A synthesis process for forming nanodendrites. The nanodendrites are utilized in a process to form a heterojunction catalyst. Nanodendrites may include PtRu.sub.8 nanodendrites that can be oxidized through annealing to form PtRuO.sub.2. One heterojunction catalyst comprises PtRuO.sub.2 on a carbon support.

A synthesis process for forming nanodendrites. The nanodendrites are utilized in a process to form a heterojunction catalyst. Nanodendrites may include PtRu.sub.8 nanodendrites that can be oxidized through annealing to form PtRuO.sub.2. One heterojunction catalyst comprises PtRuO.sub.2 on a carbon support.

A method of operating a fuel cell having an anode, a cathode and a polymer electrolyte membrane disposed between the anode and the cathode, includes feeding the anode with an impure hydrogen stream having low levels of carbon monoxide up to 5 ppm, and wherein the anode includes an anode catalyst layer including a carbon monoxide tolerant catalyst material, wherein the catalyst material includes: (i) a binary alloy of PtX, wherein X is a metal selected from the group consisting of rhodium and osmium, and wherein the atomic percentage of platinum in the alloy is from 45 to 80 atomic % and the atomic percentage of X in the alloy is from 20 to 55 atomic %; and (ii) a support material on which the PtX alloy is dispersed; wherein the total loading of platinum group metals (PGM) in the anode catalyst layer is from 0.01 to 0.2 mgPGM/cm.sup.2.

The invention relates to the use of a supported, platinum-containing and sulfur-containing shell catalyst for the partial or complete dehydrogenation of perhydrogenated or partially hydrogenated cyclic hydrocarbons. The present invention also relates to a method for producing a platinum-containing and sulfur-containing shell catalyst and to a platinum-containing and sulfur-containing shell catalyst. The present invention further relates to a method for the partial or complete dehydrogenation of perhydrogenated or partially hydrogenated cyclic hydrocarbons.

A system for treatment of an exhaust gas stream from an engine is provided, containing an upstream selective catalytic reduction (SCR) catalyst, which receives the exhaust gas stream without any intervening catalyst, a diesel oxidation catalyst (DOC) positioned downstream thereof; a catalyzed soot filter (CSF) downstream of the diesel oxidation catalyst; a second SCR catalyst positioned downstream of the catalyzed soot filter; and an ammonia oxidation (AMOx) catalyst. The application also describes use of such systems to reduce nitrogen oxides (NOx) and hydrocarbons (HC) in an exhaust gas stream.

A system for treatment of an exhaust gas stream from an engine is provided, containing an upstream selective catalytic reduction (SCR) catalyst, which receives the exhaust gas stream without any intervening catalyst, a diesel oxidation catalyst (DOC) positioned downstream thereof; a catalyzed soot filter (CSF) downstream of the diesel oxidation catalyst; a second SCR catalyst positioned downstream of the catalyzed soot filter; and an ammonia oxidation (AMOx) catalyst. The application also describes use of such systems to reduce nitrogen oxides (NOx) and hydrocarbons (HC) in an exhaust gas stream.

The present disclosure provides a method for operating a three-way catalyst system at high temperatures. The method includes passing a high-temperature exhaust stream exiting an engine over a thermally stable three-way catalyst system including a metal oxide support; two or more catalytically active metals disposed on the support; and a porous metal oxide coating disposed on one or more exposed surfaces of the support. At least one of the catalytically active metals may be platinum (Pt). The method further includes reducing an amount of the nitrogen oxides (NO.sub.x), carbon monoxide (CO), and non-methane hydrocarbons (HCs) in an effluent stream exiting the thermally stable three-way catalyst system so that the effluent stream has a combined amount of nitrogen oxides (NO.sub.x) and non-methane hydrocarbons (HCs) of less than or equal to about 30 mg/mile and less than or equal to about 0.5 g/mile of carbon monoxide (CO).

The present disclosure provides a method for operating a three-way catalyst system at high temperatures. The method includes passing a high-temperature exhaust stream exiting an engine over a thermally stable three-way catalyst system including a metal oxide support; two or more catalytically active metals disposed on the support; and a porous metal oxide coating disposed on one or more exposed surfaces of the support. At least one of the catalytically active metals may be platinum (Pt). The method further includes reducing an amount of the nitrogen oxides (NO.sub.x), carbon monoxide (CO), and non-methane hydrocarbons (HCs) in an effluent stream exiting the thermally stable three-way catalyst system so that the effluent stream has a combined amount of nitrogen oxides (NO.sub.x) and non-methane hydrocarbons (HCs) of less than or equal to about 30 mg/mile and less than or equal to about 0.5 g/mile of carbon monoxide (CO).

This exhaust gas cleaning catalytic device includes a base material and a first catalyst coat layer on the base material. The first catalyst coat layer has a pre-stage section on an exhaust gas flow upstream side, and a post-stage section on an exhaust gas flow downstream side. The first catalyst coat layer pre-stage section and post-stage section each contain inorganic oxide particles and rhodium supported by the inorganic oxide particles, while at least some of the inorganic oxide particles contain ceria. The ceria amount per unit length of the first catalyst coat layer post-stage section is larger than the ceria amount per unit length of the first catalyst coat layer pre-stage section. The first catalyst coat layer pre-stage section is disposed in such a manner that the end portion on the exhaust gas flow upstream side thereof is in direct contact with the exhaust gas flow.

The present invention relates to methods of immobilising metals on polymeric surfaces using surfactants and to products that can be formed by such methods. Polymer substrates with metal immobilised on the surface are very useful in a variety of applications. The metal is usually in the form of a nanoparticle. A major use of the invention is in catalysts. The invention can also be used in medical applications, such as to make antimicrobial surfaces.