Abstract: A polycrystalline fused product based on brownmillerite, includes, for more than 95% of its weight, of the elements Ca, Sr, Fe, O, M and M?, the contents of the elements being defined by the formula XyMzFetM?uO2.5, wherein the atomic indices are such that 0.76?y?1.10, z?0.21, 0.48?t?1.15 and u?0.52, 0.95?y+z?1.10, and 0.95?t+u?1.10, X being Ca or Sr or a mixture of Ca and Sr, M being an element chosen from the group formed by La, Ba and mixtures thereof, M? being an element chosen from the group formed by Ti, Cu, Gd, Mn, Al, Sc, Ga, Mg, Ni, Zn, Pr, In, Co, and mixtures thereof, the sum of the atomic indices of Ti and Cu being less than or equal to 0.1.

Abstract: A polycrystalline fused product based on brownmillerite, includes, for more than 95% of its weight, of the elements Ca, Sr, Fe, O, M and M?, the contents of the elements being defined by the formula XyMzFetM?uO2.5, wherein the atomic indices are such that 0.76?y?1.10, z?0.21, 0.48?t?1.15 and u?0.52, 0.95?y+z?1.10, and 0.95?t+u?1.10, X being Ca or Sr or a mixture of Ca and Sr, M being an element chosen from the group formed by La, Ba and mixtures thereof, M? being an element chosen from the group formed by Ti, Cu, Gd, Mn, Al, Sc, Ga, Mg, Ni, Zn, Pr, In, Co, and mixtures thereof, the sum of the atomic indices of Ti and Cu being less than or equal to 0.1.

Abstract: Catalyst system suitable especially for the removal of CO compounds, comprising or consisting of an oxide, preferably of fluorite crystalline structure, conforming to the following molar formulation: Ce1?uMyAzDvO2?x, wherein Ce is cerium, A represents at least one element possessing a plurality of oxidation states and selected from Ti, Ga, In, V, Cr, Mn, Fe, Sn, Co, Ni, Cu, M represents at least one element selected from Gd, Y, Sc, Sm, Nd, Pr, Zn, D represents at least one element other than A and selected from Pt, Pd, Rh, Ru, Cu, Fe, Ag, and Au, u is between 0.05 and 0.45, y is between 0.01 and 0.4, Z is greater than 0 and less than 0.4, v is between 0.001 and 0.4, and x is greater than 0.

Abstract: Catalyst system suitable especially for the removal of CO compounds, comprising or consisting of an oxide, preferably of fluorite crystalline structure, conforming to the following molar formulation: Ce1?uMyAzDvO2?x, wherein Ce is cerium, A represents at least one element possessing a plurality of oxidation states and selected from Ti, Ga, In, V, Cr, Mn, Fe, Sn, Co, Ni, Cu, M represents at least one element selected from Gd, Y, Sc, Sm, Nd, Pr, Zn, D represents at least one element other than A and selected from Pt, Pd, Rh, Ru, Cu, Fe, Ag, and Au, u is between 0.05 and 0.45, y is between 0.01 and 0.4, Z is greater than 0 and less than 0.4, v is between 0.001 and 0.4, and x is greater than 0.