Reduction of titania by methane-hydrogen-argon gas mixture

Abstract

Reduction of titania using methane-containing gas was investigated in a laboratory fixed-bed reactor in the temperature range 1373 to 1773 K. The reduction product is titanium oxycarbide, which is a solid solution of TiC and TiO. At 1373 K, the formation rate of TiC is very slow. The rate and extent of reaction increase with increasing temperature to 1723 K. A further increase in temperature to 1773 K does not affect the reaction rate and extent. An increase in methane concentration to 8 vol pct favors the reduction process. A further increase in methane concentration above 8 vol pct causes excessive carbon deposition, which has a negative effect on the reaction rate. Hydrogen partial pressure should be maintained above 35 vol pct to depress the cracking of methane. Addition of water vapor to the reducing gas strongly retards the reduction reaction, even at low concentrations of 1 to 2 vol pct. Carbon monoxide also depresses the reduction process, but its effect is significant only at higher concentrations, above 10 vol pct.