Application of in-situ temperature programmed techniques to catalytic oxidation reactions on conducting mixed oxides

A test bed for development of catalysts in a temperature programmed reactor is described. The effluent species are monitored in real time. Such data are collected into spreadsheet arrays which can be interrogated to yield kinetic data. An appropriate reactor design can therefore proceed directly from laboratory measurements to generate whole plant simulation analysis and commercial evaluation. For the oxidative coupling of methane, the hydrocarbon to oxygen ratio in the feed is of particular importance since the state of oxidation plays a significant role in determining the selectivity of the catalyst to the optimum product distribution. Homogeneous gas phase reactions may also occur at high temperatures, hence the reactor volume both upstream and downstream of the catalyst must also be considered. The stability of the catalyst under reactor conditions can be further assessed by following temperature programmed, thermal gravimetric and differential thermal analyses in diverse oxidizing, reducing or reaction atmospheres. Temperature programmed AC electrical measurements also give further insight into changes in the catalyst both at the surface and in the bulk as chemical reactions proceed. Examples of these techniques on a variety of mixed oxides such as Li-Ni-Co-O, La-Sr-Co-Fe-O and K-β′' alumina are presented. Paper presented at the 4th Euroconference on Solid State Ionics, Renvyle, Galway, Ireland