Novel beta-hydroxylated tertiary diamines, a process for their synthesis and their use for eliminating acid compounds a gaseous effluent

Abstract

The invention relates to novel nitrogen compounds belonging to the family of tertiary diamines of general formula (I) below, wherein R is an alkanediyl radical —(CH 2 )n- with n=2, 3, 4, 5 or 6. The compound according to the invention is for example N,N,N′,N′-(tetramethyl)-1,6-diamino-2,5-hexanediol or N,N,N′,N′-(tetramethyl)-1,8-diamino-2,7-octanediol. The invention also relates to the method for preparing them and to their use for removing acid compounds contained in a gaseous effluent.

1 . A nitrogen compound belonging to the family of tertiary diamines meeting general formula (I) as follows: 
       
         
           
           
               
               
           
         
         wherein R is an alkanediyl radical —(CH 2 )n- with n=2, 3, 4, 5 or 6. 
       
     
     
         2 . A nitrogen compound as claimed in  claim 1 , wherein n is equal to 2 and R is an ethylidene radical r1, named N,N,N′,N′-(tetramethyl)-1,6-diamino-2,5-hexanediol and meeting the formula as follows: 
       
         
           
           
               
               
           
         
       
     
     
         3 . A nitrogen compound as claimed in  claim 1 , wherein n is equal to 4 and R is a butylidene radical r2, named N,N,N′,N′-(tetramethyl)-1,8-diamino-2,7-octanediol and meeting the formula as follows: 
       
         
           
           
               
               
           
         
       
     
     
         4 . A synthesis method of a nitrogen compound as claimed in  claim 1 , comprising the following reactions:
 a first reaction of epoxidation of an alpha-omega-diene to achieve epoxidation of each one of the alkene functions of the alpha-omega-diene to oxirane functions so as to produce a diepoxyalkane,   a second reaction of addition of two moles of dimethylamine and one molecule of the diepoxyalkane so as to produce the nitrogen compound as claimed in  claim 1 .   
     
     
         5 . A method as claimed in  claim 4 , wherein:
 the first reaction is an epoxidation reaction of 1,5-hexadiene to produce 1,2,5,6-diepoxyhexane,   the second reaction is an addition reaction of two moles of dimethylamine and one molecule of 1,2,5,6-diepoxyhexane to produce N,N,N′,N′-(tetramethyl)-1,6-diamino-2,5-hexanediol.   
     
     
         6 . A method as claimed in  claim 4 , wherein:
 the first reaction is an epoxidation reaction of 1,7-octadiene to produce 1,2,7,8-diepoxyoctane,   the second reaction is an addition reaction of two moles of dimethylamine and one molecule of 1,2,7,8-diepoxyoctane to produce N,N,N′,N′-(tetramethyl)-1,8-diamino-2,7-octanediol.   
     
     
         7 . A method as claimed in  claim 4 , wherein the first epoxidation reaction consists in reacting the alpha-omega-diene with a peracid or a peroxide or a hydroperoxide or oxygen associated with a suitable catalytic system, and said peracid can be generated in situ by reaction between a carboxylic acid and a hydrogen peroxide. 
     
     
         8 . A method as claimed in  claim 4 , wherein the second addition reaction is carried out in the presence of excess dimethylamine. 
     
     
         9 . A method as claimed in  claim 4 , wherein the first epoxidation reaction and the second addition reaction are carried out in two successive stages. 
     
     
         10 . A method of removing acid compounds contained in a gaseous effluent wherein an acid compound absorption stage is carried out by contacting the gaseous effluent with an absorbent solution comprising water and a nitrogen compound as claimed in  claim 1 . 
     
     
         11 . A method as claimed in  claim 10 , wherein the absorbent solution comprises between 5 wt. % and 95 wt. % of said nitrogen compound, and between 5 wt. % and 95 wt. % of water. 
     
     
         12 . A method as claimed in  claim 10 , wherein the absorbent solution additionally comprises between 5 wt. % and 95 wt. % of at least one additional amine, said additional amine being either a tertiary amine or a secondary amine having two secondary carbons at nitrogen alpha position or at least one tertiary carbon at nitrogen alpha position. 
     
     
         13 . A method as claimed in  claim 12 , wherein said additional amine is a tertiary amine selected from among the group made up of:
 N-methyldiethanolamine,   triethanolamine,   diethylmonoethanolamine,   dimethylmonoethanolamine, and   ethyldiethanolamine.   
     
     
         14 . A method as claimed in  claim 10 , wherein the absorbent solution also comprises a non-zero amount less than 30 wt. % of at least one additional amine such as a primary amine or a secondary amine. 
     
     
         15 . A method as claimed in  claim 14 , wherein said additional primary or secondary amine is selected from among the group made up of:
 monoethanolamine,   diethanolamine,   N-butylethanolamine,   aminoethylethanolamine,   diglycolamine,   piperazine,   1-methylpiperazine,   2-methylpiperazine,   homopiperazine,   N-(2-hydroxyethyl)piperazine,   N-(2-aminoethyl)piperazine,   morpholine,   3-(methylamino)propylamine,   1,6-hexanediamine,   N,N-dimethyl-1,6-hexanediamine,   N,N′-dimethyl-1,6-hexanediamine,   N-methyl-1,6-hexane-diamine, and   N,N′,N′-trimethyl-1,6-hexanediamine.   
     
     
         16 . A method as claimed in  claim 10 , wherein the absorbent solution furthermore comprises at least one physical solvent selected from the group made up of methanol, ethanol, 2-ethoxyethanol, triethylene glycoldimethylether, tetra-ethylene glycoldimethylether, pentaethylene glycoldimethylether, hexaethylene glycoldimethylether, heptaethylene glycol-dimethylether, octaethylene glycol-dimethylether, diethylene glycol butoxyacetate, glycerol triacetate, sulfolane, N-methylpyrrolidone, N-methylmorpholin-3-one, N,N-dimethylformamide, N-formyl-morpholine, N,N-dimethyl-imidazolidin-2-one, N-methylimidazole, ethylene glycol, diethylene glycol, triethylene glycol, thiodiglycol and tributyl phosphate. 
     
     
         17 . A method as claimed in  claim 10 , wherein the gaseous effluent is selected from among natural gas, syngases, combustion fumes, refinery gas, acid gas from an amine plant, Claus tail gas, biomass fermentation gas, cement plant gas and incinerator fumes. 
     
     
         18 . A method as claimed in  claim 10 , implemented for selectively removing the H 2 S over the CO 2  from a gaseous effluent comprising H 2 S and CO 2 , preferably natural gas. 
     
     
         19 . A method of removing acid compounds contained in a gaseous effluent wherein an acid compound absorption stage is carried out by contacting the gaseous effluent with an absorbent solution comprising water and a nitrogen compound likely to be obtained by a synthesis method as claimed in  4 . 
     
     
         20 . A method as claimed in  claim 10 , wherein the absorbent solution comprises between 10 wt. % and 90 wt. % of said nitrogen compound, and between 10 wt. % and 90 wt. % of water.