Process for the direct synthesis of alkylhalosilanes

A process for the preparation of alkylhalosilanes comprising reacting an alkyl halide with a solid body, formed of silicon and of a catalytic system comprising (α) a copper catalyst and (β) a group of promoter additives comprising:

• at least one additive β1 selected from the group consisting of metallic zinc, and a zinc-based compound,
• at least one additive β2 selected from the group consisting of tin, and a tin-based compound,
• optionally at least one additive β3 selected from the group consisting of cesium, potassium, rubidium, phosphorus, and a compound derived from these metals/semimetals,
• wherein the copper catalyst (α) is in the form of cuprous halide beads, said beads exhibiting the following specifications:
• (i) a sphericity factor which lies within the range from 0.6 to 1;
• (ii) a particle size distribution where the value of D50 lies within the range from 50 to 1500 μm;
• (iii) a porous texture which is equal to or less than 0.2 ml/g for a pore diameter ranging from 0.1 to 10 μm;
• and (iv) a flowability which is equal to or greater than 8.