Honeycomb structure

A honeycomb structure comprising:

• at least one honeycomb unit having a longitudinal direction and including walls extending along the longitudinal direction to define through-holes;
• a center region having a smaller similarity shape in relation to a peripheral shape of the honeycomb structure in a cross section perpendicular to the longitudinal direction, the smaller similarity shape being defined by including a center of the honeycomb structure and substantially a half of a length from the center to the peripheral shape of the honeycomb structure;
• a peripheral region located outside the smaller similarity shape;
• an inorganic binder;
• zeolite ion-exchanged with at least one of Cu, Mn, Ag, and V at a first weight ratio and at a second weight ratio in the center region and in the peripheral region, respectively, relative to a total weight of the zeolite, the second weight ratio being larger than the first weight ratio;
• and
• zeolite ion-exchanged with at least one of Fe, Ti, and Co at a third weight ratio and at a fourth weight ratio in the center region and in the peripheral region, respectively, relative to a total weight of the zeolite, the third weight ratio being larger than the fourth weight ratio.