KINETIC MODELING OF HYDROGEN TRANSPORT-LIMITED REDUCTION RATE USING SHRINKING CORE MODEL

Abstract

Reduction of titanium dioxide (TiO₂) is important in the production of titanium sub- oxides such as Ti3O5 and Ti2O3 which have numerous applications. In this research, mathematical modeling of hydrogen (H₂) reduction of TiO₂ has been developed in MATLAB by using a shrinking core model (SCM). The SCM can be used to determine the transport-limited reaction rate for TiO₂ reaction in 100 volume (vol.) % of H₂ atmosphere. H₂ gas was used due to its environmental benefits and faster reaction kinetics. The reduction process was predicted from independently measured physical and thermodynamic properties of TiO₂ and H₂ components. From the theoretical modeling results, the percent of reduction (R’) for isothermal conditions was 100% at 20 minutes with a temperature range between 1373-1773 K. Experimental data showed a lowered R’ then the model, with maximum R’ of 70% at 1773 K after 40 minutes. At 1373 K, experimental R’ was about 10%. Nonisothermal reduction model showed a theoretical R’ value of 100% after 40 minutes at 1373 K. At 1773 K, the theoretical R’ of 100% was obtained after 20 minutes. Non-isothermal reduction modeling showed a better approximation to experimental data than isothermal reduction.