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Reaction engineering for materials processing in space: Reduction of ilmenite by hydrogen and carbon monoxideOxygen is a consumable material which needs to be produced continuously in most space missions. Its use for propulsion as well as life support makes oxygen one of the largest volume chemicals to be produced in space. Production of oxygen from lunar materials is of particular interest and is very attractive possibility. The kinetics and mechanism of reduction of ilmenite by carbon monoxide and hydrogen at 800 to 1100 C were investigated. The temporal profiles of conversion for carbon monoxide have a sigmoidal shape and indicate the presence of three different stages (induction, acceleration, and deceleration) during the reduction reaction. The apparent activation energy decreases from 18 kcal/mole at 10 percent conversion to 10 kcal/mole at 50 percent conversion. The reaction is first order with respect to carbon monoxide under the experimental conditions studied. Both SEM and EDX analysis show that the diffusion of Fe product away from the reaction front and through the TiO2 phase, followed by the nucleation and growth of a separate Fe phase are important steps affecting the process kinetics. The results from hydrogen reduction show that the mechanism of ilmenite reduction by hydrogen is similar to that by carbon monoxide. However, the titanium dioxide can be further reduced by hydrogen at 800 to 1000 C. The detailed comparison and theoretical modeling of both reduction processes is presented.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Zhao, Y.
(Arizona Univ. Tucson, AZ, United States)
Shadman, F.
(Arizona Univ. Tucson, AZ, United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1991
Publication Information
Publication: Resources of Near-Earth Space: Abstracts
Subject Category
Lunar And Planetary Exploration
Accession Number
Distribution Limits
Work of the US Gov. Public Use Permitted.

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