An object of the present disclosure is to provide an exhaust gas purification catalyst demonstrating superior storage of NOx contained in exhaust gas.

The exhaust gas purification catalyst of the present disclosure has a substrate, a first catalyst layer containing a catalytic metal for NOx reduction and a NOx storage material and formed on the substrate, and a second catalyst layer containing a catalytic metal for NOx oxidation and formed on the first catalyst layer. In the exhaust gas purification catalyst of the present disclosure, the value obtained by dividing the volume of all large pores having a pore volume of 1000 μm.sup.3 or more by the total volume of all medium pores of having a pore volume of 10 μm.sup.3 to 1000 μm.sup.3 in the second catalyst layer is 2.44 or less.

When sizes of particles supporting a catalyst metal remain relatively large but sizes of particles not supporting a catalyst metal are minimized among metal oxide particles included in a catalyst coating layer, it is possible to decrease a thickness of the catalyst coating layer while maintaining durability and improve gas diffusibility of the coating layer. Therefore, a thickness of the catalyst coating is decreased without decreasing durability and a catalyst can exhibit high exhaust gas purification performance even under high load conditions.

The honeycomb structure includes a honeycomb structure body made of a zeolite material containing at least a coarse particle zeolite having a large average particle diameter (coarse zeolite particles). A fine particle zeolite having an average particle diameter smaller than that of the coarse particle zeolite (fine zeolite particles), and an inorganic bonding material, the coarse particle zeolite (the coarse zeolite particles) is a chabazite type zeolite in which an average particle diameter of primary particles is 2 μm or more and 6 μm or less, and in the fine particle zeolite (the fine zeolite particles), an average particle diameter of primary particles is 0.02 μm or more and smaller than 2 μm, and in the zeolite material which is comprised the honeycomb structure body, a ratio of a volume of pores having pore diameters of 0.02 to 0.15 μm to a volume of all pores is 42% or less.

[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.

This disclosure generally relates to an oxide composition basically composed of cerium and zirconium that has exceptional and stable porosity, surface area and lattice oxygen mobility. The oxide composition can contain one or more other rare earth oxides other than cerium oxide. For example, some compositions can contain one or more of lanthanum oxide, yttrium oxide and neodymium oxide. The oxide composition can be useful as a catalyst, catalyst support, sensor applications and combinations thereof.

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. The partition walls have a porosity of 45 to 65%; the open frontal area of the pores having an equivalent circle diameter of 10 μm or more, of the pores open on the surface of each partition wall, is 20 to 50%; the pore density of the pores having an equivalent circle diameter of 10 μm or more is 200 to 1,000 pores/mm.sup.2; the median opening diameter of the pores having an equivalent circle diameter of 10 μm or more is 40 to 60 μm; the circularity of the pores having an equivalent circle diameter of 10 μm or more is 1.8 to 4.0; and the partition walls have a wet area of 16,500 μm.sup.2 or more.

The honeycomb structure includes a honeycomb structure body having porous partition walls, and a plugging portion disposed in one of open ends of each cell, a thickness of the partition walls is 0.30 mm or more and 0.51 mm or less, a cell density is 30 cells/cm.sup.2 or more and 93 cells/cm.sup.2 or less, a filtration area (cm.sup.2) of inflow cells included per cm.sup.3 of the honeycomb structure body is defined as an inflow side filtration area G (cm.sup.2/cm.sup.3), a value obtained by dividing a pore volume Vp (cm.sup.3) formed in the partition walls by a total volume Va (L) including the cells is defined as a pore volume ratio A (cm.sup.3/L), and in this case, a product of the inflow side filtration area G (cm.sup.2/cm.sup.3) and the pore volume ratio A (cm.sup.3/L) is 1800 cm.sup.2/L or more and 3200 cm.sup.2/L or less.

The present invention relates to an LED photocatalyst module comprising: a light supplying unit for irradiating light onto a photocatalyst so that the photocatalyst is activated; a photocatalyst purifying unit disposed spaced apart from the light supplying unit and purifying polluted air; and a discharging unit disposed spaced apart from the photocatalyst purifying unit and sucking in the air purified by the photocatalyst purifying unit and discharging the air to the outside, wherein the photocatalyst purifying unit includes a ceramic honeycomb structure in which a plurality of photocatalyst pores, coated with the photocatalyst, are combined in a honeycomb pattern, and the photocatalyst includes a porous metal oxide film and metal particles formed on a surface of the porous metal oxide film.

A process for producing a ceramic catalyst involves the steps of: a) providing functional particles having a catalytically inactive pore former as a support surrounded by a layer of a catalytically active material, b) processing the functional particles with inorganic particles to form a catalytic composition, c) treating the catalytic composition thermally to form a ceramic catalyst, wherein the ceramic catalyst comprises at least porous catalytically inactive cells which are formed by the pore formers in the functional particles, which are embedded in a matrix comprising the inorganic particles, which form a porous structure and which are at least partly surrounded by an active interface layer comprising the catalytically active material of the layer of the functional particles.

An SCR catalyst produced in by this method has an improved NO.sub.x conversion rate compared to a conventionally produced SCR catalyst.

A porous material includes an aggregate in which oxide films are formed on surfaces of particle bodies, and a binding material that contains cordierite and binds the aggregate together in a state where pores are formed. The binding material or the oxide films contain a rare-earth component that excludes Ce.