A pillar-shaped honeycomb structure including a plurality of first cells extending from an inlet side end surface to an outlet side end surface, and a plurality of second cells extending from the inlet side end surface to the outlet side end surface, with a porous partition wall interposed therebetween, wherein a porous film having a porosity higher than that of the partition walls is provided on a surface of each of the first cells, and at a cross-section orthogonal to the direction in which the first cells of the pillar-shaped honeycomb structure filter extend, the average thickness of the porous film in the central portion is larger than the average thickness of the porous film in the outer peripheral portion.

A honeycomb filter body comprises: a clean filter pressure drop of (P.sub.1) and a clean filtration efficiency of (FE.sub.1); a porous ceramic honeycomb body comprising a first end, a second end, and a plurality of walls having wall surfaces defining a plurality of inner channels, the porous ceramic honeycomb body comprising a base clean filter pressure drop (P.sub.0) and a base clean filtration efficiency (FE.sub.0); and a porous inorganic layer disposed on one or more of the wall surfaces of the porous ceramic honeycomb body.

A catalyst-coated, plugged honeycomb body having a honeycomb structure with a matrix of porous walls forming a plurality of channels, at least some of the plurality of channels being plugged to form inlet channels and outlet channels. At least some of the porous walls are filtration walls and at least some of the porous walls are non-filtration walls. A catalyst is preferentially disposed on the non-filtration walls, wherein the catalyst being preferentially disposed comprises CR<0.2 wherein CR is a coating ratio defined as an average percent loading of a washcoat containing the catalyst on and within the filtration walls divided by an average percent loading of the washcoat containing the catalyst on and within the non-filtration walls. Methods and apparatus configured to preferentially apply a catalyst-containing slurry to the non-filtration walls are provided, as are other aspects.

A pillar-shaped honeycomb structure including a plurality of first cells extending from an inlet side end surface to an outlet side end surface, and a plurality of second cells extending from the inlet side end surface to the outlet side end surface, with a porous partition wall interposed therebetween, wherein a porous film having a porosity higher than that of the partition walls is provided on a surface of each of the first cells, and at a cross-section orthogonal to the direction in which the first cells of the pillar-shaped honeycomb structure filter extend, the average thickness of the porous film in the central portion is larger than the average thickness of the porous film in the outer peripheral portion.

A method of making a porous structure configured for use in a particulate filter includes bonding a plurality of glass bubbles to one another, and breaching the plurality of glass bubbles. Voids within individual breached glass bubbles open into one another to form cavities that extend through the porous structure.

The honeycomb structure body has a dense part at a part in axial direction including a center region of the inflow end face, the dense part having a change ratio of porosity calculated by the following Expression (1) that is 2 to 8%, and has an outside-diameter increasing part, and the honeycomb structure body has a change ratio of average diameter calculated by the following Expression (2) that is 0.2 to 3%,

(1−Px/Py)×100, Expression (1): in Expression (1), Px denotes the porosity (%) at the center region of the inflow end face, and Py denotes the porosity (%) of a circumferential region of the inflow end face.

(1−Dx/Dy)×100,   Expression (2): in Expression (2), Dx denotes the average diameter (mm) of the inflow end face, and Dy denotes the average diameter (mm) of the outflow end face.

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%.

(1−P.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.

(1−D.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.

The honeycomb filter of the present invention comprises a ceramic honeycomb substrate formed from a porous body of sintered ceramic particles, and a filter layer formed on the surface of the cell walls, wherein a portion of the filter layer penetrates from the surface of the cell walls into pores formed by the ceramic particles to form inter-particle filtration bodies, these inter-particle filtration bodies are formed from a plurality of spherical ceramic particles and crosslinking bodies which bind the spherical ceramic particles to each other, and the spherical ceramic particles and the crosslinking bodies form a three-dimensional network structure.

A filter for the filtration of a fluid, such as a liquid, includes or is composed of a support element made of a porous ceramic material, the element exhibiting a tubular or parallelepipedal shape delimited by an external surface and including, in its internal portion, a set of adjacent channels with axes parallel to one another and separated from one another by walls of the porous inorganic material, in which at least a portion of the channels and/or at least a portion of the external surface are covered with a porous separating membrane layer, wherein the separating membrane layer is made of a material essentially composed of silicon carbide (SiC), and the content by weight of elemental nitrogen of the layer constituting the porous separating membrane layer is between 0.1% and 2%.

Disclosed is a ceramic honeycomb structure comprising a honeycomb body and a multilayered outer layer formed of a thick core layer applied and rapidly dried and a thin clad layer dried more gently to form a crack free dual skin layer. The core layer may have properties that are closer to those of the ceramic honeycomb body in service than the clad layer that may provide a tough outer shell to withstand handling and assembly.