MODELING OF EVACUATED PULSE MICRO-REACTORS

The system for temporal analysis of products consists of a micro-reactor, a high-speed gas pulsing valve, and a computer-controlled real-time quadrupole mass spectrometer. A pulse of reactant is introduced at the entrance of the micro-reactor and evacuated through the catalyst bed creating a mass spectrometer response. Quantification of kinetic parameters from such measurements requires a well-defined flow mechanism in the micro-reactor and an appropriate model of the system. Experimental methods for establishing Knudsen flow in the catalyst bed are outlined. The governing differential equation for the packed-bed micro-reactor is established, and the suitability of various boundary conditions is discussed. The effect of the inlet section on the response is illustrated and quantified. A simple boundary condition of zero exit concentration is justified. The developed model provides the foundation for quantification of results obtained in transient response experimental systems that utilize evacuated packed-bed micro-reactors.