CATALYTIC-OXIDATION OF CARBON-MONOXIDE UNDER PERIODIC OPERATION

A growing literature demonstrates resonance of the rate of CO oxidation with frequency of composition switching and that a global increase in rate under composition modulation is possible. Differences are found for the various metal catalysts used: CO oxidation is stimulated at frequencies between 0.1 and 1.0 Hz over noble metals, whereas stimulation occurs at frequencies below 0.05 Hz with oxide catalysts. Multiple resonances with an apparent harmonic relationship, "wrong-way" response, or very slow relaxation to reproducible cycles have been observed. These differences suggest mechanisms through which rate improvements arise are not the same for all catalysts.