Development of catalysts for NOx and Soot reduction

Nitrogen oxides (NO_x) and soot are both present in the exhaust gases of a diesel engine. Thus, the development of the simultaneous removal technology seeks removal of soot and NO_x in a single device, which is an ambitious purpose that would provide considerable advantages. Although many different catalytic systems for the simultaneous removal have been investigated most of them are carried out under laboratory conditions, using powder catalyst under tight or loose contact and only few authors have worked with monolithic or foam structured catalysts. In a structured catalyst one can expect loose contact between the soot and the catalyst phase, similar to real contact in a Diesel Particulate Filter where the gas flow rate is around 800 l/min, leading to a Gas Hour Space Velocity (GHSV) around 50.000 h^-1. Under such lose contact conditions GHSV becomes an important parameter in terms of assessing catalytic activity, since it can determine the fluid-dynamic patterns and the mass transfer of reactive species in the gas and towards the catalytic layer, and its influence must therefore be carefully analyzed.

In this research line, we study the simultaneous removal of soot and NO_x for catalyst prepared with a transition metal (Cu or Co) and different alkali or alkaline earth promoter (K, Ba or Cs), in experiments performed at GHSV close to the actually present in a vehicle in order to see the impact of this parameter on the activity of the different catalysts tested

Relevant publications

Gálvez, M.E., Ascaso, S. Tobías, I., Moliner, R., Lázaro M.J.. Catalytic filters for the simultaneous removal of soot and NOx: Influence of the alumina precursor on monolith washcoating and catalytic activity. Catalysis Today, 191, 2012, 96-105.

Gálvez, M.E., Ascaso, S., Moliner, R., Lázaro, M.J. Me (Cu,Co,V)-K/Al₂O₃ supported catalysts for the simultaneous removal of soot and nitrogen oxides from diesel exhausts. Chemical Engineering Science, 2013, 87, 75-90.

Gálvez, M.E., Ascaso, S., Stelmachowski, P., Legutko, P., Kotarba, A., Moliner, R., Lázaro, M.J. Influence of the surface potassium species in Fe-K/Al₂O₃ catalysts on the soot oxidation activity in the presence of NO Applied Catalysis B: Environmental 152-153, 88–98, 2014.

S. Ascaso; M. E. Galvez; R. Moliner; M.J. Lázaro; P. Da Costa.  Influence of the alumina precursor on the activity of structured Fe-K/Al₂O₃ catalysts towards the simultaneous removal of soot and NOx. Topics in Catalysis, en prensa, 2.016.