A honeycomb structure comprising: a honeycomb structure body that includes a plurality of porous partition walls and intersection parts, and a catalyst layer, wherein the porosity of the partition wall is 20 to 70%, the average pore diameter of the pores in the partition wall is 1 to 60 m, a plurality of the partition walls includes a notched partition wall having a recessed part in which at least one end is notched, the ratio of the notched partition wall in the partition walls is 1 to 100%, the recessed part of the notched partition wall has a depth of 10 to 200% of the standard length, and the recessed part of the notched partition wall is a part having a width of 33 to 100% of the standard width.

The invention relates to a wall-flow filter for cleaning exhaust gases from engines, with parallel exhaust gas inlet channels and exhaust gas outlet channels which are closed at alternate ends, said filter additionally comprising catalyst channels which are closed at both ends and contain a catalyst in solid form. The invention also relates to production methods and uses of the filter for cleaning exhaust gases, particularly from diesel engines.

A honeycomb structure includes a honeycomb structure body including porous partition walls defining a plurality of cells serving as fluid passages extending from an inflow end face to an outflow end face. A porosity of the partition walls is from 45 to 65%, an open frontal area of pores having an equivalent circle diameter of 10 m or more is from 20 to 40%, a pore density of pores having an equivalent circle diameter of 10 m or more is from 350 to 1,000 pores/mm.sup.2 and a median opening diameter of the pores having an equivalent circle diameter of 10 m or more is from 40 to 60 m, where the median opening diameter is the median value of the equivalent circle diameters.

A honeycomb structure body has an outer skin, cells arranged in an inside of the outer skin, and partition walls having pores. The partition walls are arranged in the inside of the outer skin. Each of the cells is surrounded by the partition walls. The pores have communicating pores which communicate with each other adjacent cells. Exhaust gas emitted from an engine passes adjacent cells through the communicating pores. The number of the communicating pores is at a density of not less than 18000 [pores/0.25 mm.sup.2] before a catalyst is supported in the pores. An exhaust gas purification filter having the honeycomb structure body with the catalyst is arranged in an exhaust gas pipe to purify exhaust gas containing PM emitted from an engine.

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.

An exhaust gas purification filter is provided which has a high capture ratio of particulate matter even when having a high porosity. The exhaust gas purification filter has a case, partition walls and cells. The partition walls are porous, and the interior of the case is partitioned into a plurality of the cells by the partition walls. The partition walls have a plurality of communicating pores which communicate between cells adjacent to respective partition walls. The degree of tortuosity L/T of the communicating pores satisfies L/T1.1, where T m is the thickness of the partition walls and L m is the average flow path length of the communicating pores. Furthermore the exhaust gas purification filter is manufactured using porous silica having a tapped bulk density that is no greater than a predetermined value.

The present invention provides a honeycomb structured body capable of achieving more effective use of a catalyst in partition walls and having excellent exhaust gas conversion performance. The present invention relates to a honeycomb structured body including: a honeycomb fired body in which multiple through-holes are arranged longitudinally in parallel with one another with a partition wall therebetween, wherein the honeycomb fired body contains ceria-zirconia composite oxide particles and alumina particles, the partition wall of the honeycomb fired body contains macropores having a pore size of 2 to 50 m, and in an electron microscope image of a cross section of the partition wall, the percentage of the area occupied by pores having a pore size of 5 to 15 m is at least 85% of the total area of the macropores.

The present invention relates to a porous material, wherein the pores of the porous material are uniformly distributed. The uniform distribution of the pores means that the pores are evenly distributed at any unit-level volume of the porous material. The elastic modulus of the porous material is reduced by 10-99% compared to that of the raw material used to make the porous material. This kind of porous material ensures the uniformity of its various properties. It is a porous material with excellent performance and quality. Its uniformity also ensures that its elastic modulus can be effectively reduced to meet multiple purposes.

An exhaust gas purification filter includes a plurality of cells extending in a filter axial direction, a porous partition separating and defining the plurality of cells, and a sealing section sealing the plurality of cells alternately at both filter ends. In the exhaust gas purification filter, the partition has a void volume of a reduced dale, Vvv, and a material volume of a reduced peak, Vmp, as volume parameters determined in noncontact surface roughness measurement on a surface of the partition, with their total value being 1.8 m.sup.3/m.sup.2 or less.

An exhaust gas purification filter is configured to he disposed in an exhaust passage in a gasoline engine. The exhaust gas purification filter includes partition walls including a plurality of pores, a plurality of cells partitioned by the partition walls, and sealing portions alternately sealing ends of a plurality of the cells in the exhaust gas purification filter. The partition walls each have an average pore diameter of more than 16 m and less than 21 m, and have a ratio of an average surface opening diameter of the pores in a partition wall surface to the average pore diameter of the partition wall of 0.66 or more and 0.94 or less.