Abstract: An improved Diesel exhaust filter element of the type having a rigid porous wall portion formed of an acicular ceramic (such as acicular mullite), the porous wall portion having a first side and a second side, the porous wall portion being coated with a precious metal catalyst and a Nox absorbent, such that when exhaust gas from a Diesel engine is flowed through the rigid porous wall from the first side to the second side, the exhaust gas containing excess oxygen, Nox and soot, the soot in the exhaust gas in trapped within the rigid porous wall and catalytically oxidized to carbon dioxide, the NO is catalytically oxidized to NO2, which NO2 is then absorbed by the Nox absorbent, and such that when the exhaust gas is caused to contain excess hydrocarbon and carbon monoxide, then the Nox absorbent is regenerated and the remaining hydrocarbon and carbon monoxide are catalytically converted to nitrogen and carbon dioxide.

Abstract: A ceramic honeycomb filter having improved thermal shock resistance is comprised of a ceramic honeycomb filter that has a heat absorbing material that undergoes a reversible phase change that absorbs at least in part the heat energy, for example, arising from the combustion of Diesel soot entrapped in the filter.

Abstract: An improved ceramic honeycomb filter has at least one porous partition wall defining a channel that is (1) microstructurally different along the length of the channel, (2) microstructurally different than at least a portion of a partition wall defining another channel or (3) combination thereof. The improved filter may be used for filtering Diesel exhaust and may have reduced back pressure and equivalent soot capture efficiency compared to a filter without having said microstructural differences.

Abstract: An improved soot catalyst is comprised of an alkali compound at least partially coated by a ceramic coating comprised of C bonded to a metal, semimetallic element or combination thereof. The improved soot catalyst may be employed in catalyzed Diesel particulate filters. In one method to make a catalyzed Diesel particulate filter, the improved filter is made by contacting a porous ceramic body having an alkali catalyst thereon, coating the alkali catalyst with an organic ceramic precursor, heating the ceramic body to a temperature in an atmosphere sufficient to decompose the organic ceramic precursor to form the soot catalyst on the porous ceramic body without volatilizing substantial amount of the alkali catalyst away.

Abstract: A catalyzed Diesel soot filter and process. The Diesel soot filter incorporates a porous filter element coated with a catalytic agent so that Diesel soot from Diesel exhaust gas is deposited into contact with the catalytic agent when Diesel exhaust gas is passed through the porous filter element and so that the ignition temperature or oxidation temperature of the deposited Diesel soot is reduced. The catalytic agent is a mixture of alkali metal and cerium oxides. The mole ratio of alkali metal to cerium of the catalytic agent is in the range of from 0.5 to 5.

Abstract: An improved soot catalyst is comprised of an alkali compound at least partially coated by a ceramic coating comprised of C bonded to a metal, semimetallic element or combination thereof. The improved soot catalyst may be employed in catalyzed Diesel particulate filters. In one method to make a catalyzed Diesel particulate filter, the improved filter is made by contacting a porous ceramic body having an alkali catalyst thereon, coating the alkali catalyst with an organic ceramic precursor, heating the ceramic body to a temperature in an atmosphere sufficient to decompose the organic ceramic precursor to form the soot catalyst on the porous ceramic body without volatilizing substantial amount of the alkali catalyst away.

Abstract: A porous mullite composition is made by Forming a mixture of one or more precursor compounds having the elements present in mullite (e.g., clay, alumina, silica) and a property enhancing compound. The property enhancing compound is a compound having an element selected from the group consisting of Mg, Ca, Fe, Na, K, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb, Lu, B, Y, Sc, La and combination thereof. The mixture is shaped and to form a porous green shape which is heated under an atmosphere having a fluorine containing gas to a temperature sufficient to form a mullite composition comprised substantially of acicular mullite grains that are essentially chemically bound.

Abstract: A ceramic honeycomb filter having improved thermal shock resistance is comprised of a ceramic honeycomb filter that has a heat absorbing material that undergoes a reversible phase change that absorbs at least in part the heat energy, for example, arising from the combustion of Diesel soot entrapped in the filter.

Abstract: A porous mullite composition is made by forming a mixture of one or more precursor compounds having the elements present in mullite (e.g., clay, alumina, silica) and a property enhancing compound. The property enhancing compound is a compound having an element selected from the group consisting of Mg, Ca, Fe, Na, K, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, B, Y, Sc, La and combination thereof. The mixture is shaped and to form a porous green shape which is heated under an atmosphere having a fluorine containing gas to a temperature sufficient to form a mullite composition comprised substantially of acicular mullite grains that are essentially chemically bound.

Abstract: A catalyzed Diesel soot filter and process. The Diesel soot filter incorporates a porous filter element coated with a catalytic agent so that Diesel soot from Diesel exhaust gas is deposited into contact with the catalytic agent when Diesel exhaust gas is passed through the porous filter element and so that the ignition temperature or oxidation temperature of the deposited Diesel soot is reduced. The catalytic agent is a mixture of alkali metal and cerium oxides. The mole ratio of alkali metal to cerium of the catalytic agent is in the range of from 0.5 to 5.

Abstract: An improved ceramic honeycomb filter has at least one porous partition wall defining a channel that is (1) microstructurally different along the length of the channel, (2) microstructurally different than at least a portion of a partition wall defining another channel or (3) combination thereof. The improved filter may be used for filtering Diesel exhaust and may have reduced back pressure and equivalent soot capture efficiency compared to a filter without having said microstructural differences.

Abstract: A porous mullite composition is made by forming a mixture of one or more precursor compounds having the elements present in mullite (e.g., clay, alumina, silica) and a property enhancing compound. The property enhancing compound is a compound having an element selected from the group consisting of Mg, Ca, Fe, Na, K, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, B, Y, Sc, La and combination thereof. The mixture is shaped and to form a porous green shape which is heated under an atmosphere having a fluorine containing gas to a temperature sufficient to form a mullite composition comprised substantially of acicular mullite grains that are essentially chemically bound.

Abstract: A porous mullite composition is made by forming a mixture of one or more precursor compounds having the elements present in mullite (e.g., clay, alumina, silica) and a property enhancing compound. The property enhancing compound is a compound having an element selected from the group consisting of Mg, Ca, Fe, Na, K, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb, Lu, B, Y, Sc, La and combination thereof. The mixture is shaped and to form a porous green shape which is heated under an atmosphere having a fluorine containing gas to a temperature sufficient to form a mullite composition comprised substantially of acicular mullite grains that are essentially chemically bound.

Abstract: A porous ceramic body having increased strength is formed by exposing a porous ceramic body to a source of boron and heating the porous body to a sufficient temperature in an oxygen containing atmosphere to form the porous ceramic body. The porous ceramic body has a boron containing oxide glassy phase on at least a portion of the ceramic grains of the porous ceramic body.

Abstract: A porous mullite composition is made by Forming a mixture of one or more precursor compounds having the elements present in mullite (e.g., clay, alumina, silica) and a property enhancing compound. The property enhancing compound is a compound having an element selected from the group consisting of Mg, Ca, Fe, Na, K, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb, Lu, B, Y, Sc, La and combination thereof. The mixture is shaped and to form a porous green shape which is heated under an atmosphere having a fluorine containing gas to a temperature sufficient to form a mullite composition comprised substantially of acicular mullite grains that are essentially chemically bound.

Abstract: An improved Diesel exhaust filter element of the type having a rigid porous wall portion formed of an acicular ceramic (such as acicular mullite), the porous wall portion having a first side and a second side, the porous wall portion being coated with a precious metal catalyst and a Nox absorbent, such that when exhaust gas from a Diesel engine is flowed through the rigid porous wall from the first side to the second side, the exhaust gas containing excess oxygen, Nox and soot, the soot in the exhaust gas in trapped within the rigid porous wall and catalytically oxidized to carbon dioxide, the NO is catalytically oxidized to NO2, which NO2 is then absorbed by the Nox absorbent, and such that when the exhaust gas is caused to contain excess hydrocarbon and carbon monoxide, then the Nox absorbent is regenerated and the remaining hydrocarbon and carbon monoxide are catalytically converted to nitrogen and carbon dioxide.

Abstract: An improved catalyzed soot filter is comprised of a porous ceramic having, on at least a portion of the porous ceramic, an amorphous catalytic phase comprised of an alkali containing oxide glass having therein Si, Al or combination thereof. The improved catalyzed soot filter may be formed by contacting a porous ceramic such as mullite, silcon carbide or cordierite with an alkali containing compound that is a silicate, aluminate or alumino-siliicate and heating to a temperature sufficient to form an amorphous catalytic phase fused to at least a portion of the porous ceramic.

Abstract: A porous ceramic body having increased strength is formed by exposing a porous ceramic body to a source of boron and heating the porous body to a sufficient temperature in an oxygen containing atmosphere to form the porous ceramic body. The porous ceramic body has a boron containing oxide glassy phase on at least a portion of the ceramic grains of the porous ceramic body.

Abstract: A Diesel soot catalyst has ceria and platinum present in a Diesel particulate filter in a ratio, by weight, of ceria to platinum of at most about 75. This catalyst allows for the use of very small amounts of platinum metal while still achieving low balance point temperatures for burning of Diesel soot.