A base material for a membrane filter contains 90% by mass or more of aluminum oxide and 0.1% by mass or more and 10% by mass or less of titanium oxide. In a pore distribution curve measured by a mercury porosimeter, the base material has a first peak and a second peak which is higher than the first peak and is located at a pore size larger than that of the first peak, and the volume of pores with a pore size of 7 μm or more is 0.02 cm.sup.3/g or more.

A base material for a membrane filter contains 90% by mass or more of aluminum oxide and 0.1% by mass or more and 10% by mass or less of titanium oxide. In a pore distribution curve measured by a mercury porosimeter, the base material has a first peak and a second peak which is higher than the first peak and is located at a pore size larger than that of the first peak, and the volume of pores with a pore size of 7 μm or more is 0.02 cm.sup.3/g or more.

An extrusion system (100) includes at least one sensor (102, 104) to detect localized presence of oil (701) on an exterior surface (715) or skin of wet extrudate material (714 e.g., ceramic material having a honeycomb cross-sectional shape), and at least one infrared emitting device (106, 108) configured to impinge infrared emissions on at least a portion of the exterior surface responsive to one or more sensor signals. Localized impingement of infrared emissions may reduce presence of oil streaks (701) without undue differential drying of the extrudate skin (715), and avoid surface fissures that would otherwise result in fired ceramic bodies. Separately controllable infrared emitters (502), or at least one controllable infrared blocking or redirecting element (603), may be used to impinge infrared emissions on selected areas. A humidification section (120) arranged downstream of infrared emitters (106, 108) may be used to at least partially rehydrate the wet extrudate material, if necessary.

An extrusion system (100) includes at least one sensor (102, 104) to detect localized presence of oil (701) on an exterior surface (715) or skin of wet extrudate material (714 e.g., ceramic material having a honeycomb cross-sectional shape), and at least one infrared emitting device (106, 108) configured to impinge infrared emissions on at least a portion of the exterior surface responsive to one or more sensor signals. Localized impingement of infrared emissions may reduce presence of oil streaks (701) without undue differential drying of the extrudate skin (715), and avoid surface fissures that would otherwise result in fired ceramic bodies. Separately controllable infrared emitters (502), or at least one controllable infrared blocking or redirecting element (603), may be used to impinge infrared emissions on selected areas. A humidification section (120) arranged downstream of infrared emitters (106, 108) may be used to at least partially rehydrate the wet extrudate material, if necessary.

A method of forming an inorganic oxide coating on a monolith article is disclosed. The coated monolith article is suitable for the treatment of an exhaust gas. The method comprises spraying, as a dry particulate aerosol, inorganic particles and a silicone resin to form a coating layer. The present invention also provides an uncalcined porous monolith article for use in forming a monolith article for the treatment of an exhaust gas. The uncalcined monolith article comprises a dry particulate composition comprising inorganic particles and a silicone resin.

A method of forming an inorganic oxide coating on a monolith article is disclosed. The coated monolith article is suitable for the treatment of an exhaust gas. The method comprises spraying, as a dry particulate aerosol, inorganic particles and a silicone resin to form a coating layer. The present invention also provides an uncalcined porous monolith article for use in forming a monolith article for the treatment of an exhaust gas. The uncalcined monolith article comprises a dry particulate composition comprising inorganic particles and a silicone resin.

A system and method to dry plug cement in a ceramic honeycomb body during the manufacture of plugged ceramic honeycomb bodies. The system includes a heating element (520) configured to immediately heat without contact a face (502) of a ceramic honeycomb body (500) plugged with a wet plug cement (510) to rapidly dry and stiffen the plug cement (510) on the face (502) of the ceramic honeycomb body (500). The method includes immediately applying heat without contact to a face (502) of a ceramic honeycomb body (500) having wet plug cement (510) disposed in channels (508) of the ceramic honeycomb body at the face, and rapidly drying and stiffening the plug cement on the face of the ceramic honeycomb body.

A system and method to dry plug cement in a ceramic honeycomb body during the manufacture of plugged ceramic honeycomb bodies. The system includes a heating element (520) configured to immediately heat without contact a face (502) of a ceramic honeycomb body (500) plugged with a wet plug cement (510) to rapidly dry and stiffen the plug cement (510) on the face (502) of the ceramic honeycomb body (500). The method includes immediately applying heat without contact to a face (502) of a ceramic honeycomb body (500) having wet plug cement (510) disposed in channels (508) of the ceramic honeycomb body at the face, and rapidly drying and stiffening the plug cement on the face of the ceramic honeycomb body.

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 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.