Suchergebnisse

5856 5863 6 15 ; S ; [EN] Nanosized SSZ-13 has been obtained from a one-pot synthesis procedure with the addition of CTAB to the synthesis precursor solution. Nano-SSZ-13 zeolite showed high intracrystalline mesoporosity and compared to standard SSZ-13 presented a much longer lifetime and higher conversion capacity for the reaction of methanol to olefins. The improved properties were attributed to a more efficient utilization of micropores by easier diffusion of reactants and products and slower deactivation by coke. A higher C2/C3 ratio was found for nano-SSZ-13, pointing to a lower deactivation of the aromatics cycle of the hydrocarbon pool. Financial support by the Spanish Government-MINECO through "Severo Ochoa" (SEV 2012-0267), CTQ2015-67592-P, CTQ2015-70126-R, CTQ2015-68951-C3-1-R, MAT2015-71842-P, by the European Union ERC-AdG-2014-671093-SynCatMatch and by the Generalitat Valenciana PROMETEOII/2013/011 is acknowledged. Z. Li acknowledges China Scholarship Council (CSC) for a fellowship. J. Yu thanks the Major International Joint Research Project of China for financial support (Grant No. 21320102001). Li, Z.; Navarro Villalba, MT.; Martínez Triguero, LJ.; Yu, J.; Corma Canós, A. (2016). Synthesis of nano-SSZ-13 and its application in the reaction of methanol to olefins. Catalysis Science and Technology. 6(15):5856-5863. https://doi.org/10.1039/C6CY00433D

[EN] Nanosized SSZ-13 has been obtained from a one-pot synthesis procedure with the addition of CTAB to the synthesis precursor solution. Nano-SSZ-13 zeolite showed high intracrystalline mesoporosity and compared to standard SSZ-13 presented a much longer lifetime and higher conversion capacity for the reaction of methanol to olefins. The improved properties were attributed to a more efficient utilization of micropores by easier diffusion of reactants and products and slower deactivation by coke. A higher C2/C3 ratio was found for nano-SSZ-13, pointing to a lower deactivation of the aromatics cycle of the hydrocarbon pool. ; Financial support by the Spanish Government-MINECO through "Severo Ochoa" (SEV 2012-0267), CTQ2015-67592-P, CTQ2015-70126-R, CTQ2015-68951-C3-1-R, MAT2015-71842-P, by the European Union ERC-AdG-2014-671093-SynCatMatch and by the Generalitat Valenciana PROMETEOII/2013/011 is acknowledged. Z. Li acknowledges China Scholarship Council (CSC) for a fellowship. J. Yu thanks the Major International Joint Research Project of China for financial support (Grant No. 21320102001). ; Li, Z.; Navarro Villalba, MT.; Martínez Triguero, LJ.; Yu, J.; Corma Canós, A. (2016). Synthesis of nano-SSZ-13 and its application in the reaction of methanol to olefins. Catalysis Science and Technology. 6(15):5856-5863. https://doi.org/10.1039/C6CY00433D ; S ; 5856 ; 5863 ; 6 ; 15

A two-dimensional zeolite with the topol. of MWW sheets has been obtained by direct synthesis with a combination of two org. structure-directing agents. The resultant material consists of approx. 70 % single and double layers and displays a well-structured external surface area of about 300 m2 g-1. The delaminated zeolite prepd. by means of this single-step synthetic route has a high delamination degree, and the structural integrity of the MWW layers is well preserved. The new zeolite material displayed excellent activity, selectivity, and stability when used as a catalyst for the alkylation of benzene with propylene and found to be superior to the catalysts that are currently used for producing cumene. ; Financial support by the Spanish Government-MINECO through "Severo Ochoa" (SEV 2012-0267), Consolider Ingenio 2010-Multicat, and MAT2012-31657 is acknowledged. M.E.M.-A. thanks MINECO for financial support through a pre-doctoral fellowship (BES-2013-066800). ; Margarit Benavent, VJ.; Martínez Armero, ME.; Navarro Villalba, MT.; Martínez, C.; Corma Canós, A. (2015). Direct Dual-Template Synthesis of MWW Zeolite Monolayers. Angewandte Chemie International Edition. 54(46):13724-13728. https://doi.org/10.1002/anie.201506822 ; S ; 13724 ; 13728 ; 54 ; 46

[EN] Ferrierite zeolites with nanosized crystals and external surface areas higher than 250m(2)g(-1) have been prepared at relatively low synthesis temperature (120 degrees C) by means of the collaborative effect of two organic structure directing agents (OSDA). In this way, hierarchical porosity is achieved without the use of post-synthesis treatments that usually involve leaching of Tatoms and solid loss. Adjusting the synthesis conditions it is possible to decrease the crystallite size in the directions of the 8- and 10-ring channels, [010] and [001] respectively, reducing their average pore length to 10-30nm and increasing the number of pores accessible. The small crystal size of the nano-ferrierites results in an improved accessibility of reactants to the catalytic active centers and enhanced product diffusion, leading to higher conversion and selectivity with lower deactivation rates for the oligomerization of 1-pentene into longer-chain olefins. ; This work has been supported by the European Union through the European Research Council (ERC-AdG-2014-671093, SynCatMatch) the Spanish government through the "Severo Ochoa Program" (SEV-2016-0683) and CTQ2015-70126-R, and by the Fundacion Ramon Areces through a research project within the "Life and Materials Sciences" program. M.R.D.-R. acknowledges "La Caixa-Severo Ochoa" International PhD Fellowships (call 2015). The Electron Microscopy Service of the Universitat Politecnica de Valencia is acknowledged for its help in sample characterization. We thank Dr. Manuel Moliner for helpful discussions. ; Margarit Benavent, VJ.; Díaz-Rey, MDR.; Navarro Villalba, MT.; Martínez, C.; Corma Canós, A. (2018). Direct Synthesis of Nano-Ferrierite along the 10-Ring-Channel Direction Boosts Their Catalytic Behavior. Angewandte Chemie International Edition. 57(13):3459-3463. https://doi.org/10.1002/anie.201711418 ; S ; 3459 ; 3463 ; 57 ; 13

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Catalysis, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acscatal.0c02799 ; [EN] Among the possible on-purpose technologies for propene production, direct conversion of butene-rich fractions to propene represents an attractive alternative to conventional routes such as steam cracking or fluid catalytic cracking. Here, we present an approach for designing an efficient ZSM-5-based catalyst for the selective cracking of butenes to propene by properly balancing diffusional and compositional effects. Instead of the large coffin-shaped ZSM-5 crystallites with very high Si/Al ratios generally reported, the optimal catalyst in terms of propene selectivity and catalyst life was found to be a ZSM-5 zeolite with a squared morphology, submicron-sized crystals (0.8 x 0.3 x 1.0 mu m), and a Si/Al molar ratio of around 300. For this crystal conformation, the short dimensions of both sinusoidal and straight channels facilitate propene diffusion and reduce its consumption in consecutive reactions, limiting the formation of C5+ oligomers and aromatics and maximizing propene selectivity. Coffin-type ZSM-5 crystals, with higher diffusional restrictions than square-shaped crystals, show faster catalyst deactivation than the latter, independently of the crystal size and Al content. However, among the ZSM-5 zeolite crystallites with a coffin morphology, the one presenting intergrowths on the (010) face, with a larger proportion of sinusoidal channels, shows a lower aromatic selectivity and deactivation rate, whereas the other two, with straight channels open to the clean (010) faces, favor the formation of aromatics by direct cyclization-dehydrogenation of oligomeric intermediates. ; This work has been supported by Saudi Aramco, by the Spanish Government-MICINN through "Severo Ochoa" (SEV-2016-0683) and ...

[EN] Titanosilicate zeolites are catalysts of interest in the field of fine chemicals. However, the generation and accessibility of active sites in titanosilicate materials for catalyzing reactions with large molecules is still a challenge. Herein, we prepared titanosilicate zeolite precursors with open zeolitic structures, tunable pore sizes, and controllable Si/Ti ratios through a hydrothermal crystallization strategy by using quaternary ammonium templates. A series of quaternary ammonium ions are discovered as effective organic templates. The prepared amorphous titanosilicate zeolites with some zeolite framework structural order have extra-large micropores and abundant octahedrally coordinated isolated Ti species, which lead to a superior catalytic performance in the oxidative desulfurization of dibenzothiophene (DBT) and epoxidation of cyclohexene. It is anticipated that the amorphous prezeolitic titanosilicates will benefit the catalytic conversion of bulky molecules in a wide range of reaction processes. ; The authors thank the National Key Research and Development Program of China (Grant 2016YFB0701100), the National Natural Science Foundation of China (Grant 21621001, 21920102005 and 21835002), the 111 Project (B17020), the European Union through the European Research Council (grant ERC-AdG-2014-671093, SynCatMatch), and the Spanish Government through "Severo Ochoa" (SEV-2016-0683, MINECO) for supporting this work. The APS was operated for the U.S. DOE Office of Science by the Argonne National Laboratory, and the CLS@APS facilities (Sector 20) were supported by the U.S. DOE under contract no. DEAC02-06CH11357, and the Canadian Light Source and its funding partners. R. Bai acknowledges the China Scholarship Council for the financial support. Jose Gaona Miguelez is also acknowledged for technical help. ; Bai, R.; Navarro Villalba, MT.; Song, Y.; Zhang, T.; Zou, Y.; Feng, Z.; Zhang, P. (2020). Titanosilicate zeolite precursors for highly efficient oxidation reactions. Chemical Science. 11(45):12341-12349. ...

tHydrophobic Ti-MCM-41 samples prepared by post-synthesis silylation treatment demonstrate to behighly active and selective catalysts in olefins epoxidation by using organic hydroperoxides as oxidizingagents in liquid phase reaction systems. Epoxide yields show important enhancements with increasedsilylation degrees of the Ti-mesoporous samples. Catalytic studies are combined and correlated withspectroscopic techniques (e.g. XRD, XANES, UV-Visible,29Si MAS-NMR) and calorimetric measurementsto better understand the changes in the surface chemistry of Ti-MCM-41 samples due to the post-synthesis silylation treatment and to ascertain the role of these trimethylsilyl groups incorporated inolefin epoxidation. In such manner, the effect of the organic moieties on solids, and both water and gly-col molecules contents on the catalytic activity and selectivity are analyzed in detail. Results show thatthe hydrophobicity level of the samples is responsible for the decrease in water adsorption and, conse-quently, the negligible formation of the non-desired glycol during the catalytic process. Thus, catalystdeactivation by glycol poisoning of Ti active sites is greatly diminished, this increasing catalyst stabilityand leading to practically quantitative production of the corresponding epoxide. The extended use ofthese hydrophobic Ti-MCM-41 catalysts together with organic hydroperoxides for the highly efficientand selective epoxidation of natural terpenes is also exemplified. ; The authors gratefully acknowledge financial support of Spanish Government (MAT2012-38567-C02-01, Consolider-Ingenio 2010-Multicat CSD-2009-00050 and Severo Ochoa SEV-2012-0267) and Generalitat Valenciana (Project Prometeo). M.E.D. also thanks funds from Spanish Government (CTQ-2011-27550) and CSIC (PIE 2009801063). J.S.A. and F.R.R. acknowledge financial support from MINECO (Projects MAT2013-45008-p and CONCERT Project-NASEMS (PCIN-2013-057), and from Generalitat Valenciana (PROMETEO2009/002). ; Silvestre Albero, J.; Domine ., ME.; Jorda Moret, JL.; ...

[EN] Upgrading of the heavy reformate fraction (HR), containing mainly C9+ aromatics, is usually performed by dealkylation or by transalkylation with added benzene and/or toluene to obtain the more valuable xylenes. However, when the costs related to the use of benzene and toluene are considered, the one-step dealkylation/transalkylation of the C9+ alkylaromatics to xylenes becomes economically attractive. Thus, in a first step, ethylmethylbenzenes (EMB) will have to be dealkylated to toluene, which will then react with the trimethylbenzenes (TMB) present in the HR feed to produce xylenes by transalkylation. Medium pore zeolites will favor dealkylation, whereas large pore zeolites will be more adequate for carrying out the transalkylation reaction. In this work, we present the one-pot synthesis of beta-pentasil aggregates with tunable ratios of the large pore beta to the medium pore component. We show that the close proximity of the beta and pentasil nanocrystals obtained by one-pot co-crystallization synthesis, results in a highly efficient catalyst for the consecutive dealkylation/transalkylation process. The bifunctional catalyst based on the co-crystallized aggregate is more active and selective to xylenes than a catalyst based on a physical mixture of equivalent beta and pentasil nanozeolites synthesized following an analogous procedure. The small crystallite sizes of the co-crystallized zeolites provide the additional advantage of a lower deactivation rate as compared to a reference benchmark catalyst. Results are shown on both, model molecules and industrial HR feed. ; This work has been supported by Saudi Aramco, by the Spanish Government-MICINN through "Severo Ochoa" (SEV 2012-0267) and RTI2018-101033-B-I00, by the European Union through ERC-AdG-2014-671093 (SynCatMatch) and by the Ftmdacion Ramon Areces through a research contract of the "Life and Materials Science" program. We thank Belen Esparcia for technical assistance, and the Electron Microscopy Service of the UPV for their help in sample ...