Two-Dimensional Spatial Resolution of Concentration Profiles in Catalytic Reactors by Planar Laser-Induced Fluorescence: NO Reduction over Diesel Oxidation Catalysts†
This research was supported by the German Research Foundation (DFG).
Graphical Abstract
The measurement of two-dimensional species concentration profiles in the gas phase over catalytic walls is achieved by planar laser-induced fluorescence. The interaction of catalytic surface kinetics and mass transport is exemplarily studied for the reduction of NO by hydrogen to ammonia over a diesel oxidation catalyst with platinum as an active component.
Abstract
Planar laser-induced fluorescence (PLIF) enables noninvasive in situ investigations of catalytic flow reactors. The method is based on the selective detection of two-dimensional absolute concentration maps of conversion-relevant species in the surrounding gas phase inside a catalytic channel. Exemplarily, the catalytic reduction of NO with hydrogen (2 NO+5 H2→2 H2O+2 NH3) is investigated over a Pt/Al2O3 coated diesel oxidation catalyst by NO PLIF inside an optically accessible channel reactor. Quenching-corrected 2D concentration maps of the NO fluorescence above the catalytic surface are obtained under both, nonreactive and reactive conditions. The impact of varying feed concentration, temperature, and flow velocities on NO concentration profiles are investigated in steady state. The technique presented has a high potential for a better understanding of interactions of mass transfer and surface kinetics in heterogeneously catalyzed gas-phase reactions.
