Hydrotreating of fischer-tropsch derived feeds prior to oligomerization using an ionic liquid catalyst

Abstract

A process for oligomerizing a Fischer-Tropsch derived feed containing oxygenates which comprises (a) reducing significantly the oxygenates present in the Fischer-Tropsch derived feed by contacting said feed with a hydrotreating catalyst under hydrotreating conditions in a hydrotreating zone and recovering from the hydrotreating zone a Fischer-Tropsch derived hydrotreated feed which contains a significantly reduced amount of oxygenates as compared to the Fischer-Tropsch derived feed and also a significant amount of paraffins; (b) pyrolyzing the Fischer-Tropsch derived hydrotreated feed in a thermal cracking zone under thermal cracking conditions pre-selected to crack the paraffin molecules to form olefins and collecting an olefin-enriched Fischer-Tropsch feed from the thermal cracking zone; (c) contacting the olefin-enriched Fischer-Tropsch feed with a Lewis acid ionic liquid catalyst in an oligomerization zone under oligomerization reaction conditions; and (d) recovering from the oligomerization zone a Fischer-Tropsch derived product having molecules characterized by a higher average molecular weight and increased branching as compared to the Fischer-Tropsch derived feed.

1 . A process for oligomerizing a Fischer-Tropsch derived C 5+  feed containing oxygenates to produce a Fischer-Tropsch product comprising diesel, said process comprising: 
 (a) reducing significantly the oxygenates present in the Fischer-Tropsch derived C 5+  feed by contacting said feed in a hydrotreating zone with a hydrotreating catalyst under hydrotreating conditions wherein the cracking conversion is 20 percent or less and recovering from the hydrotreating zone a Fischer-Tropsch derived hydrotreated C 5+  feed which contains a significantly reduced amount of oxygenates as compared to the Fischer-Tropsch derived C 5+  feed and also a significant amount of paraffins;    (b) pyrolyzing the Fischer-Tropsch derived hydrotreated C 5+  feed in a thermal cracking zone under thermal cracking conditions pre-selected to crack the paraffin molecules to form olefins and collecting an olefin-enriched Fischer-Tropsch feed from the thermal cracking zone;    (c) contacting the olefin-enriched Fischer-Tropsch feed with a Lewis acid ionic liquid catalyst in an oligomerization zone under oligomerization reaction conditions; and    (d) recovering from the oligomerization zone a Fischer-Tropsch derived product comprising diesel and having molecules characterized by increased branching as compared to the Fischer-Tropsch derived C 5+  feed.    
     
     
         2 . The process of  claim 1  wherein the Fischer-Tropsch derived hydrotreated C 5+  feed is substantially free of oxygenates.  
     
     
         3 . The process of  claim 2  wherein the Fischer-Tropsch derived hydrotreated C 5+  feed contains less than 200 ppmw elemental oxygen.  
     
     
         4 . The process of  claim 3  wherein the Fischer-Tropsch derived hydrotreated C 5+  feed contains less than 100 ppmw elemental oxygen.  
     
     
         5 . The process of  claim 1  wherein the hydrotreating catalyst is a non-acidic hydrotreating catalyst.  
     
     
         6 . The process of  claim 5  wherein the hydrotreating catalyst contains the metal nickel and molybdenum.  
     
     
         7 . The process of  claim 1  wherein the hydrotreating conditions in the hydrotreating zone include a temperature of between about 400 degrees F. and about 800 degrees F., an LHSV of between about 0.5 and about 5.0, and a total pressure between about 200 psig and about 2,000 psig.  
     
     
         8 . The process of  claim 7  wherein the temperature in the hydrotreating zone is less than about 675 degrees F.  
     
     
         9 . The process of  claim 7  wherein the LHSV is between about 1 and about 4.0.  
     
     
         10 . The process of  claim 1  wherein the temperature in the thermal cracking zone is within the range of from about 950 degrees F. and about 1,600 degrees F.  
     
     
         11 . The process of  claim 1  wherein the pressure in the thermal cracking zone is within the range of from about to about 0 atmospheres and about 5 atmospheres.  
     
     
         12 . The process of  claim 11  wherein the pressure in the thermal cracking zone is within the range of from about to about 0 atmospheres and about 2 atmospheres.  
     
     
         13 . The process of  claim 1  wherein the cracking conversion in the thermal cracking zone is greater than about 10 weight percent of the paraffins present.  
     
     
         14 . The process of  claim 1  wherein the ionic liquid oligomerization catalyst comprises a first component and a second component, said first component comprising a compound selected from the group consisting of aluminum halide, alkyl aluminum halide, gallium halide, and alkyl gallium halide, and said second component is a quaternary ammonium, or quaternary phosphonium salt.  
     
     
         15 . The process of  claim 14  wherein the ratio of the first component to the second component is within the range of from about 1:1 to about 2:1.  
     
     
         16 . The process of  claim 14  wherein said first component is aluminum halide or alkyl aluminum halide.  
     
     
         17 . The process of  claim 14  wherein said second component is selected from one or more of hydrocarbyl substituted ammonium halide, hydrocarbyl substituted imidazolium halide, hydrocarbyl substituted pyridinium halide, alkylene substituted pyridinium dihalide, or hydrocarbyl substituted phosphonium halide.  
     
     
         18 . The process of  claim 1  including the additional step of dewaxing the Fischer-Tropsch derived product recovered from the oligomerization zone and collecting a dewaxed Fischer-Tropsch product having improved cold flow properties relative to the Fischer-Tropsch derived product recovered from the oligomerization zone.  
     
     
         19 . The process of  claim 18  wherein the Fischer-Tropsch derived product is catalytically dewaxed.  
     
     
         20 . The process of  claim 18  including the additional step of hydrofinishing the dewaxed Fischer-Tropsch product.  
     
     
         21 . The process of  claim 1  wherein the Fischer-Tropsch derived product includes lubricant base oil.  
     
     
         22 . (canceled)  
     
     
         23 . A process for producing Fischer-Tropsch derived lubricant base oil which comprises: 
 (a) recovering from a Fischer-Tropsch plant a wax fraction;    (b) reducing significantly the oxygenates present in the Fischer-Tropsch wax fraction by contacting said wax fraction in a hydrotreating zone with a hydrotreating catalyst under hydrotreating conditions wherein the cracking conversion is 20 percent or less and recovering from the hydrotreating zone a hydrotreated Fischer-Tropsch derived wax feed which contains a significantly reduced amount of oxygenates as compared to the Fischer-Tropsch derived wax fraction and also a significant amount of paraffins;    (c) pyrolyzing the hydrotreated Fischer-Tropsch derived wax feed in a thermal cracking zone under thermal cracking conditions pre-selected to crack the paraffin molecules to form olefins and collecting an olefin-enriched Fischer-Tropsch feed from the thermal cracking zone;    (d) contacting the olefin-enriched Fischer-Tropsch feed with a Lewis acid ionic liquid catalyst in an oligomerization zone under oligomerization reaction conditions;    (e) recovering from the oligomerization zone a Fischer-Tropsch derived oligomerization effluent having molecules characterized by a higher average molecular weight and increased branching as compared to the Fischer-Tropsch derived feed;    (f) catalytically dewaxing the Fischer-Tropsch derived oligomerization effluent by contacting the Fischer-Tropsch derived oligomerization effluent with a dewaxing catalyst under catalytic conditions in a dewaxing zone and collecting a dewaxed Fischer-Tropsch product from the dewaxing zone having improved cold flow properties relative to the Fischer-Tropsch derived oligomerization effluent;    (g) hydrofinishing the dewaxed Fischer-Tropsch product in a hydrofinishing zone under hydrofinishing conditions in the presence of a hydrofinishing catalyst; and    (h) collecting a Fischer-Tropsch derived lubricant base oil from the hydrofinishing zone.    
     
     
         24 . The process of  claim 23  wherein the oxygenates in the hydrotreated Fischer-Tropsch derived wax feed recovered from the hydrotreating zone is substantially oxygenate free.  
     
     
         25 . The process of  claim 24  wherein the hydrotreated Fischer-Tropsch derived wax feed recovered from the hydrotreating zone contains less than 200 ppmw elemental oxygen.  
     
     
         26 . A process for producing Fischer-Tropsch derived lubricant base oil which comprises: 
 (a) recovering from a Fischer-Tropsch plant a condensate fraction;    (b) removing substantially all of the oxygenates present in the Fischer-Tropsch condensate fraction by contacting said condensate fraction in a hydrotreating zone with a hydrotreating catalyst under hydrotreating conditions wherein the cracking conversion is 20 percent or less and recovering from the hydrotreating zone a substantially oxygenate-free Fischer-Tropsch derived condensate feed which also contains a significant amount of paraffins;    (c) pyrolyzing the substantially oxygenate-free Fischer-Tropsch derived condensate feed in a thermal cracking zone under thermal cracking conditions pre-selected to crack the paraffin molecules to form olefins and collecting an olefin-enriched Fischer-Tropsch feed from the thermal cracking zone;    (d) contacting the olefin-enriched Fischer-Tropsch feed with a Lewis acid ionic liquid catalyst in an oligomerization zone under oligomerization reaction conditions;    (e) recovering from the oligomerization zone a Fischer-Tropsch derived oligomerization effluent having molecules characterized by a higher average molecular weight and increased branching as compared to the Fischer-Tropsch derived feed;    (f) catalytically dewaxing the Fischer-Tropsch derived oligomerization effluent by contacting the Fischer-Tropsch derived oligomerization effluent with a dewaxing catalyst under catalytic conditions in a dewaxing zone and collecting a dewaxed Fischer-Tropsch product from the dewaxing zone having improved cold flow properties relative to the Fischer-Tropsch derived oligomerization effluent;    (g) hydrofinishing the dewaxed Fischer-Tropsch product in a hydrofinishing zone under hydrofinshing conditions in the presence of a hydrofinishing catalyst; and    (h) collecting a Fischer-Tropsch derived lubricant base oil from the hydrofinishing zone.    
     
     
         27 . The process of  claim 26  wherein the substantially oxygenate-free Fischer-Tropsch derived condensate feed recovered from the hydrotreating zone contains less than 200 ppmw elemental oxygen.  
     
     
         28 . The process of  claim 27  wherein the substantially oxygenate-free Fischer-Tropsch derived condensate feed recovered from the hydrotreating zone contains less than 100 ppmw elemental oxygen.  
     
     
         29 . The process of  claim 26  wherein a diesel product is also collected from the hydrofinishing zone.