Carbonitriding reduction of TiO2 in the CH4-H2-N2 system: Reduction temperature effect and kinetics

Abstract

Understanding reaction kinetics can provide valuable information for the design and optimization of a reaction process. In this study, the reduction degree and carbonitriding ratio of TiO2 in the CH4-H2-N2 system were investigated to understand the kinetics of carbonitriding reduction. The experimental results revealed the following important findings. The reduction degree of TiO2 increased significantly within the temperature range of 1000?C to 1200?C. At the same time, the duration of complete carbonitride time decreased with increasing temperature. However, it was found that excessively high temperatures (1200?C) had a detrimental effect on the degree of reduction. Consequently, the optimal reduction temperature was set at 1100?C, in order to achieve a balance between reduction degree and reaction time. The process of carbonitride reduction of TiO2 in the CH4-H2-N2 system corresponded to the unreacted nuclear model, where the process was mainly controlled by chemical reactions. A calculated apparent activation energy of 99.35 kJ/mol was obtained for the carbonitriding reduction process. The identification of the optimal reduction temperature and the dominant role of chemical reactions provide valuable insights for the design and optimization of carbonitriding processes with titanium compounds.