An apparatus includes a dosing module structured to suspend dosing in an exhaust aftertreatment system; a selective catalytic reduction (SCR) inlet NOx module structured to interpret SCR inlet NOx data and an SCR inlet temperature; a SCR outlet NOx module structured to interpret SCR outlet NOx data; and a system diagnostic module structured to determine an efficiency of a SCR system based on the SCR inlet and outlet NOx data over a range of SCR temperatures, wherein the system diagnostic module is further structured to determine a state of at least one of a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and the SCR system based on the SCR efficiency at an elevated SCR temperature range and the SCR efficiency at a relatively lower SCR temperature range relative to a high SCR efficiency threshold and a low SCR efficiency threshold.

An apparatus for purifying an exhaust gas passing through an exhaust pipe includes a catalytic converter disposed on the exhaust pipe. The catalytic converter is provided with a lean NOx trap (LNT) device, the LNT device having an LNT catalyst coated therein, and a catalyzed particulate filter (CPF), the CPF having a catalyst coated therein, and the LNT device and the CPF are sequentially disposed in the catalytic converter. The CPF includes at least one inlet channel extending in a longitudinal direction, the at least one inlet channel having a first end into which fluid flows and a second end which is blocked, at least one outlet channel extending in the longitudinal direction, the at least one outlet channel having a first end which is blocked and a second end through which the fluid flows out, at least one porous wall that defines a boundary between neighboring inlet and outlet channels and that extends in the longitudinal direction, and a support with the catalyst coating thereon, and the support is located within at least one among the at least one inlet channel and the at least one outlet channel.

A NO.sub.x adsorber catalyst and its use in an emission treatment system for internal combustion engines, is disclosed. The NO.sub.x adsorber catalyst comprises a first layer consisting essentially of a support material, one or more platinum group metals disposed on the support material, and a NO.sub.x storage material.

An exhaust gas purification system for lowering the content of impurities in a lean exhaust gas of an internal combustion engine comprising, a feeding device that feeds ammonia or a compound decomposable to ammonia into an exhaust gas stream containing nitrogen oxides; a selective catalytic reduction catalyst comprising vanadium (V-SCR catalyst) which catalyzes the nitrogen oxides with ammonia in a temperature range of about 150° C. to about 400° C. and at an NO.sub.2/NO.sub.x ratio of about 0.3 to about 0.9; and a downstream system comprising a diesel oxidation catalyst.

A honeycomb body with a honeycomb structure having an inner zone of a first plurality of walls and an outer zone of a second plurality of walls at least partially surrounding the inner zone. The honeycomb structure has Pi that is greater than Po and MPSi that is greater than MPSo, wherein Pi is an average bulk porosity of the first plurality of walls, Po is an average bulk porosity of the second plurality of walls, MPSi is a median pore size of pores in the first plurality of walls, and MPSo is a median pore size of pores in the second plurality of walls. Various honeycomb structures, honeycomb extrusion apparatus, and co-extrusion methods are disclosed.

This oxidation catalyst for diesel engines is divided into an upstream-side catalyst layer and a downstream-side inner catalyst layer in the flow direction of the exhaust gas, and a downstream-side outer catalyst layer is additionally formed so as to cover the surface of the downstream-side inner catalyst layer. The upstream-side catalyst layer and the downstream-side inner catalyst layer contain Pd, and the downstream-side outer catalyst layer contains Pt. The amounts of Pt and Pd contained in the upstream-side catalyst layer and the amounts of Pt and Pd contained in the downstream-side inner catalyst layer are constantly set to certain values, while the amount of Pt contained in the downstream-side outer catalyst layer is set to a value which enables the oxidation efficiency to be at a predetermined value or higher.

A pleated filter structure is provided for the removal of gaseous pollutants from a gas mixture to be filtered. The structure comprises an ideally air impervious filter sheet, being pleated so as to form an adjacent series of slit shaped conduits for the passage of air through the structure, each bounded on either side by the folded sections of the filter sheet, these being joined by a series of top creases and bottom creases. The top and/or bottom creases incorporate slit-shaped openings allowing passage of a gas mixture into and/or out of the structure. Gas to be filtered enters through one side of the structure, passes laterally across the filter sheet section surfaces and exits through the other side. Also provided are methods for the manufacture of a pleated filter structure, comprising forming rows of slit-shaped openings in a filter sheet and providing folds, in alternating directions, along the lengthwise extensions of adjacent rows of openings. Methods for filtering a gas are also provided.

A honeycomb structure includes: a honeycomb structure body; and a convex part that protrudes outward from a part of circumference of the honeycomb structure body. The convex part surrounds the circumference of the honeycomb structure body like a ring. The convex part is of a tapered shape at least at one end having a tapered face. The convex part has a circumference coating layer making up the tapered face. The convex part has a maximum thickness of 1 to 20 mm, and a rough-face region on the tapered face, the rough-face region having surface roughness of 5 to 70 μm. The rough-face region has a total of a rough-face region angle of 108° or more. An inclination angle formed between the tapered face and the extending direction of the cells is 10 to 80 degrees.

A heater includes: a plate-like first heater substrate; an electrical heating wire that is provided on a first surface of the first heater substrate in a parallel circuit; electrodes that are connected to the electrical heating wire to allow current to flow in the electrical heating wire; and a plate-like cover substrate that covers the first surface of the first heater substrate, the electrical heating wire, and the electrodes with a second surface thereof. The electrical heating wire of the heater generates heat, so that the amount of heat is supplied. A honeycomb structure includes at least one heater that is provided so as to surround an outer wall thereof.

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.