An Experimental and Theoretical Investigation of the Behavior of a Monolithic Ti−V−W−Sepiolite Catalyst in the Reduction of NOx with NH₃

A novel Ti−V−W−sepiolite catalyst for the selective catalytic reduction (SCR) of NO x with NH 3 was characterized by surface area and pore size distribution measurements, SEM, EDX, XRD, and FT-IR and FT-LR spectroscopy: the catalyst consists of TiO 2 particles impregnated with vanadia and tungsta and dispersed among the sepiolite fibers. Intrinsic kinetics of NO x reduction were determined over the catalyst in powder form. The behavior of the catalyst in the shape of a honeycomb was investigated with respect to the influence of area velocity, reaction temperature, and NH 3 /NO feed ratio on the NO reduction efficiency. Based on the intrinsic kinetics and on the measured catalyst morphology, a previous mathematical model of SCR monolith reactors provided predictions of NO conversion closely in line with the data. The model was used also to investigate how the catalyst efficiency could be improved by changing its pore structure.