Document Type
Thesis
Date of Award
6-30-1961
Degree Name
Master of Science in Chemical Engineering - (M.S.)
Department
Chemical Engineering
First Advisor
C. L. Mantell
Second Advisor
Joseph Joffe
Third Advisor
George C. Keeffe
Abstract
The hydrogen reduction of Cr2O3 to chromium metal was found to be feasible at very low water vapor concentrations, approximately -38° to -24°C, over a temperature range of 1130° to 1490°C. Hydrogen reduction under these conditions was predicted by the calculated equilibrium curves which also indicated that Cr2O3 is reduced directly to chromium without forming the intermediate oxide, CrO. This reduction path was confirmed by X-ray diffraction analysis.
The percent reduction of Cr2O3 at each reaction temperature was constant with time suggesting an inhibiting effect of the gaseous reaction product, water vapor. Closer examination of the effect of water vapor indicated that a small increase in the residual water vapor concentration at a single temperature, 1490°C, strongly retarded the rate of reduction. This effect was expressed by an empirical equation which indicated a direct relationship between "distance-from-equilibrium" and the rate of reduction.
The effect of temperature over the range of 1130° to 1490°C was expressed in an Arrhenius plot of log rate versus reciprocal absolute temperature. From this curve the apparent enthalpy of activation was found to be 29,600 calories. Based on the hypothesis that the rate of reduction is controlled at the oxide-metal interface, an overall rate equation consistent with the experimental data and the theory of absolute reaction rates was formulated. A simplification of this expression to an Arrhenius equation was justified by the overriding effect of temperature on the rate of reaction for the minimum water vapor concentration range.
Recommended Citation
Strater, Kurt, "The kinetics of hydrogen reduction of chromic oxide" (1961). Theses. 3236.
https://digitalcommons.njit.edu/theses/3236
