An apparatus for purifying exhaust gas includes: an engine; an exhaust gas air-fuel ratio adjustor for adjusting an air-fuel ratio of the exhaust gas; a lean NO.sub.x trap (LNT) mounted on the exhaust pipe and generating ammonia or reducing nitrogen oxides or desorbed nitrogen oxides contained in the exhaust gas using a reducing agent including carbon monoxide, hydrocarbon, or hydrogen contained in the exhaust gas; a three way catalyst (TWC) mounted on the exhaust pipe at a rear end of the LNT, and converting noxious gas in the exhaust gas into harmless components through a redox reaction; and a controller controlling the air-fuel ratio of the exhaust gas to a stoichiometric air-fuel ratio when the nitrogen oxide storage or purification performance of the LNT is in the operating period of the engine less than a predetermined level.

A honeycomb structure body has an outer skin, cells arranged in an inside of the outer skin, and partition walls having pores. The partition walls are arranged in the inside of the outer skin. Each of the cells is surrounded by the partition walls. The pores have communicating pores which communicate with each other adjacent cells. Exhaust gas emitted from an engine passes adjacent cells through the communicating pores. The number of the communicating pores is at a density of not less than 18000 [pores/0.25 mm.sup.2] before a catalyst is supported in the pores. An exhaust gas purification filter having the honeycomb structure body with the catalyst is arranged in an exhaust gas pipe to purify exhaust gas containing PM emitted from an engine.

Provided are methods for diagnosing a selective catalytic reduction device (SCR) of an exhaust gas treatment system, wherein the system includes an engine, an ammonia-generating catalytic device (AGC) configured to receive exhaust gas generated by the engine and capable of generating ammonia from rich exhaust gas, the SCR configured to receive exhaust gas and ammonia generated by the AGC, an upstream NOx sensor disposed upstream from the SCR, and a downstream NOx sensor disposed downstream from the SCR. The method includes increasing the temperature of the SCR to substantially empty all reductant stored within the SCR, during a diagnostic period, maintaining a rich engine operating condition and communicating the generated exhaust gas to the AGC and the SCR, determining a SCR reductant storage capacity based on measurements taken by the downstream NOx sensor during the diagnostic period, and optionally implementing a control action based on the determined storage capacity.

An exhaust aftertreatment system for an internal combustion engine includes a selective catalytic reduction (SCR) device, an injection system disposed to inject reductant into the exhaust pipe upstream of the SCR device. A single ammonia sensor is disposed to monitor an exhaust gas feedstream downstream of the SCR device. A controller is in communication with the single ammonia sensor and the internal combustion engine and operatively is connected to the injection system. The controller includes an instruction set that is executable to monitor, via the single ammonia sensor, a magnitude of ammonia in the exhaust gas feedstream downstream of the SCR device and determine NOx efficiency of the SCR device based upon the magnitude of ammonia in the exhaust gas feedstream downstream of the SCR device. A fault is detected in the SCR device based upon the NOx efficiency.

An exhaust treatment system comprising: a first dosage device, arranged to supply a first additive into said exhaust stream; a first reduction catalyst device, downstream of said first dosage device arranged for reduction of nitrogen oxides in said exhaust stream through the use of said first additive; a particulate filter, at least partly comprising a catalytically oxidizing coating, which is downstream of said first reduction catalyst device to catch soot particles, and to oxidize one or several of nitrogen oxide and incompletely oxidized carbon compounds in said exhaust stream; a second dosage device, downstream of said particulate filter to supply a second additive into said exhaust stream; and a second reduction catalyst device, downstream of said second dosage device for a reduction of nitrogen oxides in said exhaust stream, with the use of at least one of said first and said second additive.

The honeycomb structure body has a dense part having a change ratio of porosity calculated by the following Expression (1) that is 1 to 5%. The honeycomb structure body also has an outside-diameter decreasing part in which the outside diameter decreases from the inflow end face to the outflow end face. The honeycomb structure body has a change ratio of average diameter calculated by the following Expression (2) that is 0.2 to 3%.
(1P.sub.x/P.sub.y)100,Expression (1): in Expression (1), P.sub.x denotes the porosity (%) at the center region of the outflow end face, and Py denotes the porosity (%) of a circumferential region of the outflow end face other than the center region.
(1D.sub.x/D.sub.y)100,Expression (2): in Expression (2), D.sub.x denotes the average diameter (mm) of the outflow end face, and D.sub.y denotes the average diameter (mm) of the inflow end face.

An internal combustion engine system includes: an internal combustion engine mounted on a vehicle; a NOx selective reduction catalyst; a reducing agent supply device including a urea water addition valve configured to add urea water into the exhaust gas passage upstream of the NOx selective reduction catalyst, a urea water tank, a urea water flow passage that connects the urea water addition valve and the urea water tank, and a pump configured to supply the urea water addition valve with the urea water from the urea water tank; and a control device. The control device is configured to perform a runoff reduction control that controls at least one of the reducing agent supply device and the internal combustion engine such that the amount of runoff of the urea water from the urea water tank becomes less when the tilt angle of the vehicle is large than when it is small.

Provide is a functional structural body that can suppress aggregation of metal oxide nanoparticles and prevent functional loss of metal oxide nanoparticles, and thus exhibit a stable function over a long period of time. A functional structural body (1) includes: a skeletal body (10) of a porous structure composed of a zeolite-type compound; and at least one type of metal oxide nanoparticles (20) containing a perovskite-type oxide present in the skeletal body (10), the skeletal body (10) having channels (11) that connect with each other, and the metal oxide nanoparticles (20) being present at least in the channels (11) of the skeletal body (10).

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.

The invention relates to a fluid suited for depollution of exhaust gas, notably in internal-combustion engines, allowing both to perform catalytic reduction of the nitrogen oxides (DeNOx) contained in the exhaust gas and to provide particulate filter (PAF) regeneration aid. The fluid is a homogeneous aqueous solution of a reductant or a reductant precursor for the DeNOx process, and it comprises a metallic additive for catalyzing the oxidation of exhaust gas particles. This metallic additive is a basic metal carbonate soluble in said aqueous solution. The invention also describes the preparation method and the use thereof for the depollution of exhaust gas of internal-combustion engines.