REMOVING ACETALDEHYDE FROM METHYL ACETATE BY HIGH-PRESSURE RECTIFICATION Russian patent published in 2012 - IPC C07C51/12 C07C45/82 C07C47/06 C07C53/08 C07C51/44 C07C67/54 

FIELD: chemistry.

SUBSTANCE: invention relates to methods of removing acetaldehyde from a mixture of methyl acetate, methanol and acetaldehyde, one of which involves: (a) feeding the mixture of methyl acetate, methanol and acetaldehyde into a rectification column; (b) rectification of the mixture of methyl acetate, methanol and acetaldehyde at pressure of 68.95 kPa (10 pounds/square inch) or higher to form a vapour stream output from the top of the column which is rich in acetaldehyde compared to the mixture, and a bottom residue poor in acetaldehyde compared to the mixture; (c) returning as reflux a portion of the vapour stream which is output from the top of the column into the rectification column; and (d) removing a stream of the bottom residue poor in acetaldehyde from the rectification column, where temperature of the vapour stream from the top of the column ranges from 85°C to 115°C. The invention also relates to a method of producing acetic acid, involving: (a) cleaning the mixture of methyl acetate, methanol and acetaldehyde with removal of acetaldehyde by: (i) feeding the mixture of methyl acetate, methanol and acetaldehyde into a rectification column; (ii) rectification of the mixture of methyl acetate, methanol and acetaldehyde at pressure of 68.95 kPa (10 pounds/square inch) or higher to form a vapour stream which is output from the top of the column which is rich in acetaldehyde compared to the mixture, and a bottom residue poor in acetaldehyde compared to the mixture; (iii) returning as reflux a portion of the vapour stream output from the top of the column into the rectification column; and (iv) removing a stream of the bottom residue poor in acetaldehyde from the rectification column; (b) feeding the cleaned stream of bottom residue into the reaction mixture for carbonylation together with carbon oxide, where the reaction mixture for carbonylation contains water, a catalyst selected from rhodium catalysts, iridium catalysts or mixtures thereof, a promoter from methyl iodide and acetic acid; and (c) extracting acetic acid from the carbonylation mixture, where temperature of the stream which is output from the top of the column ranges from 85°C to 115°C.

EFFECT: improved methods.

15 cl, 8 dwg, 6 tbl, 16 ex