CO oxidation in a fixed bed reactor with high frequency cycling of the feed

An experimental set-up is presented, which allows cycling of the feed for t ransient operation of fixed bed microreactors at frequencies up to 10 Hz. T he set-up was applied for the transient oxidation of CO by O-2 over Pt/gamm a-Al2O3,. The results gave clear evidence that CO may adsorb on oxygen cove red sites under simultaneous production of CO2. O-2 does, however, not adso rb on CO covered sites, which causes a delay in the transient of the CO2 pr oduction. A kinetic model including rate parameters was presented, which gi ves an adequate description of the experimental data and provides much more detailed information than could be obtained from steady-state experiments. A simulation study is performed, with CO oxidation as an example, to explor e how feed composition cycling is affected by diffusion inside catalyst pel lets. If the time scale of diffusion inside the catalyst is much smaller th an the time scale of the applied oscillation, intrinsic kinetics might be o btained from experiments with cycling of the feed. This statement supposes that diffusion limitation would be absent in the corresponding steady-state without composition cycling, and that the reaction kinetics is in the dyna mic regime. (C) 1999 Elsevier Science Ltd. All rights reserved.