Process for the preparation of hydrazine

A process for preparation of an azine comprising the stages:

• (i) successively:
• (a) reacting ammonia, hydrogen peroxide and a reactant carrying a carbonyl group in a working solution in a reactor to form the azine,
• (b) separating the azine from the working solution,
• (c) heating the working solution at a temperature of at least about 130° C., so that the CO2 and most of the water are removed in the form of an aqueous stream C1, wherein the stream C1 comprising NH3;
• (d) recycling the working solution to Stage a);
• and
• (ii) successively:
• (a) bringing the stream C1 in a stripping column;
• (b) separating NH3 in a gaseous state from the stream C1;
• (c) condensing the stream C1 in a liquid state and separating the condensed stream C1 into two phases, that is, an organic phase which is rich in reactant carrying a carbonyl group, and an aqueous phase comprising substantially all the CO2 present in C1;
• (d) feeding the aqueous phase into a distillation column, and collecting an aqueous stream devoid of CO2 at the top of the distillation column and an aqueous stream C2 comprising substantially all the CO2 present in C1 at the bottom of the distillation column,
• wherein
• at least a portion of the stream C2 is treated with an amount of acid such that pH of the stream C2 is adjusted to less than 6.4, then recycled to the reactor of Stage (i)(a).