Removal of acid gases from a fluid flow by means of reduced coabsorption of hydrocarbons and oxygen

Abstract

A process for removing acid gases from a hydrocarbonaceous fluid stream or an oxygen-comprising fluid stream in which the fluid stream is contacted with an aqueous solution which is essentially free from inorganic basic salts and comprises (i) at least one amine and (ii) at least one metal salt of an aminocarboxylic acid and/or an aminosulfonic acid. Conjoint use of the aminocarboxylic and/or aminosulfonic salt reduces the coabsorption of hydrocarbons or oxygen without significantly impairing the absorption rate at which acid gases are absorbed; without significantly reducing the absorption capacity of the solution for acid gases, and without significantly increasing the energy demand required for regeneration.

1 . A process for removing acid gases from a hydrocarbonaceous fluid stream or an oxygen-comprising fluid stream in which the fluid stream is contacted with an aqueous solution which is essentially free from inorganic basic salts and comprises (i) at least one amine and (ii) at least one metal salt of an aminocarboxylic acid and/or an aminosulfonic acid. 
     
     
         2 . The process according to  claim 1 , wherein the aminocarboxylic acid is an α-amino acid or a β-amino acid and/or the aminosulfonic acid is an α-amino-sulfonic acid or a β-aminosulfonic acid. 
     
     
         3 . The process according to  claim 1  or  2 , wherein the aminocarboxylic acid is a N-mono-C 1 -C 4 -alkylaminocarboxylic acid or a N,N-di-C 1 -C 4 -alkylaminocarboxylic acid. 
     
     
         4 . The process according to one of the preceding claims, in which the metal salt is an alkali metal or alkaline earth metal salt. 
     
     
         5 . The process according to  claim 3 , wherein the metal salt of the aminocarboxylic acid is the potassium salts of N,N-dimethylglycine or N-methylalanine. 
     
     
         6 . The process according to one of the preceding claims, wherein the aqueous solution comprises 2 to 5 kmol/m 3  of amine and 0.5 to 2 kmol/m 3  of metal salt of the aminocarboxylic acid and/or aminosulfonic acid. 
     
     
         7 . The process according to one of the preceding claims, wherein the amine is an alkanolamine. 
     
     
         8 . The process according to  claim 7 , wherein the alkanolamine is selected from monoethanolamine (MEA), diethanolamine (DEA), diisopropanolamine, triethanolamine (TEA), diethylethanolamine (DEEA), ethyldiethanolamine, aminoethoxyethanol (AEE), dimethylaminopropanol (DIMAP), methyldiethanolamine (MDEA), methyldiisopropanolamine (MDIPA), 2-amino-2-methyl-1-propanol (AMP), 2-amino-1-butanol (2-AB) or mixtures thereof. 
     
     
         9 . The process according to  claim 7 , wherein the alkanolamine is a tertiary alkanolamine. 
     
     
         10 . The process according to  claim 9 , in which the aqueous solution in addition comprises one or more activators. 
     
     
         11 . The process according to  claim 10 , wherein the activator is selected from piperazine, methylaminopropylamine, aminoethoxyethanol and 2-amino-1-butanol. 
     
     
         12 . The process according to  claim 10 , wherein the aquedus solution comprises:
 (i) methyldiethanolamine and piperazine,   (ii) methyldiethanolamine and methylaminopropylamine,   (iii) methyldiethanolamine and aminoethoxyethanol, or   (iv) methyldiethanolamine and 2-amino-1-butanol.   
     
     
         13 . An absorption medium for removing acid gases from a fluid stream, comprising an aqueous solution which is essentially free from inorganic basic salts and comprises (i) at least one alkanolamine and (ii) at least one metal salt of an aminocarboxylic acid and/or aminosulfonic acid. 
     
     
         14 . The absorption medium according to  claim 13 , wherein the aminocarboxylic acid is an α-amino acid or a β-amino acid and/or the aminosulfonic acid is an α-aminosulfonic acid or a β-aminosulfonic acid. 
     
     
         15 . The absorption medium according to  claim 13  or  14 , wherein the aminocarboxylic acid is a N-mono-C 1 -C 4 -alkylaminocarboxylic acid or a N,N-di-C 1 -C 4 -alkylamino-carboxylic acid. 
     
     
         16 . The absorption medium according to  claim 14 , wherein the metal salt of the aminocarboxylic acid is the potassium salt of N,N-dimethylglycine or N-methyl-alanine. 
     
     
         17 . The absorption medium according to one of  claims 13  to  16 , wherein the aqueous solution comprises 2 to 5 kmol/m 3  of alkanolamine and 0.5 to 2 kmol/m 3  of metal salt of the aminocarboxylic acid and/or aminosulfonic acid. 
     
     
         18 . The absorption medium according to one of  claims 13  to  17 , wherein the alkanolamine is selected from monoethanolamine (MEA), diethanolamine (DEA), diisopropanolamine, triethanolamine (TEA), diethylethanolamine (DEEA), ethyldiethanolamine, aminoethoxyethanol (AEE), dimethylaminopropanol (DIMAP), methyldiethanolamine (MDEA), methyldiisopropanolamine (MDIPA), 2-amino-2-methyl-1-propanol (AMP), 2-amino-1-butanol (2-AB) or mixtures thereof. 
     
     
         19 . The absorption medium according to one of  claims 13  to  17 , wherein the alkanolamine is a tertiary alkanolamine. 
     
     
         20 . The absorption medium according to  claim 19 , wherein the aqueous solution in addition comprises one or more activators. 
     
     
         21 . The absorption medium according to  claim 20 , wherein the activators are selected from piperazine, methylaminopropylamine, aminoethoxyethanol and 2-amino-1-butanol. 
     
     
         22 . The absorption medium according to  claim 20 , wherein the aqueous solution comprises:
 (i) methyldiethanolamine and piperazine,   (ii) methyldiethanolamine and methylaminopropylamine,   (iii) methyldiethanolamine and aminoethoxyethanol, or   (iv) methyldiethanolamine and 2-amino-1-butanol.