Modelling and optimization of IR cell devoted to in situ and operando characterization of catalysts

CFD modelling and tracer experiments were performed in order to improve the design of sample holder used for transmission IR experiments in flow conditions. The complexity of gas velocity field evidenced for the usual circular geometry is avoided with an alternative geometry. A new geometry involving a square pellet, multiple inlets and outlets and specific sample holder proposed in the present study leads to a more homogeneous gas velocity in the vicinity of the catalyst surface as shown by modelling with COMSOL. Experimental measurements of local tracer concentrations in different places of the reactor during transient experiments confirmed more homogeneous tracer distribution in the reactor mainly due to multiple inlets and outlets. Consequences of the presence of dead volumes identified by modelling were also examined and discussed.