Process for producing exhaust treatment catalyst powders, and their use

A process for producing a powder batch comprising a plurality of particles, comprising:

• (i) providing a precursor medium comprising a liquid medium and (a) a first catalytically active component comprising at least one transition metal or a compound thereof;
• (b) a second component different from said first component, and capable of removing oxygen from, or releasing oxygen to, an exhaust gas stream;
• and (c) a third component different from said first and second components and comprising a refractory support, wherein at least one of said components (a) to (c) is provided in the form of a precursor to said component dissolved or suspended in said liquid medium;
• and
• (ii) heating droplets of said precursor medium carried in a gas stream to remove at least part of the liquid medium, chemically convert said precursor(s) to said at least one component, and form said plurality of particles containing all of components (a) to (c),
• wherein said plurality of particles when subjected to Temperature Programmed Reduction, exhibits at least one hydrogen absorption peak at a temperature of less than 160° C., and
• wherein the first catalytically active component comprises copper, and said plurality of particles, when subjected to X-ray analysis, exhibits no peaks characteristic of CuO for copper loading up to 8 wt % Cu per 100 m2 of the surface of said particles.