Abstract: The invention relates an exhaust gas purifying catalyst containing Fe and Ce, and a new catalyst for exhaust gas which can further enhance the excellent durability to a severe temperature change is provided. Provided is an exhaust gas purifying catalyst which contains catalyst particles having a configuration in which iron (Fe), cerium (Ce), and a precious metal, and one or two or more kinds of elements (referred to as the “M element”) among cobalt (Co), manganese (Mn), copper (Cu), nickel (Ni), magnesium (Mg), lanthanum (La), and strontium (Sr) are supported on inorganic porous support particles, and in which catalyst particles having a configuration in which Ce is present at 1 at % or more, Fe is present at 0.1 at % or more, and the M element is present at 0.1 at % or more account for 80 or more when 100 of catalyst particles having a particle diameter of 6 ?m or more are randomly selected and each of these catalyst particles is quantitatively mapped by EDX.

Abstract: Provided is a method for stabilizing a size of a platinum hydroxide polymer capable of maintaining solution stability of a platinum hydroxide polymer in a solution. The method may include adding Zr ions to a solution containing a platinum hydroxide polymer at a Zr/Pt ratio of 1.0 to 40 in terms of molar concentration ratio.

Abstract: Provided is a method for producing a catalyst for purification of exhaust gas, including the steps of: adding Zr ions to a solution containing a platinum hydroxide polymer; diluting the solution to which the Zr ions are added by using an aqueous ammonium acetate solution; immersing a support made of Al2O3, SiO2, CeO2, ZrO2, or a composite oxide of any ones of these oxides in the diluted solution, followed by heating at 60 to 70° C., to thereby support the platinum hydroxide polymer on the support; and calcining the support, on which the platinum hydroxide polymer is supported, at 150 to 800° C.

Abstract: [Object] To provide a method for stabilizing a size of a platinum hydroxide polymer capable of maintaining solution stability of a platinum hydroxide polymer in a solution. [Solving Means] A method is provided for stabilizing a size of a platinum hydroxide polymer, including adding Zr ions to a solution containing a platinum hydroxide polymer at a Zr/Pt ratio of 1.0 to 40 in terms of molar concentration ratio.