GB635054A - Improvements in or relating to a process for the manufacture of acetic anhydride - Google Patents

Abstract

A continuous process for the production of acetic anhydride by the liquid phase catalytic oxidation of acetaldehyde by means of molecular oxygen comprises feeding acetaldehyde and molecular oxygen into a reaction system containing a reaction mixture whose content of acetic anhydride is not less than 40 per cent, maintaining the temperature of the reaction mixture at a value between 45 DEG and 55 DEG C., maintaining intimate contact between said molecular oxygen and said reaction mixture, controlling the feed of acetaldehyde and molecular oxygen so as to maintain the acetaldehyde content of said reaction mixture between 2 and 7 per cent, whilst maintaining the concentration of acetic anhydride therein at a value not less than 40 per cent, maintaining a concentration of a cobalt catalyst in said reaction mixture such that the concentration of cobalt is not less than 0.02 per cent and is at least sufficient to control the concentration of per-compounds to a value of less than 1 per cent and withdrawing reaction mixture from said reaction system to maintain the amount of reaction mixture therein substantially constant whilst maintaining a residence time in said reaction system not exceeding half an hour. Pressures of 1 to 5 atmospheres may be employed, and a copper catalyst may be present as well as the cobalt. Examples are given. Specifications 446,259, 514,268, 628,034 and 628,035 are referred to.