Pyrolysis of natural gas: chemistry and process concepts

Holmén, Anders; Olsvik, Ola; Rokstad, O.A.

doi:10.1016/0378-3820(94)00109-7

Cited by 244 publications

(168 citation statements)

References 29 publications

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“…For the case of CH 4 , gas-phase reaction provides CH 3 , H, H 2 , and C 2 H y (y = 1 to 6). [20] The role of the gas-phase reaction may be neglected when the methane partial pressure is low or the gas residence time of the gas flow in the CVD chamber is short, but will become considerable with increasing methane partial pressure or residence time. [16,21] Gas-phase reaction is likely to provide more C-containing species that are active for graphene growth and may break the selflimited process by depositing adlayers on top of the first grown graphene layer.…”

Section: Research Newsmentioning

confidence: 99%

Synthesis of Graphene Films on Copper Foils by Chemical Vapor Deposition

2016

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Over the past decade, graphene has advanced rapidly as one of the most promising materials changing human life. Development of production-worthy synthetic methodologies for the preparation of various types of graphene forms the basis for its investigation and applications. Graphene can be used in the forms of either microflake powders or large-area thin films. Graphene powders are prepared by the exfoliation of graphite or the reduction of graphene oxide, while graphene films are prepared predominantly by chemical vapor deposition (CVD) on a variety of substrates. Both metal and dielectric substrates have been explored; while dielectric substrates are preferred over any other substrate, much higher quality graphene large-area films have been grown on metal substrates such as Cu. The focus here is on the progress of graphene synthesis on Cu foils by CVD, including various CVD techniques, graphene growth mechanisms and kinetics, strategies for synthesizing large-area graphene single crystals, graphene transfer techniques, and, finally, challenges and prospects are discussed.

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Section: Research Newsmentioning

confidence: 99%

Synthesis of Graphene Films on Copper Foils by Chemical Vapor Deposition

2016

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“…[39] Pyrolysis of methane has also been widely studied. [40,41] At temperatures below 700 8C, a small amount of oxygen can react with methane to form H 2 O and carbon monoxide. [42] This water can in turn react with the gaseous borane radicals to form boric acid.…”

Section: Growth Mechanismmentioning

confidence: 99%

Catalyst‐Free Synthesis and Characterization of Metastable Boron Carbide Nanowires

Velamakanni

Ganesh

Zhu

et al. 2009

Adv Funct Materials

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Catalyst‐free growth of boron carbide nanowires is achieved by pyrolysis of diborane and methane at 650–750 °C and around 500 mTorr in a quartz tube furnace. Electron‐diffraction analysis using a novel diffraction‐scanning transmission electron microscopy (D‐STEM) technique indicates that the crystalline nanowires are single‐crystal orthorhombic boron carbide. TEM images show that the nanowires are covered by a 1–3 nm thick amorphous layer of carbon. Elemental analysis by electron energy loss spectroscopy (EELS) shows only boron and carbon while energy‐dispersive X‐ray spectroscopy (EDX) and X‐ray photoelectron spectroscopy (XPS) show the presence of oxygen as well as boron and carbon.

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“…Direct conversion of methane using various plasma processing technologies has been studied for many years with significantly more attention since the 1980's. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] Several types of discharges, including AC and DC corona discharges, dielectric-barrier discharge, arc plasma and the combination of microwave plasma and catalysts have been reported to produce acetylene, ethylene, hydrogen, methanol, and other liquid products. [18][19][20][21][22] The direct conversion of methane into acetylene in a thermal arc plasma, developed by Hüls, 20 has been used for more than 40 years by Dupont.…”

Section: Introductionmentioning

confidence: 99%

“…[18][19][20][21][22] The direct conversion of methane into acetylene in a thermal arc plasma, developed by Hüls, 20 has been used for more than 40 years by Dupont. 21 This process has also been used for hydrogen production. 22 However, thermal plasmas are a highly energetic state of matter characterized by extremely high temperatures 20,[23][24][25][26] and a high degree of ionization resulting in the need for specialized materials of construction.…”

Section: Introductionmentioning

confidence: 99%

“…To summarize, the flow rate for previous investigations [18][19][20][21][22][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] has been limited to less than 300 ml/min (0.64 ft 3 /h), which is far from practical for a commercial operation. The primary shortcomings of non-thermal plasma technology for methane conversion are higher energy consumption or low energy efficiency and low selectivity towards desired hydrocarbons.…”

Section: Introductionmentioning

confidence: 99%

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Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

Argyle¹,

Ackerman²,

Muknahallipatna³

et al. 2004

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The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H 2 S) in a non-thermal plasma and recover hydrogen (H 2 ) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. Experiments involving methane conversion reactions were conducted with a preliminary pulsed corona discharge reactor design in order to test and improve the reactor and membrane designs using a non-toxic reactant.This report details the direct methane conversion experiments to produce hydrogen, acetylene, and higher hydrocarbons utilizing a co-axial cylinder (CAC) corona discharge reactor, pulsed with a thyratron switch. The reactor was designed to accommodate relatively high flow rates (655×10 -6 m 3 /s) representing a pilot scale easily converted to commercial scale. Parameters expected to influence methane conversion including pulse frequency, charge voltage, capacitance, residence time, and electrode material were investigated. Conversion, selectivity and energy consumption were measured or estimated. C 2 and C 3 hydrocarbon products were analyzed with a residual gas analyzer (RGA). In order to obtain quantitative results, the complex sample spectra were de-convoluted via a linear least squares method. Methane conversion as high as 51% was achieved. The products are typically 50% -60% acetylene, 20% propane, 10% ethane and ethylene, and 5% propylene. First Law thermodynamic energy efficiencies for the system (electrical and reactor) were estimated to range from 38% to 6%, with the highest efficiencies occurring at short residence time and low power input (low specific energy) where conversion is the lowest (less than 5%). The highest methane conversion of 51% occurred at a residence time of 18.8 s with a flow rate of 39.4×10 -6 m 3 /s (5 ft 3 /h) and a specific energy of 13,000 J/l using niobium and platinum coated stainless steel tubes as cathodes. Under these conditions, the First Law efficiency for the system was 8%. Under similar reaction conditions, methane conversions were ~50% higher with niobium and platinum coated stainless steel cathodes than with a stainless steel cathode.

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Pyrolysis of natural gas: chemistry and process concepts

Cited by 244 publications

References 29 publications

Synthesis of Graphene Films on Copper Foils by Chemical Vapor Deposition

Synthesis of Graphene Films on Copper Foils by Chemical Vapor Deposition

Catalyst‐Free Synthesis and Characterization of Metastable Boron Carbide Nanowires

Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

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