Kinetic instabilities and intra-thread diffusion limitations in CO oxidation reaction at Pt/fiber-glass catalysts

Experimental and mathematical simulation studies of CO oxidation reaction at Pt-based glass-fiber catalyst showed that reaction phenomena in fabric and threads of woven glass-fiber catalysts is rather complicated by transfer limitations, which may impose especially valuable influence on reactions with strongly non-linear kinetics. Such limitations are related to extra-thread and intra-thread heat and mass transfer. Additionally, in thin beds, consisting of one or few layers of woven catalyst, the significant role may be played by experimentally confirmed transient oscillations between CSTR and plug-flow regimes, therefore, the axial heat and mass dispersion is an important transfer factor for such beds as well. Mathematical modelling of phenomena inside the catalyst thread on the basis of elaborated kinetic model showed possibility of existence of steady-state multiplicity as a self-sufficient result of intra-thread transfer limitations. In general, observed reaction rates at the catalyst thread and location of multiplicity region may depend upon many factors (thread diameter and porosity, surface CO concentration and temperature and even choice of reaction media balance gas), which should be taken into account for correct formulation of lab experimental procedure, interpretation of experimental data and process scale-up.