Abstract: The present invention provides an oxidation catalyst for cleaning exhaust gas, capable of achieving an excellent catalytic activity at a lower temperature for particulates and high boiling point hydrocarbons in exhaust gas from internal-combustion engines. The oxidation catalyst for cleaning exhaust gas according to the present invention is a composite metal oxide represented by the general formula: LnyMn1-xAxO3, wherein Ln is a metal selected from the group consisting of Sc, Y, Ho, Er, Tm, Yb, and Lu; A is a metal selected from the group consisting of Ti, Nb, Ta, and Ru; 0.005?x?0.2; and 0.9?y?1. Ln is Y. The composite metal oxide has a hexagonal structure.

Abstract: An oxidation catalyst for cleaning exhaust gas, excellent in the function of oxidizing high boiling point materials such as particulates and polycyclic aromatic hydrocarbons contained in the exhaust gas of internal-combustion engines is provided. The catalyst is a composite oxide containing two kinds of metal elements, wherein, when the two kinds of metal elements are defined as A and B, the value of the ionic radius of metal element A/the ionic radius of metal element B is in the range of from 1.349 to 1.580. The metal element A is selected from the group consisting of Sc, Y, Ho, Er, Tm, Yb, and Lu, and the metal element B is Mn. The composite oxide has a hexagonal structure.

Abstract: An apparatus for removing particulate matter is provided which is able to lower a temperature to burn particulate matter. The apparatus for removing particulate matter burns and removes the particulate matter emitted from an internal combustion engine, and comprises a perovskite-type complex oxide which is represented by the general formula ABO3 where B is a metal having a valence of +3 or more. The metal having a valence of +3 or more for B of the general formula comprises at least one metal selected from the group consisting of Ti, Zr, Hf, V, Cr, Mo, W, Mn, Fe, Ru, Co, Ni, Cu, Ag, and Au. The perovskite-type complex oxide comprises at least one complex oxide selected from the group consisting of LaMn(III)O3, LaSrMn(III)O3, and LaCo(III)O3. The perovskite-type complex oxide supports Pt or Pd.