A perforated metallic base material for purging exhaust is obtained by laminating a wavy foil having pores and a flat foil having pores and forming the same into a cylindrical shape, wherein the wavy foil and/or the flat foil has axially perforated portions having pores throughout the axial direction of the cylindrical shape and axially non-perforated portions not having pores overall in the axial direction of the cylindrical form.

A honeycomb structure comprising a pillar-shaped honeycomb structure body having a porous partition wall disposed so as to surround a plurality of cells, wherein let that A denotes an absolute value of open frontal area (%) in a plane of the honeycomb structure body orthogonal to the extending direction of the cells and P denotes an absolute value of porosity (%) of the partition wall, the honeycomb structure has a value represented by the following expression (1) that is 0.05 to 0.12, let that D denotes an average pore diameter (m) of the partition wall and G denotes a geometric surface area (mm.sup.2/mm.sup.3) of the partition wall, the honeycomb structure has a value represented by the following expression (2) that is 8 to 50 (μm×mm.sup.2/mm.sup.3), and the honeycomb structure has a hydraulic diameter of the cells that is 1.1 mm or more,
(1−A/100)×(1−P/100),  Expression (1)
D×G.  Expression (2)

A honeycomb filter includes a pillar-shaped honeycomb structure body having a porous partition wall disposed to surround a plurality of cells and a plugging portion, wherein the partition wall is composed of a material containing cordierite as a main component thereof, porosity of the partition wall measured by a mercury press-in method is 55 to 65%, an average pore diameter of the partition wall measured by a mercury press-in method is 5 to 10 μm, and in a pore diameter distribution indicating a cumulative pore volume of the partition wall measured by a mercury press-in method, with a pore diameter (μm) on an abscissa axis and a log differential pore volume (cm.sup.3/g) on an ordinate axis, a first peak including a maximum value of the log differential pore volume has a pore diameter value of 8 μm or less, the pore diameter value corresponding to a ⅓ value width of the maximum value.

A honeycomb structure includes a pillar-shaped honeycomb structure body having a porous partition wall and a circumferential wall, wherein in a section orthogonal to the extending direction of the cells of the honeycomb structure body, the shape of the cell is a polygonal shape with a corner having an arc shape, a thickness T1[mm] of the partition wall is 0.0500 to 0.1400 mm, a radius of curvature R1[mm] of the corner having the arc shape of the cell and the thickness T1[mm] of the partition wall satisfy the relationship of Equation (1), in the section orthogonal to the extending direction of the cells of the honeycomb structure body, the outer diameter of the honeycomb structure body is 190.5 to 355.6 mm, and a porosity of the partition wall is 20 to 40%.

0.0050≤R1×T1≤0.0150  Equation (1):

A diesel engine emissions catalyst which may be used to fill a niche between standard oxidation catalyst and diesel particulate filters for control of diesel particulate matter. The catalyst includes a structure (substrate) comprising one or more coated, corrugated micro-expanded metal foil layers. The coated surface may be a high surface area, stabilized, and promoted washcoat layer. The corrugated pattern may include a herringbone-style pattern that, when in use, is oriented in a longitudinal direction of the diesel engine exhaust flow. The micro-expanded metal foil provides small openings or eyes that, as the exhaust flow passes through the catalyst (transverse to the eye opening), particulates in the flow impinge on the surface and becomes trapped in the eyes. The catalyst may be used to treat a locomotive engine exhaust stream and may be used with a selective catalyst reduction system.

Provided is a porous structure for exhaust purification catalysts having excellent light-off temperature characteristics. The porous structure for exhaust purification catalysts includes an oxygen storage component and an inorganic porous solid. The porous structure has a pore volume distribution such that the ratio of the pore volume of pores with a diameter of from 15 nm to less than 25 nm to the pore volume of pores with a diameter of from 5 nm to less than 15 nm is 1.3 to 2.5 as measured with a mercury porosimeter. The pore volume distribution preferably has at least one peak top in a pore diameter range of from 15 nm to less than 25 nm.

A honeycomb structure includes plugged honeycomb segments, circumferential bonding layers, central bonding layers and a circumferential wall. An angle θ between a first direction of extension of at least one of the circumferential bonding layers and a second direction of extension of a line segment that connects a centroid of the honeycomb structure and an intersection point at which the circumferential bonding layer in the first direction intersects with the circumferential wall is 25 to 45°, and the outermost segment bonded by the circumferential bonding layer in the first direction exists on a parallel line to a direction of extension of the central bonding layer passing through the centroid.

Provided is a porous structure for exhaust purification catalysts having excellent light-off temperature characteristics. The porous structure for exhaust purification catalysts includes an oxygen storage component and an inorganic porous solid. The porous structure has a pore volume distribution such that the ratio of the pore volume of pores with a diameter of from 15 nm to less than 25 nm to the pore volume of pores with a diameter of from 5 nm to less than 15 nm is 1.3 to 2.5 as measured with a mercury porosimeter. The pore volume distribution preferably has at least one peak top in a pore diameter range of from 15 nm to less than 25 nm.

A pillar-shaped honeycomb structure body of a honeycomb structure includes a circumferential cell structure, a central cell structure and a boundary wall therebetween. On a surface orthogonal to the cells there are a circumferential reinforcing region having the partition wall thicker than a basic partition wall thickness in the circumferential cell structure and existing outside a range of a distance from a centroid of the surface; and at least one of a first boundary reinforcing region having the partition wall thicker than the basic partition wall thickness and existing in a range of a distance from the centroid within a range of the circumferential cell structure and a second boundary reinforcing region having the partition wall thicker than a basic partition wall thickness in the central cell structure and existing outside of a range of a distance from the centroid within a range of the central cell structure.

A honeycomb structure including: a pillar-shaped honeycomb structure body, the honeycomb structure body being configured to include a circumferential portion and a central portion, wherein a shape of the cells is a triangle or a hexagon having at least one symmetrical axis, in the shape of the cells, a number of the symmetrical axes is defined as A, a number of vertices of the shape of the cells is defined as N, and a value shown in a following Equation (1) is defined as θ, an arrangement direction of the cells in the circumferential portion is inclined in a range of θ−15° to θ+15° with respect to an arrangement direction of the cells in the central portion. $\begin{array}{cc}\theta =\frac{180}{A}.Math.\frac{N}{6}& \mathrm{Equation}\left(1\right)\end{array}$