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Rafiq Q, Khan MT, Hayat SS, Azam S, Rahman AU, Elansary HO, Shan M. Adsorption and solar light activity of noble metal adatoms (Au and Zn) on Fe(111) surface: a first-principles study. Phys Chem Chem Phys 2024; 26:17118-17131. [PMID: 38845366 DOI: 10.1039/d3cp04504h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
Noble metals such as gold (Au), zinc (Zn), and iron (Fe) are highly significant in both fundamental and technological contexts owing to their applications in optoelectronics, optical coatings, transparent coatings, photodetectors, light-emitting devices, photovoltaics, nanotechnology, batteries, and thermal barrier coatings. This study presents a comprehensive investigation of the optoelectronic properties of Fe(111) and Au, Zn/Fe(111) materials using density functional theory (DFT) first-principles method with a focus on both materials' spin orientations. The optoelectronic properties were obtained employing the generalized gradient approximation (GGA) and the full-potential linearized augmented plane wave (FP-LAPW) approach, integrating the exchange-correlation function with the Hubbard potential U for improved accuracy. The arrangement of Fe(111) and Au, Zn/Fe(111) materials was found to lack an energy gap, indicating a metallic behavior in both the spin-up state and the spin-down state. The optical properties of Fe(111) and Au, Zn/Fe(111) materials, including their absorption coefficient, reflectivity, energy-loss function, refractive index, extinction coefficient, and optical conductivity, were thoroughly examined for both spin channels in the spectral region from 0.0 eV to 14 eV. The calculations revealed significant spin-dependent effects in the optical properties of the materials. Furthermore, this study explored the properties of the electronic bonding between several species in Fe(111) and Au, Zn/Fe(111) materials by examining the density distribution mapping of charge within the crystal symmetries.
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Affiliation(s)
- Qaiser Rafiq
- Department of Physics, International Islamic University, Islamabad, 44000, Pakistan.
| | - Muhammad Tahir Khan
- Key Laboratory of Urban Rail Transit Intelligent Operation and Maintenance Technology & Equipment of Zhejiang Province, College of Engineering, Zhejiang Normal University, Jinhua 321004, People's Republic of China.
- School of computer science and technology, Zhejiang Normal University, Jinhua 321004, People's Republic of China
| | - Sardar Sikandar Hayat
- Department of Physics, International Islamic University, Islamabad, 44000, Pakistan.
| | - Sikander Azam
- Faculty of engineering and applied sciences, Riphah International University, Islamabad 44000, Pakistan.
| | - Amin Ur Rahman
- Faculty of engineering and applied sciences, Riphah International University, Islamabad 44000, Pakistan.
| | - Hosam O Elansary
- Prince Sultan Bin Abdulaziz International Prize for Water Chair, Prince Sultan Institute for Environmental, Water and Desert Research, King Saud University, Riyadh 11451, Saudi Arabia
| | - Muhammad Shan
- Materials simulation Research Laboratory (MSRL), Institute of Physics, Bahauddin Zakariya University Multan, Multan, 60800, Pakistan
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Dai C, Zhang Y, Liu N, Yu G, Wang N, Xu R, Chen B. Mechanistic insight into the effect of active site motif structures on direct oxidation of methane to methanol over Cu-ZSM-5. Phys Chem Chem Phys 2023; 25:24894-24903. [PMID: 37681261 DOI: 10.1039/d3cp01906c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
Direct oxidation of methane to methanol (DMTM), a highly challenging reaction in C1 chemistry, has attracted lots of attention. Herein, we investigate the continuous H2O-mediated N2O-DMTM over a series of Cu-ZSM-5-n zeolites prepared by a solid-state ion-exchange method. Excellent CH3OH productivity (194.8 μmol gcat-1 h-1) and selectivity (67.1%) can be achieved over Cu-ZSM-5-0.3%, which surpasses most recently reported zeolite catalysts. The effect of the active site motif structure on the reaction was systematically investigated by the combined experimental and theoretical studies. It has been revealed that both the monomeric [Cu]+ and binuclear [Cu]+-[Cu]+ sites function to produce CH3OH, following the radical rebound mechanism, wherein the latter one plays a dominant role due to the synergistic effect of neighboring [Cu]+ that can efficiently reduce the N2O dissociation barrier to generate active oxygen for CH4 oxidation. Microkinetic modeling results further show that the dicopper site possesses a much higher net reaction rate (1.23 × 105 s-1) than the monomeric Cu site (0.962 s-1); moreover, H2O can shift the rate determining step from the CH3OH desorption step to the N2O dissociation step over the dicopper site, thereby efficiently favoring CH3OH production and resisting carbon deposition. Generally, the study in the present work would substantially favor other highly efficient catalyst designs.
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Affiliation(s)
- Chengna Dai
- Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124, China.
| | - Yuchan Zhang
- Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124, China.
| | - Ning Liu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124, China.
| | - Gangqiang Yu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124, China.
| | - Ning Wang
- Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124, China.
| | - Ruinian Xu
- Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124, China.
| | - Biaohua Chen
- Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124, China.
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Thang HV, Frolich K, Shamzhy M, Eliášová P, Rubeš M, Čejka J, Bulánek R, Nachtigall P. The effect of the zeolite pore size on the Lewis acid strength of extra-framework cations. Phys Chem Chem Phys 2016; 18:18063-73. [PMID: 27326803 DOI: 10.1039/c6cp03343a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The catalytic activity and the adsorption properties of zeolites depend on their topology and composition. For a better understanding of the structure-activity relationship it is advantageous to focus just on one of these parameters. Zeolites synthesized recently by the ADOR protocol offer a new possibility to investigate the effect of the channel diameter on the adsorption and catalytic properties of zeolites: UTL, OKO, and PCR zeolites consist of the same dense 2D layers (IPC-1P) that are connected with different linkers (D4R, S4R, O-atom, respectively) resulting in the channel systems of different sizes (14R × 12R, 12R × 10R, 10R × 8R, respectively). Consequently, extra-framework cation sites compensating charge of framework Al located in these dense 2D layers (channel-wall sites) are the same in all three zeolites. Therefore, the effect of the zeolite channel size on the Lewis properties of the cationic sites can be investigated independent of other factors determining the quality of Lewis sites. UTL, OKO, and PCR and pillared 2D IPC-1PI materials were prepared in Li-form and their properties were studied by a combination of experimental and theoretical methods. Qualitatively different conclusions are drawn for Li(+) located at the channel-wall sites and at the intersection sites (Li(+) located at the intersection of two zeolite channels): the Lewis acid strength of Li(+) at intersection sites is larger than that at channel-wall sites. The Lewis acid strength of Li(+) at channel-wall sites increases with decreasing channel size. When intersecting channels are small (10R × 8R in PCR) the intersection Li(+) sites are no longer stable and Li(+) is preferentially located at the channel-wall sites. Last but not least, the increase in adsorption heats with the decreasing channel size (due to enlarged dispersion contribution) is clearly demonstrated.
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Affiliation(s)
- Ho Viet Thang
- Department of Physical and Macromolecular Chemistry, Faculty of Sciences, Charles University, Hlavova 8, 128 40 Prague 2, Czech Republic.
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Van Speybroeck V, Hemelsoet K, Joos L, Waroquier M, Bell RG, Catlow CRA. Advances in theory and their application within the field of zeolite chemistry. Chem Soc Rev 2015; 44:7044-111. [PMID: 25976164 DOI: 10.1039/c5cs00029g] [Citation(s) in RCA: 246] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Zeolites are versatile and fascinating materials which are vital for a wide range of industries, due to their unique structural and chemical properties, which are the basis of applications in gas separation, ion exchange and catalysis. Given their economic impact, there is a powerful incentive for smart design of new materials with enhanced functionalities to obtain the best material for a given application. Over the last decades, theoretical modeling has matured to a level that model guided design has become within reach. Major hurdles have been overcome to reach this point and almost all contemporary methods in computational materials chemistry are actively used in the field of modeling zeolite chemistry and applications. Integration of complementary modeling approaches is necessary to obtain reliable predictions and rationalizations from theory. A close synergy between experimentalists and theoreticians has led to a deep understanding of the complexity of the system at hand, but also allowed the identification of shortcomings in current theoretical approaches. Inspired by the importance of zeolite characterization which can now be performed at the single atom and single molecule level from experiment, computational spectroscopy has grown in importance in the last decade. In this review most of the currently available modeling tools are introduced and illustrated on the most challenging problems in zeolite science. Directions for future model developments will be given.
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Voleská I, Nachtigall P, Ivanova E, Hadjiivanov K, Bulánek R. Theoretical and experimental study of CO adsorption on Ca-FER zeolite. Catal Today 2015. [DOI: 10.1016/j.cattod.2014.07.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Morpurgo S. A DFT study on Cu(I) coordination in Cu-ZSM-5: Effects of the functional choice and tuning of the ONIOM approach. J Comput Chem 2015; 36:660-9. [DOI: 10.1002/jcc.23843] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 12/07/2014] [Accepted: 01/02/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Simone Morpurgo
- Dipartimento di Chimica, Università degli Studi di Roma “La Sapienza,”; P.le Aldo Moro 5 00185 Roma Italia
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Göltl F, Hafner J. Structure and properties of metal-exchanged zeolites studied using gradient-corrected and hybrid functionals. I. Structure and energetics. J Chem Phys 2012; 136:064501. [PMID: 22360189 DOI: 10.1063/1.3676408] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The structural and energetic properties of purely siliceous, proton-, and Cu- and Co-exchanged chabazite have been studied using periodic density-functional (DFT) calculations with both conventional gradient-corrected exchange-correlation functionals and hybrid functionals mixing exact (i.e., Hartree-Fock) and DFT exchange. Spin-polarized and fixed-moment calculations have been performed to determine the equilibrium and excited spin-configurations of the metal-exchanged chabazites. For the purely siliceous chabazite, hybrid functionals predict a slightly more accurate cell volume and lattice geometry. For isolated Al/Si substitution sites, gradient-corrected functionals predict that the lattice distortion induced by the substitution preserves the local tetrahedral symmetry, whereas hybrid functionals lead to a distorted Al coordination with two short and two long Al-O bonds. Hybrid functionals yield a stronger cation-framework binding that conventional functionals in metal-exchanged zeolites, they favor shorter cation-oxygen bonds and eventually also a higher coordination of the cation. Both types of functionals predict the same spin in the ground-state. The structural optimization of the excited spin-states shows that the formation of a high-spin configuration leads to a strong lattice relaxation and a weaker cation-framework bonding. For both Cu- and Co-exchanged chabazite, the prediction of a preferred location of the cation in a six-membered ring of the zeolite agrees with experiment, but the energy differences between possible cation locations and the lattice distortion induced by the Al/Si substitution and the bonding of the cation depends quite significantly on the choice of the functional. All functionals predict similar energy differences for excited spin states. Spin-excitations are shown to be accompanied by significant changes in the cation coordination, which are more pronounced with hybrid functionals. The consequences of electronic spectra and chemical reactivity are analyzed in the following papers.
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Affiliation(s)
- Florian Göltl
- Fakultät für Physik and Center for Computational Materials Science, Universität Wien, Sensengasse 8/12, A-1090 Wien, Austria
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Morpurgo S, Moretti G, Bossa M. A computational study on the mechanism of NO decomposition catalyzed by Cu-ZSM-5: A comparison between single and dimeric Cu+ active sites. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/j.molcata.2012.03.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Morpurgo S, Moretti G, Bossa M. Basis set effects on Cu(I) coordination in Cu-ZSM-5: a computational study. Theor Chem Acc 2012. [DOI: 10.1007/s00214-012-1180-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Göltl F, Hafner J. Structure and properties of metal-exchanged zeolites studied using gradient-corrected and hybrid functionals. III. Energetics and vibrational spectroscopy of adsorbates. J Chem Phys 2012; 136:064503. [DOI: 10.1063/1.3676410] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Bludský O, Nachtigall P, Špirko V. Vibrational dynamics of adsorbed CO2: Separability of the CO2 asymmetric stretching mode. ACTA ACUST UNITED AC 2011. [DOI: 10.1135/cccc2011028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Separability of the CO2 asymmetric stretching mode is probed theoretically by performing highly accurate vibrational calculations on the CO2 and K+CO2 model systems. The proposed approach is applied to a model case of the vibrational dynamics of the CO2 molecule adsorbed in K-FER zeolite. The CCSD(T) level is fully adequate for quantitative decription of the CO2 vibrational dynamics, and all important effects on the vibrational dynamics of CO2 adsorption complexes can be estimated rather accurately (within 5 cm–1) at the DFT level of theory.
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Areán CO, Delgado MR, Bibiloni GF, Bludský O, Nachtigall P. Variable-Temperature IR Spectroscopic and Theoretical Studies on CO2 Adsorbed in Zeolite K-FER. Chemphyschem 2011; 12:1435-43. [DOI: 10.1002/cphc.201000995] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Indexed: 11/10/2022]
Affiliation(s)
- Carlos Otero Areán
- Departamento de Química, Universidad de las Islas Baleares, E-07122 Palma de Mallorca, Spain
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Yumura T, Hasegawa S, Itadani A, Kobayashi H, Kuroda Y. The Variety of Carbon-Metal Bonds inside Cu-ZSM-5 Zeolites: A Density Functional Theory Study. MATERIALS 2010. [PMCID: PMC5445841 DOI: 10.3390/ma3042516] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Large-scale density functional theory calculations (DFT) found various types of binding of an unsaturated hydrocarbon (C2H2 and C2H4) to a ZSM-5 zeolite extraframework copper cation. We employed the DFT calculations based on the B3LYP functional to obtain local minima of an unsaturated hydrocarbon adsorbed on one or two copper cations embedded inside ZSM-5, and then compared their stabilization energies. The DFT results show that the stabilization energies are strongly dependent on the copper coordination environment as well as configurations of two copper cations. Consequently, the inner copper-carbon bonds are influenced substantially by a nanometer-scale cavity of ZSM-5.
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Affiliation(s)
- Takashi Yumura
- Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: + 81-75-724-7571; Fax: 81-75-724-7580
| | | | - Atsushi Itadani
- Department of Fundamental Material Science, Division of Molecular and Material Science, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama 700-8530, Japan
| | - Hisayoshi Kobayashi
- Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Yasushige Kuroda
- Department of Fundamental Material Science, Division of Molecular and Material Science, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama 700-8530, Japan
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Rejmak P, Mitoraj M, Broclawik E. Electronic view on ethene adsorption in Cu(I) exchanged zeolites. Phys Chem Chem Phys 2010; 12:2321-30. [PMID: 20449345 DOI: 10.1039/b920551a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ethene adsorption on isolated Cu(i) sites in two types of zeolites (faujasite and MFI) is investigated by means of the embedded cluster method. Structures, energetic stabilities and C[double bond, length as m-dash]C stretching vibrations in adsorption complexes are discussed. Furthermore, for interpretative purposes, the interaction energies are decomposed, using novel approaches based on so called natural orbitals for chemical valence. Ethene is always symmetrically bound to Cu(i) ion by both C atoms. In some cases two local minima of similar stability on the potential energy surface, differing by Cu(i) site relaxation can be found that may be simultaneously populated in equilibrium. Binding energies usually decrease with the degree of reconstruction of Cu(i) site after adsorption, however, in particular cases, a more distorted structure can be slightly more stable if favorable pi* back donation overwhelms the distortion effects. Calculated values of binding energies for Cu(i)-Y zeolite (about 80 kJ mol(-1)) agree well with microcalorimetric data. We predict that ethene binding in MFI is over two times stronger (to the best of our knowledge no experimental data are available). The C[double bond, length as m-dash]C stretching frequency is not site specific, but depends only on the type of copper connectivity to oxygen nodes. The appearance of two C[double bond, length as m-dash]C bands in IR spectra of Cu(i)-faujasite can be explained as the effect of coexistence of two types of adsorption complexes, with Cu(i) coordinated to one or two framework tetrahedrons, respectively. In Cu(i)-MFI, only one type of adsorption complex with Cu(i) ion coordinated to a single tetrahedron exists, as only a single C[double bond, length as m-dash]C band is present in IR spectra.
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Affiliation(s)
- Pawel Rejmak
- Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, 30-239 Krakow, Niezapominajek 8, Poland.
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Zukal A, Pulido A, Gil B, Nachtigall P, Bludský O, Rubeš M, Čejka J. Experimental and theoretical determination of adsorption heats of CO2 over alkali metal exchanged ferrierites with different Si/Al ratio. Phys Chem Chem Phys 2010; 12:6413-22. [DOI: 10.1039/c001950j] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Yumura T, Yamashita H, Torigoe H, Kobayashi H, Kuroda Y. Site-specific Xe additions into Cu–ZSM-5 zeolite. Phys Chem Chem Phys 2010; 12:2392-400. [DOI: 10.1039/b919032e] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Grajciar L, Areán CO, Pulido A, Nachtigall P. Periodic DFT investigation of the effect of aluminium content on the properties of the acid zeolite H-FER. Phys Chem Chem Phys 2010; 12:1497-506. [DOI: 10.1039/b917969k] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Correlation Between Catalytic Activity and Metal Cation Coordination: NO Decomposition Over Cu/Zeolites. ChemCatChem 2009. [DOI: 10.1002/cctc.200900219] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Santra S, Archipov T, Ene AB, Komnik H, Stoll H, Roduner E, Rauhut G. Adsorption of dioxygen to copper in CuHY zeolite. Phys Chem Chem Phys 2009; 11:8855-66. [PMID: 20449032 DOI: 10.1039/b904152d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The adsorption of dioxygen to copper in CuHY zeolites has been studied by means of FTIR spectroscopy and model calculations at the quantum mechanical/molecular mechanics (QM/MM) level. Different Si/Al ratios, substitution patterns and adsorption sites within the cavities of the zeolite lead to a large number of different isomers to be studied. In addition, these parameters control the end-on vs. side-on adsorption of dioxygen. High-level multireference benchmark calculations for the singlet and triplet states of such adsorption complexes corroborate the use of density functional theory for the investigation of these systems. Comparison of the experimental and computed data allows for the identification of a preferred adsorption site and a small number of isomers which appear to be most relevant for the adsorption process. Redshifts of >250 cm(-1) are obtained for the vibrational frequencies of adsorbed O(2).
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Affiliation(s)
- Shampa Santra
- Institute of Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
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Pulido A, Nachtigall P. Theoretical investigation of dinitrosyl complexes in Cu-zeolites as intermediates in deNOx process. Phys Chem Chem Phys 2009; 11:1447-58. [PMID: 19224046 DOI: 10.1039/b818116k] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The structure and stability of nitrosyl complexes formed in Cu-FER zeolite were investigated using a periodic DFT model. The reliability of both DFT methods and cluster models when describing the Cu(+) interaction with NO molecules was examined. The relative stabilities of mononitrosyl complexes on various Cu(+) sites in Cu-FER are governed by the deformation energy of the particular site. Three types of dinitrosyl complexes with different coordination on the Cu(+) cation were identified: (i) four-fold tetrahedral, (ii) four-fold square-planar and (iii) three-fold trigonal-planar complexes. The most stable dinitrosyl complex, formed when the two NO molecules interact with Cu(+)via the N atom, has a tetrahedral coordination on Cu(+). The cyclic adsorption complex, having a square-planar arrangement of ligands on Cu(+) and interaction via O atoms, is only about 10 kJ mol(-1) less stable than the N-down dinitrosyl complex. This cyclic dinitrosyl complex is suggested to be the key intermediate in the deNO(x) process taking place in Cu-zeolites.
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Affiliation(s)
- Angeles Pulido
- Institute of Organic Chemistry and Biochemistry, ASCR, v.v.i., Flemingovo nám. 2, 16610, Prague 6, Czech Republic
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Sirijaraensre J, Limtrakul J. Effect of the acidic strength on the vapor phase Beckmann rearrangement of cyclohexanone oxime over the MFI zeolite: an embedded ONIOM study. Phys Chem Chem Phys 2009; 11:578-85. [DOI: 10.1039/b808662a] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Yumura T, Takeuchi M, Kobayashi H, Kuroda Y. Effects of ZSM-5 Zeolite Confinement on Reaction Intermediates during Dioxygen Activation by Enclosed Dicopper Cations. Inorg Chem 2008; 48:508-17. [DOI: 10.1021/ic8010184] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Takashi Yumura
- Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan, and Department of Fundamental Material Science, Division of Molecular and Material Science, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Okayama 700-8530, Japan
| | - Mina Takeuchi
- Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan, and Department of Fundamental Material Science, Division of Molecular and Material Science, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Okayama 700-8530, Japan
| | - Hisayoshi Kobayashi
- Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan, and Department of Fundamental Material Science, Division of Molecular and Material Science, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Okayama 700-8530, Japan
| | - Yasushige Kuroda
- Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan, and Department of Fundamental Material Science, Division of Molecular and Material Science, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Okayama 700-8530, Japan
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Nachtigall P, Bludský O, Grajciar L, Nachtigallová D, Delgado MR, Areán CO. Computational and FTIR spectroscopic studies on carbon monoxide and dinitrogen adsorption on a high-silica H-FER zeolite. Phys Chem Chem Phys 2008; 11:791-802. [PMID: 19290325 DOI: 10.1039/b812873a] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Adsorption (at a low temperature) of carbon monoxide and dinitrogen on a high-silica ferrierite-type zeolite (H-FER, Si : Al = 27.5 : 1) was investigated by means of variable temperature infrared spectroscopy and theoretical calculations at the periodic DFT level. This combined experimental and computational approach led to detailed characterization of several types of hydrogen-bonded OHCO and OHN(2) complexes, formed by interaction between the adsorbed molecules and the Brønsted acid OH groups of the zeolite. CO or N(2), forming linear complexes with OH groups pointing towards a sufficiently ample void space, show the largest adsorption enthalpy which was found to be in the (approximate) range of -25 to -29 kJ mol(-1) for CO and -15 to -19 kJ mol(-1) for N(2). Less stable OHCO or OHN(2) complexes can be formed when either the Brønsted acid OH group is involved in intra-zeolite hydrogen bonding or when the free space available is too small to allow formation of linear complexes without previous re-location of the proton of the OH group involved. The details of experimental IR spectra in the O-H, C-O, and N-N stretching regions could be interpreted on the basis of good agreement between experimental and calculated results.
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Affiliation(s)
- P Nachtigall
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10, Praha 6, Czech Republic
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Milanesio M, Croce G, Viterbo D, Pastore HO, Mascarenhas AJDS, Munsignatti ECDO, Meda L. A Combined High-Resolution X-ray Powder Diffraction, Computational, and XPS Study of the Local Structure of Extra-Framework Copper Ions in Over-Exchanged Cu-MCM22 Zeolite. J Phys Chem A 2008; 112:8403-10. [DOI: 10.1021/jp803619r] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Marco Milanesio
- Dipartimento di Scienze e Tecnologie Avanzate and Nano-SiSTeMI
Interdisciplinary Centre, Università del Piemonte Orientale
“A. Avogadro”, Via Bellini 25/G, 15100 Alessandria,
Italy, Instituto de Química, Universidade Estadual de Campinas,
CP 6154, CEP 13084−971, Campinas, SP, Brazil, and Nano-SiSTeMI
Interdisciplinary Centre and Instituto ENI Donegani via Fauser 4,
28066 Novara, Italy
| | - Gianluca Croce
- Dipartimento di Scienze e Tecnologie Avanzate and Nano-SiSTeMI
Interdisciplinary Centre, Università del Piemonte Orientale
“A. Avogadro”, Via Bellini 25/G, 15100 Alessandria,
Italy, Instituto de Química, Universidade Estadual de Campinas,
CP 6154, CEP 13084−971, Campinas, SP, Brazil, and Nano-SiSTeMI
Interdisciplinary Centre and Instituto ENI Donegani via Fauser 4,
28066 Novara, Italy
| | - Davide Viterbo
- Dipartimento di Scienze e Tecnologie Avanzate and Nano-SiSTeMI
Interdisciplinary Centre, Università del Piemonte Orientale
“A. Avogadro”, Via Bellini 25/G, 15100 Alessandria,
Italy, Instituto de Química, Universidade Estadual de Campinas,
CP 6154, CEP 13084−971, Campinas, SP, Brazil, and Nano-SiSTeMI
Interdisciplinary Centre and Instituto ENI Donegani via Fauser 4,
28066 Novara, Italy
| | - Heloise O. Pastore
- Dipartimento di Scienze e Tecnologie Avanzate and Nano-SiSTeMI
Interdisciplinary Centre, Università del Piemonte Orientale
“A. Avogadro”, Via Bellini 25/G, 15100 Alessandria,
Italy, Instituto de Química, Universidade Estadual de Campinas,
CP 6154, CEP 13084−971, Campinas, SP, Brazil, and Nano-SiSTeMI
Interdisciplinary Centre and Instituto ENI Donegani via Fauser 4,
28066 Novara, Italy
| | - Artur J. dos Santos Mascarenhas
- Dipartimento di Scienze e Tecnologie Avanzate and Nano-SiSTeMI
Interdisciplinary Centre, Università del Piemonte Orientale
“A. Avogadro”, Via Bellini 25/G, 15100 Alessandria,
Italy, Instituto de Química, Universidade Estadual de Campinas,
CP 6154, CEP 13084−971, Campinas, SP, Brazil, and Nano-SiSTeMI
Interdisciplinary Centre and Instituto ENI Donegani via Fauser 4,
28066 Novara, Italy
| | - Erica C. de Oliveira Munsignatti
- Dipartimento di Scienze e Tecnologie Avanzate and Nano-SiSTeMI
Interdisciplinary Centre, Università del Piemonte Orientale
“A. Avogadro”, Via Bellini 25/G, 15100 Alessandria,
Italy, Instituto de Química, Universidade Estadual de Campinas,
CP 6154, CEP 13084−971, Campinas, SP, Brazil, and Nano-SiSTeMI
Interdisciplinary Centre and Instituto ENI Donegani via Fauser 4,
28066 Novara, Italy
| | - Laura Meda
- Dipartimento di Scienze e Tecnologie Avanzate and Nano-SiSTeMI
Interdisciplinary Centre, Università del Piemonte Orientale
“A. Avogadro”, Via Bellini 25/G, 15100 Alessandria,
Italy, Instituto de Química, Universidade Estadual de Campinas,
CP 6154, CEP 13084−971, Campinas, SP, Brazil, and Nano-SiSTeMI
Interdisciplinary Centre and Instituto ENI Donegani via Fauser 4,
28066 Novara, Italy
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26
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Nachtigallová D, Vrbka L, Bludský O, Nachtigall P. Interaction of acetonitrile with Na-zeolites: adsorption modes and vibrational dynamics in the zeolite channels and cavities. Phys Chem Chem Phys 2008; 10:4189-98. [DOI: 10.1039/b803024c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Combined TPD and theoretical investigation of CO desorption from Cu-K-FER zeolite. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/s0167-2991(08)80032-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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28
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Vibrational dynamics of small molecules adsorbed on cation sites in zeolite channel systems: IR and DFT investigation. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/s0167-2991(08)80026-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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29
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Evidence of heterogeneous dual cation sites in zeolites by combined IR and DFT investigation. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/s0167-2991(08)80060-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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30
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Jardillier N, Villagomez EA, Delahay G, Coq B, Berthomieu D. Probing Cu(I)-exchanged zeolite with CO: DFT modeling and experiment. J Phys Chem B 2007; 110:16413-21. [PMID: 16913772 DOI: 10.1021/jp063190u] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Addition of CO on Cu-exchanged zeolite was investigated by means of quantum chemical calculations based on density functional theory. The aim of this investigation was to get insights about changes of electronic properties of a copper site with zeolite composition by using a CO probe molecule. Calculated nu(CO) frequency values show that various Si/Al ratios of faujasite zeolite reproduce the expected experimental decrease of the nu(CO) values with decreasing Si/Al ratio. These calculations predict that H/Na ratio variations also induce changes in the nu(CO) values. These results illustrate that different compositions of the zeolite change the electronic properties of copper that are reflected in the nu(CO) frequency values. DFT results showed also that different structures and CO adsorption energies are obtained due to various Si/Al and H/Na ratios of the zeolite. Finally, these calculations evidence the possibility for CO to be connected at the same time to Cu(I) and to a close Na cation, Cu being at site II and Na at site II in Cu(I)-exchanged faujasite. A DRIFT experiment on two samples of faujasite, Cu(28)H(51)NaY and Cu(25)H(0)NaY, supports nu(CO) displacements to higher energy values with increasing H/Na ratio.
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Affiliation(s)
- Nicolas Jardillier
- Laboratoire de Matériaux Catalytiques et Catalyse en Chimie Organique, UMR CNRS-ENSCM-UM1 5618, FR 1878, ENSCM, 8, rue de l'Ecole Normale, 34296 Montpellier Cedex 5, France
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31
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Rejmak P, Sierka M, Sauer J. Theoretical studies of Cu(I) sites in faujasite and their interaction with carbon monoxide. Phys Chem Chem Phys 2007; 9:5446-56. [PMID: 17925971 DOI: 10.1039/b710051e] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Sitting, coordination, and properties of Cu(I) cations in zeolite faujasite are investigated using a combined quantum mechanics-interatomic potential function method. The coordination of Cu(I) ions depends on their location within the zeolite lattice. Cu(I) located inside the hexagonal prisms (site I') and in the plane of six-membered aluminosilicate rings on the walls of sodalite units (site II) is threefold coordinated, whereas Cu(I) located in the supercages (site III) is twofold coordinated. In agreement with available experimental data Cu(I) appears to be more strongly bound in sites I' and II than in site III. The binding energy of site II Cu(I) ions increases with the number of Al atoms, but only closest Al atoms have a substantial influence. The CO molecule binds more strongly onto sites with weaker bound cations and lower coordination. We assign the two CO stretching IR bands observed for Cu(I)-Y zeolites to sites II with one Al (2157-2161 cm(-1)) and two Al atoms (2140-2148 cm(-1)) in the six-membered aluminosilicate ring. For Cu(I)-X we tentatively assign the high frequency band to site III (2156-2168 cm(-1)) and the low-frequency band to site II with three Al atoms in the six-membered ring (2136-2138 cm(-1)).
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Affiliation(s)
- Pawel Rejmak
- Humboldt-Universität, Institut für Chemie, Unter den Linden 6, 10099, Berlin, Germany
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32
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Zhang Y, Lin H, Truhlar DG. Self-Consistent Polarization of the Boundary in the Redistributed Charge and Dipole Scheme for Combined Quantum-Mechanical and Molecular-Mechanical Calculations. J Chem Theory Comput 2007; 3:1378-98. [DOI: 10.1021/ct7000107] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yan Zhang
- Chemistry Department, University of Colorado at Denver and Health Sciences Center, Denver, Colorado 80217-3364, and Chemistry Department and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431
| | - Hai Lin
- Chemistry Department, University of Colorado at Denver and Health Sciences Center, Denver, Colorado 80217-3364, and Chemistry Department and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431
| | - Donald G. Truhlar
- Chemistry Department, University of Colorado at Denver and Health Sciences Center, Denver, Colorado 80217-3364, and Chemistry Department and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431
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33
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Garrone E, Bulánek R, Frolich K, Otero Aréan C, Rodríguez Delgado M, Palomino GT, Nachtigallová D, Nachtigall P. Single and dual cation sites in zeolites: theoretical calculations and FTIR spectroscopic studies on CO adsorption on K-FER. J Phys Chem B 2007; 110:22542-50. [PMID: 17091999 DOI: 10.1021/jp0631331] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Interaction of CO with K-FER zeolite was investigated by a combination of variable-temperature IR spectroscopy and computational study. Calculations were performed using omega(CO)/r(CO) correlation method in combination with a periodic density functional theory model. On the basis of agreement between experimental and calculated results, the following carbonyl complexes were identified: (i) mono- and dicarbonyl C-down complexes on single K(+) sites characterized by IR absorption bands at 2163 and 2161 cm(-1), respectively; (ii) complexes formed by CO bridging two K(+) ions separated by about 7-8 A (dual sites) characterized by a band at 2148 cm(-1); and (iii) isocarbonyl (O-down) complexes characterized by a band at 2116 cm(-1). The bridged carbonyl complexes on dual K(+) sites are about 5 kJ/mol more stable than monodentate (monocarbonyl) CO complexes. The C-O stretching frequency of monocarbonyl species in K-FER depends on K(+) location in the zeolite, and not on K(+) coordination to the framework. A combination of theoretical calculations using a periodic density functional model and experimental results showed formation of two types of monocarbonyls. The most abundant type appears at 2163 cm(-1), and the less abundant one at 2172 cm(-1). These experimentally determined wavenumber values coincide, within +/-2 cm(-1), with those derived from theoretical calculations.
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Affiliation(s)
- E Garrone
- Dipartimento di Scienza dei Materiali ed Ingegneria Chimica, Politecnico di Torino, I-10126 Turin, Italy
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34
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Nachtigall P, Sauer J. Applications of Quantum Chemical Methods in Zeolite Science. STUDIES IN SURFACE SCIENCE AND CATALYSIS 2007. [DOI: 10.1016/s0167-2991(07)80808-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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35
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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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36
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Otero Areán C, Nachtigallová D, Nachtigall P, Garrone E, Rodríguez Delgado M. Thermodynamics of reversible gas adsorption on alkali-metal exchanged zeolites—the interplay of infrared spectroscopy and theoretical calculations. Phys Chem Chem Phys 2007; 9:1421-37. [PMID: 17356750 DOI: 10.1039/b615535a] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Detailed understanding of weak solid-gas interactions giving rise to reversible gas adsorption on zeolites and related materials is relevant to both, fundamental studies on gas adsorption and potential improvement on a number of (adsorption based) technological processes. Combination of variable-temperature infrared spectroscopy with theoretical calculations constitutes a fruitful approach towards both of these aims. Such an approach is demonstrated here (mainly) by reviewing recent studies on hydrogen and carbon monoxide adsorption (at a low temperature) on alkali-metal exchanged ferrierite. However, the methodology discussed, which involves the interplay of experimental measurements and theoretical calculations at the periodic DFT level, should be equally valid for many other gas-solid systems. Specific aspects considered are the identification of gas adsorption complexes and thermodynamic studies related to standard adsorption enthalpy and entropy.
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Affiliation(s)
- C Otero Areán
- Departamento de Química, Universidad de las Islas Baleares, E-07122 Palma de Mallorca, Spain.
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37
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Morpurgo S, Moretti G, Bossa M. A computational study on N2adsorption in Cu-ZSM-5. Phys Chem Chem Phys 2007; 9:417-24. [PMID: 17199158 DOI: 10.1039/b608411g] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The present computational study investigates the adsorption of N(2) by Cu-ZSM-5, with particular regard to the interaction with pairs of Cu(+) ions, employing simple cluster models in the calculations. It shows that several interaction patterns between N(2) and couples of Cu(+) sites are possible within the Cu-ZSM-5 structure. In particular, when pairs of Cu(+) ions are located at opposite sides of ten-membered rings, in the region where linear and sinusoidal channels intersect each other, a quasi-linear Cu-N-N-Cu adsorption occurs. Although lattice restraints cause small deviations from linearity, such interaction turned out to be more favourable than other adsorption patterns within the Cu-ZSM-5 structure. The linearity of the Cu-N-N-Cu fragment and the relatively low concentration of the related sites cause a low extinction coefficient for the N-N IR stretching mode, which is usually detected with very low intensity or not detected at all. The results of the present calculations may explain the experimental evidence for a nearly IR-silent fraction of nitrogen strongly adsorbed in the Cu-ZSM-5 catalyst which, as shown in a previous work, is linearly related to the number of active sites for NO decomposition.
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Affiliation(s)
- Simone Morpurgo
- Dipartimento di Chimica, Università degli Studi di Roma La Sapienza, P. le A. Moro 5, 00185 Roma, Italia.
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38
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Sirijaraensre J, Limtrakul J. Vapor-Phase Beckmann Rearrangement of Oxime Molecules over H-Faujasite Zeolite. Chemphyschem 2006; 7:2424-32. [PMID: 17004280 DOI: 10.1002/cphc.200600403] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The Beckmann rearrangement (BR) plays an important role in a variety of industries. The mechanism of this reaction rearrangement of oximes with different molecular sizes, specifically, the oximes of formaldehyde (H(2)C=NOH), Z-acetaldehyde (CH(3)HC=NOH), E-acetaldehyde (CH(3)HC=NOH) and acetone (CH(3))(2)C=NOH, catalyzed by the Faujasite zeolite is investigated by both the quantum cluster and embedded cluster approaches at the B3LYP level of theory using the 6-31G (d,p) basis set. To enhance the energetic properties, single point calculations are undertaken at MP2/6-311G(d,p). The rearrangement step, using the bare cluster model, is the rate determining step of the entire reaction of these oxime molecules of which the energy barrier is between 50-70 kcal mol(-1). The more accurate embedded cluster model, in which the effect of the zeolitic framework is included, yields as the rate determining step, the formaldehyde oxime reaction rearrangement with an energy barrier of 50.4 kcal mol(-1). With the inclusion of the methyl substitution at the carbon-end of formaldehyde oxime, the rate determining step of the reaction becomes the 1,2 H-shift step for Z-acetaldehyde oxime (30.5 kcal mol(-1)) and acetone oxime (31.2 kcal mol(-1)), while, in the E-acetaldehyde oxime, the rate determining step is either the 1,2 H-shift (26.2 kcal mol(-1)) or the rearrangement step (26.6 kcal mol(-1)). These results signify the important role that the effect of the zeolite framework plays in lowering the activation energy by stabilizing all of the ionic species in the process. It should, however, be noted that the sizeable turnover of a reaction catalyzed by the Brønsted acid site might be delayed by the quantitatively high desorption energy of the product and readsorption of the reactant at the active center.
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Affiliation(s)
- Jakkapan Sirijaraensre
- Laboratory for Computational and Applied Chemistry, Chemistry Department, Faculty of Science, Kasetsart University, Bangkok, Thailand
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39
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Nachtigallová D, Bludský O, Otero Areán C, Bulánek R, Nachtigall P. The vibrational dynamics of carbon monoxide in a confined space-CO in zeolites. Phys Chem Chem Phys 2006; 8:4849-52. [PMID: 17066173 DOI: 10.1039/b612238h] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Based on theoretical calculations, and a survey of infrared spectra of CO adsorbed on different cation exchanged zeolites, a model is proposed to explain the influence of the zeolite framework on the vibrational behaviour of CO confined into small void spaces (zeolite channels and cavities). The concepts developed should help to understand a number of details relevant to both, precise interpretation of IR spectra and a better understanding of the vibrational dynamics of small molecules in a confined space.
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Affiliation(s)
- Dana Nachtigallová
- Center for Biomolecules and Complex Molecular Systems, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10, Prague 6, Czech Republic.
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40
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CO2 adsorption in alkali cation exchanged Y faujasites: A quantum chemical study compared to experiments. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.05.096] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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41
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42
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Nachtigall P, Garrone E, Palomino GT, Delgado MR, Nachtigallová D, Areán CO. FTIR spectroscopic and computational studies on hydrogen adsorption on the zeolite Li–FER. Phys Chem Chem Phys 2006; 8:2286-92. [PMID: 16688311 DOI: 10.1039/b602362b] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The interaction, at a low temperature, between molecular hydrogen and the zeolite Li-FER was studied by means of variable temperature infrared spectroscopy and theoretical calculations using a periodic DFT model. The adsorbed dihydrogen molecule becomes infrared active, giving a characteristic IR absorption band (H-H stretching) at 4090 cm(-1). Three different Li(+) site types with respect to H(2) adsorption were found in the zeolite, two of which adsorb H(2). Calculations showed a similar interaction energy for these two sites, which was found to agree with the experimentally determined value of standard adsorption enthalpy of DeltaH(0) = -4.1 (+/-0.8) kJ mol(-1). The results are discussed in the broader context of previously reported data for H(2) adsorption on Na-FER and K-FER.
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Affiliation(s)
- P Nachtigall
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Centre for Biomolecules and Complex Molecular Systems, Prague
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43
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Bulánek R, Drobná H, Nachtigall P, Rubes M, Bludský O. On the site-specificity of polycarbonyl complexes in Cu/zeolites: combined experimental and DFT study. Phys Chem Chem Phys 2006; 8:5535-42. [PMID: 17136268 DOI: 10.1039/b613805e] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The preferred Cu(+) sites and formation of mono-, di-, and tricarbonyl complexes in the Cu-FER were investigated at the periodic density functional theory level and by means of FTIR spectroscopy. The site-specificity of adsorption enthalpies of CO on Cu-FER and of vibrational frequencies of polycarbonyl complexes were investigated for various Cu(+) sites in Cu-FER. Large changes in the Cu(+) interaction with the zeolite framework were observed upon the formation of carbonyl complexes. The dicarbonyl complexes formed on Cu(+) in the main channel or on the intersection of the main and perpendicular channels are stable and both, adsorption enthalpies and CO stretching frequencies are not site-specific. The fraction of Cu(+) ions in the FER cage, that cannot form dicarbonyl can be determined from IR spectra (about 7% for the Cu-FER with Si/Al = 27.5 investigated here). The tricarbonyl complexes can be formed at the Cu(+) ions located at the 8-member ring window at the intersection of main and perpendicular channel. The stability of tricarbonyl complexes is very low (DeltaH degrees (0 K)>or=-4 kJ mol(-1)).
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Affiliation(s)
- Roman Bulánek
- Department of Physical Chemistry, University of Pardubice, Nám. Cs. Legií 565, 53010 Pardubice, Czech Republic
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44
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Areán CO, Palomino GT, Garrone E, Nachtigallová D, Nachtigall P. Combined Theoretical and FTIR Spectroscopic Studies on Hydrogen Adsorption on the Zeolites Na−FER and K−FER. J Phys Chem B 2005; 110:395-402. [PMID: 16471548 DOI: 10.1021/jp055190k] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The interaction between molecular hydrogen and the alkali-metal-exchanged zeolites Na-FER and K-FER at a low temperature was investigated by combining variable-temperature infrared spectroscopy and theoretical calculations by using a periodic DFT model. The experimentally determined values of standard adsorption enthalpy, DeltaH degrees , were -6.0 (+/-0.8) and -3.5 (+/-0.8) kJ mol(-1) for Na-FER and K-FER, respectively. These results were found to be in agreement with corresponding DeltaH degrees values obtained from calculations on the periodic model. Two types of alkali-metal cation sites in FER were found: channel intersection sites and channel wall sites. Calculations showed a similar interaction energy for both site types, and similar structures of adsorption complexes. Up to two dihydrogen molecules can be physisorbed on the alkali-metal cation located on the intersection of two channels, while only one H2 molecule is physisorbed on the cation at the channel wall site. The adsorption enthalpies of H2 on alkali-metal-exchanged FER are significantly smaller than those found previously for the MFI-type zeolites Na-ZSM-5 and K-ZSM-5, which is likely due to a difference in the alkali-metal cation coordination in the two zeolite frameworks.
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Affiliation(s)
- C Otero Areán
- Departamento de Química, Universidad de las Islas Baleares, E-07122 Palma de Mallorca, Spain
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45
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Benco L, Bucko T, Hafner J, Toulhoat H. A Density Functional Theory Study of Molecular and Dissociative Adsorption of H2 on Active Sites in Mordenite. J Phys Chem B 2005; 109:22491-501. [PMID: 16853930 DOI: 10.1021/jp0533729] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Adsorption and chemisorption of H2 in mordenite is studied using ab initio density functional theory (DFT) calculations. The geometries of the adsorption complex, the adsorption energies, stretching frequencies, and the capacity to dissociate the adsorbed molecule are compared for different active sites. The active centers include a Brønsted acid site, a three-coordinated surface Al site, and Lewis sites formed by extraframework cations: Na+, Cu+, Ag+, Zn2+, Cu2+, Ga3+, and Al3+. Adsorption properties of cations are compared for a location of the cation in the five-membered ring. This location differs from the location in the six-membered ring observed for hydrated cations. The five-membered ring, however, represents a stable location of the bare cation. In this position any cation exhibits higher reactivity compared with the location in the six-membered ring and is well accessible by molecules adsorbed in the main channel of the zeolite. Calculated adsorption energies range from 4 to 87 kJ/mol, depending on electronegativity and ionic radius of the cation and the stability of the cation-zeolite complex. The largest adsorption energy is observed for Cu+ and the lowest for Al3+ integrated into the interstitial site of the zeolite framework. A linear dependence is observed between the stretching frequency and the bond length of the adsorbed H2 molecule. The capacity of the metal-exchanged zeolite to dissociate the H2 molecule does not correlate with the adsorption energy. Dissociation is not possible on single Cu+ cation. The best performance is observed for the Ga3+, Zn2+, and Al3+ extraframework cations, in good agreement with experimental data.
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Affiliation(s)
- L Benco
- Institut für Materialphysik and Center for Computational Materials Science, Universität Wien, Sensengasse 8, A-1090 Wien, Austria.
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