Provided is an exhaust gas purification catalyst improved in warm-up performance while suppressing HC poisoning of a noble metal in an atmosphere in which an air-fuel ratio (A/F) is rich and the HC poisoning easily occurs. The present disclosure relates to an exhaust gas purification catalyst that includes a substrate and a catalyst coating layer coated on the substrate. The catalyst coating layer includes a lower coating layer coated on the substrate and an upper coating layer coated on the lower coating layer. The lower coating layer contains a noble metal. The upper coating layer contains Pd and/or Pt. The Pd and/or Pt contained in the upper coating layer is supported on A1.sub.2O.sub.3 by a certain amount or more. A thickness of the upper coating layer is adjusted.

A honeycomb filter includes a pillar-shaped honeycomb structure body having a porous partition wall disposed to surround a plurality of cells and a plugging portion, wherein the partition wall is composed of a material containing cordierite as a main component thereof, porosity of the partition wall measured by a mercury press-in method is 60 to 68%, an average pore diameter of the partition wall measured by a mercury press-in method is 8 to 12 and in a pore diameter distribution which indicates a cumulative pore volume of the partition wall measured by a mercury press-in method, with a pore diameter (μm) on an abscissa axis and a log differential pore volume (cm.sup.3/g) on an ordinate axis, a first peak that includes a maximum value of the log differential pore volume has a pore diameter value of 10 μm or less, the pore diameter value corresponding to a ⅓ value width of the maximum value.

A honeycomb filter includes a pillar-shaped honeycomb structure body having a porous partition wall disposed to surround a plurality of cells and a plugging portion, wherein the partition wall is composed of a material containing cordierite as a main component thereof, porosity of the partition wall measured by a mercury press-in method is 60 to 68%, an average pore diameter of the partition wall measured by a mercury press-in method is 13 to 18 μm, and in a pore diameter distribution indicating a cumulative pore volume of the partition wall measured by a mercury press-in method, with a pore diameter (μm) on an abscissa axis and a log differential pore volume (cm.sup.3/g) on an ordinate axis, a first peak including a maximum value of the log differential pore volume has a pore diameter value of 15 μm or less, the pore diameter value corresponding to a ⅓ value width of the maximum value.

A passive NOx absorber for treating an exhaust gas from a diesel engine is described. The passive NOx absorber comprises a first washcoat region comprising a zeolite catalyst, the zeolite catalyst comprising a noble metal and a zeolite having a SAR of 2-15.

One object is to provide a useful aldehyde decomposition catalyst, and an exhaust gas treatment apparatus and an exhaust gas treatment method using the aldehyde decomposition catalyst that achieve low cost and sufficient aldehyde decomposition performance with a small amount of the catalyst. An aldehyde decomposition catalyst of the present invention is made of a zeolite in a cation form NH.sub.4 having a structure of CHA or MOR and carrying Cu.

The invention discloses a visible light responsive tricobalt tetraoxide dodecahedron/carbon nitride nanosheet composite and an application thereof in exhaust gas treatment. The preparation method of the composite comprises the following steps: with urea as a precursor, carrying out twice calcination to obtain carbon nitride nanosheet; dispersing the carbon nitride nanosheet into methanol, sequentially adding cobalt nitrate hexahydrate and 2-methylimidazole, and carrying out a reaction to obtain a carbon nitride nanosheet composite; and calcining the carbon nitride nanosheet composite in an air atmosphere at a low temperature to obtain the tricobalt tetraoxide dodecahedron/carbon nitride nanosheet composite. The in-situ growth synthesis method can ensure that the tricobalt tetraoxide obtained by follow-up calcination is uniformly coated on the carbon nitride nanosheet to improve the catalytic performance; the low temperature calcination ensures that the carbon nitride can maintain its wrinkle state and chemical structure during the calcination process.

A catalysator element comprising a mixed metal oxide compound for conversion of nitrogen oxides (NO.sub.x). Methods for the preparation of the present mixed metal oxide compound for use in the present catalysator element and to exhaust systems for a combustion engine comprising the present catalysator element for conversion of (NO.sub.x) in exhaust gasses. Specifically, a catalysator element for conversion of nitrogen oxides (NOx) comprises a solid support coated with a calcined mixed metal oxide hydrotalcite-like compound. The calcined mixed metal oxide hydrotalcite-like compound comprises at least one bivalent metal (M.sup.2+) and at least one trivalent metal (M.sup.3+).

A mobile emissions control system having an emission capturing system and emission control system is provided for diesel engines operated on ocean-going ships at-berth. The emissions control system may be mounted on a towable chassis or mounted on a barge, allowing it to be placed alongside ocean-going ships at-berth. A crane or boom transfers a duct of the emissions capturing system extending from the emissions control system to the ship to capture exhaust from its engine. Alternatively, the system may be mounted on an automated guided vehicle (AGV) equipped with a tower and a crane. The crane mounted on the AGV then lifts the duct forming part of the emissions capture system to the ship's exhaust system to capture exhaust from the ship's diesel engine and transfers it to the emissions control system, which cleans the exhaust and then passes clean air into the atmosphere through an exhaust outlet.

A urea removing apparatus has: a determining section that determines whether or not a urea aqueous solution is injected from an injection nozzle when control is performed to inject the urea aqueous solution from the injection nozzle into an exhaust pipe where exhaust gas of an engine flows; a supply control section that controls a pump that supplies the urea aqueous solution to the injection nozzle from a tank that stores the urea aqueous solution, and causes the urea aqueous solution to be supplied from the tank to the injection nozzle in a case that it is determined that the urea aqueous solution is not injected from the injection nozzle; and a temperature control section that performs control to raise the temperature of exhaust gas in a state where the urea aqueous solution supplied from the tank has been poured into the injection nozzle.

A method for making a functional structural body includes a skeletal body of a porous structure composed of a zeolite-type compound, and at least one type of metallic nanoparticles present in the skeletal body, the skeletal body having channels connecting with each other, the metallic nanoparticles being present at least in the channels of the skeletal body.