A method for operating an exhaust system of an internal combustion engine of a motor vehicle, in which exhaust gas from the internal combustion engine flows through a first SCR catalytic converter, which is followed by an ammonia barrier catalytic converter, and flows through a second SCR catalytic converter which is disposed downstream of the ammonia barrier catalyst, includes introducing a reducing agent introduced into the exhaust gas by a first metering device upstream of the first SCR catalytic converter and by a second metering device upstream of the second SCR catalytic converter. When a predetermined threshold value of a temperature of a region of the exhaust system is exceeded, a quantity of reducing agent introduced into the exhaust gas by the first metering device is increased.

The present disclosure provides SCR catalyst compositions, catalyst articles, and catalyst systems, as well as methods of reducing the amount of NOx present in an engine exhaust gas, particularly exhaust from a gasoline engine. The catalyst compositions particularly can comprise a doped ceria substrate, particularly a ceria support doped with at least a niobia component, and optionally further doped with a further material, particularly a base metal oxide (BMO).

A catalyst containing a washcoat including copper or iron on a small pore molecular sieve material having a maximum ring size of eight tetrahedral atoms physically mixed with platinum and rhodium on a refractory metal oxide support including alumina, silica, zirconia, titania, and a physical mixture or a chemical combination or an atomically doped combination thereof is described. A catalyst containing a first washcoat zone substantially free of platinum group metal and including copper or iron on a small pore molecular sieve material having a maximum ring size of eight tetrahedral atoms; and a second washcoat zone including copper or iron on a small pore molecular sieve material having a maximum ring size of eight tetrahedral atoms physically mixed with platinum or platinum and rhodium on a refractory metal oxide support including alumina, silica, zirconia, titania, and a physical mixture or a chemical combination or an atomically doped combination thereof is provided. A method and a system for treating emissions using the catalyst are also described.

A mobile emissions control system having an emission capturing system and emission control system is provided for diesel engines operated on ocean-going ships at-berth. The emissions control system may be mounted on a towable chassis or mounted on a barge, allowing it to be placed alongside ocean-going ships at-berth. A crane or boom transfers a duct of the emissions capturing system extending from the emissions control system to the ship to capture exhaust from its engine. Alternatively, the system may be mounted on an automated guided vehicle (AGV) equipped with a tower and a crane. The crane mounted on the AGV then lifts the duct forming part of the emissions capture system to the ship's exhaust system to capture exhaust from the ship's diesel engine and transfers it to the emissions control system, which cleans the exhaust and then passes clean air into the atmosphere through an exhaust outlet.

The invention relates to a catalytic article comprising a substrate having an inlet and an outlet; a first coating comprising a blend of: (1) platinum on a support, and (2) a first SCR catalyst; and a second coating comprising a second SCR catalyst; wherein the support comprises at least one of a zeolite or a SiO.sub.2—Al.sub.2O.sub.3 mixed oxide. The platinum may be fixed on the support in solution.

The present disclosure relates to an exhaust gas treatment system for treating an exhaust gas stream leaving an internal combustion engine, wherein said exhaust gas treatment system comprises (i) a first catalyst comprising a coating and a first substrate, wherein the coating comprises a vanadium oxide supported on a first oxidic support comprising titanium; (ii) a hydrocarbon injector for injecting a fluid comprising hydrocarbons into the exhaust gas stream exiting the outlet end of the first catalyst according to (i); (iii) a second catalyst comprising a coating and a second substrate, wherein the coating comprises palladium on a second oxidic support comprising one or more of zirconium, silicon, aluminum and titanium.

A method of forming an SSZ-13 zeolite in a hydrothermal synthesis yields an SSZ-13 zeolite that exhibits a silica to alumina (SiO.sub.2:Al.sub.2O.sub.3) molar ratio (SAR) that is less than 16:1; has a morphology that includes one or more of cubic, spheroidal, or rhombic particles with a crystal size that is in the range of about 0.1 micrometer (μm) to 10 μm. This SSZ-13 also exhibits a Brönsted acidity that is in the range of 2.0 mmol/g to 3.4 mmol/g as measured by ammonia temperature programmed desorption. A catalyst formed by substituting a metal into the framework of the zeolite provides for low temperature light-off of the NOx conversion reactions, while maintaining substantial performance at higher temperatures demonstrating hydrothermal stability.

There is disclosed an organic-free, metal-containing zeolite Beta with a silica-to-alumina ratio (SAR) ranging from 5 and 20, and a metal content of at least 0.5 wt. %. There is also disclosed a method of making such a zeolite Beta without organic structure directing agent (SDA). The metal, which may comprise Fe or Cu, can be found in amounts ranging from 1-10 wt. %. A method of selective catalytic reduction of nitrogen oxides in exhaust gases using the disclosed zeolite is also disclosed.

The present disclosure relates to a method for forming a catalyst article comprising: (a) forming a plastic mixture having a solids content of greater than 50% by weight by mixing together a crystalline small pore or medium pore molecular sieve in an H.sup.+ or NH.sub.4.sup.+ form, an insoluble active metal precursor, an inorganic matrix component, an organic auxiliary agent, an aqueous solvent and optionally inorganic fibres; (b) moulding the plastic mixture into a shaped article; and (c) calcining the shaped article to form a solid catalyst body. The present disclosure further relates to a catalyst article, particularly a catalyst article which is suitable for use in the selective catalytic reduction of nitrogen oxides, and to an exhaust system.

An exhaust gas treatment system includes in order: an intake for receiving an exhaust gas from a lean burn combustion engine; an injector for the provision of a nitrogenous reductant; a close-coupled vanadium-containing SCR catalyst composition; one or more downstream PGM-containing oxidation catalyst compositions, wherein the close-coupled vanadium-containing SCR catalyst composition includes cerium in a Ce:V molar ratio of greater than 0.3.