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.

Described herein are catalysts and methods for converting waste biogas (e.g., a mixture of carbon dioxide and methane) into useful products. In some embodiments, the biogas is converted into a highly purified methane, that can be further processed to generate fuel products, including recycled natural gas (RNG) and liquid fuels. The described catalysts and methods may be advantageous over conventional methods, including by reducing catalyst costs, decreasing temperature requirements and/or providing higher purity products by reducing carbon dioxide and carbon monoxide in product streams.

A process of recovering propylene and N-butyraldehyde from a purge gas includes forming a first product stream including N-butyraldehyde by reacting propylene and a first synthesis gas in the presence of a first catalyst in a first reactor and a second reactor; withdrawing a mixed stream from the second reactor; separating a liquid stream and purge gas from the mixed stream and recycling the liquid stream to the second reactor; reacting the purge gas and a second synthesis gas in the presence of a second catalyst in a purge gas reactor to form a second product stream including N-butyraldehyde; withdrawing the second product stream including N-butyraldehyde from the purge gas reactor and combining the second product stream including N-butyraldehyde and the first product stream including N-butyraldehyde; and withdrawing a stream including N-butyraldehyde from the purge gas reactor and recovering N-butyraldehyde from the stream including N-butyraldehyde product stream.

The present invention relates to a particulate filter for removing particles, carbon monoxide, hydrocarbons and nitrogen oxides from the exhaust gas from internal combustion engines operated with a stoichiometric air-fuel mixture. Two coatings Y and Z are located in the porous walls and are present from the first end of the wall-flow filter over the entire length L of the particulate filter. Both contain active alumina, at least one cerium-zirconium-rare earth metal mixed oxide and at least one platinum group metal.

The invention relates to a particulate filter which comprises a wall flow filter of length L and two catalytically active coatings Y and Z, wherein the wall flow filter comprises channels E and A that extend in parallel between a first and a second end of the wall flow filter and are separated by porous walls which form surfaces OE and OA, respectively, and wherein the channels E are closed at the second end and the channels A are closed at the first end, and the coatings Y and Z have the same oxygen storage components and the same carrier materials for noble metals. The invention is characterised in that the coating Y is located in the channels E on the surfaces OE and the coating Z is located in the channels Aon the surfaces OA.

An exhaust gas purifying catalyst (10) according to the present invention is an exhaust gas purifying catalyst including the first catalyst layer (12). The first catalyst layer (12) includes the first section (14) and the second section (15) in the exhaust gas flow direction. The first section (14) is located on the upstream side in the exhaust gas flow direction relative to the second section (15). A catalyst layer (16) contains a catalytically active component including a specific element. The concentration of the specific element in the catalyst layer (12) is higher in the first section (14) than in the second section (15), in terms of mass per unit volume. When the first section is divided in half along the thickness direction of the first catalyst layer (12), the ratio of a1 to a2, a1/a2, is 1.1 or more, where a1 represents the mass of the specific element that is present on the surface side of the catalyst layer (12) and a2 represents the mass of the specific element that is present on the other side than the surface side of the catalyst layer.

An exhaust gas purification catalyst provides excellent removal performance of methane, which is chemically stable. Exhaust gas purification catalyst includes a substrate that divides cells through which an exhaust gas flows and a catalyst layer that is provided on a surface of the substrate. The catalyst layer includes a palladium layer containing palladium that extends from a first end part which is an end part on the side into which an exhaust gas in the cells flows to a second end part which is an end part on the side from which an exhaust gas flows out, a platinum layer containing platinum that extends from the second end part to the first end part, and a rhodium layer containing rhodium that is laminated with both the palladium layer and the platinum layer.

An exhaust gas purification catalyst device having a substrate, a first catalyst coating layer on the substrate, and a second catalyst coating layer on the first catalyst coating layer. The first catalyst coating layer includes inorganic oxide particles, palladium carried on the inorganic oxide particles, and a barium compound. The second catalyst coating layer includes alumina particles and rhodium carried by the alumina particles. The ratio (M.sub.Ba/M.sub.Rh) between the mass (M.sub.Ba) of barium in the first catalyst coating layer and the mass (M.sub.Rh) of rhodium in the second catalyst coating layer is 5.0-60.0 inclusive.

An exhaust gas purification catalyst device has catalyst coating layers, which extend from the upstream side to the downstream side of the exhaust gas flow. The catalyst coating layers each have at least three zones present in order from the upstream side to the downstream side of the exhaust gas flow, and each of these at least three zones is an oxidation catalyst zone or a reduction catalyst zone. In the uppermost layer of an oxidation catalyst zone, the total number of atoms of platinum and palladium is greater than the number of atoms of rhodium; in the upper most layer of a reduction catalyst zone, the number of atoms of rhodium is greater than the total number of atoms of platinum and palladium. The oxidation catalyst zones and the reduction catalyst zones alternate at least twice in the exhaust gas flow direction.

The invention relates to a particulate filter which comprises a wall flow filter of length L and two different catalytically active coatings Y and Z, wherein the wall flow filter comprises channels E and A that extend in parallel between a first and a second end of the wall flow filter and are separated by porous walls which form surfaces OE and OA, respectively, and the channels E are closed at the second end and the channels A are closed at the first end. The invention is characterised in that the coating Y is located in the channels E on the surfaces OE and the coating Z is located in the channels A on the surfaces OA.