Oxidative Coupling of Methane Over Na–W–Mn–Zr–S–P/SiO2 Catalyst: Effect of S, P Addition on the Catalytic Performance

Chen, Fengqiu; Zheng, Wen; Zhu, Ning; Cheng, Dang-guo; Zhan, Xiaoli

doi:10.1007/s10562-008-9571-9

Cited by 37 publications

(47 citation statements)

References 19 publications

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“…Only the two brightest ones in K S had been previously recognized as carbon stars, and most of the others are IRAS point sources. We also note that one of the stars that we classify as a red giant in Table 6, star #9, has been identified as a carbon star by Chen & Chen (2003), although we do not identify its characteristic features in the near-infrared. -Long-period variables: the infrared colors of Mira and semiregular long-period variables makes them another potential contaminant of the early-type locus.…”

Section: -Stars With Obvious Brγ Absorption and Possibly Othermentioning

confidence: 60%

The outskirts of Cygnus OB2

Comerón¹,

Pasquali²,

Figueras

et al. 2008

A&A

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Context. Cygnus OB2 is one of the richest OB associations in the local Galaxy, and is located in a vast complex containing several other associations, clusters, molecular clouds, and HII regions. However, the stellar content of Cygnus OB2 and its surroundings remains rather poorly known largely due to the considerable reddening in its direction at visible wavelength. Aims. We investigate the possible existence of an extended halo of early-type stars around Cygnus OB2, which is hinted at by nearinfrared color-color diagrams, and its relationship to Cygnus OB2 itself, as well as to the nearby association Cygnus OB9 and to the star forming regions in the Cygnus X North complex. Methods. Candidate selection is made with photometry in the 2MASS all-sky point source catalog. The early-type nature of the selected candidates is confirmed or discarded through our infrared spectroscopy at low resolution. In addition, spectral classifications in the visible are presented for many lightly-reddened stars. Results. A total of 96 early-type stars are identified in the targeted region, which amounts to nearly half of the observed sample. Most of them have featureless near-infrared spectra as expected from OB stars at the available resolution. Another 18 stars that display Brackett emission lines can be divided between evolved massive stars (most likely Be stars) and Herbig Ae/Be stars based on their infrared excesses. A component associated with Cygnus OB9/NGC 6910 is clearly identified, as well as an enhancement in the surface density of early-type stars at Cygnus X North. We also find a field population, consisting largely of early B giants and supergiants, which is probably the same as identified in recent studies of the inner 1• circle around Cygnus OB2. The age and large extension of this population discards a direct relationship with Cygnus OB2 or any other particular association. Conclusions. Earlier claims of the possible large extent of Cygnus OB2 beyond its central, very massive aggregate seem to be dismissed by our findings. The existence of a nearly ubiquitous population of evolved stars with massive precursors suggests a massive star formation history in Cygnus having started long before the formation of the currently observed OB associations in the region.

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Section: -Stars With Obvious Brγ Absorption and Possibly Othermentioning

confidence: 60%

The outskirts of Cygnus OB2

Comerón¹,

Pasquali²,

Figueras

et al. 2008

A&A

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“…The other model based on the formate decomposition suggests that CO is formed from decomposition of formate intermediate, derived from the association of hydrogen with CO 2 . 35,52,53 Chen et al examined desorption energies of CO 2 , active sites, and reaction mechanism of the RWGS reaction on Cu nanoparticles. 54 The Cu nanoparticles strongly bind CO 2 molecules, as evidenced by two main peaks with maxima at 353 K (a peak) and 525 K (b peak) in CO 2 -TPD (temperatureprogrammed desorption of CO 2 ) spectra.…”

Section: Reaction Mechanismmentioning

confidence: 99%

Recent advances in catalytic hydrogenation of carbon dioxide

et al. 2011

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Owing to the increasing emissions of carbon dioxide (CO 2 ), human life and the ecological environment have been affected by global warming and climate changes. To mitigate the concentration of CO 2 in the atmosphere various strategies have been implemented such as separation, storage, and utilization of CO 2 . Although it has been explored for many years, hydrogenation reaction, an important representative among chemical conversions of CO 2 , offers challenging opportunities for sustainable development in energy and the environment. Indeed, the hydrogenation of CO 2 not only reduces the increasing CO 2 buildup but also produces fuels and chemicals. In this critical review we discuss recent developments in this area, with emphases on catalytic reactivity, reactor innovation, and reaction mechanism. We also provide an overview regarding the challenges and opportunities for future research in the field (319 references).

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“…The conversion of methane, which is the major constituent of natural gas, into value-added chemicals has increasingly received attention in recent years [1][2][3][4][5][6][7][8][9]. Among the processes studied, oxidative coupling of methane (OCM) has shown a promising alternative route to convert methane directly into higher hydrocarbons [1][2][3][4][5][6][7], while extensive studies has been focused on converting methane into synthesis gas [8,9], which can then be converted to higher hydrocarbons through the Fischer-Tropsch chemistry [9].…”

Section: Introductionmentioning

confidence: 99%

“…Among the processes studied, oxidative coupling of methane (OCM) has shown a promising alternative route to convert methane directly into higher hydrocarbons [1][2][3][4][5][6][7], while extensive studies has been focused on converting methane into synthesis gas [8,9], which can then be converted to higher hydrocarbons through the Fischer-Tropsch chemistry [9]. In the OCM process, methane and oxygen are generally fed over a metal or metal oxide catalyst at moderate temperatures (500-800°C) to produce mainly ethane and ethylene.…”

Section: Introductionmentioning

confidence: 99%

“…In the OCM process, methane and oxygen are generally fed over a metal or metal oxide catalyst at moderate temperatures (500-800°C) to produce mainly ethane and ethylene. The majority of the previous studies on OCM have been focused on the development of catalysts ranging from metals to rare-earth metal oxides, and this still dominates the current relevant work [1][2][3][4][5]. The overall process has been found to be endothermic and energy intensive although the OCM reaction itself is highly exothermic when two methyl radicals are coupled after the abstraction of one hydrogen atom from the methane molecule [2].…”

Section: Introductionmentioning

confidence: 99%

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Microwave assisted heterogeneous catalysis: effects of varying oxygen concentrations on the oxidative coupling of methane

Binghua

Lee

Sun

et al. 2009

React Kinet Catal Lett

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The oxidative coupling of methane was investigated over alumina supported La 2 O 3 /CeO 2 catalysts under microwave dielectric heating conditions at different oxygen concentrations. It was observed that, at a given temperature using microwave heating, selectivities for both ethane and ethylene were notably higher when oxygen was absent than that in oxygen/methane mixtures. The differences were attributed to the localised heating of microwave radiation resulting in temperature inhomogeneity in the catalyst bed. A simplified model was used to estimate the temperature inhomogeneity; the temperature at the centre of the catalyst bed was 85°C greater than that at the periphery when the catalyst was heated by microwaves in a gas mixture with an oxygen concentration of 12.5% (v/v), and the temperature difference was estimated to be 168°C in the absence of oxygen.

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Oxidative Coupling of Methane Over Na–W–Mn–Zr–S–P/SiO2 Catalyst: Effect of S, P Addition on the Catalytic Performance

Cited by 37 publications

References 19 publications

The outskirts of Cygnus OB2

The outskirts of Cygnus OB2

Recent advances in catalytic hydrogenation of carbon dioxide

Microwave assisted heterogeneous catalysis: effects of varying oxygen concentrations on the oxidative coupling of methane

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