Chemical Transient Kinetics (CTK) are used to study the time response of a catalytic reaction following sudden changes in the gas phase composition at given flow rates. The build-up of the steady-state is traced, as is the scavenging. In this manner insight is gained into the time-dependent construction/destruction of the "catalytically active phase".
Partial pressures of reactants and products are followed using quadrupolar mass spetrometry, Balzers QMG-422 (and gas chromatography in the near future). The quantitative evaluation of pressures and fluxes, by solving the mass balance, enables the determination of atomic quantities on the surface at any time during build-up and scavenging. Thus mechanistic insight into the catalytic process is gained which would otherwise be impossible by simple steady-state analysis.
CTK analytic system
(quadrupole mass spectrometer)
CTK gas introduction circuit
The experimental set-up is mass-flow controlled. A pyrex/quartz micro-reactor is used and operated to reach atmospheric pressures. The same set-up enables as to carry out temperature-programmed experiments as well as selective chemisorption and non-selective physisorption to determine active and overall (specific) surface area, respectively. A second CTK set-up is actually being constructed.
Gas introduction circuit
TP experiments controllers