Mixed-metal oxide particles by liquid feed flame spray pyrolysis of oxide precursors in oxygenated solvents

A process for the preparation of mixed-metal oxide particles, comprising combusting a liquid feed stream comprising two or more metal oxide source compounds dissolved in an oxygen group-containing combustible solvent, and aerosolized by atomization with an oxygen-containing gas to form a combustible liquid aerosol, followed by direct ignition and combustion of said solvent and flame pyrolysis of said metal oxide source compounds wherein

• a) said two or more metal oxide source compounds include
• a)i) at least one first metal oxide source compound which is a first metal alkoxide, first metal carboxylate, or mixture thereof;
• a)ii) at least one second metal source compound which is a second metal alkoxide, second metal carboxylate, or mixture thereof;
• a)iii) optionally one or more further metal oxide source compound(s) which are further metal alkoxides, further metal carboxylates, or mixtures thereof;
• and
• a)iv) optionally a dopant metal compound, said dopant metal compound comprising a dopant metal metalloorganic compound, or, in the case where the dopant metal concentration is insufficient to cause phase segregation in said mixed-metal oxide particles, a dopant metal halide, a dopant metal oxyhalide, or a dopant metal nitrate,
• wherein upon pyrolysis, phase segregation into at least two compositionally different phases occurs, at least one phase being a homogenous phase comprising two different metal oxides;
• or
• b) said two or more metal oxide source compounds include
• b)i) at least one first metal oxide source compound which comprises a metal carboxylate of the formula
• M(OH)n(OC(O)—R)m (I)
• where M is said first metal, n is at least 1, m is at least 1, and OC(O)—R is a carboxylate group derived from an organic carboxylic acid, where the sum of n and m equal the valence of metal M;
• b)ii) optionally a second metal oxide precursor compound which is a second metal alkoxide, a second metal carboxylate, or mixture thereof;
• wherein at least two different metals are present from the metal oxide source compounds b)i) and b)ii);
• or
• c)said two or more metal oxide source compounds include
• c)i) at least one first metal carboxylate, and
• c)ii) at least one second metal source compound which in said oxygenated solvent is insoluble in the concentration desired to be used, but is soluble in the concentration desired to be used when in the presence of a first metal carboxylate,
• said oxygen gas-containing stream optionally further comprising hydrogen gas, and collecting a pulverulent product having a mean particle size of less than 1 μm.