Atmosphere methane oxidation cycle

The methane oxidation to methanal is thus realized in the catalytic cycle in which atmospheric 02 is the oxidant and the OH radicals are the catalyst, and which is coupled to photoassisted dissociation of nitrogen dioxide (Figure 9.7). The latter process yields two ozone molecules per photocatalytic cycle. 

Koschorreck M. and Conrad R. (1993) Oxidation of atmospheric methane in soil measurements in the field, in soil cores, and in soil samples. Global Biogeochem. Cycles 7, 109-121. 

Figure 8 Variations in deuterium <5D black), a proxy for local temperature, and atmospheric concentrations of the greenhouse gases carbon dioxide CO2 red), and methane CH4 green), from measurements of air trapped within Antarctic ice cores. Data from Spahni R, Chappeliaz J, Stocker TF, et al. (2005) Atmospheric methane and nitrous oxide of the late Pleistocene from Antarctica ice cores. Science 3 0 . 1317-1321 and Siegenthaler U, Stocker TF, Monnin E, et al. (2005) Stable carbon cycle-climate relationship during the late Pleistocene. Science 310 1313-1317.

It is clear that the observed increase in carbon dioxide, methane, and nitrous oxide in the atmosphere cannot be explained by anthropogenic causes only. We need to bear in mind that the changeability of GHG biogeochemical cycles is a complex function of numerous parameters controlled by the NSS. Unfortunately, there is no reliable information about the correlations between many of them. This fact is admitted by experts in IPCC (2007). 

The steam reforming of methane cycle suffers from the problem of coke deposition on the catalyst bed. The primary objective of this project was to study the stability of a commercial nickel oxide catalyst for the steam reforming of methane. The theoretical minimum ratios of steam to methane that are required to avoid deposition of coke on the catalyst at various temperatures were calculated, based on equilibrium considerations. Coking experiments were conducted in a tubular reactor at atmospheric pressure in the range of 740-915°C. 

Keller, M., and W. A. Reiners. 1994. "Soil-atmosphere exchange of nitrous oxide, nitric oxide, and methane under secondary succession of pasture to forest in the Atlantic lowlands of Costa Rica." Global Biogeochemical Cycles 8 399-409. 

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