A ceramic honeycomb structure having pluralities of flow paths partitioned by porous cell walls, (a) the cell walls having porosity of 50-63%; and (b) in a pore diameter distribution in the cell walls measured by mercury porosimetry, (i) pore diameters at cumulative pore volumes corresponding to particular percentages of the total pore volume being within specific ranges and having specific relationships; (ii) the difference between a logarithm of the pore diameter at a cumulative pore volume corresponding to 20% of the total pore volume and a logarithm of the pore diameter at 80% being 0.39 or less; and (iii) the volume of pores of more than 100 μm being 0.03 cm.sup.3/g or less.

A ceramic honeycomb structure having pluralities of flow paths partitioned by porous cell walls, (a) the cell walls having porosity of 50-63%; and (b) in a pore diameter distribution in the cell walls measured by mercury porosimetry, (i) pore diameters at cumulative pore volumes corresponding to particular percentages of the total pore volume being within specific ranges and having specific relationships; (ii) the difference between a logarithm of the pore diameter at a cumulative pore volume corresponding to 20% of the total pore volume and a logarithm of the pore diameter at 80% being 0.39 or less; and (iii) the volume of pores of more than 100 μm being 0.03 cm.sup.3/g or less.

An object of the present invention is to provide a honeycomb filter capable of preventing depth filtration and achieving a combination of high collection efficiency and low pressure loss. The honeycomb filter of the present invention comprises a ceramic honeycomb substrate in which a multitude of cells through which a fluid flows are disposed in parallel in a longitudinal direction and are separated by cell walls, each cell being sealed at an end section at either the fluid inlet side or the fluid outlet side, and a filter layer which, among the surfaces of the cell walls, is formed on the surface of the cell walls of those cells in which the end section at the fluid inlet side is open and the end section at the fluid outlet side is sealed, wherein the filter layer is composed of a plurality of spherical ceramic particles, and crosslinking bodies which bind the spherical ceramic particles to each other by crosslinking the spherical ceramic particles, and the spherical ceramic particles and the crosslinking bodies form a three-dimensional network structure.

An exhaust gas purification catalyst is provided for which a purification performance is excellent and particle growth of a catalyst metal is suppressed. The exhaust gas purification catalyst is provided with a substrate and a catalyst layer formed on the substrate. The catalyst layer contains a catalyst metal that functions as an oxidation and/or reduction catalyst and contains a support that supports the catalyst metal. The support is constituted of a porous ceramic that, in its volumetric pore diameter distribution measured based on a nitrogen gas adsorption method, has a pore diameter P.sub.10 corresponding to a cumulative 10% from a small pore side and a pore diameter P.sub.90 corresponding to a cumulative 90% from the small pore side that are both in a range from 5 to 50 nm.

A composite heat storage material includes a heat storage material and an inorganic material. The heat storage material is made of a strongly correlated electron material that stores and dissipates heat via solid-solid phase transition. The inorganic material is different from the material of the heat storage material. The heat storage material and the inorganic material are mixed. The composite heat storage material can have characteristics of both the heat storage material and the inorganic material.

A ceramic honeycomb structure having pluralities of flow paths partitioned by porous cell walls; (a) the cell walls having porosity of 50-60%; and (b) in a pore diameter distribution in the cell walls measured by mercury porosimetry, (i) pore diameters at cumulative pore volumes corresponding to particular percentages of the total pore volume being within specific ranges and having specific relationships; and (ii) the difference between a logarithm of the pore diameter at a cumulative pore volume corresponding to 20% of the total pore volume and a logarithm of the pore diameter at 80% being 0.39 or less, and its production method.

The present disclosure relates to porous ceramic compositions and porous ceramic articles, such as honeycomb structure bodies and porous ceramic filters. In various embodiments, a particulate filter is disclosed herein; in some of these embodiments, the particulate filter is a gasoline particulate filter (GPF) and is suitable for use with a gasoline engine and treating its exhaust, and in some of the embodiments, the particulate filter is a diesel particulate filter (DPF) and is suitable for use with a diesel engine and treating its exhaust.

The risk of a particulate filter from being damaged is reduced while an increase in pressure loss of the particulate filter due to ash is suppressed. Micropore zones are defined at upstream sides of partition walls of a particulate filter and macropore zones are defined at downstream sides of partition walls. The pore size of the partition walls at the micropore zones is set so that the particulate matter and the ash can be trapped by the partition walls at the micropore zones, while the pore size of the partition walls at the macropore zones is set so that the ash can pass through the partition walls at the macropore zones. When the difference dQPM between the quantity of the particulate matter which is trapped at the micropore zones and the quantity of particulate matter which is trapped at the macropore zones exceeds a predetermined threshold value, PM removal control is executed.

In a green honeycomb molded body including a columnar body of the green honeycomb molded body in which a plurality of hexagonal cells mutually partitioned by partition walls are open at an end surface of the columnar body, a center closing jig is inserted into a part of a plurality of cells at the center of the end surface to join partition walls to each other using the center closing jig, thereby closing the cells at the center of the end surface and the outer periphery of the end surface including the plurality of cells is pressed by a cylindrical outer periphery closing jig having an inner peripheral surface with the inner diameter being continuously reduced from one end to the other end, thereby collapsing the cells at the outer periphery of the end surface to close the cells at the outer periphery of the end surface.

[Summary]

[Problem]

The problem addressed by the present invention lies in providing an exhaust gas purification filter which can efficiently treat particulate matter in exhaust gas.

[Solution]

The present invention provides an exhaust gas purification filter including a substrate comprising a plurality of porous partitions, wherein the partitions form an exhaust gas flow path, a porous catalytic layer is provided on the partitions and the catalytic layer having a thickness of 10 μm or greater is provided over at least 20% of the total length of the partitions in the lengthwise direction thereof, and the catalytic layer having a thickness of 10 μm or greater is not present on the partitions 15 mm from an outflow side.