"Reduction Kinetics of the Binary Metal Oxide" 

Sudipta Mondal, MSE PhD Candidate 

Advisor: Professor Ken Sandhage

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ABSTRACT

A binary metal oxide solid solution refers to a homogeneous crystalline material composed of two different metal oxide compounds that are mixed at the atomic or molecular level. The reduction of binary oxide solid solution by gaseous phase results in the formation of a binary metallic alloy. Depending on the reduction conditions, intermediate oxide phases might transiently form before reaching the final reduced metallic state. The presence of these intermediate phases can significantly influence the kinetics of the reduction process. The kinetics of gas-solid reactions for the reduction of binary metal oxide solid solutions are discussed using various kinetic models and factors that impact the reduction rates. Emphasis is placed on capturing the influences of temperature, particle size, and dopant concentration on the rate and extent of reduction. The rate-controlling step also plays a pivotal role in dictating the rate and pathway of a reaction. Understanding and identifying this step is crucial for elucidating reaction mechanisms, predicting reaction rates, and optimizing chemical processes. A detailed overview is provided for the reduction mechanism of metal oxides using H2 gas, employing shrinking core model (SCM) to explain the reduction of iron oxide by H2 gas. The diversity of kinetic models reflects the variety of conditions, materials, and mechanisms involved in reduction reactions. This report discusses various kinetic models and rate-limiting steps for the isothermal reduction of several binary metal oxide mixtures.