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Lew CM, Chen CY, Long GJ, Grandjean F, Ichimura AS, Xie D, Grosso-Giordano NA, Chakarawet K, Lacheen HS, Jensen KO, Martinez A, Katz A, Zhan BZ, Zones SI. Synthesis, Physicochemical Characterization, and Catalytic Evaluation of Fe 3+-Containing SSZ-70 Zeolite. ACS Catal 2022. [DOI: 10.1021/acscatal.2c01361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Cong-Yan Chen
- Chevron Technical Center, Richmond, California 94801, United States
| | - Gary J. Long
- Missouri University of Science and Technology, University of Missouri, Rolla, Missouri 65409-0010, United States
| | - Fernande Grandjean
- Missouri University of Science and Technology, University of Missouri, Rolla, Missouri 65409-0010, United States
| | - Andrew S. Ichimura
- San Francisco State University, San Francisco, California 94132, United States
| | - Dan Xie
- Chevron Technical Center, Richmond, California 94801, United States
| | | | | | | | - Kurt O. Jensen
- Chevron Technical Center, Richmond, California 94801, United States
| | - Abraham Martinez
- University of California Berkeley, Berkeley, California 94720, United States
| | - Alexander Katz
- University of California Berkeley, Berkeley, California 94720, United States
| | - Bi-Zeng Zhan
- Chevron Technical Center, Richmond, California 94801, United States
| | - Stacey I. Zones
- Chevron Technical Center, Richmond, California 94801, United States
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Adsorption and dehydration of ethanol on isomorphously B, Al, and Ga substituted H-ZSM-5 zeolite: an embedded ONIOM study. J Mol Model 2021; 27:354. [PMID: 34786608 DOI: 10.1007/s00894-021-04979-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 11/08/2021] [Indexed: 10/19/2022]
Abstract
Dehydration reactions are important in the petroleum and petrochemical industries, especially for the feedstock production. In this work, the catalytic activity of zeolites with different acidities for the dehydration of ethanol to ethylene and diethylether is investigated by density functional calculations on cluster models of three isomorphous B, Al, and Ga substituted H-ZSM-5 zeolites. Both unimolecular and bimolecular mechanisms are investigated. Detailed reaction profiles for the dehydration reaction, assuming either a stepwise or a concerted mechanism, were calculated by using the ONIOM(MP2:M06-2X) + SCREEP method. The adsorption energies of ethanol are -21.6, -28.1, and -27.7 kcal mol-1 on H-[B]-ZSM-5, H-[Al]-ZSM-5, and H-[Ga]-ZSM-5 zeolites, respectively. The activation energies for the rate-determining step of the unimolecular concerted mechanism for the ethylene formation are 48.5, 42.6, and 43.6 kcal mol-1 on H-[B]-ZSM-5, H-[Al]-ZSM-5, and H-[Ga]-ZSM-5 zeolites, respectively. The activation energies for the ethoxy formation as the rate-determining step for the bimolecular formation of diethylether are 42.3, 40.0, and 41.1 kcal mol-1 on H-[B]-ZSM-5, H-[Al]-ZSM-5, and H-[Ga]-ZSM-5 zeolites, respectively. The results indicate that the catalytic activities for the dehydration of ethanol decrease in the order H-[Al]-ZSM-5 ~ H-[Ga]-ZSM-5 > H-[B]-ZSM-5. Besides the acid strength, the zeolite framework affects the reaction by stabilizing the reaction intermediates, leading to more stable adsorption complexes and lower activation barriers.
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Wang S, Wei Z, Chen Y, Qin Z, Ma H, Dong M, Fan W, Wang J. Methanol to Olefins over H-MCM-22 Zeolite: Theoretical Study on the Catalytic Roles of Various Pores. ACS Catal 2015. [DOI: 10.1021/cs501232r] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Sen Wang
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Zhihong Wei
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001, People’s Republic of China
| | - Yanyan Chen
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001, People’s Republic of China
| | - Zhangfeng Qin
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001, People’s Republic of China
| | - Hong Ma
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Mei Dong
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001, People’s Republic of China
| | - Weibin Fan
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001, People’s Republic of China
| | - Jianguo Wang
- State
Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001, People’s Republic of China
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Huang Y, Dong X, Li M, Yu Y. A density functional theory study on ethylene formation and conversion over P modified ZSM-5. Catal Sci Technol 2015. [DOI: 10.1039/c4cy01205d] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Density functional theory (DFT) was used to study the effect of P modification of ZSM-5 on ethylene protonation.
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Affiliation(s)
- Yanping Huang
- Key Laboratory for Green Chemical Technology of Ministry of Education
- R&D Center for Petrochemical Technology
- Tianjin University
- Tianjin 300072
- PR China
| | - Xiuqin Dong
- Key Laboratory for Green Chemical Technology of Ministry of Education
- R&D Center for Petrochemical Technology
- Tianjin University
- Tianjin 300072
- PR China
| | - Mengmeng Li
- Key Laboratory for Green Chemical Technology of Ministry of Education
- R&D Center for Petrochemical Technology
- Tianjin University
- Tianjin 300072
- PR China
| | - Yingzhe Yu
- Key Laboratory for Green Chemical Technology of Ministry of Education
- R&D Center for Petrochemical Technology
- Tianjin University
- Tianjin 300072
- PR China
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Lewis and Brönsted acidic sites in M4+-doped zeolites (M=Ti, Zr, Ge, Sn, Pb) as well as interactions with probe molecules: A DFT study. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/j.molcata.2012.07.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Yang G, Zhou L, Liu X, Han X, Bao X. Density functional calculations on the distribution, acidity, and catalysis of Ti(IV) and Ti(III) ions in MCM-22 zeolite. Chemistry 2011; 17:1614-21. [PMID: 21268164 DOI: 10.1002/chem.201002241] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Indexed: 11/11/2022]
Abstract
Isolated Ti species in zeolites show unique catalytic activities for a variety of chemical reactions. In this work, density functional calculations were used to explore three current concerns: 1) the distributions of Ti(IV) and Ti(III) ions in the MCM-22 zeolite; 2) the Lewis acidity of the Ti(IV) and Ti(III) sites; and 3) activation of alkane C-H bonds by photocatalysis with Ti-doped zeolites. Neither the Ti(IV) nor Ti(III) ions are randomly distributed in the MCM-22 zeolite. The orders of relative stability are very close for the eight Ti(IV) and Ti(III) sites, and the T3 site is the most probable in both cases. The wavelengths for Ti(IV)-Ti(III) excitations were calculated to lie in the range λ=246.9-290.2 nm. The Ti3(IV) site shows Lewis acidity toward NH(3) in two different modes, and these two modes can coexist with each other. The calculated Ti(IV) coordination numbers, Ti(IV)-O bond elongations, and charge transfers caused by NH(3) adsorption are in good agreement with previous results. Similarly, two different NH(3) adsorption modes exist for the Ti3(III) site; the site that exhibits radical transfer from the lattice O to N atoms is preferred due to the higher adsorption energy. This indicates that the Ti3(III) site does not show Lewis acidity, in contrast to the Ti3(IV) site. At the Ti3(III) site, the energy barrier for activating the methane C-H bond was calculated to be 33.3 kJ mol(-1) and is greatly reduced by replacing the hydrogen atoms with methyl groups. In addition, the reactivity is improved when switching from MCM-22 to TS-1 zeolite. The studies on the various Ti species reveal that lattice O atoms rather than Ti(III) radicals are crucial to the activation of alkane C-H bonds. This work provides new insights into and aids understanding of the catalysis by isolated Ti species in zeolites.
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Affiliation(s)
- Gang Yang
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China.
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Berlier G, Prestipino C, Rivallan M, Bordiga S, Lamberti C, Zecchina A. Behavior of Extraframework Fe Sites in MFI and MCM-22 Zeolites upon Interaction with N2O and NO. J Phys Chem B 2005; 109:22377-85. [PMID: 16853915 DOI: 10.1021/jp052210+] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report on the characterization of an isomorphously substituted Fe-MCM-22 sample containing both Fe and Al in framework positions (Si/Fe = 44, Si/Al = 25). XANES spectroscopy was used to study the evolution of Fe sites as a consequence of thermal activation at high temperature (1073 K) and subsequent oxidation with N2O. The results were compared to those obtained in the same conditions on a well-known Fe-silicalite sample (Si/Fe = 68, Si/Al = infinity). In both samples, thermal activation causes migration of a fraction of Fe ions from framework to extraframework positions, this migration being accompanied by a reduction of Fe3+ to Fe2+. Upon oxidation with N2O at 523 K, the two samples show a different behavior. While in Fe-silicalite practically all of the Fe2+ sites formed by thermal activation are reoxidized to Fe3+, in Fe-MCM-22 only a fraction of the extraframework iron sites is involved in the reoxidation process. The accessibility of the extraframework Fe sites was also investigated by using the NO molecule as a surface probe. Upon NO dosage on the sample, the modification of the pre-edge peak and of the edge position suggests an important charge release from the extraframework Fe2+ ions to the adsorbed molecules. This could be formalized with the formation of Fe3+(NO-) complexes, compatible (on the basis of the simple molecular orbital theory) with a bent NO geometry. The formation of a complex family of Fe2+ mono-, di-, and trinitrosyl complexes was also confirmed by FTIR spectroscopy. Similarly to what was observed in the oxidation experiments, the fraction of extraframework Fe sites able to interact with NO in Fe-MCM-22 sample is smaller than that in Fe-silicalite treated in the same conditions. This trend is explained with a major clustering of extraframework Fe sites in Fe-MCM-22 sample, as was also suggested by FTIR experiments. These results suggest that the dispersion of iron in zeolitic matrixes prepared by isomorphous substitution could also depend on the zeolitic structure.
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Affiliation(s)
- Gloria Berlier
- Department of Inorganic, Physical and Materials Chemistry, and INSTM Research Unity of Turin University, NIS Center of Excellence, University of Torino, via P. Giuria, 7 I-10125 Torino, Italy
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DFT study of the acid strength of MCM-22 with double Si/Al substitutions in 12MR supercage. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.theochem.2005.08.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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