A method for preparing a supported noble metal catalyst, comprising: i) melting a noble metal sponge, a peroxide, and a support and/or a support precursor together; ii) dispersing the molten mixture in water; and iii) adjusting the pH to 4 to 10, thereby obtaining a supported noble metal catalyst. The method uses a noble metal sponge rather than an intermediate noble metal precursor, such as a noble metal nitrate salt, a noble metal halide salt, a halogenated noble metal acid, or a salt of the halogenated noble metal acid, for example, H.sub.3IrCl.sub.6, H.sub.2IrCl.sub.6, or IrCl.sub.3. The method does not produce any intermediate product, and does not use any chlorine-containing material, thereby avoiding contamination of the final catalyst by chlorine. The catalyst produced by the present invention has high activity, high surface area, and the RDE OER overpotential is less than 230 mV (at 10 mA cm.sup.2).

A method for preparing a supported noble metal catalyst, comprising: i) melting a noble metal sponge, a peroxide, and a support and/or a support precursor together; ii) dispersing the molten mixture in water; and iii) adjusting the pH to 4 to 10, thereby obtaining a supported noble metal catalyst. The method uses a noble metal sponge rather than an intermediate noble metal precursor, such as a noble metal nitrate salt, a noble metal halide salt, a halogenated noble metal acid, or a salt of the halogenated noble metal acid, for example, H.sub.3IrCl.sub.6, H.sub.2IrCl.sub.6, or IrCl.sub.3. The method does not produce any intermediate product, and does not use any chlorine-containing material, thereby avoiding contamination of the final catalyst by chlorine. The catalyst produced by the present invention has high activity, high surface area, and the RDE OER overpotential is less than 230 mV (at 10 mA cm.sup.2).

The present invention relates to a method for coating wall-flow filters. It also relates to correspondingly produced wall-flow filters and to their use in exhaust gas cleaning.

The present invention provides titania particles which are formed by providing a titania sol and spray drying the titania sol. A morphology of the dried titania particles is controlled by producing the titania sol from a TiO.sub.2 containing slurry and controlling the pH of the slurry to be 3 pH units or more from the iso-electric point of the titania by adding a peptizing agent to reduce an extent to which the titania sol is flocculated, or by producing the titania sol from a TiO.sub.2 containing slurry and adjusting the iso-electric point to be 3 pH units or more from the pH of the slurry by adding a dispersant to reduce an extent to which the titania sol is flocculated. The titania particles have a continuous exterior convex surface, a diameter of 30 m or less, a BET specific surface area of 50 m.sup.2/g or more, and are porous.

The present invention provides titania particles which are formed by providing a titania sol and spray drying the titania sol. A morphology of the dried titania particles is controlled by producing the titania sol from a TiO.sub.2 containing slurry and controlling the pH of the slurry to be 3 pH units or more from the iso-electric point of the titania by adding a peptizing agent to reduce an extent to which the titania sol is flocculated, or by producing the titania sol from a TiO.sub.2 containing slurry and adjusting the iso-electric point to be 3 pH units or more from the pH of the slurry by adding a dispersant to reduce an extent to which the titania sol is flocculated. The titania particles have a continuous exterior convex surface, a diameter of 30 m or less, a BET specific surface area of 50 m.sup.2/g or more, and are porous.

A catalysed soot filter comprises an oxidation catalyst for oxidizing NO to NO.sub.2 and/or oxidizing CO to CO.sub.2 and/or HC to CO.sub.2 and H.sub.2O disposed on a wall flow filter monolithic substrate, the oxidation catalyst comprising: a platinum group metal component, and a pre-calcined support material comprising a mixed magnesium aluminium metal oxide having a magnesium content, calculated as Mg, of 15 wt % Mg or lower.

The present invention discloses a method for preparing the nano-porous oxide-noble metal composite material by deoxidation, comprising dissolving the noble metal ion or fine particles, the oxide salt to be dissolved and the target oxide salt in the pure water in a proportion to form the mixed solution, adding the surface active agent, and stirring magnetically; dropping the precipitant gradually to form the precipitate, stirring for 4 h, separating and cleaning the precipitate, and drying, grinding and calcining at a high temperature; corroding fully and dissolving part of the oxide with an etchant, preserving the noble metal and the target oxide, separating, cleaning, drying at 80 C., and heat treating at a high temperature to obtain the nano-porous oxide-noble metal composite material. The present invention has the technological advantages of simple operation, low energy consumption, environmental protection and suitable for batching, etc.

A catalyst article comprises an SCR catalyst and a NOx adsorber catalyst, where each of these catalysts comprise a metal molecular sieve, each with a different metal. The catalyst article can be close coupled with other components to give a NO.sub.X performance advantage from cold start to a combined DOC and SCRF system. Higher NO.sub.X conversion is also shown in under-floor location due to NOx storage before SCR light off and selective NH.sub.3 slip control, allowing higher NH3 fill levels. Systems comprising the catalyst article and methods of using the catalyst article to give improved hydrocarbon and carbon monoxide control, as well as ammonia slip control, are described. The systems can include flow-through or wall-flow monoliths.

The invention provides a process for the production of titania particles with a desired morphology. The process comprises providing a titania sol and then drying the sol to provide dried titania particles. The process is characterized in that the morphology of the dried titania particles is controlled by applying one or more of the following criteria: (a) the titania sol is produced from a TiO.sub.2 containing slurry obtained using a precipitation step in a sulphate process, wherein the size of micelles formed during the precipitation is controlled; (b) the titania sol is produced from a TiO.sub.2 containing slurry and the pH of the slurry is controlled in order to affect the extent to which the titania sol is flocculated; (c) the titania sol is produced from a TiO.sub.2 containing slurry and the iso-electric point of the titania is adjusted in order to affect the extent to which the titania sol is flocculated; (d) the titania sol is dried by application of heat and the temperature used during the drying step is controlled.

The invention provides a process for the production of titania particles with a desired morphology. The process comprises providing a titania sol and then drying the sol to provide dried titania particles. The process is characterized in that the morphology of the dried titania particles is controlled by applying one or more of the following criteria: (a) the titania sol is produced from a TiO.sub.2 containing slurry obtained using a precipitation step in a sulphate process, wherein the size of micelles formed during the precipitation is controlled; (b) the titania sol is produced from a TiO.sub.2 containing slurry and the pH of the slurry is controlled in order to affect the extent to which the titania sol is flocculated; (c) the titania sol is produced from a TiO.sub.2 containing slurry and the iso-electric point of the titania is adjusted in order to affect the extent to which the titania sol is flocculated; (d) the titania sol is dried by application of heat and the temperature used during the drying step is controlled.