Conversion of Bioethanol to Propylene over ZSM-5 Zeolites

Takahashi, Atsushi; Fujitani, Tadahiro

doi:10.1627/jpi.61.20

Cited by 5 publications

(4 citation statements)

References 26 publications

(18 reference statements)

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“…We conclude that there is really strong evidence for the formation/presence of carbene/ylide species in MTH chemistry; however, the direct and clear spectroscopic evidence would put an end to the discussions in MTH chemistry. , Although there is indeed indirect experimental evidence, including carbene’s participation in typical insertion reactions, the impact of carbene intermediates in MTH chemistry is still unclear. Fleeting carbene species are also considered as key reactive intermediates besides MTH in other zeolite catalyzed reactions (i.e., ethanol/ethylene to propylene). − However, most proposals are without direct and concrete experimental evidence. Moreover, one should be careful with the terminology.…”

Section: Carbene Chemistry In Zeolite Catalysismentioning

confidence: 99%

First-Generation Organic Reaction Intermediates in Zeolite Chemistry and Catalysis

Gong

Çağlayan

et al. 2022

Chem. Rev.

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Zeolite chemistry and catalysis are expected to play a decisive role in the next decade(s) to build a more decentralized renewable feedstock-dependent sustainable society owing to the increased scrutiny over carbon emissions. Therefore, the lack of fundamental and mechanistic understanding of these processes is a critical “technical bottleneck” that must be eliminated to maximize economic value and minimize waste. We have identified, considering this objective, that the chemistry related to the first-generation reaction intermediates (i.e., carbocations, radicals, carbenes, ketenes, and carbanions) in zeolite chemistry and catalysis is highly underdeveloped or undervalued compared to other catalysis streams (e.g., homogeneous catalysis). This limitation can often be attributed to the technological restrictions to detect such “short-lived and highly reactive” intermediates at the interface (gas–solid/solid–liquid); however, the recent rise of sophisticated spectroscopic/analytical techniques (including under in situ/operando conditions) and modern data analysis methods collectively compete to unravel the impact of these organic intermediates. This comprehensive review summarizes the state-of-the-art first-generation organic reaction intermediates in zeolite chemistry and catalysis and evaluates their existing challenges and future prospects, to contribute significantly to the “circular carbon economy” initiatives.

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Section: Carbene Chemistry In Zeolite Catalysismentioning

confidence: 99%

First-Generation Organic Reaction Intermediates in Zeolite Chemistry and Catalysis

Gong

Çağlayan

et al. 2022

Chem. Rev.

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“…The binding energies were referenced to the C 1s line at 284. 8 29 Si MAS NMR experiments were performed on a Bruker AVANCE III 500WB spectrometer at a resonance frequency of 99.36 MHz using a 7 mm double-resonance MAS probe. The magic-angle spinning speed was 5 kHz in all experiments, and a typical π/6 pulse length of 1.8 μs was adopted for 29 Si resonance.…”

Section: Methodsmentioning

confidence: 99%

“…With strong demands on aromatics, BTX could be produced from C6–C8 hydrocarbons via an aromatization process. − Meanwhile, BTX could also be produced from more available sources such as fossils, coal, shale gas, and biomass. ZSM-5 has been demonstrated to be the main active component of the catalysts for hydrocarbon aromatization, light alkane aromatization, methanol to aromatics (MTA), and biomass to aromatics, as a consequence of excellent shape selectivity of MFI topological structure and tunable acidity. − To further improve the selectivity toward aromatics, modifications on H-ZSM-5 catalysts have been widely developed with a focus on metal modification with Zn, Ga, Pt, Mo, Ni, La, Cu, Fe, and Ag included, among which Ga exhibited superior aromatization performance and stability. − …”

Section: Introductionmentioning

confidence: 99%

Ga Substitution during Modification of ZSM-5 and Its Influences on Catalytic Aromatization Performance

Xin

Xing

Gao

et al. 2019

Ind. Eng. Chem. Res.

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ZSM-5 zeolites, Ga modified via different methods (in situ hydrothermal synthesis, mechanical mixing, incipient wetness impregnation, solid-state ion exchange, and liquid phase ion exchange), were systematically investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), 29Si, 27Al, and 71Ga magic-angle spinning (MAS) NMR, and H2 temperature-programmed reduction (H2-TPR). It is important to prove that both impregnation and liquid phase ion exchange could facilitate the incorporation of Ga species into the framework in addition to in situ hydrothermal synthesis. The liquid phase ion exchange method drove part of the Ga species into the framework, and it was further migrated into the framework by drying, while the incipient wetness impregnation method promoted part of the Ga species into the framework only during the calcination process. In the n-heptane catalytic aromatization procedure on the fixed bed, Ga modified ZSM-5 by in situ hydrothermal synthesis showed the highest benzene, toluene, ethylbenzene and xylene (BTEX) selectivity, owing to the increased strong Lewis acidic sites and mesopore volumes induced by the framework Ga species.

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“…Among of the various heterogeneous catalysts, zeolites have uniform pore structure, high surface area as well as adjustable acidity, which makes it a popular catalyst in ethanol conversion reaction, especially ZSM-5 zeolite. , Many published works have been done to investigate the details in ethanol conversion, including the reaction temperature, , contact time, , and Si/Al ratios , of used zeolites. It was concluded that a high temperature and long contact time favors the formation of the long chain olefins.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Ethanol Conversion on H-ZSM-5 Zeolite by in Situ Solid-State NMR

Zeng

Wang

et al. 2021

Energy Fuels

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The process of ethanol conversion on H-ZSM-5 zeolite with different Si/Al ratios was well-studied with the assistance of in situ solid-state 13C NMR experiments under continuous flow (CF) and batch-like conditions, respectively. Except for the adsorbed ethanol and diethyl ether, the surface ethoxy species, triethyloxonium ion, and even cyclopentadienyl cations were captured on the working catalyst and identified as active intermediates in ethanol conversion. The evolution process of these captured intermediates was exhaustively illustrated subsequently. Especially, two kinds of configuration of the adsorbed ethanol, referred to as side-on and end-on orientations, and diethyl ether (DEE) with an activated state were also revealed in this work. In addition, involved as one of the important active intermediates in MTO reaction, the cyclopentadienyl cations were also speculated to play important roles in the ethanol conversion and have close relation to propene formation.

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Conversion of Bioethanol to Propylene over ZSM-5 Zeolites

Cited by 5 publications

References 26 publications

First-Generation Organic Reaction Intermediates in Zeolite Chemistry and Catalysis

First-Generation Organic Reaction Intermediates in Zeolite Chemistry and Catalysis

Ga Substitution during Modification of ZSM-5 and Its Influences on Catalytic Aromatization Performance

Investigation of Ethanol Conversion on H-ZSM-5 Zeolite by in Situ Solid-State NMR

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