Method for the synthesis of a rare-earth organophosphate and use thereof for preparing a preformed catalytic system

A process for the synthesis of a rare-earth organophosphate comprising the steps of:

• dispersion, under high shear, in a mixer having agitator impellers, of a rare-earth oxide in a two-phase reaction medium comprising at least one organophosphoric acid and a mixture of at least two immiscible solvents and, simultaneously or sequentially;
• and
• reaction of the rare-earth oxide with the organophosphoric acid,
• the reaction medium being driven, during the dispersion, by a shear rate of greater than 200 s−1, expressed by the equation:
• Γaverage=kN
• in which k is a constant ranging from 10 to 13 and N is the speed of the agitator impellers, by a blade tip peripheral speed of greater than 4 m·s−1, expressed by the equation:
• VperiphπND
• in which D is the diameter of the agitator impellers expressed in meters and N is their rotational speed expressed in s−1.