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Lei C, Erlebach A, Brivio F, Grajciar L, Tošner Z, Heard CJ, Nachtigall P. The need for operando modelling of 27Al NMR in zeolites: the effect of temperature, topology and water. Chem Sci 2023; 14:9101-9113. [PMID: 37655014 PMCID: PMC10466278 DOI: 10.1039/d3sc02492j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 08/02/2023] [Indexed: 09/02/2023] Open
Abstract
Solid state (ss-) 27Al NMR is one of the most valuable tools for the experimental characterization of zeolites, owing to its high sensitivity and the detailed structural information which can be extracted from the spectra. Unfortunately, the interpretation of ss-NMR is complex and the determination of aluminum distributions remains generally unfeasible. As a result, computational modelling of 27Al ss-NMR spectra has grown increasingly popular as a means to support experimental characterization. However, a number of simplifying assumptions are commonly made in NMR modelling, several of which are not fully justified. In this work, we systematically evaluate the effects of various common models on the prediction of 27Al NMR chemical shifts in zeolites CHA and MOR. We demonstrate the necessity of operando modelling; in particular, taking into account the effects of water loading, temperature and the character of the charge-compensating cation. We observe that conclusions drawn from simple, high symmetry model systems such as CHA do not transfer well to more complex zeolites and can lead to qualitatively wrong interpretations of peak positions, Al assignment and even the number of signals. We use machine learning regression to develop a simple yet robust relationship between chemical shift and local structural parameters in Al-zeolites. This work highlights the need for sophisticated models and high-quality sampling in the field of NMR modelling and provides correlations which allow for the accurate prediction of chemical shifts from dynamical simulations.
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Affiliation(s)
- Chen Lei
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague 128 43 Prague 2 Czech Republic
| | - Andreas Erlebach
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague 128 43 Prague 2 Czech Republic
| | - Federico Brivio
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague 128 43 Prague 2 Czech Republic
| | - Lukáš Grajciar
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague 128 43 Prague 2 Czech Republic
| | - Zdeněk Tošner
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague 128 43 Prague 2 Czech Republic
| | - Christopher J Heard
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague 128 43 Prague 2 Czech Republic
| | - Petr Nachtigall
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague 128 43 Prague 2 Czech Republic
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Zhakisheva B, José Gutiérrez-Sevillano J, Calero S. AMMONIA AND WATER IN ZEOLITES: EFFECT OF ALUMINUM DISTRIBUTION ON THE HEAT OF ADSORPTION. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.122564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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3
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Deplano G, Signorile M, Crocellà V, Porcaro NG, Atzori C, Solemsli BG, Svelle S, Bordiga S. Titration of Cu(I) Sites in Cu-ZSM-5 by Volumetric CO Adsorption. ACS APPLIED MATERIALS & INTERFACES 2022; 14:21059-21068. [PMID: 35482942 PMCID: PMC9100488 DOI: 10.1021/acsami.2c03370] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 04/18/2022] [Indexed: 06/14/2023]
Abstract
Cu-exchanged zeolites are widely studied materials because of their importance in industrial energetic and environmental processes. Cu redox speciation lies at the center of many of these processes but is experimentally difficult to investigate in a quantitative manner with regular laboratory equipment. This work presents a novel technique for this purpose that exploits the selective adsorption of CO over accessible Cu(I) sites to quantify them. In particular, isothermal volumetric adsorption measurements are performed at 50 °C on a series of opportunely pre-reduced Cu-ZSM-5 to assess the relative fraction of Cu(I); the setup is fairly simple and only requires a regular volumetric adsorption apparatus to perform the actual measurement. Repeatability tests are carried out on the measurement and activation protocols to assess the precision of the technique, and the relative standard deviation (RSD) obtained is less than 5%. Based on the results obtained for these materials, the same CO adsorption protocol is studied for the sample using infrared spectroscopy, and a good correlation is found between the results of the volumetric measurements and the absorbance of the peak assigned to the Cu(I)-CO adducts. A linear model is built for this correlation, and the molar attenuation coefficient is obtained, allowing for spectrophotometric quantification. The good sensitivity of the spectrophotometric approach and the precision and simplicity of the volumetric approach form a complementary set of tools to quantitatively study Cu redox speciation in these materials at the laboratory scale, allowing for a wide range of Cu compositions to be accurately investigated.
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Affiliation(s)
- Gabriele Deplano
- Department
of Chemistry, NIS and INSTM Reference Centre, Università di Torino, Via P. Giuria 7-10125 and Via G. Quarello 15/A, 10135 Torino, TO, Italy
| | - Matteo Signorile
- Department
of Chemistry, NIS and INSTM Reference Centre, Università di Torino, Via P. Giuria 7-10125 and Via G. Quarello 15/A, 10135 Torino, TO, Italy
| | - Valentina Crocellà
- Department
of Chemistry, NIS and INSTM Reference Centre, Università di Torino, Via P. Giuria 7-10125 and Via G. Quarello 15/A, 10135 Torino, TO, Italy
| | - Natale Gabriele Porcaro
- Department
of Chemistry, NIS and INSTM Reference Centre, Università di Torino, Via P. Giuria 7-10125 and Via G. Quarello 15/A, 10135 Torino, TO, Italy
| | - Cesare Atzori
- Department
of Chemistry, NIS and INSTM Reference Centre, Università di Torino, Via P. Giuria 7-10125 and Via G. Quarello 15/A, 10135 Torino, TO, Italy
| | - Bjørn Gading Solemsli
- SMN
Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N-0315 Oslo, NO, Norway
| | - Stian Svelle
- SMN
Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N-0315 Oslo, NO, Norway
| | - Silvia Bordiga
- Department
of Chemistry, NIS and INSTM Reference Centre, Università di Torino, Via P. Giuria 7-10125 and Via G. Quarello 15/A, 10135 Torino, TO, Italy
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Abstract
AbstractNanoporous solids are ubiquitous in chemical, energy, and environmental processes, where controlled transport of molecules through the pores plays a crucial role. They are used as sorbents, chromatographic or membrane materials for separations, and as catalysts and catalyst supports. Defined as materials where confinement effects lead to substantial deviations from bulk diffusion, nanoporous materials include crystalline microporous zeotypes and metal–organic frameworks (MOFs), and a number of semi-crystalline and amorphous mesoporous solids, as well as hierarchically structured materials, containing both nanopores and wider meso- or macropores to facilitate transport over macroscopic distances. The ranges of pore sizes, shapes, and topologies spanned by these materials represent a considerable challenge for predicting molecular diffusivities, but fundamental understanding also provides an opportunity to guide the design of new nanoporous materials to increase the performance of transport limited processes. Remarkable progress in synthesis increasingly allows these designs to be put into practice. Molecular simulation techniques have been used in conjunction with experimental measurements to examine in detail the fundamental diffusion processes within nanoporous solids, to provide insight into the free energy landscape navigated by adsorbates, and to better understand nano-confinement effects. Pore network models, discrete particle models and synthesis-mimicking atomistic models allow to tackle diffusion in mesoporous and hierarchically structured porous materials, where multiscale approaches benefit from ever cheaper parallel computing and higher resolution imaging. Here, we discuss synergistic combinations of simulation and experiment to showcase theoretical progress and computational techniques that have been successful in predicting guest diffusion and providing insights. We also outline where new fundamental developments and experimental techniques are needed to enable more accurate predictions for complex systems.
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Serra RM, de Vilhena FS, Gutierrez LB, Júnior JMS, Ferreira GB, dos Santos TC, Ronconi CM, de Carneiro JWM, Boix AV. Experimental and theoretical investigation of the Na+ → Li+ cation exchange in mordenite and its effect on CO2 adsorption properties. ADSORPTION 2021. [DOI: 10.1007/s10450-020-00288-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Heard CJ, Grajciar L, Uhlík F, Shamzhy M, Opanasenko M, Čejka J, Nachtigall P. Zeolite (In)Stability under Aqueous or Steaming Conditions. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2003264. [PMID: 32780912 DOI: 10.1002/adma.202003264] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/30/2020] [Indexed: 06/11/2023]
Abstract
Zeolites are among the most environmentally friendly materials produced industrially at the Megaton scale. They find numerous commercial applications, particularly in catalysis, adsorption, and separation. Under ambient conditions aluminosilicate zeolites are stable when exposed to water or water vapor. However, at extreme conditions as high temperature, high water vapor pressure or increased acidity/basicity, their crystalline framework can be destroyed. The stability of the zeolite framework under aqueous conditions also depends on the concentration and character of heteroatoms (other than Al) and the topology of the zeolite. The factors critical for zeolite (in)stability in the presence of water under various conditions are reviewed from the experimental as well as computational sides. Nonreactive and reactive interactions of water with zeolites are addressed. The goal of this review is to provide a comparative overview of all-silica zeolites, aluminosilicates and zeolites with other heteroatoms (Ti, Sn, and Ge) when contacted with water. Due attention is also devoted to the situation when partial zeolite hydrolysis is used beneficially, such as the formation of hierarchical zeolites, synthesis of new zeolites or fine-tuning catalytic or adsorption characteristics of zeolites.
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Affiliation(s)
- Christopher James Heard
- Department of Physical and Macromolecular Chemistry & Charles University Center of Advanced Materials, Faculty of Science, Charles University, Hlavova 8, Prague 2, Prague, 128 43, Czech Republic
| | - Lukáš Grajciar
- Department of Physical and Macromolecular Chemistry & Charles University Center of Advanced Materials, Faculty of Science, Charles University, Hlavova 8, Prague 2, Prague, 128 43, Czech Republic
| | - Filip Uhlík
- Department of Physical and Macromolecular Chemistry & Charles University Center of Advanced Materials, Faculty of Science, Charles University, Hlavova 8, Prague 2, Prague, 128 43, Czech Republic
| | - Mariya Shamzhy
- Department of Physical and Macromolecular Chemistry & Charles University Center of Advanced Materials, Faculty of Science, Charles University, Hlavova 8, Prague 2, Prague, 128 43, Czech Republic
| | - Maksym Opanasenko
- Department of Physical and Macromolecular Chemistry & Charles University Center of Advanced Materials, Faculty of Science, Charles University, Hlavova 8, Prague 2, Prague, 128 43, Czech Republic
| | - Jiří Čejka
- Department of Physical and Macromolecular Chemistry & Charles University Center of Advanced Materials, Faculty of Science, Charles University, Hlavova 8, Prague 2, Prague, 128 43, Czech Republic
| | - Petr Nachtigall
- Department of Physical and Macromolecular Chemistry & Charles University Center of Advanced Materials, Faculty of Science, Charles University, Hlavova 8, Prague 2, Prague, 128 43, Czech Republic
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7
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Adsorption and separation of CO 2 from N 2 -rich gas on zeolites: Na-X faujasite vs Na-mordenite. J CO2 UTIL 2017. [DOI: 10.1016/j.jcou.2017.03.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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8
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de S. Vilhena F, Serra RM, Boix AV, Ferreira GB, de M. Carneiro JW. DFT study of Li+ and Na+ positions in mordenites and hydration stability. COMPUT THEOR CHEM 2016. [DOI: 10.1016/j.comptc.2016.07.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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Coudert FX, Fuchs AH. Computational characterization and prediction of metal–organic framework properties. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2015.08.001] [Citation(s) in RCA: 166] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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11
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Bikaï J, Limousy L, Dutournié P, Josien L, Blel W. Stabilisation of the water permeability of mineral ultrafiltration membranes: An empirical modelling of surface and pore hydration. CR CHIM 2015. [DOI: 10.1016/j.crci.2014.09.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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12
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Joos L, Swisher JA, Smit B. Molecular simulation study of the competitive adsorption of H2O and CO2 in zeolite 13X. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:15936-15942. [PMID: 24313865 DOI: 10.1021/la403824g] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The presence of H2O in postcombustion gas streams is an important technical issue for deploying CO2-selective adsorbents. Because of its permanent dipole, H2O can interact strongly with materials where the selectivity for CO2 is a consequence of its quadrupole interacting with charges in the material. We performed molecular simulations to model the adsorption of pure H2O and CO2 as well as H2O/CO2 mixtures in 13X, a popular zeolite for CO2 capture processes that is commercially available. The simulations show that H2O reduces the capacity of these materials for adsorbing CO2 by an order of magnitude and that at the partial pressures of H2O relevant for postcombustion capture, 13X will be essentially saturated with H2O .
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Affiliation(s)
- Lennart Joos
- Department of Chemical and Biomolecular Engineering, University of California , Berkeley, California 94720, United States
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13
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Castillo JM, Silvestre-Albero J, Rodriguez-Reinoso F, Vlugt TJH, Calero S. Water adsorption in hydrophilic zeolites: experiment and simulation. Phys Chem Chem Phys 2013; 15:17374-82. [DOI: 10.1039/c3cp52910j] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Navrotsky A, Trofymluk O, Levchenko AA. Thermochemistry of microporous and mesoporous materials. Chem Rev 2009; 109:3885-902. [PMID: 19637927 DOI: 10.1021/cr800495t] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alexandra Navrotsky
- Peter A. Rock Thermochemistry Laboratory, University of California at Davis, Davis, California 95616, USA.
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15
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Coudert FX, Cailliez F, Vuilleumier R, Fuchs AH, Boutin A. Water nanodroplets confined in zeolite pores. Faraday Discuss 2009; 141:377-98; discussion 443-65. [DOI: 10.1039/b804992k] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Krokidas P, Skouras E, Nikolakis V, Burganos V. Simulated annealing effects on Na-FAU crystal reconstruction and sorption efficiency. MOLECULAR SIMULATION 2008. [DOI: 10.1080/08927020802208950] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- P. Krokidas
- a Foundation for Research and Technology Hellas , Institute of Chemical Engineering and High Temperature Chemical Processes , Patras, Greece
- b Department of Materials Science , University of Patras , Patras, Greece
| | - E.D. Skouras
- a Foundation for Research and Technology Hellas , Institute of Chemical Engineering and High Temperature Chemical Processes , Patras, Greece
| | - V. Nikolakis
- a Foundation for Research and Technology Hellas , Institute of Chemical Engineering and High Temperature Chemical Processes , Patras, Greece
| | - V.N. Burganos
- a Foundation for Research and Technology Hellas , Institute of Chemical Engineering and High Temperature Chemical Processes , Patras, Greece
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17
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18
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Henn F, Durand C, Cerepi A, Brosse E, Giuntini JC. DC conductivity, cationic exchange capacity, and specific surface area related to chemical composition of pore lining chlorites. J Colloid Interface Sci 2007; 311:571-8. [PMID: 17433348 DOI: 10.1016/j.jcis.2007.02.062] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Revised: 02/21/2007] [Accepted: 02/21/2007] [Indexed: 11/16/2022]
Abstract
Low resistivity in argillaceous sandstone reservoirs may be attributed either to the effect of microporosity, or to specific effects due to intrinsic clays' conducting properties or to other conducting minerals. In order to distinguish these effects, cation exchange capacity, specific surface areas, and dc conductivity of various pore lining chlorite-bearing sandstones from different hydrocarbon reservoir measurements are investigated. Cation exchange capacity and specific surface area are measured on whole rocks as well as on size-separated fractions. Both sets of values are low, in agreement with the structural and textural observations. The conductivity of these chlorites, measured in air conditions and after dehydration, is investigated by means of complex impedance spectroscopy on size-separated fractions as a function of temperature and compared to that of reference clays. The results show a large influence of moisture, applied electric field frequency, and temperature on the electrical properties. The magnitude of the dehydrated clays' conductivity is such that its influence on the conductivity of argillaceous sandstone is lower than that related to the presence of water or brine by several orders of magnitude. The dc conductivity and the related activation energy of the dehydrated samples appear to be related to the chemical composition of the clays. More specifically, a clear correlation occurs with the electrical charges of the clay network, that is to say with the location, i.e., tetrahedral or octahedral sites, of the substituting trivalent elements.
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Affiliation(s)
- François Henn
- Laboratoire de Physicochimie de la Matière Condensée, UMR 5617 CNRS, Université Montpellier II, Place Eugène Bataillon, 34095 Montpellier cedex 5, France
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19
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Maurin G, Llewellyn P, Poyet T, Kuchta B. Influence of extra-framework cations on the adsorption properties of X-faujasite systems: microcalorimetry and molecular simulations. J Phys Chem B 2007; 109:125-9. [PMID: 16850994 DOI: 10.1021/jp0461753] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Isotherms and differential enthalpies of adsorption are obtained for nitrogen at ambient temperature on monovalent (Li(+), Na(+), K(+)) and divalent (Ca(2+), Ba(2+), Sr(2+), Mn(2+)) substituted X-faujasite systems by microcalorimetry measurements. These experimental data are compared with those obtained by combining grand canonical Monte Carlo simulations and newly derived force fields for describing the interactions between the extra-framework cations and the adsorbates obtained from a simple model based only on the intrinsic properties of the cations. It is the first time that such good qualitative agreement is reported between experiment and simulation for a series of both monovalent and divalent cations.
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Affiliation(s)
- G Maurin
- Laboratoire MADIREL, UMR CNRS 6121, Université de Provence, Centre St Jérôme, Av. Escadrille Normandie Niemen, 13397 Marseille Cedex 20.
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20
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Ruiz-Salvador AR, Almora-Barrios N, Gómez A, Lewis DW. Interplay of water, extra-framework cations and framework atoms in the structure of low-silicazeolites: the case of the natural zeolite Goosecreekite as studied by computer simulation. Phys Chem Chem Phys 2007; 9:521-32. [PMID: 17216068 DOI: 10.1039/b607030b] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Computational methods are described that model accurately the structure of hydrated Ca-bearing zeolites. Using Goosecreekite as a model system we probe the influence of framework ordering, cation siting and hydration of pores on the structure and its stability. We develop a methodology which allows the location of Al within the framework to be determined together with the position of extra-framework cations, in a stepwise fashion, progressing from an anhydrous model, via a dielectric continuum model, to finally, a fully atomistic model of the water in the intrazeolite pore space. Our methods reveal the complex interplay of short- and long-range interactions on the optimal structure of such materials.
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Affiliation(s)
- A Rabdel Ruiz-Salvador
- Zeolites Engineering Laboratory, Institute of Materials and Reagents (IMRE), University of Havana, Havana, 10400, Cuba.
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21
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Bougeard D, Smirnov KS. Modelling studies of water in crystalline nanoporous aluminosilicates. Phys Chem Chem Phys 2007; 9:226-45. [PMID: 17186066 DOI: 10.1039/b614463m] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The paper presents a review of molecular modelling studies of hydrated nanoporous aluminosilicates (zeolites and clays) performed during the last decade. A special emphasis is set on the calculation of the dynamical quantities and collective properties of the confined water. Some new results concerning the behaviour of water molecules in the siliceous silicalite and zeolite beta structures are presented.
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Affiliation(s)
- Daniel Bougeard
- Laboratoire de Spectrochimie Infrarouge et Raman, UMR 8516 CNRS-USTL, Bât. C5, Université des Sciences et Technologies de Lille, 59655, Villeneuve d'Ascq Cédex, France.
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22
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Llewellyn PL, Maurin G. Gas Adsorption in Zeolites and Related Materials. STUDIES IN SURFACE SCIENCE AND CATALYSIS 2007. [DOI: 10.1016/s0167-2991(07)80805-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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23
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Di Lella A, Desbiens N, Boutin A, Demachy I, Ungerer P, Bellat JP, Fuchs AH. Molecular simulation studies of water physisorption in zeolites. Phys Chem Chem Phys 2006; 8:5396-406. [PMID: 17119646 DOI: 10.1039/b610621h] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a series of Grand Canonical Monte Carlo simulations of water adsorption in NaY and NaX faujasite, as well as in silicalite-1. Computed adsorption isotherms and heats of adsorption were in good agreement with the available experiments. The existence of cyclic water hexamers in NaX located in the 12-ring windows, recently disclosed by neutron diffraction experiments (Hunger et al., J. Phys. Chem. B, 2006, 110, 342-353) was reproduced in our simulations. Interestingly enough, such cyclic hexamer clusters were also observed in the case of NaY, in which no stabilizing cation is present in the 12-ring window. We also report cation redistribution upon water adsorption for sodium faujasite with varying cation contents (Si ratio Al ratio in the range 1.53-3). A simple and transferable forcefield was used, that enabled to reproduce the different aspects of water physisorption in stable zeolites. The high pressure water condensation in hydrophobic silicalite-1 was reproduced without any parameter readjustment. The method and forcefield used here should be useful for engineering oriented applications such as the prediction of multi-component mixture adsorptive separations in various stable zeolites. It allows to address the issue of the effect of the small amounts of water that are almost inevitably present in zeolite-based separation processes.
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Affiliation(s)
- Angela Di Lella
- Laboratoire de Chimie Physique, Bâtiment 349, UMR 8000 CNRS and Université Paris-Sud, F-91405, Orsay, France
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24
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Maurin G, Plant DF, Henn F, Bell RG. Cation Migration upon Adsorption of Methanol in NaY and NaX Faujasite Systems: A Molecular Dynamics Approach. J Phys Chem B 2006; 110:18447-54. [PMID: 16970470 DOI: 10.1021/jp062059j] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular dynamics simulations have been carried out to address the question of cation migration upon adsorption of methanol in NaY and NaX faujasite systems as a function of the loading. For NaY, it has been shown that, at low and intermediate loadings, SII cations can migrate toward the center of the supercage due to strong interactions with the adsorbates, followed by a hopping of SI' from the sodalite cage into the supercage to fill the vacant SII site. A SI' cation can also migrate across the double six ring and takes a SI' vacant position. SI cations mainly remain trapped in their initial sites whatever the loading. At high loading, only limited motions are observed for SII cations due to steric effects induced by the presence of adsorbates within the supercage. For NaX, the SIII' cations which occupy the most accessible adsorption sites are significantly moving upon coordination to the methanol molecules; the extent of this mobility exhibits a maximum for 48 methanol molecules per unit cell before decreasing at higher loadings due to steric hindrance. In addition, the SI' and SII cations remain almost trapped in their initial sites whatever the loading. Indeed, the most probable migration mechanism involves SIII' cation displacements into nearby SIII' sites.
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Affiliation(s)
- G Maurin
- Laboratoire LPMC, UMR CNRS 5617, Université Montpellier II, Pl. E. Bataillon, 34095 Montpellier Cedex 05, France.
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25
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Plant DF, Maurin G, Jobic H, Llewellyn PL. Molecular Dynamics Simulation of the Cation Motion upon Adsorption of CO2 in Faujasite Zeolite Systems. J Phys Chem B 2006; 110:14372-8. [PMID: 16854144 DOI: 10.1021/jp062381u] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular Dynamics simulations have been carried out in NaX and NaY Faujasite systems to deepen understanding of the cation rearrangement during the CO2 adsorption process suggested by our recent diffusivity measurements. This study is a major contribution since the rearrangement of the cations in Faujasite, the most promising adsorbent for CO2 storage, can represent a significant breakthrough in understanding the adsorption and diffusion processes at the mircroscopic scale. For NaY, it has been shown that at low and intermediate loadings, SII cations can migrate toward the center of the supercage due to strong interactions with the adsorbates, followed by a hopping of SI'cation from the sodalite cage into the supercage to fill the vacant SII site. The SI cations are only displaced at a higher loading, leading to cation de-trapping out of the double six rings into the vacant SI' sites. For NaX, the SIII' cations which occupy the most accessible adsorption sites move significantly upon coordination to the carbon dioxide molecules. The SI' and SII cations remain consistently located in their initial sites whatever the loading. Indeed, the most probable migration mechanism involves SIII' cation displacements into nearby vacant SIII' sites.
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Affiliation(s)
- D F Plant
- Laboratoire LPMC, UMR CNRS 5617, Université Montpellier II, Pl. E. Bataillon, 34095 Montpellier Cedex 05, France
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Liu B, Smit B. Molecular simulation of adsorption of alkanes in sodium MOR-type zeolites using a new force field. Phys Chem Chem Phys 2006; 8:1852-7. [PMID: 16633672 DOI: 10.1039/b517774j] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The applicability of a recently proposed force field of Calero et al. (J. Am. Chem. Soc., 2004, 126, 11377) to Na-MOR zeolites is evaluated. The Henry law coefficients of ethane and C(5)-C(9) as well as the adsorption isotherms of ethane, propane, butane, and hexane in various Na-MOR zeolites are computed and compared with experimental values. These comparisons show that the new force field is suitable for Na-MOR zeolites. Furthermore, this force field is used to study the effects of sodium cations on the adsorption behavior of larger alkanes, such as C(4)-C(7), in MOR-type zeolites. These simulations give a better understanding of the underlying mechanisms of the cations' position and density influence on adsorption. In addition, a characteristic pressure named "reversal pressure" is introduced which characterizes the efficiency of the presence of cations in zeolites.
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Affiliation(s)
- Bei Liu
- Centre Européen de Calcul Atomique et Moléculaire (CECAM), Ecole Normale Supérieure, 46 allée d'Italie, 69007 Lyon, France.
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Beauvais C, Boutin A, Fuchs AH. Adsorption of Water and Aromatics in Faujasite Zeolites: A Molecular Simulation Study. ADSORPTION 2005. [DOI: 10.1007/s10450-005-5937-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kuchta B, Firlej L, Maurin G. Modeling of adsorption in nanopores. J Mol Model 2005; 11:293-300. [PMID: 15889289 DOI: 10.1007/s00894-005-0266-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Accepted: 01/17/2005] [Indexed: 10/25/2022]
Abstract
Adsorption in nonporous materials has been studied using Grand Canonical Monte Carlo simulations. We discuss three types of materials: (a) a model of cylindrical pores with smooth walls, representing MCM-41 like materials, (b) a model of cylindrical pores with regular structured walls (model of carbon nanotubes) and (c) a material with crystalline wall structure (zeolites). Typical problems related to the stability of adsorbed layers have been analyzed. We have shown that the mechanism of adsorption is strongly dependent on the structure of the pore walls. In the case of amorphous walls it may lead to metastable configurations. In nanotubes, the ordered corrugation structure of walls determines the low temperature structure of the adsorbed system. In 3D ordered porous system, such as zeolites, the mechanism of adsorption is mostly determined by characteristic sites of adsorption. [Figure: see text]. Adsorbed atoms and energy fluctuations at the pressure of the first layer formation of krypton atoms: (a) instantaneous numbers of adsorbed atoms (per nm2 of the pore wall) as a function of the time of simulation (Monte Carlo steps) observed in a relatively long run, (b) the bimodal distribution of the energy fluctuations is a consequence of the behavior of the systems as shown in (a).
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Affiliation(s)
- Bogdan Kuchta
- Laboratoire des Matériaux Divises, Revêtement, Electrocéramiques (MADIREL), Université de Provence, Centre de Saint-Jérôme, 13397, Marseille, France.
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Llewellyn PL, Maurin G. Gas adsorption microcalorimetry and modelling to characterise zeolites and related materials. CR CHIM 2005. [DOI: 10.1016/j.crci.2004.11.004] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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