Thermodynamics of Reduction of Titania by CH4-H2 Gas Mixture

Abstract:

Given the considerable global interest in the preparation of Ti and TiC, a novel reduction method for TiO₂ in a CH₄-H₂ atmosphere was proposed, and the reduction thermodynamic behavior, phase equilibrium, and energy consumption of TiO₂ during its reaction with a CH₄-H₂ gas mixture were investigated. The results indicate that the reaction proceeds via a stepwise reduction pathway from TiO₂ to Ti(C, O), with the Magnéli phase (Ti_nO_2n-1) and Ti₃O₅ serving as intermediate phases. Notably, the reduction of TiO₂ by H₂ is more challenging than that by CH₄, which may be attributed to the inhibitory effect of H₂ on the surface carbon precipitation. For the complete carbonization of 1 mol TiO₂, the total energy required at 1000, 1100, and 1200 ℃ is 1159, 925, and 977 kJ/mol, respectively, which may be related to the shift of gas-phase equilibrium and the increase in side reactions at high temperatures.