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Avelino Corma - One of the best experts on this subject based on the ideXlab platform.
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a machine learning approach to zeolite synthesis enabled by automatic literature data extraction
ACS central science, 2019Co-Authors: Zach Jensen, Manuel Moliner, Avelino Corma, Edward Kim, Soonhyoung Kwon, Terry Z H Gani, Yuriy Romanleshkov, Elsa OlivettiAbstract:Zeolites are porous, aluminosilicate materials with many industrial and “green” applications. Despite their industrial relevance, many aspects of zeolite synthesis remain poorly understood requiring costly trial and error synthesis. In this paper, we create natural language processing techniques and text markup parsing tools to automatically extract synthesis information and trends from zeolite journal articles. We further engineer a data set of germanium-containing zeolites to test the accuracy of the extracted data and to discover potential opportunities for zeolites containing germanium. We also create a regression model for a zeolite’s Framework Density from the synthesis conditions. This model has a cross-validated root mean squared error of 0.98 T/1000 A3, and many of the model decision boundaries correspond to known synthesis heuristics in germanium-containing zeolites. We propose that this automatic data extraction can be applied to many different problems in zeolite synthesis and enable novel zeo...
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extra large pore zeolite itq 40 with the lowest Framework Density containing double four and double three rings
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Avelino Corma, M J Diazcabanas, Jiuxing Jiang, Mobae Afeworki, Douglas L Dorset, Stuart L Soled, Karl G StrohmaierAbstract:Abstract The first zeolite structure (ITQ-40) that contains double four (D4) and double three (D3) member ring secondary building units has been synthesized by introducing Ge and NH4F and working in concentrated synthesis gels. It is the first time that D3-Rs have been observed in a zeolite structure. As was previously analyzed [Brunner GO, Meier, WM (1989) Nature 337:146–147], such a structure has a very low Framework Density (10.1 T/1,000 A3). Indeed, ITQ-40 has the lowest Framework Density ever achieved in oxygen-containing zeolites. Furthermore, it contains large pore openings, i.e., 15-member rings parallel to the [001] hexagonal axis and 16-member ring channels perpendicular to this axis. The results presented here push ahead the possibilities of zeolites for uses in electronics, control delivery of drugs and chemicals, as well as for catalysis.
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the synthesis of an extra large pore zeolite with double three ring building units and a low Framework Density
Angewandte Chemie, 2010Co-Authors: Jiuxing Jiang, M J Diazcabanas, Jose L Jorda, Jihong Yu, Avelino CormaAbstract:Zeolites are crystalline inorganic solids formed by TO4 tetrahedra (T=Si, P, Al, Ge, etc.) with a well-defined system of regular pores having diameters up to about 2 nm. The possibility of tuning pore dimensions and Framework compositions have made zeolites the most successful materials for applications in gas adsorption and separation and for catalysis. Their uses have been further expanded to microelectronics for preparing materials with low values of the high-frequency dielectric constant or manufacturing encapsulated light-emitting devices (LEDs), to medicine for diagnostic treatments and controlled drug delivery, or for release of semiotics for controlling insect populations in agricultural uses. Those applications often require structures with low Framework densities, large internal volumes, and preferentially, extra-large pores. However, up to now, the number of known zeolites with a low Framework Density (FD 12) is almost negligible, and the number with extra-large pores ( 18-R) is also extremely small. Computational methods can predict a large number of thermodynamically feasible new structures, and they can stimulate and inspire the discovery of new structures. For example, Foster and Treacy have used a symmetry-constrained intersite bond searching method and have generated more than two million structures. With that methodology, the authors predicted a series of thermodynamically feasible extra-large-pore zeolites. Deem et al. have also modeled relatively large number of low Density zeolites and were able to show that the low-energy and low-Density materials also tend to have desirably large rings. Among the zeolite structures with extra large pores predicted by Foster and Treacy, there is one with 18 10 10-R pore topology that could be of particular interest for catalysis, as it combines an extra-large pore (18-R) for molecular accessibility with connected 10-R pores that can introduce shape-selectivity effects. Recently, the predicted zeolite was synthesized and named ITQ-33. This zeolite has 3-R and D4R units in the structure, and was at the time the silicate-based zeolite with the lowest Framework Density (12.3.T/1000 ). The pore topology of this extra-large-pore zeolite presented quite unique and interesting catalytic properties: The pore accessibility to large molecules through the 18-R was combined with shape selectivity in the 10-R pores for the primary products formed. In the same data base, Foster and Treacy also predicted an extra-large-pore zeolite that was closely related to ITQ-33 (Zeolite reference 191_4_1985). In that new structure, the 10-R pores of ITQ-33 were expanded to 12-R pores connecting the larger perpendicular 18-R channels. The result was a zeolite with 18 12 12 pore topology instead of the 18 10 10 for ITQ-33. In particular, along with D4R units, the new zeolite contains D3R units that have never been seen in synthesized zeolites, which could be related to geometric strains introduced in the Framework owing to the formation of D3R based on silicon. In any case, the pore expansion with the 18 12 12-R pore system in the new zeolite should result in a decrease of the Framework Density from 12.3 in the case of ITQ-33 to 10.9 T atoms/1000 . Herein, we show that the zeolite containing D3R that was predicted above can be successfully synthesized (ITQ-44) as a silicogermanate by combining a relatively inexpensive, rigid and bulky organic structure-directing agent (SDA) with the directing effect of germanium. Furthermore, we show that in ITQ-44, germanium locates preferentially in D3R (with 50% Ge occupancy), followed by D4R (with 37% Ge occupancy). ITQ-44 was synthesized using (2’-(R),6’-(S))-2’,6’-dimethylspiro[isoindole-2,1’-piperidin-1’-ium] as the SDA (Supporting Information, Figure S1). The synthesis of ITQ-44 was carried out in fluoride media using high-throughput (HT) synthesis techniques, which involve the use of a 15-well multiautoclave. The XRD pattern of a calcined ITQ-44 sample (Figure 1) was collected (as described in the Supporting Information), and the crystal structure was solved using the program FOCUS. The agreement between the observed and calculated XRD patterns are shown in Figure 1; it certainly confirms that this structure corresponds to that of the pure silica polymorph of this material predicted by Foster and Treacy (reference number 191_4_19854). The structure of ITQ-44 is closely related to the previously described zeolite ITQ-33 (Figure 2). It also comprises a building unit formed by a [346] cage with two additional [*] J. Jiang, Dr. J. L. Jorda, Dr. M. J. Diaz-Cabanas, Prof. A. Corma Instituto de Tecnologia Quimica (UPV-CSIC) Universidad Politecnica de Valencia Consejo Superior de Investigaciones Cientificas Av. de los Naranjos s/n, 46022 Valencia (Spain) Fax: (+34)96-387-7809 E-mail: acorma@itq.upv.es
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extra large pore zeolites bridging the gap between micro and mesoporous structures
Angewandte Chemie, 2010Co-Authors: Jiuxing Jiang, Avelino CormaAbstract:The conditions required to produce zeolites with low Framework Density and extra-large pores are discussed. Correlations between Framework stability and geometrical and topological descriptors are presented. An attempt has been made to rationalize the synthesis of extra-large-pore zeolites in terms of the synthesis mechanism, the directing effect of the organic structure directing agent (OSDA), the Framework atoms, and the gel concentration. Extra-large-pore zeolites, including the recently discovered chiral mesoporous ITQ-37, are described and their catalytic and adsorption properties discussed. Finally, strategies are presented for the preparation of extra-large-pore zeolites with different pore topologies that can fulfill pre-established catalytic and adsorption targets.
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The ITQ-37 mesoporous chiral zeolite
Nature, 2009Co-Authors: Junliang Sun, Charlotte Bonneau, María J. Díaz-cabãas, Manuel Moliner, Mingrun Li, Angel Cantin, Daliang Zhang, Avelino Corma, Xiaodong ZouAbstract:The synthesis of crystalline molecular sieves with pore dimensions that fill the gap between microporous and mesoporous materials is a matter of fundamental and industrial interest. The preparation of zeolitic materials with extralarge pores and chiral Frameworks would permit many new applications. Two important steps in this direction include the synthesis of ITQ-33, a stable zeolite with 18 x 10 x 10 ring windows, and the synthesis of SU-32, which has an intrinsically chiral zeolite structure and where each crystal exhibits only one handedness. Here we present a germanosilicate zeolite (ITQ-37) with extralarge 30-ring windows. Its structure was determined by combining selected area electron diffraction (SAED) and powder X-ray diffraction (PXRD) in a charge-flipping algorithm. The Framework follows the SrSi(2) (srs) minimal net and forms two unique cavities, each of which is connected to three other cavities to form a gyroidal channel system. These cavities comprise the enantiomorphous srs net of the Framework. ITQ-37 is the first chiral zeolite with one single gyroidal channel. It has the lowest Framework Density (10.3 T atoms per 1,000 A(3)) of all existing 4-coordinated crystalline oxide Frameworks, and the pore volume of the corresponding silica polymorph would be 0.38 cm(3) g(-1).
Mercouri G Kanatzidis - One of the best experts on this subject based on the ideXlab platform.
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organic cation alloying on intralayer a and interlayer a sites in 2d hybrid dion jacobson lead bromide perovskites a a pb2br7
Journal of the American Chemical Society, 2020Co-Authors: Mikaa L Kepenekian, Ioannis Spanopoulos, Yihui He, Claudine Katan, Jacky Even, Richard D Schaller, Ram Seshadri, Constantinos C Stoumpos, Mercouri G KanatzidisAbstract:: Hybrid layered halide perovskites have achieved impressive performance in optoelectronics. New structural types in the two-dimensional (2D) halide system such as the Dion-Jacobson phases have attracted wide research attention due to the short interlayer distance and unique layer orientation that facilitate better charge-transport and higher stability in optoelectronic devices. Here, we report the first solid solution series incorporating both A and A' cations in the 2D Dion-Jacobson family, with the general formula (A')(A)Pb2Br7 ((A' = 3-(aminomethyl)piperidinium (3AMP) and 4-(aminomethyl)piperidinium) (4AMP); A = methylammonium (MA) and formamidinium (FA)). Mixing the spacing A' cations and perovskitizer A cations generates the new (3AMP)a(4AMP)1-a(FA)b(MA)1-bPb2Br7 perovskites. The crystallographically refined crystal structures using single-crystal X-ray diffraction data reveal that the distortion of the inorganic Framework is heavily influenced by the degree of A' and A alloying. A rising fraction of 4AMP in the structure, decreases the Pb-Br-Pb angles, making the Framework more distorted. On the contrary, higher FA fractions increase the Pb-Br-Pb angles. This structural evolution fine-tunes the optical properties where the larger the Pb-Br-Pb angle, the narrower the band gap. The photoluminescence emission energy mirrors this trend. Raman spectroscopy reveals a highly dynamical lattice similar to MAPbBr3 and consistent with the local distortion environment of the [Pb2Br7] Framework. Density functional theory (DFT) calculations of the electronic structures reveal the same trend as the experimental results where (3AMP)(FA)Pb2Br7 has the smallest band gap while (4AMP)(MA)Pb2Br7 has the largest band gap. The structural effects from solely the organic cations in the 2D system highlight the importance of understanding the high sensitivity of the optoelectronic properties on the structural tuning in this broad class of materials.
Richard D Schaller - One of the best experts on this subject based on the ideXlab platform.
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organic cation alloying on intralayer a and interlayer a sites in 2d hybrid dion jacobson lead bromide perovskites a a pb2br7
Journal of the American Chemical Society, 2020Co-Authors: Mikaa L Kepenekian, Ioannis Spanopoulos, Yihui He, Claudine Katan, Jacky Even, Richard D Schaller, Ram Seshadri, Constantinos C Stoumpos, Mercouri G KanatzidisAbstract:: Hybrid layered halide perovskites have achieved impressive performance in optoelectronics. New structural types in the two-dimensional (2D) halide system such as the Dion-Jacobson phases have attracted wide research attention due to the short interlayer distance and unique layer orientation that facilitate better charge-transport and higher stability in optoelectronic devices. Here, we report the first solid solution series incorporating both A and A' cations in the 2D Dion-Jacobson family, with the general formula (A')(A)Pb2Br7 ((A' = 3-(aminomethyl)piperidinium (3AMP) and 4-(aminomethyl)piperidinium) (4AMP); A = methylammonium (MA) and formamidinium (FA)). Mixing the spacing A' cations and perovskitizer A cations generates the new (3AMP)a(4AMP)1-a(FA)b(MA)1-bPb2Br7 perovskites. The crystallographically refined crystal structures using single-crystal X-ray diffraction data reveal that the distortion of the inorganic Framework is heavily influenced by the degree of A' and A alloying. A rising fraction of 4AMP in the structure, decreases the Pb-Br-Pb angles, making the Framework more distorted. On the contrary, higher FA fractions increase the Pb-Br-Pb angles. This structural evolution fine-tunes the optical properties where the larger the Pb-Br-Pb angle, the narrower the band gap. The photoluminescence emission energy mirrors this trend. Raman spectroscopy reveals a highly dynamical lattice similar to MAPbBr3 and consistent with the local distortion environment of the [Pb2Br7] Framework. Density functional theory (DFT) calculations of the electronic structures reveal the same trend as the experimental results where (3AMP)(FA)Pb2Br7 has the smallest band gap while (4AMP)(MA)Pb2Br7 has the largest band gap. The structural effects from solely the organic cations in the 2D system highlight the importance of understanding the high sensitivity of the optoelectronic properties on the structural tuning in this broad class of materials.
Mark E Davis - One of the best experts on this subject based on the ideXlab platform.
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pure silica zeolite thin films by vapor phase transport of fluoride for low k applications
Microporous and Mesoporous Materials, 2010Co-Authors: Heather K Hunt, Yushan Yan, Christopher M Lew, Minwei Sun, Mark E DavisAbstract:A new method to synthesize pure-silica zeolite films is presented. Specifically, this method uses fluoridemediated syntheses that involve the vapor phase transport of the mineralizing agent, fluoride, to crystallize a precursor film deposited by dip-coating techniques to obtain thin films of pure-silica zeolites with LTA, CHA, and ITW topologies. The films are characterized by a combination of X-ray diffraction, field emission scanning electron microscopy, and X-ray energy dispersive analyses. The films are polycrystalline, intergrown, continuous and well-adhered to their substrates. The usefulness of these thin films as low-k materials, that are needed to reduce cross-talk noise and energy dissipation between transistors in an integrated circuit, is demonstrated via evaluation of the pure-silica LTA film. The LTA topology has the lowest Framework Density (FD = 14.2) of the 19 known pure-silica zeolites, and theoretically could have the lowest dielectric constant. The average dielectric constants of the LTA films are calculated from capacitance measurements at a frequency of 1 MHz with metal–insulator–metal structures on lowresistivity silicon substrates, and yield an average k = 1.69, well within the ultra low-k material requirements (k between 2.3 and 2.6).
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issues in the synthesis of crystalline molecular sieves towards the crystallization of low Framework Density structures
ChemPhysChem, 2004Co-Authors: Avelino Corma, Mark E DavisAbstract:Fundamental and practical interest in crystalline, microporous, molecular sieves is largely a direct consequence of the fact that their bulk properties can be manipulated through variations in atomic structure. This correspondence between the macroscale and the atomic scale is due to the uniformity of these crystalline materials. Control of the atomic structure therefore is of extreme importance, and is the thesis of this Review. Synthesis mechanisms and the parameters that can direct the crystal assembly pathway and the ultimate product formed are discussed and rationalized.
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thermochemistry of pure silica zeolites
Journal of Physical Chemistry B, 2000Co-Authors: Patrick M Piccione, Miguel A Camblor, Christel Laberty, Sanyuan Yang, And Alexandra Navrotsky, Mark E DavisAbstract:A series of pure-silica molecular sieves (structural codes AST, BEA, CFI, CHA, IFR, ISV, ITE, MEL, MFI, MWW, and STT) is investigated by high-temperature drop solution calorimetry using lead borate solvent at 974 K. The enthalpies of transition from quartz at 298 K (in kJ/mol) are AST, 10.9 ± 1.2; BEA, 9.3 ± 0.8; CFI, 8.8 ± 0.8; CHA, 11.4 ± 1.5; IFR, 10.0 ± 1.2; ISV, 14.4 ± 1.1; ITE, 10.1 ± 1.2; MEL, 8.2 ± 1.3; MFI, 6.8 ± 0.8; MWW, 10.4 ± 1.5; and STT, 9.2 ± 1.2. The range of energies observed is quite narrow at only 6.8−14.4 kJ/mol above that of quartz, and these data are consistent with and extend the earlier findings of Petrovic et al. The enthalpy variations are correlated with the following structural parameters: Framework Density, nonbonded distance between Si atoms, and Framework loop configurations. A strong linear correlation between enthalpy and Framework Density is observed, implying that it is the overall packing quality that determines the relative enthalpies of zeolite Frameworks. The presence of internal silanol groups is shown to result in a slight (≤2.4 kJ/mol) destabilization of the calcined molecular sieves by comparing calorimetric data for MFI and BEA samples synthesized in hydroxide (containing internal silanol groups) and fluoride (low internal silanol group Density) media.
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synthesis optimization and structure analysis of the zincosilicate molecular sieve vpi 9
Microporous Materials, 1996Co-Authors: Lynne B Mccusker, Christian Baerlocher, R W Grossekunstleve, Masahito Yoshikawa, Mark E DavisAbstract:Abstract The synthesis of the zincosilicate molecular sieve VPI-9 has been optimized to produce a pure and highly crystalline material reproducibly. Its complex Framework topology (structure type code VNI) has been determined in the space group P42/ncm (a=9.8946, c=36.8715A) from high resolution synchrotron powder diffraction data collected on an NH4+-exchanged sample. Attempts to solve the structure by conventional methods or by exploiting anomalous scattering effects were unsuccessful. However, the application of a new approach to structure solution from powder data (FOCUS), which incorporates some of the principles used intuitively in model building into an automated structure determination procedure, generated the correct Framework. With 7 T-sites, this Framework topology is the most complex yet solved from powder diffraction data without manual intervention. The topology can be described in terms of two types of layers joined via isolated tetrahedra. One layer is a simple 4.82 net, and the other contains chains of pairs of [533] polyhedra. There is a 2-dimensional 8-ring channel system between the [533] polyhedra layers. Rietveld refinement of the structure of VPI-9 in the as-synthesized form (Rb44K4[Si96Zn24O240]·48H2O) required a doubling of the c-axis (a=9.8837, c=73.6505A; V=7195 A3), and a reduction of the symmetry to P41212. In addition to the 15 T-atoms and 30 oxygens in the Framework, 9 Rb, 2 K and 3 H2O positions could be located within the 8-ring channels. Refinement of the 170 structural parameters using synchrotron data converged with Rwp=0.147 (Rexp=0.099) and RF=0.069. The Zn atoms in the Framework are completely ordered in layers. Each Zn is surrounded by four Si, and each Si by three Si and one Zn. The peaks in the 29Si MAS NMR spectrum can be interpreted very convincingly in terms of the average SiOT angles found in the refinement. While the structure of VPI-9 has several features in common with those of the related zincosilicate molecular sieves VPI-7 and RUB-17, such as the Framework Density, 4.82 layers, 3-rings, and a subunit containing Zn, there are also some interesting differences, which might be related to the lower Zn concentration in VPI-9.
Mikaa L Kepenekian - One of the best experts on this subject based on the ideXlab platform.
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organic cation alloying on intralayer a and interlayer a sites in 2d hybrid dion jacobson lead bromide perovskites a a pb2br7
Journal of the American Chemical Society, 2020Co-Authors: Mikaa L Kepenekian, Ioannis Spanopoulos, Yihui He, Claudine Katan, Jacky Even, Richard D Schaller, Ram Seshadri, Constantinos C Stoumpos, Mercouri G KanatzidisAbstract:: Hybrid layered halide perovskites have achieved impressive performance in optoelectronics. New structural types in the two-dimensional (2D) halide system such as the Dion-Jacobson phases have attracted wide research attention due to the short interlayer distance and unique layer orientation that facilitate better charge-transport and higher stability in optoelectronic devices. Here, we report the first solid solution series incorporating both A and A' cations in the 2D Dion-Jacobson family, with the general formula (A')(A)Pb2Br7 ((A' = 3-(aminomethyl)piperidinium (3AMP) and 4-(aminomethyl)piperidinium) (4AMP); A = methylammonium (MA) and formamidinium (FA)). Mixing the spacing A' cations and perovskitizer A cations generates the new (3AMP)a(4AMP)1-a(FA)b(MA)1-bPb2Br7 perovskites. The crystallographically refined crystal structures using single-crystal X-ray diffraction data reveal that the distortion of the inorganic Framework is heavily influenced by the degree of A' and A alloying. A rising fraction of 4AMP in the structure, decreases the Pb-Br-Pb angles, making the Framework more distorted. On the contrary, higher FA fractions increase the Pb-Br-Pb angles. This structural evolution fine-tunes the optical properties where the larger the Pb-Br-Pb angle, the narrower the band gap. The photoluminescence emission energy mirrors this trend. Raman spectroscopy reveals a highly dynamical lattice similar to MAPbBr3 and consistent with the local distortion environment of the [Pb2Br7] Framework. Density functional theory (DFT) calculations of the electronic structures reveal the same trend as the experimental results where (3AMP)(FA)Pb2Br7 has the smallest band gap while (4AMP)(MA)Pb2Br7 has the largest band gap. The structural effects from solely the organic cations in the 2D system highlight the importance of understanding the high sensitivity of the optoelectronic properties on the structural tuning in this broad class of materials.
