Degassing impact

Tajika, E. and Matsui, T. (1993) Degassing history and carbon cycle From an impact-induced steam atmosphere to the present atmosphere. Lithos, 30, 267-280. 

One way to get a representative product distribution for a specific period is to remove all FT products in the reactor system and replace them with a substance that will not influence selectivity determination. The FT reaction is then run for a specific period, after which a full analysis can be done that will represent only the products produced during that specific period. In Figure 13.8, data are presented for a run started with the catalyst suspended in a highly paraffinic wax (FT HI wax, C30-C90). After a certain time of synthesis, the FT run was stopped and the catalyst placed under inert conditions (argon). The reactor content was then displaced with degassed and dried polyalphaolefin oil (Durasyn). After restarting the FT synthesis, the total product spectrum was determined (HI run after displacement). It was found that the value of a2 was much lower than before the displacement of the HI wax. In fact, the a2 values were quite comparable to those measured when the FT synthesis was started up with Durasyn (compare with Durasyn runs 1, 2, and 3). This clearly illustrates the impact that the reactor medium used to start the FT reaction can have on the determination of the a-value. The results further show that there was no change in the value of a2 of the iron catalyst up to 500 h on-line. 

The mat is pyrophoric and can be shock-ignited if enclosed in a glass bottle which ruptures on impact. Also, degassing of the catalyst by heat and vacuum releases H2 which may expld (Ref 5). However H2 can be safely removed from the catalyst by prolonged aeration of the. w slurry. This process also eliminates the pyrophoricity of the alloy (Ref 4a)... 

Azuma, S., Hiyagon, H., Futagami, T., Syono, Y., Fukuoka, K. (1994) Impact-induced degassing of noble gases from olivine. In A.I.P. Conference Proc., vol. 341, K. A. Farley, Ed., pp. 270-5. Amer. Institute Physics. 

CO2, the latter being dispersed in the environment and eventually degassed to the atmosphere), whereas the other part of the carbon (i.e. only 6.4%) is used to increase the biomass. These figures demonstrate the far-reaching impact of such processes on organic carbon mineralization and sequestration. 

Ahrens (1990) has modeled the effects of impact-induced degassing on the Earth. He considers that the Earth probably alternated between two extreme states as accretion proceeded. When the Earth was degassed it would accumulate a large reducing atmosphere. This would provide a blanket that also allowed enormous surface temperatures to be reached ... 

Delmelle P. (2003) Environmental impacts of tropospheric volcanic gas plumes. In Volcanic Degassing, Geological Society of London Special Publication 213. (eds. C. Oppenheimer, D. M. Pyle, and J. Barclay). Geological Society of London, pp. 381-399. 

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