Method for the continuous preparation of benzyl alcohol

摘要

Preparation of benzyl alcohol (BA) by high temperature hydrolysis of benzyl chloride (BCl) with water is carried out continuously by (a) feeding BCl and water in 1:(10-70) molar ratio into a reactor with dispersion equipment and reaction at 80-160 degrees C until the BCl conversion is 30-90%; (b) separating the reaction product into an aqueous and an organic phase after discharge from the reactor; (c) separating the organic phase into BCl and crude BA in a first distillation unit; (d) recycling this BCl to the reactor; (e) refining the crude BA to very pure BA in a second distillation unit, in which the by-products (especially dibenzyl ether, DB) accumulate in the sump; (f) treating the aqueous phase containing dilute hydrochloric acid (HCl) with a solvent for the organic constituents, especially benzyl alcohol, still dissolved in the dilute HCl; (g) freeing this extract from solvent in a third distillation unit and recycling it to the extractor; (h) adding the sump from the third distillation to the first to recover BA; and BA concentrating the dilute aqueous HCl from extraction in an HCl absorption unit, after removing residual organics, and passing the very pure HCl to further use or to HCl electrolysis for recovering chlorine (Cl2) for side-chain chlorination of toluene.