Non‐Oxidative Activation of Alkanes

Traa, Yvonne

doi:10.1002/9783527610044.hetcat0161

Cited by 3 publications

(5 citation statements)

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“…The dehydroalkylation of aromatics with alkanes is thermodynamically strongly limited . At the experimental conditions used in this work, the equilibrium conversions of benzene for the reactions in Scheme are 10% for ethylbenzene production, 7% for i-propylbenzene production, and 10% for n -propylbenzene production.…”

Section: Resultsmentioning

confidence: 96%

“…Secondary products, such as xylenes, ethylbenzene, and toluene, are formed in larger amounts. The largest product fraction consists of butanes, besides ethane, pentanes, and some methane, which is due to disproportionation/cracking of propane. , This reaction is thermodynamically favored, which also becomes evident, if ethane and propane are converted without benzene (Figure ). In this case, also small amounts of ethylbenzene and toluene are produced by ethane/propane aromatization .…”

Section: Resultsmentioning

confidence: 99%

“…If certain alkylaromatics are to be produced, it also has to be noted that the alkylation with alkanes produces more terminal alkylbenzenes than the alkylation with the corresponding olefin. , Therefore, more n -propylbenzene than i-propylbenzene is usually formed (Tables and ). This is unexpected because most mechanistic considerations of dehydroalkylation actually assume that the alkane is first dehydrogenated to the alkene, which afterward alkylates the aromatic reactant. , This would rather lead to i-propylbenzene. A possible explanation for the preferred formation of terminal alkylbenzenes is the activation of alkanes by aromatic carbenium ions .…”

Section: Resultsmentioning

confidence: 99%

“…This is unexpected because most mechanistic considerations of dehydroalkylation actually assume that the alkane is first dehydrogenated to the alkene, which afterward alkylates the aromatic reactant. 4,5 This would rather lead to i-propylbenzene. A possible explanation for the preferred formation of terminal alkylbenzenes is the activation of alkanes by aromatic carbenium ions.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…One approach to this issue is the conversion of methane, the main component of NG, via dehydroaromatization to benzene, which subsequently can be converted with the residual components of NG, ethane and propane, to alkylaromatics via dehydroalkylation (Scheme ). The use of alkanes as alkylating agents for aromatic alkylation has been studied before, hereby using either ethane or propane to alkylate benzene or toluene. − In contrast, this contribution focuses on the dehydroalkylation of benzene with mixtures of ethane and propane for the production of superior fuel components, i.e., with the aim to maximize octane numbers (Scheme ). Alkylation of benzene, produced by dehydroaromatization of methane, with ethane and propane, thus, not only ensures the valorization of all components of NG but also considerably increases the research octane number (RON), because all alkylaromatics have a much higher RON than benzene (Scheme ).…”

Section: Introductionmentioning

confidence: 99%

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Production of High-Octane Fuel Components by Dehydroalkylation of Benzene with Mixtures of Ethane and Propane

Traa

Hussin

2014

Energy Fuels

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The production of superior fuel components from natural gas was studied using a feed stream comprising ethane, propane, and benzene. For a better understanding of the different reactions occurring, product distributions of more simple reaction networks with only two of the three components are also presented. The dehydroalkylation reaction was conducted over a Pt−H-MFI catalyst at temperatures between 300 and 400 °C and a pressure of 6 bar. Three reaction cycles were conducted with intermittent regeneration with hydrogen to remove coke deposits. The research octane number of the received liquid fraction was calculated as a measure of quality of the produced alkylaromatic fuel components. The research octane number of the liquid fraction could be increased from 99 to at least 103 via dehydroalkylation with a mixture of cheap and abundant alkanes from natural gas.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Production of High-Octane Fuel Components by Dehydroalkylation of Benzene with Mixtures of Ethane and Propane

Traa

Hussin

2014

Energy Fuels

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Alkane Activation Initiated by Hydride Transfer: Co‐conversion of Propane and Methanol over H‐ZSM‐5 Zeolite

Liu

et al. 2015

Angewandte Chemie

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Co-conversion of alkane with another reactant over zeolite catalysts has emerged as an ew approach to the longstanding challenge of alkane transformation. With the aid of solid-state NMR spectroscopya nd GC-MS analysis,i tw as found that the co-conversion of propane and methanol can be readily initiated by hydride transfer at temperatures of ! 449 K over the acidic zeoliteH-ZSM-5. The formation of 13 C-labeled methane and singly 13 C-labeled n-butanes in selective labeling experiments provided the first evidence for the initial hydride transfer from propane to surface methoxy intermediates.T he results not only providenew insight into carbocation chemistry of solid acids,b ut also shed light on the low-temperature transformation of alkanes for industrial applications.Alkanes are the main components in natural gas and crude oil. Thec onversion of abundant but inert alkanes into highvalue-added products has been al ong-standing challenge to chemists. [1] Thed irect transformation of alkanes [2] suffers from the inertness of C À H/C À Cb onds and unfavorable thermodynamics which result in high reaction temperature, low product yield/selectivity,and unrealistic cost for industrial applications.Alternatively,the co-conversion of alkanes with reactive hydrocarbons [3] or oxygenates [4] over zeolites has recently been explored to overcome these limitations.M ethanol is ak ey platform chemical produced from various sources and can be readily converted over acidic zeolites through the industrial process. [5] Many efforts have accordingly been attempted to use methanol as the co-reactant [6] for coupling with methane, [6a] ethane, [6b] C 3 -C 4 alkanes, [6c] nbutane, [6d] n-hexane, [6e] and petroleum naphtha. [6f] However, the development of robust catalytic systems for efficient activation and further conversion of alkanes is severely hindered by the lack of mechanistic understanding.I nt his regard, solid-state NMR spectroscopy has been applied as ap owerful tool for monitoring the mechanistic events on heterogeneous catalysts. [7] In addition, GC-MS analysis on the distribution of either 13 Cor 2 Hlabels in the reaction products may offer the complementary information on many mechanistic details.T hrough solid-state magic-angle-spinning (MAS) NMR spectroscopy and GC-MS analysis,w ef ound herein, that upon addition of methanol, the C À Hb ond activation of propane was initiated by hydride transfer to surface methoxy species over zeolite H-ZSM-5 (Scheme 1). Initiated by hydride transfer, even at temperature as low as 449 K, the co-conversion of propane and methanol can be further achieved by secondary reactions,s uch as propene methylation (Scheme 2). This work not only details the longpursued evidence for hydride transfer over zeolite catalysts, but also offers insightful information on practical utilization of alkanes through the co-conversion strategy.To obtain unambiguous evidence for the initial hydride transfer, we chose 13 C-labeled methanol and nonlabeled propane (as the model compound of inert alkane) for ...

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Alkane Activation Initiated by Hydride Transfer: Co‐conversion of Propane and Methanol over H‐ZSM‐5 Zeolite

Liu

et al. 2015

Angew Chem Int Ed

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Co-conversion of alkane with another reactant over zeolite catalysts has emerged as a new approach to the long-standing challenge of alkane transformation. With the aid of solid-state NMR spectroscopy and GC-MS analysis, it was found that the co-conversion of propane and methanol can be readily initiated by hydride transfer at temperatures of ≥449 K over the acidic zeolite H-ZSM-5. The formation of (13)C-labeled methane and singly (13)C-labeled n-butanes in selective labeling experiments provided the first evidence for the initial hydride transfer from propane to surface methoxy intermediates. The results not only provide new insight into carbocation chemistry of solid acids, but also shed light on the low-temperature transformation of alkanes for industrial applications.

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Non‐Oxidative Activation of Alkanes

Abstract: The sections in this article are Introduction Thermodynamic Aspects Activation of Methane Catalytic Decomposition of Methane to Hydrogen and Carbon Conversion of Methane to Ethane and other Aliphatics Aromatization of Methane The Catalyst T… Show more

Cited by 3 publications

References 81 publications

Production of High-Octane Fuel Components by Dehydroalkylation of Benzene with Mixtures of Ethane and Propane

Production of High-Octane Fuel Components by Dehydroalkylation of Benzene with Mixtures of Ethane and Propane

Alkane Activation Initiated by Hydride Transfer: Co‐conversion of Propane and Methanol over H‐ZSM‐5 Zeolite

Alkane Activation Initiated by Hydride Transfer: Co‐conversion of Propane and Methanol over H‐ZSM‐5 Zeolite

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