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On the reactions 2 C + O 2 and C + CO 2 at very low pressure
Author(s) -
Knacke Ottmar,
Lemperle Michael,
Seidl Ursula
Publication year - 2000
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.200001216
Subject(s) - chemistry , chemisorption , bar (unit) , graphite , oxygen , ambient pressure , analytical chemistry (journal) , thermodynamics , physics , organic chemistry , adsorption , meteorology
In an ultra high vacuum heterogeneous gas reactions such as 2 C + O 2 G → 2 CO G and C + CO 2 G → 2 CO G often show a less complicated reaction path than under normal pressure. In the present study the graphite sample is a commercial light‐bulb filament, which is extremely resistant against oxidation. Under low pressure the combustion reaction is of first order with a continuous transition to zero order at temperatures between 900 and 1300 K depending on the oxygen pressure. The Boudouard reaction behaves similarly but obeys zero order only around 2000 K and for CO 2 pressures around 1 bar. The measured and the statistically calculated reaction rates agree well. An insight of the details of the reaction and chemisorption is determined by the evaluation of experiments carried out in an ultra high vacuum using isotopes such as 13 CO 2 G . The Boudouard equilibrium for graphite can be reached only catalytically, e.g., with sponge iron in statu nascendi.