Process for separating internal and alpha olefins from saturated compounds

Abstract

This invention relates to a process for separating and isolating saturated hydrocarbons from olefins, and in particular, to a process for separating and isolating saturated hydrocarbons from olefins in a Fisher-Tropsch stream. There is provided a process for separating olefins from saturated hydrocarbons in a feedstock, comprising: a) contacting a feedstock comprising olefins and saturated hydrocarbons, such as paraffins, 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 optionally d) separating the linear polyaromatic compound 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 saturated hydrocarbons over the concentration of saturated hydrocarbons in the feedstock.

What we claim is:  
     
         1 . A process for treating a feedstock composition comprising linear alpha olefins, internal olefins, and saturated hydrocarbons, comprising: 
 a) contacting the feedstock composition with a linear polyaromatic compound in a first reaction zone under conditions effective to form a reaction mixture comprising linear polyaromatic compound-olefin adducts and saturated hydrocarbons;    b) separating the first linear polyaromatic compound-olefin adducts from the saturated hydrocarbons in the reaction mixture to form an adducted olefin stream and a first saturated hydrocarbon stream enriched in the concentration of saturated hydrocarbons over the concentration of saturated hydrocarbons in the feedstock composition;    si) contacting the saturated hydrocarbon stream with a polyaromatic compound in a second reaction zone under conditions effective to form a reaction mixture comprising second linear polyaromatic compound-olefin adducts and saturated hydrocarbons;    sii) separating the second linear polyaromatic compound-olefin adducts from the saturated hydrocarbons in the reaction mixture to form a second adducted olefin stream comprising the second linear polyaromatic compound-olefin adducts, and a second saturated hydrocarbon stream enriched in the concentration of saturated hydrocarbons over the concentration of saturated hydrocarbons in the first saturated hydrocarbon stream;    siii) dissociating the second linear polyaromatic compound-olefin adducts to form linear polyaromatic compounds and a second olefin composition comprising alpha olefins and internal olefins enriched in the concentration of alpha olefins and internal olefins over each of their concentrations in the first saturated, hydrocarbon stream.    
     
     
         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 240° 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 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 200° 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 oi) is separated from the olefin composition by vacuum or flash distillation.  
     
     
         8 . The process of  claim 1 , wherein the feedstock comprises a stream derived from a Fisher-Tropsch process.  
     
     
         9 . The process of  claim 8 , wherein the feedstock comprises from 15 wt. % to 70 wt. % olefin, based on the weight of all ingredients in the feedstock.  
     
     
         10 . The process of  claim 9 , wherein the feedstock comprises from 15 wt. % to 65 wt. % linear alpha olefin, based on the weight of all ingredients in the feedstock.  
     
     
         11 . The process of  claim 10 , wherein the feedstock comprises from 5 wt. % to 65 wt. %. paraffin, 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 5 wt. % to 45 wt. %, based on the weight of all ingredients in the feedstock.  
     
     
         13 . The process of  claim 1 , wherein the amount of paraffin ranges from 65 to 99 wt. % of all ingredients in the feedstock.  
     
     
         14 . The process of  claim 1 , wherein the average carbon number of the feedstock ranges from C 5 -C 20  and wherein the predominant olefin species in the feedstock is within said range, inclusive.  
     
     
         15 . The process of  claim 14 , wherein the average carbon number of the feedstock ranges from C 6 -C 18  and wherein the predominant olefin species in the feedstock is within said range, inclusive.  
     
     
         16 . The process of  claim 1 , wherein the linear polyaromatic compound has a greater selectivity for linear alpha olefin compounds over other olefins in an amount of greater than 2:1 by mole.  
     
     
         17 . The process of  claim 1 , wherein the linear polyaromatic compound comprises substituted or unsubstituted anthracene and/or benzanthracene.  
     
     
         18 . The process of  claim 1 , wherein the linear polyaromatic compound comprises unsubstituted anthracene.  
     
     
         19 . The process of  claim 1 , wherein the rate of olefin recovery from the feedstock ranges from 0.10 to 0.4 moles/unit time based on a feedstock rate of 1.0 moles/unit time.  
     
     
         20 . The process of  claim 1 , wherein the recovery of olefins from the feedstock ranges from 40 to 100%.  
     
     
         21 . The process of  claim 1 , wherein the first saturated hydrocarbon stream is enriched in saturated hydrocarbons by at least 10%.  
     
     
         22 . The process of  claim 1 , wherein the concentration of linear alpha olefins in the first saturated hydrocarbon stream are reduced in one pass by at least 40% over the concentration of linear alpha olefins present in the feedstock stream.  
     
     
         23 . The process of  claim 1 , wherein the feedstock comprises a single carbon cut composition.  
     
     
         24 . The process of  claim 1 , wherein the feedstock comprises a single cut C 6 , C 8 , C 9 , C 10 , C 11 , C 12 , C 14 , or C 16 , composition.  
     
     
         25 . The process of  claim 1 , wherein the concentration of saturated hydrocarbons in the second saturated hydrocarbon stream is enriched by at least 5%.  
     
     
         26 . The process of  claim 25 , wherein the concentration of internal olefins in the second saturated hydrocarbon stream is reduced by at least 20%.  
     
     
         27 . The process of  claim 1 , wherein the concentration of internal olefins in the second olefin composition is enriched by at least 50% over the concentration of internal olefins in the first saturated hydrocarbon stream.  
     
     
         28 . The process of  claim 27 , wherein the concentration of linear alpha olefins present in the second olefin composition is enriched by at least 100% over the concentration of linear alpha olefins present in the first saturated hydrocarbon stream.  
     
     
         29 . A process for contacting a linear polyaromatic compound with a feedstock composition comprising linear alpha olefins, internal olefins, and saturated hydrocarbons, separating the olefins from the saturated hydrocarbons in the feedstock composition to form an olefin composition and a saturated hydrocarbon stream, subsequently contacting a linear polyaromatic compound with the saturated hydrocarbon stream comprising linear alpha olefins and internal olefins, and separating the internal olefins and linear alpha olefins from the saturated hydrocarbons in the saturated hydrocarbon stream to form a second saturated hydrocarbon stream and a second olefin composition, whereby the concentration of each of internal olefins and linear alpha olefins in the second olefin composition is enriched over the concentration of each of internal olefins and linear alpha olefins in the feedstock and in the olefin composition.  
     
     
         30 . The process of  claim 29 , wherein the average carbon number of the feedstock ranges from C 5 -C 20  and wherein the predominant olefin species in the feedstock is within said range, inclusive.  
     
     
         31 . The process of  claim 30 , wherein the average carbon number of the feedstock ranges from C 6 -C 18  and wherein the predominant olefin species in the feedstock is within said range, inclusive.  
     
     
         32 . The process of  claim 31 , wherein the linear polyaromatic compound comprises substituted or unsubstituted anthracene or benzanthranene.  
     
     
         33 . The process of  claim 29 , wherein the feed comprises a Fisher-Tropsch stream.  
     
     
         34 . The process of  claim 33 , wherein the feedstock comprises a single carbon cut composition.  
     
     
         35 . A composition comprising odd and even numbered olefins, said composition having an average carbon number ranging from C 5  to C 20 , comprising: 
 a) at least two linear alpha olefin species having different carbon chain lengths;    b) the two most predominant (on a mole basis) linear alpha olefin species of the at least two linear alpha olefin species are each within the range of C 5  to C 20 ;    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 40 wt. %, based on the weight of the olefins in the composition;    e) one or more odd numbered olefins within the range are present in an amount of at least 10 wt. %, cumulative; and    f) a cumulative amount of aromatics, saturated hydrocarbons, and oxygenates of 10 wt. % or less, based on the weight of the composition.    
     
     
         36 . The composition of  claim 35 , wherein the amount of said two most predominately linear alpha olefins is at least 30 wt. %.  
     
     
         37 . The composition of  claim 35 , wherein the amount of odd numbered olefins is at least 20 wt. %, cumulative.  
     
     
         38 . The composition of  claim 35 , wherein one of said two most predominant linear alpha olefin species is an odd numbered linear alpha olefin.  
     
     
         39 . The composition of  claim 35 , wherein said total cumulative amount of linear alpha olefins is at least 70 wt. %.  
     
     
         40 . The composition of  claim 35 , wherein the average carbon number of the composition ranges from C 6  to C 18 .  
     
     
         41 . The composition of  claim 35 , wherein the cumulative amount of linear alpha olefins is at least 70 wt. %, and the amount of odd numbered olefins is at least 30 wt. %.  
     
     
         42 . A 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, where the composition has 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; wherein said composition comprises 10 wt. % or less of saturated hydrocarbons.