Method of recovering primary and secondary amines
OwnerLazar Isaevich Blyakhman, Sergei Lvovich Davydov +1inventors
InventorsLazar Isaevich Blyakhman, Sergei Lvovich Davydov, Valentina Fedorovna Kashina
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Abstract
A method of recovering primary or secondary amines from aqueous, organic or aquo-organic solutions of said amines by subjecting these solutions to distillation or rectification in the presence of carbonic acid.
Claims23
A method of concentrating a solution of an amine selected from the group consisting of primary amines and secondary amines, said amine having a pK.sub.a value equal to at least 8.5, in a solvent selected from the group consisting of water, an organic liquid other than a primary or secondary amine and mixtures of water and said organic liquid, wherein said solution is obtained from a crude reaction mass, and said organic liquid is a conventional diluent present within said crude reaction mass, said method comprising the steps of continuously distilling said solution of said amine in the presence of CO.sub.2 in a rectification column, wherein the middle part of said column is supplied with said solution of said amine, the bottom part of said column is supplied with gaseous CO.sub.2 and a mixture of CO.sub.2 and vapors of said solvent are directed from the top part of the column to a cooler where the vapors of said solvent are condensed and a gaseous stream comprising CO.sub.2 is recycled to the bottom part of said column;
- returning part of the condensed solvent vapors in said cooler in reflux form to said rectification column;
- recovering the remainder of said condensed solvent vapors free from said amine;
- and supplying the amine from the bottom part of said rectification column to a boiler where said amine is partly evaporated;
- directing the vapors of said amine from said boiler into the bottom part of said rectification column and withdrawing the part of the amine which has not evaporated from the bottom part of said rectification column and said boiler as the final product, said CO.sub.2 functioning to reduce the volatility of the amine without affecting the volatility of the solvent.
A method of concentrating a solution of an amine selected from the group consisting of primary amines and secondary amines, said amine having a pK.sub.a value equal to at least 8.5, in a solvent selected from the group consisting of water, an organic liquid other than a primary or secondary amine and mixtures of water and said organic liquid, wherein said solution is obtained from a crude reaction mass, and said organic liquid is a conventional diluent present within said crude reaction mass, said method comprising the steps of charging said solution of said amine to a rectification still, passing gaseous CO.sub.2 continuously through said still, heating said solution of said amine to boiling, condensing vapors of said solvent in a cooler, recycling a gaseous stream comprising CO.sub.2 through said solution in said still, and separating said amine, free from said solvent, as bottoms from said still, said CO.sub.2 functioning to reduce the volatility of the amine without affecting the volatility of the solvent.
In the method of concentrating a solution of an amine selected from the group consisting of primary amines and secondary amines in a solvent selected from the group consisting of water, an organic liquid other than a primary or secondary amine and mixtures of water and said organic liquid wherein said amine has a pK.sub.a value of at least 8.5, by rectification in a rectification column having an overhead outlet, a bottoms outlet, and an amine solution inlet located between said overhead outlet and said bottoms outlet, wherein said solution is obtained from a crude reaction mass, and said organic liquid is a conventional diluent present within said crude reaction mass, the improvement comprising carrying out said rectification in the presence of a gaseous stream comprising CO.sub.2 said CO.sub.2 functioning to reduce the volatility of the amine without affecting the volatility of the solvent.
In a method of concentrating a solution of an amine selected from the group consisting of primary and secondary amines in a solvent selected from the group consisting of water, an organic liquid other than a primary or secondary amine, and mixtures of water and said organic liquid wherein said amine has a pK.sub.a value of at least 8.5, by fractional distillation of said solution of said amine, wherein said solution is obtained from a crude reaction mass, and said organic liquid is a conventional diluent present within said crude reaction mass, the improvement comprising carrying out the distillation in the presence of gaseous CO.sub.2 and separating said amine as bottoms and said solvent as overhead, said CO.sub.2 functioning to reduce the volatility of the amine without affecting the volatility of the solvent.
Dependencies are inferred from the claim text.