SUPPORTED PLATINUM COLLOIDAL PARTICLES IN THE SELECTIVE CATALYTIC REDUCTION OF NITROGEN-OXIDES

The experimental results discussed in this paper are a part of a broader study undertaken in order to develop an industrial process for the abatement of NO(x) emissions from nitric acid plant. Supported 0,1% wt Pt catalyst has been prepared by adsorption of the colloidal platinum particles onto a nu-alumina support (190 m2/g). The behaviour of this catalyst has been studied for the nitric oxide reduction with ammonia in the presence of oxygen. A first order kinetic equation fits the experimental data of the ammonia total conversion. The Pt/Al2O3 catalyst showed a high activity in both NO and NH3 elimination, maintaining its activity for operating temperatures above 250-degrees-C and very low NO2 concentrations in the gas. Both conditions are accomplished at the exit gas of a low temperature SCR process which uses CuO.NiO/Al2O3 as catalyst; consecuently the Pt/Al2O3 catalyst may be well placed as a second bed in that SCR process to complete with high efficacy the removal of residual NO and NH3 (less-than-or-equal-to 300 ppm).