An exhaust gas-purifying catalyst includes a catalyst-coated filter. The catalyst-coated filter includes a filter substrate and a catalyst layer on a pore wall of the filter substrate. The exhaust gas-purifying catalyst has a first end, a second end, a porous wall, a first cell, and a second cell. The first cell is closed at the second end, the second cell is closed at the first end, and the first cell and the second cell are adjacent to each other with the porous wall interposed therebetween. At a surface of the porous wall on the first cell side, a proportion S.sub.S/S of a total area S.sub.S of pores having an opening diameter of less than 40 μm in a total area S of all pores is 65% or more.

An exhaust gas-purifying catalyst includes a catalyst-coated filter. The catalyst-coated filter includes a filter substrate and a catalyst layer on a pore wall of the filter substrate. The exhaust gas-purifying catalyst has a first end, a second end, a porous wall, a first cell, and a second cell. The first cell is closed at the second end, the second cell is closed at the first end, and the first cell and the second cell are adjacent to each other with the porous wall interposed therebetween. At a surface of the porous wall on the first cell side, a proportion S.sub.S/S of a total area S.sub.S of pores having an opening diameter of less than 40 μm in a total area S of all pores is 65% or more.

A particulate filter disclosed herein includes a wall-flow structure substrate 10 and a wash coat layer 20 held inside a partition 16 of the substrate 10. The wash coat layer 20 includes an inlet layer 22 formed to have predetermined length L.sub.A and thickness T.sub.A from near an end thereof on an exhaust gas inflow side X1, and an outlet layer 24 formed to have predetermined length L.sub.B and thickness T.sub.B from near an end thereof on an exhaust gas outflow side X2. The inlet layer 22 and the outlet layer 24 partially overlap each other. In the particulate filter disclosed herein, the inlet layer 22 contains a precious metal catalyst, while the outlet layer 24 contains substantially no precious metal catalyst. The length L.sub.A of the inlet layer is 50% or more and 75% or less of a total length L of the partition 16. Thus, the particulate filter is capable of achieving both PM collection performance and pressure-drop reduction performance at high levels.

A particulate filter disclosed herein includes a wall-flow structure substrate 10 and a wash coat layer 20 held inside a partition 16 of the substrate 10. The wash coat layer 20 includes an inlet layer 22 formed to have predetermined length L.sub.A and thickness T.sub.A from near an end thereof on an exhaust gas inflow side X1, and an outlet layer 24 formed to have predetermined length L.sub.B and thickness T.sub.B from near an end thereof on an exhaust gas outflow side X2. The inlet layer 22 and the outlet layer 24 partially overlap each other. In the particulate filter disclosed herein, the inlet layer 22 contains a precious metal catalyst, while the outlet layer 24 contains substantially no precious metal catalyst. The length L.sub.A of the inlet layer is 50% or more and 75% or less of a total length L of the partition 16. Thus, the particulate filter is capable of achieving both PM collection performance and pressure-drop reduction performance at high levels.

To provide a platinum-loaded alumina catalyst with an improved catalyst life.

A platinum-loaded alumina catalyst includes an alumina carrier, and platinum loaded on the alumina carrier, wherein the alumina carrier includes a γ-alumina carrier having a surface area of 200 m.sup.2/g or more, a pore volume of 0.50 m.sup.2/g or more, an average pore diameter in a range of 60 to 150 Å, with pores having a pore diameter in a range of ±30 Å from the average pore diameter occupying 60% or more of a total pore volume, platinum particles are loaded on γ-alumina carrier in a range of 0.1 to 1.5% by weight calculated as elemental platinum (Pt), and 70% or more of the platinum particles have a size of 8 to 15 Å by direct observation using a transmission electron microscope.

The exhaust gas purification device includes: a substrate including an upstream end through which an exhaust gas is introduced and a downstream end through which the exhaust gas is discharged; a first catalyst layer containing a rhodium-containing catalyst containing a metal oxide carrier and rhodium particles supported on the metal oxide carrier, the first catalyst layer extending across a first region; and a second catalyst layer containing palladium particles and a material having a basicity higher than a basicity of the metal oxide carrier, the second catalyst layer extending across a second region. A mean of a particle size distribution of the rhodium particles is from 1.5 nm to 18 nm.

The exhaust gas purification device includes: a substrate including an upstream end through which an exhaust gas is introduced and a downstream end through which the exhaust gas is discharged; a first catalyst layer containing a rhodium-containing catalyst containing a metal oxide carrier and rhodium particles supported on the metal oxide carrier, the first catalyst layer extending across a first region; and a second catalyst layer containing palladium particles and a material having a basicity higher than a basicity of the metal oxide carrier, the second catalyst layer extending across a second region. A mean of a particle size distribution of the rhodium particles is from 1.5 nm to 18 nm.

This invention relates to a supported catalyst for synthesizing ammonia (NH.sub.3) from nitrogen gas (N.sub.2) and hydrogen gas (H.sub.2), method of making the support, and methods of decorating the support with the catalyst.

An exhaust gas purification system of the present disclosure includes a first exhaust gas purification device that purifies exhaust gas discharged from an internal combustion engine and a second exhaust gas purification device that additionally purifies the exhaust gas purified by the first exhaust gas purification device, wherein the exhaust gas is exhaust gas with a gaseous composition in which an amount of reducing agents is in excess compared to a stoichiometric gaseous composition and a gaseous composition in which an amount of oxidants is in excess compared to the stoichiometric gaseous composition are alternately switched between, the first exhaust gas purification device includes a three-way catalyst, and the second exhaust gas purification device includes an exhaust gas purification catalyst containing spinel-type MgAl.sub.xFe.sub.2.00−xO.sub.4.00 supporting particles on which Rh is supported, where 0.00<×≤1.50.

An exhaust gas purification system of the present disclosure includes a first exhaust gas purification device that purifies exhaust gas discharged from an internal combustion engine and a second exhaust gas purification device that additionally purifies the exhaust gas purified by the first exhaust gas purification device, wherein the exhaust gas is exhaust gas with a gaseous composition in which an amount of reducing agents is in excess compared to a stoichiometric gaseous composition and a gaseous composition in which an amount of oxidants is in excess compared to the stoichiometric gaseous composition are alternately switched between, the first exhaust gas purification device includes a three-way catalyst, and the second exhaust gas purification device includes an exhaust gas purification catalyst containing spinel-type MgAl.sub.xFe.sub.2.00−xO.sub.4.00 supporting particles on which Rh is supported, where 0.00<×≤1.50.