Catalytic dehydrogenative coupling of methane on active carbon. Effect of metal supported on active carbon

Yagita, Hiroshi; Ogata, Atsushi; Obuchi, Akira; Mizuno, Katsuhiko; Maeda, Toshiyuki; Fujimoto, Kaoru

doi:10.1016/0920-5861(95)00316-9

Cited by 7 publications

(5 citation statements)

References 12 publications

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“…According to thermodynamic calculation, the free energy change of the dehydrogenative coupling of methane without oxygen is positive at temperatures below 1373 K. Consequently, the reaction temperature should be as high as 1373K in conventionally catalytic methods [7] . But under pulse corona plasma, this reaction may proceed at normal temperature and pressure.…”

Section: Comparing Positive Corona With Negative Coronamentioning

confidence: 99%

Coupling of methane under pulse corona plasma (I)

Zhu

Gong

Zhang

et al. 2000

Sc. China Ser. B-Chem.

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At normal temperature and pressure, pulse corona plasma was used as a new method for the dehydrogenative coupling of methane in the absence of oxygen. The effects of voltage polarity and input energy on the dehydrogenative coupling of methane were investigated. The parameter "energy efficiency" was introduced to examine the coupling of the input energy and the dehydrogenative coupling of methane. The experimental results show that positive corona gives higher energy efficiency than negative corona. When the positive corona was chosen, C 2 yield per pass was 31.6% and acetylene yield per pass was 30.1% with 44.6% methane conversion at an input energy density of 1788kJ/mol and a pulse repetition frequency of 66Hz. The function of input energy density towards methane conversion may be expressed as a formula of -ln(1-X) = k (P/F). In the range of input energy employed, C 2 yield is proportional to input energy density, but energy efficiency drops off with increasing input energy density.

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Section: Comparing Positive Corona With Negative Coronamentioning

confidence: 99%

Coupling of methane under pulse corona plasma (I)

Zhu

Gong

Zhang

et al. 2000

Sc. China Ser. B-Chem.

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“…The Mo/zeolite catalysts can convert CH 4 into benzene (C 6 H 6 ) with a good yield, although deactivation of the catalyst by carbon deposition is serious. In addition, some effective catalysts such as carbonaceous materials, − Pt–SO 4 /ZrO 2 , TaH/SiO 2 , GaN, and Pt-modified zeolite catalysts , were found for the DCM reaction. Recently, the catalysis of single Fe sites in a silica matrix (Fe@SiO 2 ) was reported for the DCM catalyst. , Fe@SiO 2 achieved a high hydrocarbon yield (48%) without carbon deposition at 1363 K. Kjølseth et al succeeded to suppress the carbon deposition on the Mo/HMCM-22 catalyst by using a coionic membrane reactor …”

Section: Introductionmentioning

confidence: 99%

Catalytic Mechanism of Liquid-Metal Indium for Direct Dehydrogenative Conversion of Methane to Higher Hydrocarbons

et al. 2020

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There is a great interest in direct conversion of methane to valuable chemicals. Recently, we reported that silica-supported liquid-metal indium catalysts (In/SiO2) were effective for direct dehydrogenative conversion of methane to higher hydrocarbons. However, the catalytic mechanism of liquid-metal indium has not been clear. Here, we show the catalytic mechanism of the In/SiO2 catalyst in terms of both experiments and calculations in detail. Kinetic studies clearly show that liquid-metal indium activates a C–H bond of methane and converts methane to ethane. The apparent activation energy of the In/SiO2 catalyst is 170 kJ mol–1, which is much lower than that of SiO2, 365 kJ mol–1. Temperature-programmed reactions in CH4, C2H6, and C2H4 and reactivity of C2H6 for the In/SiO2 catalyst indicate that indium selectively activates methane among hydrocarbons. In addition, density functional theory calculations and first-principles molecular dynamics calculations were performed to evaluate activation free energy for methane activation, its reverse reaction, CH3–CH3 coupling via Langmuir–Hinshelwood (LH) and Eley–Rideal mechanisms, and other side reactions. A qualitative level of interpretation is as follows. CH3–In and H–In species form after the activation of methane. The CH3–In species wander on liquid-metal indium surfaces and couple each other with ethane via the LH mechanism. The solubility of H species into the bulk phase of In is important to enhance the coupling of CH3–In species to C2H6 by decreasing the formation of CH4 though the coupling of CH3–In species and H–In species. Results of isotope experiments by combinations of CD4, CH4, D2, and H2 corresponded to the LH mechanism.

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“…However, these reactions require a high-temperature condition and are cost-intensive. To reduce the energy consumption, various approaches have been proposed. − The oxidative coupling of CH 4 and the partial oxidation of CH 4 can produce higher hydrocarbons and oxygenated compounds, respectively. − Although various catalysts for these reactions have been proposed, the performances are still low because of the complete oxidation to CO 2 . The dehydrogenative conversion of methane (DCM) can be used for the synthesis of higher hydrocarbons. − Wang et al pioneered the catalytic reaction for DCM using Mo/zeolite catalysts, which converts methane to benzene .…”

Section: Introductionmentioning

confidence: 99%

“…To reduce the energy consumption, various approaches have been proposed. − The oxidative coupling of CH 4 and the partial oxidation of CH 4 can produce higher hydrocarbons and oxygenated compounds, respectively. − Although various catalysts for these reactions have been proposed, the performances are still low because of the complete oxidation to CO 2 . The dehydrogenative conversion of methane (DCM) can be used for the synthesis of higher hydrocarbons. − Wang et al pioneered the catalytic reaction for DCM using Mo/zeolite catalysts, which converts methane to benzene . For DCM, the deactivation due to carbon deposition is problematic, especially for the transition-metal catalysts such as supported Fe, Ni, and Pd catalysts, which decompose CH 4 to C and H 2 . − Recently, Bao et al obtained remarkable selectivity (>99%) using single Fe sites in a silica matrix .…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study on the C–H Activation of Methane by Liquid Metal Indium: Catalytic Activity of Small Indium Clusters

et al. 2019

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The mechanism of C−H activation of methane by liquid indium, which is the first step of the dehydrogenative conversion of methane to higher hydrocarbons, was investigated using density functional theory calculations. In the first-principle molecular dynamics trajectory at the experimental temperature (1200 K), low-coordinated indium atoms continuously appear on the disordered liquid surface. The C−H cleavage is endothermic on clean surfaces, while the lowcoordinated indium atoms reduce the endothermicity significantly. In small indium clusters, which are models of low-coordinated atoms on a surface, the calculated activation energy is much smaller than that on the clean surface. The energy level of the methane C−H σ* orbital is reduced by the interaction with the indium 5pσ orbitals. In 2 shows the lowest activation energy and exothermicity in the C−H bond cleavage.

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Catalytic dehydrogenative coupling of methane on active carbon. Effect of metal supported on active carbon

Cited by 7 publications

References 12 publications

Coupling of methane under pulse corona plasma (I)

Coupling of methane under pulse corona plasma (I)

Catalytic Mechanism of Liquid-Metal Indium for Direct Dehydrogenative Conversion of Methane to Higher Hydrocarbons

Theoretical Study on the C–H Activation of Methane by Liquid Metal Indium: Catalytic Activity of Small Indium Clusters

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