Catalysed self-cleaning of air on the earth's surface |
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| Authors: | G Hultquist P Szakálos |
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| Institution: | 1. Royal Institute of Technology, Drottning Kristinas V?g 51, SE-100 44, Stockholm, Sweden
2. Szakálos Material Science AB, Fridhemsgatan 29B, S-112 40, Stockholm, Sweden
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| Abstract: | Generally, it is assumed that UV-light, high temperature or reactive molecules like O3 and OH are needed to activate gas reactions in air. In consequence, the catalytic activity on natural materials such as sand and soil on the earth's surface is assumed to be insignificant. We have measured O2-dissociation rates on natural quartz sand at 40˚C and compared these with O2-dissociation rates near 500˚C on materials with well-known catalytic activity. In terms of probabilities for dissociation of impinging O2-molecules the measured rates are in the 10−12–10−4 range. We have also measured dissociation rates of H2 and N2, water-formation from H2 and O2 mixtures, exchange of N between N2, NO
x
and a breakdown of HNO3, NO2 and CH4 on natural quartz sand at 40˚C. The measured rates together with an effective global land area have been used to estimate the impact of thermodynamically driven reactions on the earth's surface on the global atmospheric budgets of H2, NO2 and CH4. The experimental data on natural quartz sand together with data from equilibrium calculations of air suggest that an expected increase in anthropogenic supply of air pollutants, such as NO
x
or other “reactive” nitrogen compounds, hydrogen and methane, will be counter-acted by catalysis on the earth's surface. On the other hand, at Polar Regions and boreal forests where the “reactive” nitrogen concentration is below equilibrium, the same catalytic effect activates formation of bio-available nitrogen compounds from N2, O2 and H2O. |
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| Keywords: | Molecular dissociation H2 O2 N2 Natural quartz sand NO x -decomposition H2-removal Mass spectrometry Isotopes Ambient air |
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