A honeycomb structure includes a honeycomb structure body having porous partition walls, wherein a value of a porosity of the partition wall in a partitioning wall portion between the two cells is defined as a porosity A, a value of a porosity of the partition wall in an intersecting portion that is a region connecting two or more wall portions is defined as a porosity B, a value of A/B obtained by dividing the porosity A by the porosity B is from 0.5 to 0.95, and the porosity A is from 10 to 40%.

An exhaust purification system includes an electrochemical reactor provided in an engine exhaust passage; a bypass passage bypassing the electrochemical reactor; a flow control valve controlling an amount of exhaust gas, discharged from an engine body, flowing into the electrochemical reactor and the bypass passage; and a control device controlling the flow control valve. The electrochemical reactor includes a holding material holding NO.sub.X or HC and is configured so as to purify NO.sub.X or HC held at the holding material if energized. The control device controls the flow control valve so as to control the amount of exhaust gas flowing into the electrochemical reactor so that a temperature of the electrochemical reactor is maintained at less than a desorption start temperature where NO.sub.X or HC starts to be desorbed from the holding material.

A catalyst device includes a heating element that generates heat when energized, a case that accommodates a catalyst support (heating element), an inflow pipe that draws exhaust gas into the case, and a connecting pipe that connects the inflow pipe and the case to each other. The case includes an end portion, which protrudes further in an upstream direction than an end face of the catalyst support. The inflow pipe is disposed inside the case. The catalyst device includes a triple-walled pipe structure, in which the connecting pipe overlaps with the end portion of the case and the inflow pipe in a covering manner.

A method (200) for heating an exhaust system (120) downstream of an internal combustion engine (1) by means of an electric heating device (14, 15). In one example, the method includes determining a current temperature (t_EHC, t_EHC{circumflex over ( )}Us, t_Cat) in the exhaust system (120), determining a heating demand (t_EHC{circumflex over ( )}Des) based on the determined current temperature (t_Cat) and a target temperature, calculating a required amount of heat (Pwr{circumflex over ( )}Des) on the basis of the heating demand and an amount of energy required to heat the electric heating device (14, 15), and controlling (Pwr{circumflex over ( )}Req) the electric heating device (14, 15) to generate the calculated amount of heat.

A substrate (11) of an exhaust gas purification catalyst (10) includes inflow-side cells (21), outflow-side cells (22), and porous partition walls (23), each porous partition wall separating the cells (21, 22) from each other. A first catalyst portions (14) is provided at least on a portion of a side of the partition wall (23) that faces the inflow-side cell (21), the portion being located on an upstream side in an exhaust gas flow direction, and a second catalyst portion (15) is provided at least on a portion of a side of the partition wall that faces the outflow-side cell, the portion being located on a downstream side in the exhaust gas flow direction. A first pore volume is greater than a second pore volume, where the first pore volume is a pore volume of pores with a pore size of 10 μm to 18 μm, as measured on the first catalyst portions (14) and the partition walls (23) within a region where the first catalyst portions (14) are provided, and the second pore volume is a pore volume of pores with a pore size of 10 μm to 18 μm, as measured on the second catalyst portions (15) and the partition walls (23) within a region where the second catalyst portions (15) are provided. The first catalyst portion (14) exhibits the peak top of the pore size at between 20 nm and 500 nm.

The present invention relates to an exhaust gas purification system comprising two catalytic sub-systems, wherein the first catalytic sub-system is for conversion of NOx, HC, CO and optionally particulate matter, and the second sub-system is for conversion of CO. The second sub-system locates at the downstream of the first catalytic sub-system. An air injection is positioned between the first catalytic sub-system and second catalytic sub-system.

An exhaust gas purification filter is used so as to support a NO.sub.X purification catalyst. The exhaust gas purification filter includes a honeycomb structure portion and a plug portion. The honeycomb structure portion includes a partition wall and cells. Numerous pores are formed in the partition wall. The cells are partitioned by the partition walls and form a flow path for an exhaust gas. The plug portion alternately seals an inflow end surface or an outflow end surface for the exhaust gas in the cells. The partition wall has a gas permeability coefficient that is equal to or greater than 0.35×10.sup.−12 m.sup.2, a pore volume ratio of pore diameters of 9 μm or less that is equal to or less than 25%, and an average pore diameter that is equal to or greater than 12 μm.

A three-way catalyst article, and its use in an exhaust system for compressed natural gas engines, is disclosed. The catalyst article for treating exhaust gas from compressed natural gas (CNG) engine comprising: a substrate comprising an inlet end, an outlet end with an axial length L; a first catalytic region beginning at the outlet end and extending for less than the axial length L, wherein the first catalytic region comprises a first PGM component; and a second catalytic region beginning at the inlet end, wherein the second catalytic region comprises a second PGM component; wherein the first PGM component comprises palladium, platinum, or a combination thereof; and wherein the second PGM component comprises rhodium.

A honeycomb structure includes a pillar-shaped honeycomb structure body having a porous partition wall so as to surround a plurality of cells extending from a first end face to a second end face, and a circumferential coating layer composed of a circumferential coating material coated on at least a part of circumference of the honeycomb structure body, wherein the circumferential coating layer has a printing area for printing on the surface thereof, the printing area has a lightness (L*) in L*a*b* color space (CIE1976) defined by International Commission on Illumination (CIE) of 35 or more, and the printing area has a surface roughness Ra of 30 μm or less.

An energy recovery converter for exhaust gases or waste heat is provided. The converter includes a membrane electrode assembly (MEA), an exhaust gas having a first molecular oxygen content, and an external electrical load. The MEA includes a first electrode, a second electrode and an oxygen ion conductive membrane sandwiched between the first and second electrodes. Each of the first and second electrodes includes at least one oxidation catalyst configured to promote an electrochemical reaction. The second electrode of the MEA is exposed to the exhaust gas and the first electrode of the MEA is exposed to a gas having a second molecular oxygen content. The second molecular oxygen content is higher than the first molecular oxygen content. The external electrical load is connected between the first and second electrodes of the MEA.