Eliminación de carbonilla en gases de escape con catalizadores DeNOx. Determinación de parámetros cinéticos

摘要

DeNOx catalysts eliminate nitrogen oxides in diesel vehicles and, in addition, can come in contact with soot or, even, be used as Diesel Particulate NOx Reduction (DPNR) material. Therefore, the understanding of the interaction mechanism between soot and catalyst is of high interest. The Printex U model soot and a Pt-K/Al2O3 catalyst have been used, with potassium in the form of oxide and hydrated hydroxycarbonate. The process of elimination in different oxidizing atmospheres has been studied by TG-MS. The processes have been decoupled by establishing the distribution function of activation energy. In the absence of catalyst, the combustion of the soot with the molecular oxygen in the gas phase occurs at temperatures around 1100K. In the presence of NO, the reduction takes place at a lower temperature due to its more oxidizing character and the species of nitrogen oxides retained and in the gas phase. If the carbon is in contact with the Pt-K/Al2O3 catalyst, the Pt-OH-K centers are responsible for the elimination via gasification at 780K with an activation energy around 85 kJ·mol-1.