The present disclosure provides Low Temperature NO.sub.x-Absorber (LT-NA) catalyst compositions, catalyst articles, and an emission treatment system for treating an exhaust gas, each including the LT-NA catalyst compositions. Further provided are methods for reducing a NO.sub.x level in an exhaust gas stream using the LT-NA catalyst articles. In particular, the LT-NA catalyst compositions include a first zeolite, a first palladium component, and a plurality of platinum nanoparticles. The LT-NA catalyst compositions exhibit enhanced regeneration efficiency with respect to NO.sub.x adsorption capacity, even after hydrothermal aging.

An electrically heating converter includes: a pillar shaped honeycomb structure made of conductive ceramics, including: an outer peripheral wall; and a partition wall disposed on an inner side of the outer peripheral wall, the partition wall defining a plurality of cells, each of the cells penetrating from one end face to other end face to form a flow path; metal electrodes; a pressing member configured to press each of the metal electrodes against the pillar shaped honeycomb structure, so that the pillar shaped honeycomb structure is electrically connected to each of the metal electrodes; and an antioxidant material of (i) or (ii) below: (i) an antioxidant material provided between the pillar shaped honeycomb structure and each of the metal electrodes, or (ii) an antioxidant material provided from a surface of the pillar shaped honeycomb structure over an outer surface of each of the metal electrodes.

An electrically heating converter includes: a pillar shaped honeycomb structure made of conductive ceramics, including: an outer peripheral wall; and a partition wall disposed on an inner side of the outer peripheral wall, the partition wall defining a plurality of cells, each of the cells penetrating from one end face to other end face to form a flow path; metal electrodes; a pressing member configured to press each of the metal electrodes against the pillar shaped honeycomb structure, so that the pillar shaped honeycomb structure is electrically connected to each of the metal electrodes; and an antioxidant material of (i) or (ii) below: (i) an antioxidant material provided between the pillar shaped honeycomb structure and each of the metal electrodes, or (ii) an antioxidant material provided from a surface of the pillar shaped honeycomb structure over an outer surface of each of the metal electrodes.

A honeycomb structure made of ceramics, wherein the honeycomb structure includes: a borosilicate; and silicon particles doped with at least one dopant, the dopant is a Group 13 element or a Group 15 element, the silicon particles have a dopant amount (A) of 1×10.sup.16 to 5×10.sup.20/cm.sup.3, and the honeycomb structure has a silicon particle content (B) of 30 to 80% by mass.

A honeycomb structure made of ceramics, wherein the honeycomb structure includes: a borosilicate; and silicon particles doped with at least one dopant, the dopant is a Group 13 element or a Group 15 element, the silicon particles have a dopant amount (A) of 1×10.sup.16 to 5×10.sup.20/cm.sup.3, and the honeycomb structure has a silicon particle content (B) of 30 to 80% by mass.

A pillar shaped honeycomb structure for induction heating, the honeycomb structure being made of ceramics and including: an outer peripheral wall; and a partition wall disposed on an inner side of the outer peripheral wall, the partition wall defining a plurality of cells, each of the cells penetrating from one end face to other end face to form a flow path, wherein a composite material containing a conductor and a non-conductor is provided in the cells in a region of 50% or less of the total length of the honeycomb structure from one end face, and wherein the conductor is a conductor that generates heat in response to a change in a magnetic field.

A pillar shaped honeycomb structure for induction heating, the honeycomb structure being made of ceramics and including: an outer peripheral wall; and a partition wall disposed on an inner side of the outer peripheral wall, the partition wall defining a plurality of cells, each of the cells penetrating from one end face to other end face to form a flow path, wherein a composite material containing a conductor and a non-conductor is provided in the cells in a region of 50% or less of the total length of the honeycomb structure from one end face, and wherein the conductor is a conductor that generates heat in response to a change in a magnetic field.

Emissions treatment systems of combustion engines are provided, which comprise a platinum-containing catalyst that is degreened during production, which is before exposure to operating conditions of a vehicle having a diesel engine. The platinum-containing catalyst, in the form of a platinum component on a high surface area refractory metal oxide support, exhibits a vibration frequency of about 2085 to about 2105 cm.sup.−1 as measured by CO-DRIFTS. Such catalytic material is essentially-free of platinum oxide species found at greater than about 2110 cm.sup.−1 as measured by CO-DRIFTS. Such catalysts can provide excellent and consistent conversion of nitrogen oxide (NO) to nitrogen dioxide (NO.sub.2).

Emissions treatment systems of combustion engines are provided, which comprise a platinum-containing catalyst that is degreened during production, which is before exposure to operating conditions of a vehicle having a diesel engine. The platinum-containing catalyst, in the form of a platinum component on a high surface area refractory metal oxide support, exhibits a vibration frequency of about 2085 to about 2105 cm.sup.−1 as measured by CO-DRIFTS. Such catalytic material is essentially-free of platinum oxide species found at greater than about 2110 cm.sup.−1 as measured by CO-DRIFTS. Such catalysts can provide excellent and consistent conversion of nitrogen oxide (NO) to nitrogen dioxide (NO.sub.2).

A honeycomb extrusion die body (401) including inlet (414) and exit (402) faces, and a plurality of pins (406) on the exit face (402) defining a matrix of intersecting wide slots (425) and narrow slots (427). The wide slots (425) have an exit width (W1) greater than an exit width (W2) of the narrow slots (427). The die body (401) further includes feedholes (422) at the inlet face (414) and intersecting with inlet portions (416) to the wide slots (425) and/or the narrow slots (427). Some of the pins (406) defining the wide slots (425) include a first surface indentation feature (430) that is (i) located between the inlet portion (416) and the wide slot exit and (ii) spaced away from the wide slot exit. Some of the pins (406) defining the narrow slots (427) include a second surface indentation feature (434) that is (i) located between the inlet portion and the narrow slot exit and (ii) spaced away from the narrow slot exit.