The two-dimensional (2D) temporal evolution of the NO-concentration
over a NOx-storage catalyst is investigated in situ with
planar laser-induced fluorescence (PLIF) in an optically accessible
parallel wall channel reactor. Signal accumulated phase-correlated
2D-recordings of repetitive adsorption/desorption cycles are obtained
by synchronizing the switching of the NO gas flow (on/off) with the
laser and detection system, thereby significantly increasing the signal-to-
noise ratio. The gas compositions at the reactor outlet are
additionally monitored by ex-situ analytics. The impacts of varying
feed concentration, temperature and flow velocities are investigated
in unsteady state. Transient kinetics and the mass transfer limitations
can be interpreted in terms of the NO concentration gradient changes.
The technique presented here is a very useful tool to investigate the
interaction between surface kinetics and the surrounding gas flow,
especially for transient catalytic processes.