(618b) Kinetic Analysis of the Reactivity of Lattice Oxygen in Molybdenum Dioxide Based Catalysts Under Pulse-Type Experiments

Molybdenum dioxide (MoO₂) is a distorted rutile oxide which displays metallic character, high oxygen anion conductivity and recently has been reported to exhibit catalytic activity towards a partial oxidation of a variety of hydrocarbons to produce syngas with a high coke resistance. The coke resistance is believed to be possible due to the high mobility of its lattice oxygen that facilitates the oxidation of the adsorbed carbon species. However, when MoO₂ is exposed to reducing conditions, such as low O₂/C ratio in the partial oxidation or is employed as an anode material for a solid oxide fuel cell (SOFC), MoO₂ will undergo a thermodynamic phase transformation to Mo₂C, and thus, catalytic activity and selectivity would be modified. In order to better understand this phenomenon, a fundamental study is presented to analyze and correlate the role of lattice oxygen driven force with its oxidation activity by using a pulse technique approach. This assessment was done under different operating temperatures where repeated pulses of a reducing gas were sent to the sample to titrate the lattice oxygen while product gases were analyzed using a Real Time Gas Analyzer (RTGA). Changes in the stoichiometric formula and phase composition were obtained using Thermogravimetric Analysis (TGA) and X – Ray diffraction (XRD).