Modeling adsorption equilibria of xylene isomers in a microporous metal–organic framework

Bárcia, Patrick da Silva; Nicolau, Marco Paulo Marques; Gallegos, Jose M.; Chen, Banglin; Rodrigues, Alı́rio E.; Silva, José A.C.

doi:10.1016/j.micromeso.2012.01.033

Cited by 27 publications

(13 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While breakthrough, adsorption, and modeling studies have shown that UiO-66 exhibits a reverse shape selectivity with hydrocarbons and, as a result, retains o -xylene more favorably than m - and p -xylene, a complete picture of the xylene isomer diffusion mechanism has yet to be elucidated. ,,, Our objective is to provide a fundamental understanding of how the interactions between BTX compounds and UiO-66 influence transport and ultimately the ability of UiO-66 to separate these important compounds. The work presented below utilized in situ infrared (IR) spectroscopy within the pristine confines of an ultra-high vacuum (UHV) system to monitor changes in UiO-66 during BTX adsorption, diffusion, and desorption.…”

Section: Introductionmentioning

confidence: 99%

Benzene, Toluene, and Xylene Transport through UiO-66: Diffusion Rates, Energetics, and the Role of Hydrogen Bonding

et al. 2018

View full text Add to dashboard Cite

The high-energy demand of benzene, toluene, and xylene (BTX) separation highlights the need for improved nonthermal separation techniques and materials. Because of their high surface areas, tunable structures, and chemical stabilities, metal–organic frameworks (MOFs) are a promising class of materials for use in more energy efficient, adsorption-based separations. In this work, BTX compounds in the pore environment of UiO-66 were systematically examined using in situ infrared (IR) spectroscopy to understand the fundamental interactions that influence molecular transport through the MOF. Isothermal diffusion experiments revealed BTX diffusivities between 10–8 and 10–12 cm2 s–1, where the rate follows the trend: o-xylene < m-xylene < p-xylene. Corresponding activation energies of diffusion (E diff) were determined to be 44 kJ mol–1 for the xylene isomers and 34 kJ mol–1 for both benzene and toluene, with the diffusion-limiting barrier identified to be molecular passage through the small triangular pore apertures of UiO-66. Furthermore, IR spectroscopy and computational methods showed the formation of two types of hydrogen bonds between BTX molecules and the μ3-OH groups located in the tetrahedral cavities of UiO-66, which indicates that BTX molecules are capable of fully accessing the inner pore environment of the MOF. The molecular-level insight into the diffusion mechanism and energetics of BTX transport through UiO-66 presented in this work provides rich insight for the design of next-generation MOFs for cost-effective separation processes.

show abstract

Section: Introductionmentioning

confidence: 99%

Benzene, Toluene, and Xylene Transport through UiO-66: Diffusion Rates, Energetics, and the Role of Hydrogen Bonding

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Examples of these models include, extended Langmuir model (ELM), ideal adsorption solution theory (IAST), the vacancy solution theory (VST), the statistical thermodynamic model and the Polanyi potential theory. Bárcia et al (2012) used extended dual-site Langmuir model to describe xylene isomer coadsorption on MOF, Zn(BDC)(Dabco) 0.5 . Bae et al (2008) used IAST to model binary adsorption isotherms of CH 4 and CO 2 on MOF (Zn 2 (NDC) 2 (DPNI).…”

Section: Introductionmentioning

confidence: 99%

Multicomponent adsorption of biogas compositions containing CO2, CH4 and N2 on Maxsorb and Cu-BTC using extended Langmuir and Doong–Yang models

et al. 2015

View full text Add to dashboard Cite

Upgrading raw biogas and landfill gas to methane purity [98 % is a vital prerequisite for the utilization of biogas for compressed natural gas pipeline applications. Pressure swing adsorption (PSA) is an industrial separation technology widely used for the separation and purification of methane rich streams from raw biogas and landfill gas. Current PSA technologies make use of differential adsorption of gases on traditional adsorbents, such as zeolites, activated alumina and molecular sieves. In order to evaluate the potential of new adsorbent materials, such as metal-organic frameworks (MOFs) for PSA applications, and for PSA process development, thermodynamic equilibrium adsorption isotherms data of the pure components and mixtures and their adsorption isosteric heats are required. In this work we use extended Langmuir (ELM) model and Doong-Yang multi-component (DYM) adsorption model to predict the isotherms of biogas compositions containing binary and ternary mixtures of CO 2 , CH 4 and N 2 on activated carbon Maxsorb and metal-organic framework Cu-BTC. The model parameters required for predicting the mixture adsorption isotherms using the ELM and DYM are obtained, respectively from the singlesite Langmuir and Dubinin-Astakhov non-linear regression of pure gas isotherms experimentally measured at 298 K and over a pressure range of 0-5 MPa. Predicted data are compared with the experimental binary and ternary mixture adsorption isotherms on Norit R1 extra and Cu-BTC available in the literature. Selectivity and thermodynamic delta-loading of equimolar mixtures of CH 4 and CO 2 on Cu-BTC and Maxsorb are determined from the predicted mixture isotherms and are compared with that of a traditional PSA adsorbent, zeolite 13X.

show abstract

“…The activated carbon, with elevated specific area (1330 m 2 g −1 ), offered the highest adsorption capacity of 676 mg g −1 . However, our natural and modified clays mark adsorption capacities in the same order of silica gel, porous clay heterostructures, metal organic framework, multiwalled carbon nanotubes and calgon carbon . On the other hand, our adsorbents have higher efficiency compared with other materials as morocco and Algeria bentonites, diatomite and faujasite, NaY‐type, KY‐type, BaY‐type zeolites whose adsorption capacities were, respectively, 110, 20, 29, 98, 235, 216 and 189 mg g −1 …”

Section: Resultsmentioning

confidence: 81%

“…The evaluation of the adsorption kinetic results showed that the sorption interactions are likely to be the step governing the diffusion rate. [43] Porous clay heterostructures/25-40°C 381-347 [42] Diatomite/27°C 16-29 [44] Metal organic framework/125-175°C 340-220 [45] Multiwalled carbon nanotubes (CNT)/25°C 173 0.051 [46] CNT(NaOCl)/25°C 414 0.059 [46] GAC (F400, Calgon Carbon Co., Tianjia, China)/25°C 301 0.055 [46] Bentonite Morocco/27-85°C 110-20 0.29-0.265 [20] Faujasite-type zeolite/30-180°C 98-91 1.03-0.095 [47] Bentonite Algeria/25°C 20 0.012 [48] NaY-type zeolite/25°C 235-225 [49] KY-type zeolite/25°C 216-212 [49] …”

Section: Resultsmentioning

confidence: 99%

“…[43] However, our natural and modified clays mark adsorption capacities in the same order of silica gel, porous clay heterostructures, metal organic framework, multiwalled carbon nanotubes and calgon carbon. [42,[44][45][46] On the other hand, our adsorbents have higher efficiency compared with other materials as morocco and Algeria bentonites, diatomite and faujasite, NaY-type, KY-type, BaY-type zeolites whose adsorption capacities were, respectively, 110, 20, 29, 98, 235, 216 and 189 mg g À1 . [29,[46][47][48][49] Thus, modified clay materials (HDTMAC, DDMAC, NaX zeolite), from south Tunisia, presented good removal efficiency, especially in the case of HDTMA clay.…”

Section: Comparison To Other Studiesmentioning

confidence: 87%

See 1 more Smart Citation

Adsorption equilibrium studies for O‐xylene vapour and modified clays system

Dammak

Ouledltaief

Fakhfakh

et al. 2014

Surface & Interface Analysis

View full text Add to dashboard Cite

Tunisian bentonites were used to prepare three modified clays: two organoclays by intercalating respectively didodecyldimethylammoniumbromide (DDMAC) and hexadecyltrimethylammoniumbromide (HDTMAC), and synthesis of NaX zeolite. The X-ray diffraction, infrared and thermogravimetric analyses enabled us to differentiate between the structures obtained. Clay materials systems were used as adsorbent for the investigation of the adsorption isotherms and saturation capacity of O-xylene, a toxic volatile organic compound, by gravimetric method at three different temperatures 20, 30, and 40°C. The absolute values of the volatile organic compound adsorbed amounts in the intercalated clays (604 mg g À1 ) were higher than for the zeolite (296 mg g À1 ). The adsorption isotherms were analysed by the Freundlich and Langmuir equations. The latter was found to describe better the equilibrium adsorption data. Mass transfer coefficient of O-xylene is evaluated using uptake curve method, and all values are in the order of 10 À2 s À1 .

show abstract

Modeling adsorption equilibria of xylene isomers in a microporous metal–organic framework

Cited by 27 publications

References 43 publications

Benzene, Toluene, and Xylene Transport through UiO-66: Diffusion Rates, Energetics, and the Role of Hydrogen Bonding

Benzene, Toluene, and Xylene Transport through UiO-66: Diffusion Rates, Energetics, and the Role of Hydrogen Bonding

Multicomponent adsorption of biogas compositions containing CO2, CH4 and N2 on Maxsorb and Cu-BTC using extended Langmuir and Doong–Yang models

Adsorption equilibrium studies for O‐xylene vapour and modified clays system

Contact Info

Product

Resources

About