Catalyst for the reduction of nitrogen oxides in an oxidising atmosphere, preparation and utilisation

摘要

An active and selective catalyst for the redn. of nitrogen oxides to molecular nitrogen in a hyper-stoichiometric medium of oxidising cpds., comprises a refractory inorganic oxide-contg. Al2O3; a rare earth element (A); a transition (B) from gps. VIB, VIIB, VIII and IB; an element (C) comprising a precious metal Pt, Rh, Ru, Ir and Os and opt., an element (D) comprising an alkaline earth (IIa). Part of element (A) is combined with part of the Al2O3 to form (at the surface of the latter) a micro-layer of rare earth aluminate. Also claimed are the prepn. and use of the catalysts.