Laboratory Studies of Catalysis of CO to Organics on Grain Analogs

Ferrante, R. F.

doi:10.1006/icar.2000.6350

Cited by 26 publications

(21 citation statements)

References 11 publications

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“…This once popular idea, that was an adjunct to an overall hypothesis of solar system formation from a cooling nebula gas of solar composition, has declined in importance following refinement of models of nebular dynamics. However, FTT is currently undergoing something of a renaissance (Ferrante et al, 2000;Hill and Nuth, 2000), where its operation with more realistic catalysts and under generic astrophysical conditions puts it once more back into consideration. It should be said that the degree of isotopic fractionation observed during FTT reactions in the laboratory (75%0 at 375 K; Hayatsu and Anders, 1981) is only just adequate to explain the full range of a13C values observed in meteoritic carbonates.…”

mentioning

confidence: 99%

Light dement geochemistry of the Tagish Lake CI2 chondrite: Comparison with CI1 and CM2 meteorites

Grady

Verchovsky

Franchi

et al. 2002

Meteorit & Planetary Scien

102

105

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Abstract-We have studied the carbon and nitrogen stable isotope geochemistry of a small pristine sample of the Tagish Lake carbonaceous chondrite by high-resolution stepped-combustion mass spectrometry, and compared the results with data from the Orgueil (CIl), Elephant Moraine (EET) 83334 (CM1) and Murchison (CM2) chondrites. The small chip of Tagish Lake analysed herein had a higher carbon abundance (5.81 wt%) than any other chondrite, and a nitrogen content (~1220 ppm) between that of CIl and CM2 chondrites. Owing to the heterogeneous nature of the meteorite, the measured carbon abundance might be artificially high: the carbon inventory and whole-rock carbon isotopic composition (o13C~+24.4%0) of the chip was dominated by 13C-enriched carbon from the decomposition of carbonates (between 1.29 and 2.69 wt%; o13C~+67%0 and 0 18 0~+35%0, in the proportions~4: 1 dolomite to calcite). In addition to carbonates, Tagish Lake contains organic carbon (~2.6 wt%, o13C~-9%0; 1033 ppm N, 015N~+77%0), a level intermediate between CI and CM chondrites. Around 2% of the organic material is thermally labile and solvent soluble. A further 18% ofthe organic species are liberated by acid hydrolysis. Tagish Lake also contains a complement of pre solar grains. It has a higher nanodiamond abundance (approximately 3650-4330 ppm) than other carbonaceous chondrites, along with~8 ppm silicon carbide. Whilst carbon and nitrogen isotope geochemistry is not diagnostic, the data are consistent with classification of Tagish Lake as a CI2 chondrite.

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mentioning

confidence: 99%

Light dement geochemistry of the Tagish Lake CI2 chondrite: Comparison with CI1 and CM2 meteorites

Grady

Verchovsky

Franchi

et al. 2002

Meteorit & Planetary Scien

102

105

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“…Phase Q is distributed in the fine-grained rims around chondrules together with presolar diamonds (Nakamura et al, 1999). Q gases may be trapped in very thin coatings of grains, since grain surface catalysis is one of the mechanisms of organic formation (e.g., Ferrante et al, 2000). Therefore, the weight of the carrier phase of Q where the noble gases are actually preserved is very little compared to the entire weight of the acid residue.…”

Section: Discussionmentioning

confidence: 99%

Argon retentivity of carbonaceous materials: feasibility of kerogen as a carrier phase of Q-noble gases in primitive meteorites

et al. 2009

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Extremely large amounts of heavy noble gases are concentrated in phase Q, which seems to be a carbonaceous phase analogous to terrestrial Type III kerogen. Phase Q must have very high noble gas retentivity based on the presence of such extremely large amounts of heavy noble gases in a very minor fraction of the meteorite. To verify that kerogen is a carrier phase of Q-noble gases, X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) using synchrotron radiation were carried on for kerogens (coals) and carbon allotropes that had been bombarded by 3-keV Ar ions, and the Ar retentivities of the two materials were compared. This comparison of the estimated Ar concentrations in the target materials revealed that carbon allotropes (graphite, fullerene, carbon nanotube, and diamond) have a much higher Ar retentivity than kerogens. This unexpected result clearly shows that the terrestrial kerogens tested in our study are not suitable as a carrier phase of Ar and, consequently, that phase Q may not be similar to the terrestrial kerogen tested. If heavy noble gases are really concentrated in carbonaceous components of primitive meteorites, phase Q may have a more ordered structure than terrestrial kerogen based on the fact that the greatest difference between terrestrial kerogen and carbon allotropes is the degree of order of the molecular structure.

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“…These hypotheses have been studied and both have had some success in explaining volatiles in comets (55). Gas-grain reaction experiments appropriate for such environments are in their infancy (82) and must be extended by using more realistic catalytic materials. Another new avenue for research is coupled accretion, chemistry, and dynamic evolution of planetesimals.…”

Section: Implications For Astrobiologymentioning

confidence: 99%

Constraints on nebular dynamics and chemistry based on observations of annealed magnesium silicate grains in comets and in disks surrounding Herbig Ae/Be stars

Hill

Grady

Nuth

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

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Understanding dynamic conditions in the Solar Nebula is the key to prediction of the material to be found in comets. We suggest that a dynamic, large-scale circulation pattern brings processed dust and gas from the inner nebula back out into the region of cometesimal formation-extending possibly hundreds of astronomical units (AU) from the sun-and that the composition of comets is determined by a chemical reaction network closely coupled to the dynamic transport of dust and gas in the system. This scenario is supported by laboratory studies of Mg silicates and the astronomical data for comets and for protoplanetary disks associated with young stars, which demonstrate that annealing of nebular silicates must occur in conjunction with a large-scale circulation. Mass recycling of dust should have a significant effect on the chemical kinetics of the outer nebula by introducing reduced, gas-phase species produced in the higher temperature and pressure environment of the inner nebula, along with freshly processed grains with ''clean'' catalytic surfaces to the region of cometesimal formation. Because comets probably form throughout the lifetime of the Solar Nebula and processed (crystalline) grains are not immediately available for incorporation into the first generation of comets, an increasing fraction of dust incorporated into a growing comet should be crystalline olivine and this fraction can serve as a crude chronometer of the relative ages of comets. The formation and evolution of key organic and biogenic molecules in comets are potentially of great consequence to astrobiology. Comets: Ancestors and Antecedents of the Solar SystemI t is almost an article of faith among members of the planetary science community that comets are the most primitive bodies in the Solar System. In general, this is taken to mean that materials in comets are preserved in nearly the same state today as when the material originally aggregated from the Solar Nebula to form cometesimals. Nothing we say below will contradict this axiom. However, we will show that comets are not simply collections of unaltered presolar grains and ices formed in the precollapse molecular cloud, but are instead aggregates of materials representative of the building blocks then present in the nebula at the time of their accretion. In our opinion, comets represent the best grab bag samples of material from the primitive Solar Nebula. However, this does not imply that materials incorporated into cometesimals did not undergo very significant processing in the nebula itself, only that little further processing occurred once material was incorporated into the cometesimal.In this paper, we show that grains incorporated into comets and seen around young A and B stars as their protoplanetary disks begin to clear contain silicate grains that have undergone processing at temperatures as high as 1,100 K for periods of minutes, or more likely, at temperatures near 1,000 K for days to weeks, and that such processing can only have occurred in the inner nebula. After processi...

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Laboratory Studies of Catalysis of CO to Organics on Grain Analogs

Cited by 26 publications

References 11 publications

Light dement geochemistry of the Tagish Lake CI2 chondrite: Comparison with CI1 and CM2 meteorites

Light dement geochemistry of the Tagish Lake CI2 chondrite: Comparison with CI1 and CM2 meteorites

Argon retentivity of carbonaceous materials: feasibility of kerogen as a carrier phase of Q-noble gases in primitive meteorites

Constraints on nebular dynamics and chemistry based on observations of annealed magnesium silicate grains in comets and in disks surrounding Herbig Ae/Be stars

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