.86 and 22.58 kJ/mol, with the highest values observed for DFC removal. Therefore, the adsorption of these organic molecules was associated with physisorption interactions: van der Waals forces and hydrogen bonds. These findings enhance the understanding of the depollution processes of pharmaceutical compounds using carbon-based adsorbents and highlight the potential of utilizing waste biomass for environmental remediation.


Asunto(s)
Carbón Orgánico , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico/química , Contaminantes Químicos del Agua/química , Diclofenaco/química , Preparaciones Farmacéuticas/química , Carbono/química , Acetaminofén/química
14.
ACS Appl Mater Interfaces ; 16(1): 742-751, 2024 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-38110327

RESUMEN

Electrochemical CO2 reduction reaction (eCO2RR) is a viable approach to achieve carbon neutrality. Bismuth-based electrocatalysts demonstrate exceptional selectivity in CO2-to-formate conversion, but their reconstruction mechanisms during the eCO2RR remain elusive. Herein, the reconstruction processes of bismuth molybdate (Bi2MoO6) nanoplates are elucidated during the eCO2RR. Operando and ex situ measurements reveal the in situ partial reduction of Bi2MoO6 to Bi metal, forming Bi@Bi2MoO6 at negative potentials. Meanwhile, CO32- ions in the electrolyte spontaneously exchange with MoO42- in Bi2MoO6. The obtained Bi@Bi2MoO6/Bi2O2CO3 delivers a formate Faradaic efficiency (FE) of 95.2% at -1.0 V. Notably, high formate FEs (>90%) are maintained within a wide 500 mV window. Although computational calculations indicate a higher energy barrier for *OCHO formation on Bi2O2CO3, the prevention of excessive reduction to metal Bi significantly enhances long-term stability. Furthermore, the CO32- ion exchange process occurs in various 2D Bi-containing precatalysts, which should be emphasized in further studies.

15.
Small Methods ; : e2400838, 2024 Jul 29.
Artículo en Inglés | MEDLINE | ID: mdl-39075810

RESUMEN

Molecular sieving of propylene (C3H6) from propane (C3H8) is highly demanded for C3H6 purification. However, delicate control over aperture size to achieve both high C3H6 uptake and C3H6/C3H8 selectivity with low cost remains a significant challenge. Herein, a green and scalable approach is reported for preparing an isomeric CALF-20 adsorbent, termed as NCU-20, using water as the only solvent with a cost of $10 per kilogram. NCU-20 features a contracted pore size (4.2 × 4.7 Å2) compared to CALF-20 (5.2 × 5.7 Å2), which enables molecular sieving of C3H6 (4.16 × 4.65 Å2) from C3H8 (4.20 × 4.80 Å2). Notably, NCU-20 exhibits record-high C3H6 adsorption capacity (94.41 cm3 cm-3) at 298 K and 1.0 bar, outperforming all C3H6/C3H8 molecular sieving adsorbents. The sieving performances of C3H6/C3H8 are well maintained at elevated temperatures. Therefore, a delicate balance between C3H6 adsorption capacity (91.62 cm3 cm-3) and C3H6/C3H8 selectivity (uptake ratio of 22.2) is obtained on NCU-20 at 298 K and 0.5 bar. Furthermore, dynamic breakthrough experiments demonstrate a high productivity of 65.39 cm3 cm-3 for high-purity C3H6 (>99.5%) from an equimolar C3H6/C3H8 gas-mixture.

16.
Adv Mater ; 36(29): e2401693, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38733317

RESUMEN

Flexible metal-organic framework (MOF) adsorbents commonly encounter limitations in removing trace impurities below gate-opening threshold pressures. Topology reconfiguration can fundamentally eliminate intrinsic structural flexibility, yet remains a formidable challenge and is rarely achieved in practical applications. Herein, a solvent-mediated approach is presented to regulate the flexible CuSnF6-dpds-sql (dpds = 4,4''-dipyridyldisulfide) with sql topology into rigid CuSnF6-dpds-cds with cds topology. Notably, the cds topology is unprecedented and first obtained in anion-pillared MOF materials. As a result, rigid CuSnF6-dpds-cds exhibits enhanced C2H2 adsorption capacity of 48.61 cm3 g-1 at 0.01 bar compared to flexible CuSnF6-dpds-sql (21.06 cm3 g-1). The topology transformation also facilitates the adsorption kinetics for C2H2, exhibiting a 6.5-fold enhanced diffusion time constant (D/r2) of 1.71 × 10-3 s-1 on CuSnF6-dpds-cds than that of CuSnF6-dpds-sql (2.64 × 10-4 s-1). Multiple computational simulations reveal the structural transformations and guest-host interactions in both adsorbents. Furthermore, dynamic breakthrough experiments demonstrate that high-purity C2H4 (>99.996%) effluent with a productivity of 93.9 mmol g-1 can be directly collected from C2H2/C2H4 (1/99, v/v) gas-mixture in a single CuSnF6-dpds-cds column.

17.
Nat Commun ; 15(1): 625, 2024 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-38245536

RESUMEN

Olefin/paraffin separations are among the most energy-intensive processes in the petrochemical industry, with ethylene being the most widely consumed chemical feedstock. Adsorptive separation utilizing molecular sieving adsorbents can optimize energy efficiency, whereas the size-exclusive mechanism alone cannot achieve multiple olefin/paraffin sieving in a single adsorbent. Herein, an unprecedented sieving adsorbent, BFFOUR-Cu-dpds (BFFOUR = BF4-, dpds = 4,4'-bipyridinedisulfide), is reported for simultaneous sieving of C2-C4 olefins from their corresponding paraffins. The interlayer spaces can be selectively opened through stronger guest-host interactions induced by unsaturated C = C bonds in olefins, as opposed to saturated paraffins. In equimolar six-component breakthrough experiments (C2H4/C2H6/C3H6/C3H8/n-C4H8/n-C4H10), BFFOUR-Cu-dpds can simultaneously divide olefins from paraffins in the first column, while high-purity ethylene ( > 99.99%) can be directly obtained through the subsequent column using granular porous carbons. Moreover, gas-loaded single-crystal analysis, in-situ infrared spectroscopy measurements, and computational simulations demonstrate the accommodation patterns, interaction bonds, and energy pathways for olefin/paraffin separations.

18.
Nat Commun ; 15(1): 2222, 2024 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-38472257

RESUMEN

Iso-butene (iso-C4H8) is an important raw material in chemical industry, whereas its efficient separation remains challenging due to similar molecular properties of C4 olefins. The ideal adsorbent should possess simultaneous high uptakes for 1,3-butadiene (C4H6) and n-butene (n-C4H8) counterparts, endowing high efficiency for iso-C4H8 separation in adsorption columns. Herein, a sulfate-pillared adsorbent, SOFOUR-DPDS-Ni (DPDS = 4,4'-dipyridyldisulfide), is reported for the efficient iso-C4H8 separation from binary and ternary C4 olefin mixtures. The rigidity in pore sizes and shapes of SOFOUR-DPDS-Ni exerts the molecular sieving of iso-C4H8, while exhibiting high C4H6 and n-C4H8 uptakes. The benchmark Henry's selectivity for C4H6/iso-C4H8 (2321.8) and n-C4H8/iso-C4H8 (233.5) outperforms most reported adsorbents. Computational simulations reveal the strong interactions for C4H6 and n-C4H8. Furthermore, dynamic breakthrough experiments demonstrate the direct production of high-purity iso-C4H8 (>99.9%) from C4H6/iso-C4H8 (50/50, v/v), n-C4H8/iso-C4H8 (50/50, v/v), and C4H6/n-C4H8/iso-C4H8 (50/15/35, v/v/v) gas-mixtures.

19.
Environ Sci Technol ; 47(10): 5474-80, 2013 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-23688273

RESUMEN

Separation of CO2 and N2 from CH4 is significantly important in natural gas upgrading, and capture/removal of CO2, CH4 from air (N2) is essential to greenhouse gas emission control. Adsorption equilibrium and kinetics of CO2, CH4, and N2 on an ordered mesoporous carbon (OMC) sample were systematically investigated to evaluate its capability in the above two applications. The OMC was synthesized and characterized with TEM, TGA, small-angle XRD, and nitrogen adsorption/desorption measurements. Pure component adsorption isotherms of CO2, CH4, and N2 were measured at 278, 298, and 318 K and pressures up to 100 kPa, and correlated with the Langmuir model. These data were used to estimate the separation selectivities for CO2/CH4, CH4/N2, and CO2/N2 binary mixtures at different compositions and pressures according to the ideal adsorbed solution theory (IAST) model. At 278 K and 100 kPa, the predicted selectivities for equimolar CO2/CH4, CH4/N2, and CO2/N2 are 3.4, 3.7, and 12.8, respectively; and the adsorption capacities for CH4 and CO2 are 1.3 and 3.0 mmol/g, respectively. This is the first report of a versatile mesoporous material that displays both high selectivities and large adsorption capacities for separating CO2/CH4, CH4/N2, and CO2/N2 mixtures.


Asunto(s)
Biocombustibles , Dióxido de Carbono/química , Carbono/química , Efecto Invernadero , Metano/química , Nitrógeno/química , Adsorción , Microscopía Electrónica de Transmisión , Termogravimetría , Difracción de Rayos X
20.
Adv Mater ; 35(20): e2210415, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36856017

RESUMEN

Engineering pore environments exhibit great potential in improving gas adsorption and separation performances but require specific means for acetylene/carbon dioxide (C2 H2 /CO2 ) separation due to their identical dynamic diameters and similar properties. Herein, a novel sulfate-pillared MOF adsorbent (SOFOUR-TEPE-Zn) using 1,1,2,2-tetra(pyridin-4-yl) ethene (TEPE) ligand with dense electronegative pore surfaces is reported. Compared to the prototype SOFOUR-1-Zn, SOFOUR-TEPE-Zn exhibits a higher C2 H2 uptake (89.1 cm3 g-1 ), meanwhile the CO2 uptake reduces to 14.1 cm3 g-1 , only 17.4% of that on SOFOUR-1-Zn (81.0 cm3 g-1 ). The high affinity toward C2 H2 than CO2 is demonstrated by the benchmark C2 H2 /CO2 selectivity (16 833). Furthermore, dynamic breakthrough experiments confirm its application feasibility and good cyclability at various flow rates. During the desorption cycle, 60.1 cm3 g-1 C2 H2 of 99.5% purity or 33.2 cm3 g-1 C2 H2 of 99.99% purity can be recovered by stepped purging and mild heating. The simulated pressure swing adsorption processes reveal that 75.5 cm3 g-1 C2 H2 of 99.5+% purity with a high gas recovery of 99.82% can be produced in a counter-current blowdown process. Modeling studies disclose four favorable adsorption sites and dense packing for C2 H2 .

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA