Patent ID: 8226898

Claim:
A honeycomb structure comprising: at least one honeycomb unit having a first end face and a second end face opposite to the first end face along a longitudinal direction of the at least one honeycomb unit and comprising: an inorganic particle; an inorganic binder; cell walls extending along the longitudinal direction from the first end face to the second end face to define a plurality of cells; a NOx storage catalyst provided at the cell walls, the NOx storage catalyst being substantially uniformly disposed over an entirety of the cell walls; and a noble metal catalyst provided at the cell walls, an amount of the noble metal catalyst provided at a vicinity of the first end face being substantially different from an amount of the noble metal catalyst provided at a vicinity of the second end face, wherein an amount of the noble metal catalyst decreases from the vicinity of the first end face toward the vicinity of the second end face while an amount of the NOx storage catalyst is substantially uniform from the vicinity of the first end face toward the vicinity of the second end face, so that a ratio of the amount of the noble metal catalyst to the amount of the NOx storage catalyst changes from the vicinity of the first end face toward the vicinity of the second end face.