Process for separating oxygen-containing compounds contained in a hydrocarbon feed, employing an ionic liquid

Abstract

In order to separate oxygen-containing compounds contained in a hydrocarbon feed containing 1 to 100 carbon atoms and having any distribution of chemical categories, a process is carried out in which: said hydrocarbon feed is brought into contact with an extraction phase which contains at least one non-aqueous ionic liquid with general formula Q + A − , the proportion of ionic liquid in the extraction phase representing at least 25% by weight; the extraction effluent is separated into said extraction phase which contains at least one ionic liquid and at least all or a portion of the oxygen-containing compounds initially present in the hydrocarbon feed, and into the hydrocarbon feed which is depleted in oxygen-containing compounds.

1 . A process for separating oxygen-containing compounds contained in a hydrocarbon feed containing 1 to 100 carbon atoms, and with any chemical category distribution, said process being characterized in that: 
 said hydrocarbon feed containing oxygen-containing compounds (Cox) is brought into contact in a contacter (A) with an extraction phase (Pex) which contains at least one non-aqueous ionic liquid with general formula Q + A − , the proportion of ionic liquid in the extraction phase representing at least 25% by weight;    the effluent from the unit (A) is separated in a decanting unit (B) into said extraction phase which contains at least one ionic liquid and at least all or a portion of the oxygen-containing compounds initially present in the hydrocarbon feed, and into the hydrocarbon feed depleted in oxygen-containing compounds (Cpur).    
   
   
       2 . A process according to  claim 1 , in which the effluent from the decanting unit (B) is introduced into the separation unit (C) from which the extraction phase containing at least one ionic liquid and a minor portion of the oxygen-containing compounds, and the major portion of the oxygen-containing compounds (Cext) are separated.  
   
   
       3 . A process according to  claim 1 , in which the extraction phase from the separation unit (C) is reintroduced into the contacter (A) with the hydrocarbon feed to be treated.  
   
   
       4 . A process according to  claim 1 , characterized in that in the non-aqueous ionic liquid with formula Q + A − , the anions A −  are selected from halides, nitrate, sulphate, alkylsulphates, phosphate, alkylphosphates, acetate, halogenoacetates, tetrafluoroborate, tetrachloroborate, hexafluorophosphate. trifluoro-tris-(pentafluoroethyl)phosphate, hexafluoroantimonate, fluorosulphonate, alkyl sulphonates, perfluoroalkylsulphonates, bis(perfluoroalkylsulphonyl)amides, tris-trifluoromethylsulphonyl methylide with formula C(CF 3 SO 2 ) 3   − , bis-trifluoromethylsulphonyl methylide with formula HC(CF 3 SO 2 ) 3   − , arenesulphonates, optionally substituted with halogen or halogenalkyl groups, the tetraphenylborate anion and tetraphenylhorate anions the aromatic rings of which are substituted, tetra-(trifluoroacetoxy)-borate, bis-(oxalato)-borate, dicyanamide, tricyanomethylide, and the tetrachloroaluminate anion.  
   
   
       5 . A process according to  claim 1 , characterized in that cation Q +  is selected from quaternary phosphonium, ammonium, guanidinium and/or sulphonium cations.  
   
   
       6 . A process according to  claim 5 , characterized in that quaternary ammonium and/or phosphonium cation Q +  has one of general formulae NR 1 R 2 R 3 R 4+  and PR 1 R 2 R 3 R 4+  or one of general formulae R 1 R 2 N═CR 3 R 4+  and R 1 R 2 P═C R 3 R 4+  in which R 1 , R 2 , R 3  and R 4 , which may be identical or different, each represent hydrogen of a hydrocarbyl residue containing 1 to 30 carbon atoms.  
   
   
       7 . A process according to  claim 6 , characterized in that R 1 , R 2 , R 3  and R 4  each represent an alkyl group, a saturated or non saturated group, a cycloalkyl or aromatic group or an aryl or aralkyl group, which may be substituted.  
   
   
       8 . A process according to  claim 6 , characterized in that at least one of groups R 1 , R 2 , R 3  and R 4  carries one or more functions selected from the following: —CO 2 R, —C(O)R, —OR, —C(O)NRR′, —C(O)N(R)NR′R″, —NRR′, —SR, —S(O)R, -S(O) 2 R, —SO 3 R, —CN, —N(R)P(O)R′R′, in which R, R′ and R″, which may be identical or different, each represent hydrogen or hydrocarbyl radicals containing 1 to 30 carbon atoms.  
   
   
       9 . A process according to  claim 5 , characterized in that the ammonium and/or phosphonium ion is derived from a nitrogen-containing and/or phosphorus-containing heterocycles comprising 1, 2 or 3 nitrogen and/or phosphorus atoms, with general formulae  
     
       
         
         
             
             
         
       
     
     in which the cycles are constituted by 4 to 10 atoms, preferably 5 to 6 atoms, and R 1  and R 2 , which may be identical or different, are as defined above.  
   
   
       10 . A process according to  claim 5 , characterized in that the quaternary ammonium or phosphonium cation has one of the following formulae:  
       R 1 R 2+ N═CR 3 —R 7 —R 3 C═N + R 1 R 2  and R 1 R 2+ P═CR 3 —R 7 —R 3 C═P + R 1 R 2    
     in which R 1 , R 2  and R 3 , which may be identical or different, are as defined above and R 7  represents an alkylene or phenylene residue.  
   
   
       11 . A process according to  claim 6 , characterized in that the groups R 1 , R 2 , R 3  and R 4  represent methyl, ethyl, propyl, isopropyl, butyl, secondary butyl, tertiary butyl, amyl, phenyl, benzyl or 2-hydroxyethyl radicals and R 7  represents a methylene, ethylene, propylene or phenylene group.  
   
   
       12 . A process according to  claim 5 , characterized in that the quaternary ammonium and/or phosphonium cation Q +  is selected from the group formed by N-butylpyridinium, N-ethylpyridinium, pyridinium, 3-ethyl-1-methylimidazolium, 3-butyl-1-methylimidazolium, 3-hexyl-1-methylimidazolium, 3-butyl-1,2-dimethylimidazolium, the 1-(2-hydroxyethyl)-3-methylinidazolium cation, the 1-(2-carboxyethyl)-3-methylimidazolium cation, diethylpyrazolium, N-butyl-N-methylpyrrolidinium, N-butyl-N-methylmorpholinium, trimethylphenylammonium, tetrabutylphosphonium and tributyl-tetradecylphosphonium.  
   
   
       13 . A process according to  claim 5 , characterized in that the quaternary sulphonium and/or quaternary guanidinium cations have one of the following general formulae:  
       SR 1 R 2 R 3+  or C(NR 1 R 2 )(NR 3 R 4 )(NR 5 R 6 ) +   
     in which R 1 , R 2 , R 3 , R 4 , R 5  and R 6 , which may be identical or different, each representing hydrogen or a hydrocarbyl residue containing 1 to 30 carbon atoms.  
   
   
       14 . A process according to  claim 13 , characterized in that R 1 , R 2 , R 3 , R 4 , R 5  and R 6  each represent an alkyl group, a saturated or non saturated group, a cycloalkyl or aromatic group or an aryl or aralkyl group, which may be substituted.  
   
   
       15 . A process according to  claim 13 , characterized in that at least one of groups R 1 , R 2 , R 3  and R 4  carries hydrocarbyl radicals carrying one or more functions selected from the following: —CO 2 R, —C(O)R, —OR, —C(O)NRR′, —C(O)N(R)NR′R″, —NR′R″, —SR, —S(O)R, —S(O) 2 R, —SO 3 R, —CN, —N(R)P(O)R′R′, —PRR′, —P(O)RR′, —P(OR)(OR′), P(O)(OR)(OR′), in which R, R′ and R″, which may be identical or different, each represent hydrogen or hydrocarbyl radicals containing 1 to 30 carbon atoms.  
   
   
       16 . A process according to  claim 1 , characterized in that the non-aqueous ionic liquid is 3-butyl-1-methylimidazolium bis(trifluoromethylsulphonyl)amide, 3-butyl-1,2-dimethylimidazolium bis(trifluoromethylsulphonyl)amide, N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulphonyl)amide, 3-butyl-1-methylimidazolium tetrafluoroborate, 3-butyl-1,2-dimethylimidazolium tetrafluoroborate, 3-ethyl-1-methylimidazolium tetrafluoroborate, 3-butyl-1-methylimidazolium hexafluoroantimonate, 3-butyl-1-methylimidazolium trifluoroacetate, 3-ethyl-1-methylimidazolium triflate, 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethylsulphonyl)amide, 1-(2-carboxyethyl)-3-methylimidazolium bis(trifluoromethylsulphonyl)amide, and N-butyl-N-methylmorpholinium bis(trifluoromethylsulphonyl)amide.  
   
   
       17 . A process for separating oxygen-containing compounds contained in a hydrocarbon feed according to  claim 1 , in which the contacter (A) and the decanting unit (B) are combined in a single piece of equipment.  
   
   
       18 . A process according to  claim 1  comprising separating oxygen-containing compounds contained in a hydrocarbon cut composed mainly of olefins and paraffins.  
   
   
       19 . A process according to  claim 18  comprising separating oxygen-containing compounds contained in a hydrocarbon cut containing 0 to 50% by weight of olefins and 50% to 100% by weight of paraffins.  
   
   
       20 . A process according to  claim 1  comprising separating oxygen-containing compounds contained in Fischer-Tropsch synthesis effulents, said oxygen-containing compounds containing 1 to 50 carbon atoms.