A honeycomb structure including: a honeycomb structure body having porous partition walls which are disposed to surround a plurality of cells and a circumferential wall, wherein the partition walls are provided with protrusions, at least one of the plurality of cells includes a specific cell configured so that the protrusions protrude into the cell from the respective partition walls, and the specific cell is provided with a porous material made of the same material as the partition walls in a range of 5 to 50% including an intersection with respect to a pentagonal area which is formed by connecting the intersection when two partition walls configuring the peripheral edge of the specific cell extend and two points of bottom parts and top parts, respectively, of the respective protrusions disposed on the two partition walls, in the cross section orthogonal to the extending direction of the cells.

A honeycomb structure includes a pillar-shaped honeycomb structure body having a porous partition wall. The honeycomb structure body includes a plurality of cells defined by the partition wall so as to extend from a first end face to a second end face of the honeycomb structure body, the partition wall is formed by a porous body including a silicon phase as a main phase and an oxide, and the oxide includes a first oxide made of an alkali earth metal oxide, Al.sub.2O.sub.3, and SiO.sub.2.

The honeycomb structure body has a dense part having a change ratio of porosity calculated by the following Expression (1) that is 1 to 5%. The honeycomb structure body also has an outside-diameter decreasing part in which the outside diameter decreases from the inflow end face to the outflow end face. The honeycomb structure body has a change ratio of average diameter calculated by the following Expression (2) that is 0.2 to 3%.
(1P.sub.x/P.sub.y)100,Expression (1): in Expression (1), P.sub.x denotes the porosity (%) at the center region of the outflow end face, and Py denotes the porosity (%) of a circumferential region of the outflow end face other than the center region.
(1D.sub.x/D.sub.y)100,Expression (2): in Expression (2), D.sub.x denotes the average diameter (mm) of the outflow end face, and D.sub.y denotes the average diameter (mm) of the inflow end face.

A honeycomb filter includes a pillar-shaped honeycomb substrate and a plugging portion provided at an end portion on either an inflow or outflow end face side of cells, wherein, in a section orthogonal to the cell extending direction, the shapes of an inflow cell having the plugging portion and an outflow cell having the plugging portion are hexagonal. In the plurality of cells, a plurality of inflow cells surround one outflow cell such that one side of the inflow cell and one side of the outflow cell adjacent to the inflow cell are parallel. The partition wall includes a first partition wall and a second partition wall, at least one of the first partition walls is configured such that a ratio of a thickness of the second partition wall to the first partition wall is 1.0 to 2.5, and a total open frontal area is 35% to 95%.

In one aspect, a material structure is disclosed, which includes a macroscopic porous substrate configured to receive a flow of a medium for passage of at least a portion thereof through the porous substrate. At least one porous coating is disposed on at least a portion of an inner surface of the porous substrate, wherein the porous coating comprises a matrix having a plurality of interconnected passages. The porous substrate and the coating are configured to treat at least one contaminant, if any, present in the flowing medium.

The honeycomb structure includes a pillar-shaped honeycomb structure body, and a circumferential coating layer disposed to surround a circumference of the honeycomb structure body, and cells which are formed at an outermost circumference of the honeycomb structure body and in which peripheries of the cells are defined by the partition walls without any lacks are defined as outermost circumference complete cells, and in a cross section of the honeycomb structure body which is perpendicular to an extending direction of the cells a minimum distance T (mm) among distances from the outermost circumference complete cells to the surface of the circumferential coating layer and a porosity P (%) of the circumferential coating layer satisfy relations of Equation (1) and Equation (2) as follows:
1.5T16(100P).sup.1.4; andEquation (1):
20P75Equation (2).

The disclosure provides a monolithic wall-flow filter catalytic article including a substrate having an aspect ratio of from about 1 to about 20, and having a functional coating composition disposed on the substrate, the functional coating composition including a first sorbent composition, an oxidation catalyst composition, and optionally, a second sorbent composition. The monolithic wall-flow filter catalytic article may be in a close-coupled position close to the engine. The disclosure further provides an integrated exhaust gas treatment system including the monolithic wall-flow filter catalytic article and may additionally include a flow-through monolith catalytic article. The flow-through monolith catalytic article includes a substrate having a selective catalytic reduction (SCR) coating composition disposed thereon. The integrated exhaust gas treatment system simplifies the traditional four-article system into a two-article Catalyzed Soot Filter (CSF) plus Selective Catalytic Reduction (SCR) CSF+SCR arrangement.

A honeycomb structure including prismatic columnar honeycomb segments and a bonding layer, wherein the bonding layer has rows in each of which bonding layer portions each disposed between two honeycomb segments arranged to face each other are arranged to extend from one point of a peripheral edge of a bonded body of the honeycomb segments to the other point thereof, in a cross section, the bonding layer of each of the-rows is disposed so that among the bonding layer portions arranged in one direction, an outermost circumference bonding layer portion and at least one of the other bonding layer portions are not superimposed on each other on an extension line of the one direction, and a ratio of shift of side surfaces of adjacent honeycomb segments to a length of one side of a side surface of honeycomb segments having the same cross-sectional shape is 10% or less.

A honeycomb filter includes a pillar-shaped honeycomb substrate including a porous partition wall that defines a plurality of cells extending from an inflow end face to an outflow end face, an inflow side plugging portion disposed at the inflow end face of the honeycomb substrate to plug open ends of outflow cells and an outflow side plugging portion disposed at the outflow end face of the honeycomb substrate to plug open ends of inflow cells other than the outflow cells. The honeycomb substrate includes the partition wall that defines two of the inflow cells by division. An average of the plugging length L.sub.IN of the inflow side plugging portions disposed in the outflow cells of the honeycomb substrate is larger than an average of the plugging length L.sub.OUT of the outflow side plugging portions disposed in the inflow cells of the honeycomb substrate.

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.