US 7,309,403 B2Granted

Method for avoiding corrosion

AssigneeBASF SE

InventorsWerner Reutemann, Theodor Weber, Karl-Heinz Ross, Manfred Julius

Life of this patent

Estimating the term…

Loading patent…

Abstract

The invention relates to a method of avoiding corrosion in the separation of methylamine from a product stream (10) which is obtained in the preparation of methylamines by gas-phase reaction of methanol and ammonia and includes monomethylamine, dimethylamine, trimethylamine, ammonia and methanol as components, where ammonia is separated off by pure distillation in a first column (1), the remaining components of the product stream obtained as bottoms (12) are fed to a second column (2). Trimethylamine (14) is separated off in the second column (2) by extractive distillation with introduction of water. The further of the product stream obtained as bottoms (15) from the second column (2) are fed to a third column (3), in which monomethylamine and dimethylamine are separated off at the top. The monomethylamine and dimethylamine are separated by distillation in a fourth column (4). To avoid corrosion alkali metal hydroxide is added to the second or third column (3).

Claims8

Dependent claims

A method of avoiding corrosion of a distillation plant for the separation of methylamines from a product stream which is obtained in the preparation of methylamines by gas-phase reaction of methanol and ammonia and which comprises monomethylamine, dimethylamine, trimethylamine, ammonia and methanol as components, wherein the separation comprises the steps of;

distilling the product stream in a first distillation column to separate off ammonia,
feeding the remaining components of the product stream obtained as bottoms to a second column,
carrying out an extractive distillation with introduction of water to separate off trimethylamine in the second column,
feeding the further components of the product stream obtained as bottoms from the second column as feed to a third column,
separating off monomethylamine and trimethylamine in the third column, and separating the monomethylamine and dimethylamine by distillation in a fourth column,
wherein alkali metal hydroxide is added to the second or third column to prevent corrosion in the distillation plant.

3 more elements

Dependencies are inferred from the claim text.