Process for separating olefins from saturated hydrocarbons

Abstract

This invention relates to a process for separating and isolating olefins from saturated hydrocarbons, and in particular, to a process for separating and isolating olefins from saturated hydrocarbons in a Fisher-Tropsch stream.

What we claim is:  
     
         1 . A process for separating olefins from saturated hydrocarbons in a feedstock, comprising: 
 a) contacting a feedstock comprising olefins and saturated hydrocarbons with a linear polyaromatic compound under conditions effective to form a reaction mixture comprising linear polyaromatic compound-olefin adducts and saturated hydrocarbons;    b) separating the linear polyaromatic compound-olefin adducts from the saturated hydrocarbons in the reaction mixture to form a saturated hydrocarbon stream and an adducted olefin stream;    c) dissociating the linear polyaromatic compound-olefin adducts to form linear polyaromatic compounds and an olefin composition;    whereby the olefin composition is enriched in the concentration of olefins over the concentration of olefins in the feedstock.    
     
     
         2 . The process of  claim 1 , wherein the feedstock is contacted with a linear polyaromatic compound at a temperature ranging from 150° to about 290° C.  
     
     
         3 . The process of  claim 2 , wherein the feedstock is contacted with linear polyaromatic compound at a temperature ranging from about 220° to about 265° C.  
     
     
         4 . The process of  claim 1 , wherein the molar ratio of olefins in the feedstock to linear polyaromatic compounds ranges from greater than 0.25:1 to 10:1.  
     
     
         5 . The process of  claim 1 , wherein the linear polyaromatic compound-olefin adduct is dissociated by heating the linear polyaromatic compound-olefin adduct to a temperature ranging from about 250° C. to 500° C.  
     
     
         6 . The process of  claim 5 , wherein the linear polyaromatic compound-olefin adduct is heated to a temperature ranging from about 300° C. to 350° C.  
     
     
         7 . The process of  claim 1 , wherein the linear polyaromatic compound formed in step c) is separated from the olefin composition by vacuum or flash distillation.  
     
     
         8 . The process of  claim 1 , wherein the separation in step b) is carried out by first cooling followed by filtration or centrifugation.  
     
     
         9 . The process of  claim 1 , wherein the feedstock comprises a stream derived from a Fisher-Tropsch process.  
     
     
         10 . The process of  claim 9 , wherein the feedstock comprises from 15 wt. % to 70 wt. % olefin, based on the weight of all ingredients in the feedstock.  
     
     
         11 . The process of  claim 10 , wherein the feedstock comprises from 15 wt. % to 60 wt. % linear alpha olefin, based on the weight of all ingredients in the feedstock.  
     
     
         12 . The process of  claim 11 , wherein the amount of all olefins in the feedstock other than linear alpha olefins ranges from 1 wt. % to 55 wt. %, based on the weight of all ingredients in the feedstock.  
     
     
         13 . The process of  claim 1 , wherein the amount of all olefins other than linear alpha olefins in the feedstock ranges from 5 wt. % to 45 wt. %, based on the weight of all ingredients in the feedstock.  
     
     
         14 . The process of  claim 10 , wherein the feedstock comprises paraffins in an amount ranging from 5 wt. % to 99 wt. % based on the weight of all ingredients in the feedstock.  
     
     
         15 . The process of  claim 15 , wherein the amount of paraffin ranges from 5 to 65 wt % based on the weight of all ingredients in the feedstock.  
     
     
         16 . The process of  claim 15 , wherein the amount of paraffin in the feedstock ranges from 65 wt. % to 99 wt. %.  
     
     
         17 . The process of  claim 1 , wherein the feedstock comprises oxygenates and aromatics collectively present in the feedstock in an amount ranging from 5 wt. % to 30 wt. %, based on the weight of all ingredients in the feedstock.  
     
     
         18 . The process of  claim 1 , wherein the feedstock has an average carbon number ranging from C 5 -C 20  and wherein the predominant olefin species in the feedstock is within the range of C 5 -C 20 , inclusive.  
     
     
         19 . The process of  claim 1 , wherein the total concentration of olefins and the concentration of linear alpha olefins are enriched in the olefin stream over the concentration of olefins and linear alpha olefins in the feedstock stream, and the concentration of saturated hydrocarbons are reduced in the olefin stream over the concentration of saturated hydrocarbons in the feedstock stream.  
     
     
         20 . The process of  claim 1 , wherein the saturated hydrocarbon stream in enriched in its concentration of saturated hydrocarbons over the concentration over the concentration of saturated hydrocarbons in the feedstock stream.  
     
     
         21 . The process of  claim 20 , wherein the saturated hydrocarbon stream comprises olefins, and the concentration of all olefins in the saturated hydrocarbon stream are reduced in one pass by at least 15% over the concentration of all olefins present in the feedstock.  
     
     
         22 . The process of  claim 21 , wherein the concentration of all olefins in the saturated hydrocarbon stream are reduced in one pass by at least 30%.  
     
     
         23 . The process of  claim 22 , wherein the concentration of all olefins in the saturated hydrocarbon stream are reduced in one pass by at least 40%.  
     
     
         24 . The process of  claim 20 , wherein the saturated hydrocarbon stream comprises linear alpha olefins, and wherein the concentration of linear alpha olefins in the saturated hydrocarbon stream are reduced in one pass by at least 30% over the concentration of linear alpha olefins present in the feedstock stream.  
     
     
         25 . The process of  claim 24 , wherein the concentration of linear alpha olefins in the saturated hydrocarbon stream are reduced in one pass by at least 40% over the concentration of linear alpha olefins present in the feedstock stream.  
     
     
         26 . The process of  claim 25 , wherein the concentration of linear alpha olefins in the saturated hydrocarbon stream are reduced in one pass by at least 50% over the concentration of linear alpha olefins present in the feedstock stream.  
     
     
         27 . The process of  claim 20 , wherein the concentration of saturated hydrocarbon in the saturated hydrocarbon stream is enriched by at least 20% over the concentration of saturated hydrocarbon in the feedstock stream.  
     
     
         28 . The process of  claim 1 , wherein the concentration of saturated hydrocarbons in the olefin composition is reduced in one pass by at least 80% over the concentration of saturated hydrocarbon in the feedstock.  
     
     
         29 . The process of  claim 28 , wherein the concentration of saturated hydrocarbons in the olefin composition is reduced in one pass by at least 90% over the concentration of saturated hydrocarbon in the feedstock.  
     
     
         30 . The process of  claim 29 , wherein the concentration of saturated hydrocarbons in the olefin composition is reduced in one pass by at least 95% over the concentration of saturated hydrocarbon in the feedstock.  
     
     
         31 . The process of  claim 1 , wherein the concentration of saturated hydrocarbons in the olefin composition is reduced in one pass by 100% over the concentration of saturated hydrocarbon in the feedstock.  
     
     
         32 . The process of  claim 1 , wherein the feedstock comprises branched olefins, and the concentration of branched olefins in the olefin composition is reduced over the concentration of branched olefins in the feedstock.  
     
     
         33 . The process of  claim 1 , wherein the feedstock comprises internal olefins, and the concentration of internal olefin in the olefin composition is enriched by 10% to 250% over the concentration of internal olefin present in the feedstock.  
     
     
         34 . The process of  claim 1 , wherein the feedstock comprises linear alpha olefins, and the concentration of linear alpha olefins in the olefin composition is enriched over the concentration of linear alpha olefins present in the feedstock stream.  
     
     
         35 . The process of  claim 34 , wherein the concentration of linear alpha olefins present in the olefin stream is enriched by at least 30% over the concentration of linear alpha olefins present in the feedstock composition.  
     
     
         36 . The process of  claim 35 , wherein the concentration of linear alpha olefins present in the olefin stream is enriched by at least 40% over the concentration of linear alpha olefins present in the feedstock composition.  
     
     
         37 . The process of  claim 36 , wherein the concentration of all olefins in the olefin stream is enriched by at least 60% over the concentration of all olefins in the feedstock.  
     
     
         38 . The process of  claim 1 , wherein the feedstock consists essentially of saturated hydrocarbons, oxygenates, aromatics, and olefins, and the concentration of olefins in the olefin composition ranges from 90% to 100%.  
     
     
         39 . The process of  claim 1 , wherein the average carbon number of the feedstock olefins ranges from 6 to 16, and the predominant olefin species in the feedstock is within said range, inclusive.  
     
     
         40 . A process for separating olefins from saturated hydrocarbons in a feedstock, comprising: 
 a) a feedstock having an average carbon number ranging from C 5 -C 20  and having a predominant olefin species within said range, said feedstock comprising olefins and saturated hydrocarbons, and contacting said feedstock with a linear polyaromatic compound under conditions effective to form a reaction mixture comprising linear polyaromatic compound-olefin adducts and saturated hydrocarbons;    b) separating the linear polyaromatic compound-olefin adducts from the saturated hydrocarbons in the reaction mixture to form a saturated hydrocarbon stream and an adducted olefin stream;    c) dissociating the linear polyaromatic compound-olefin adducts to form linear polyaromatic compounds and an olefin composition; and    d) separating the linear polyaromatic compounds formed in step c) from the olefin composition;    whereby the olefin composition is enriched in the concentration of olefins over the concentration of olefins in the feedstock, and the saturated hydrocarbon stream is enriched in the concentration of saturated hydrocarbons over the concentration of saturated hydrocarbon in the feedstock.    
     
     
         41 . The process of  claim 40 , wherein the feedstock comprises a Fisher-Tropsch stream.  
     
     
         42 . The process of  claim 41 , wherein the feedstock comprises from 15 wt. % to 60 wt. % linear alpha olefin, from 5 wt. % to 45 wt. % olefins other than linear alpha olefins, 5 wt. % to 99 wt. %. paraffins, and 15 wt. % to 30 wt. % oxygenates and aromatics.  
     
     
         43 . The process of  claim 42 , wherein the linear polyaromatic compound comprises anthracene or benzanthracene.  
     
     
         44 . The process of  claim 42 , wherein the feedstock comprises linear alpha olefins, and the concentration of linear alpha olefins in the olefin composition is enriched by at least 40% over the concentration of linear alpha olefins present in the feedstock stream, and the concentration of saturated hydrocarbons in the olefin composition is reduced by at least 90% over the concentration of saturated hydrocarbons present in the feedstock.  
     
     
         45 . A process for separating olefins from saturated hydrocarbons in a feedstock, comprising: 
 a) a Fisher-Tropsch feedstock having an average carbon number ranging from C 6 -C 16  and having a predominant olefin species within said range, said feedstock comprising linear alpha olefins, olefins other than linear alpha olefins, and saturated hydrocarbons, and contacting said feedstock with a linear polyaromatic compound comprising anthracene or benzanthracene under conditions effective to form a reaction mixture comprising linear polyaromatic compound-olefin adducts and saturated hydrocarbons;    b) separating the linear polyaromatic compound-olefin adducts from the saturated hydrocarbons in the reaction mixture by distillation to form a saturated hydrocarbon stream and an adducted olefin stream;    c) dissociating the linear polyaromatic compound-olefin adducts to form linear polyaromatic compounds and an olefin composition; and    d) separating the linear polyaromatic compounds formed in step c) from the olefin composition;    whereby the olefin composition is enriched in the concentration of olefins over the concentration of olefins in the feedstock, the saturated hydrocarbon stream is enriched in the concentration of saturated hydrocarbons over the concentration of saturated hydrocarbon in the feedstock, the concentration of linear alpha olefins in the olefin composition is enriched by at least 40% over the concentration of linear alpha olefins present in the feedstock stream, and the concentration of saturated hydrocarbons in the olefin composition is reduced by at least 90% over the concentration of saturated hydrocarbons present in the feedstock.    
     
     
         46 . A Fisher-Tropsch composition comprising odd and even numbered olefins, said composition having an average carbon number ranging from C 6  to C 18 , comprising: 
 a) at least two linear alpha olefin species having different carbon chain lengths;    b) the two most predominant linear alpha olefin species of said at least two linear alpha olefin species are each within the range of C 6  to C 18 , inclusive;    c) said two most predominant linear alpha olefin species are present in an amount of at least 20 wt % based on the weight of the olefins in the composition;    d) cumulatively, the total amount of linear alpha olefins present in the composition within said range, inclusive, is at least at least 40 wt. %, based on the weight of the olefins in the composition;    e) one or more odd numbered olefins within said range present in an amount of at least 10 wt. %, cumulative; and    f) a cumulative amount of aromatics, saturated hydrocarbons, and oxygenates of 5 wt. % or less, each based on the weight of the composition.    
     
     
         47 . The composition of  claim 46 , wherein the composition additionally comprises branched olefins in an amount of at least 5 wt. % based on the weight of the olefins in the composition.  
     
     
         48 . The composition of  claim 48 , wherein the composition additionally comprises branched olefins in an amount of at least 10 wt. %.  
     
     
         49 . The composition of  claim 46 , wherein the composition comprises internal olefins present in an amount ranging from 5 wt. % to 20 wt. %.  
     
     
         50 . The composition of  claim 46 , wherein the amount of said two most predominately linear alpha olefins is at least 30 wt. %  
     
     
         51 . The composition of  claim 46 , wherein the amount of odd numbered olefins is at least 20 wt. %, cumulative.  
     
     
         52 . The composition of  claim 46 , wherein one of said two most predominant linear alpha olefin species is an odd numbered linear alpha olefin.  
     
     
         53 . The composition of  claim 52 , wherein said total cumulative amount of linear alpha olefins is at least 60 wt. %.  
     
     
         54 . The composition of  claim 52 , wherein said total amount of aromatics, saturated hydrocarbons, and oxygenates is 2 wt. % or less.  
     
     
         55 . The composition of  claim 46 , wherein the carbon number range of the composition ranges from C 6  to C 12 , and the composition further comprises branched olefins in an amount of at least 10 wt. %.  
     
     
         56 . A Fisher-Tropsch composition having an average carbon number ranging from C 6  to C 18  comprising at least two linear alpha olefin species having different carbon chain lengths within said range, inclusive, at least 50 wt. % of linear alpha olefins, said composition comprising a most predominant olefin species represented by n carbon numbers, wherein the next most predominant olefin species has either n+1 or n−1 carbon numbers; and wherein said composition comprises 2 wt. % or less of saturated hydrocarbons.  
     
     
         57 . The composition of  claim 56 , wherein the composition comprises 1 wt. % or less of saturated hydrocarbons.  
     
     
         58 . The composition of  claim 56 , further comprising branched olefin present in an amount of at least 5 wt. %.  
     
     
         59 . The composition of  claim 56 , further comprising internal olefins present in an amount of at least 5 wt. %.