Systems and Methods for Producing N-Paraffins From Low Value Feedstocks

Abstract

Systems and methods for producing n-paraffins are provided. The method can include hydroprocessing at least a portion of a kerosene fraction recovered from a thermally cracked hydrocarbon product to produce a hydroprocessed kerosene product comprising n-paraffins. The n-paraffins can be separated from the hydroprocessed kerosene product to produce an n-paraffins product.

1 . A method for producing n-paraffins, comprising:
 hydroprocessing at least a portion of a kerosene fraction recovered from a thermally cracked hydrocarbon product to produce a hydroprocessed kerosene product comprising n-paraffins; and   separating the n-paraffins from the hydroprocessed kerosene product to produce an n-paraffins product.   
   
   
       2 . The method of  claim 1 , wherein the kerosene fraction is hydroprocessed in the presence of hydrogen and one or more catalysts at a temperature of from about 200° C. to about 420° C. and a pressure of from about 3,000 kPa to about 8,000 kPa. 
   
   
       3 . The method of  claim 1 , wherein the hydroprocessed kerosene fraction further comprises at least 1 ppmw nitrogen-containing compounds. 
   
   
       4 . The method of  claim 1 , wherein the hydroprocessed kerosene fraction has a bromine index of at least 10. 
   
   
       5 . The method of  claim 1 , wherein the hydroprocessed kerosene fraction further comprises at least 1 ppmw sulfur-containing compounds. 
   
   
       6 . The method of  claim 1 , wherein a kerosene fraction recovered from an atmospheric distillation unit is mixed with at least one of the thermally cracked hydrocarbon product and the hydroprocessed kerosene product. 
   
   
       7 . The method of  claim 1 , wherein separating the n-paraffins comprises an adsorption process, a solvent extraction process, a distillation process, or any combination thereof. 
   
   
       8 . The method of  claim 1 , wherein separating the n-paraffins comprises an adsorption process comprising:
 contacting the hydroprocessed kerosene product with a first adsorbent material at conditions sufficient to cause the first adsorbent material to adsorb at least a portion of the n-paraffins;   contacting the adsorbed n-paraffins with a displacing medium at conditions sufficient to cause at least a portion of the adsorbed n-paraffins to be desorbed; and   recovering the desorbed n-paraffins as the n-paraffins product.   
   
   
       9 . The method of  claim 8 , wherein the recovered n-paraffins comprise one or more impurities, and wherein the adsorption process further comprises contacting the recovered n-paraffins with a second adsorbent material at conditions sufficient to cause the second adsorbent material to adsorb at least a portion of the one or more impurities to produce an n-paraffins product having a reduced concentration of impurities relative to the recovered n-paraffins. 
   
   
       10 . The method of  claim 9 , wherein the impurities comprise aromatic hydrocarbons, and wherein the n-paraffins product has a concentration of less than about 100 ppmw aromatics. 
   
   
       11 . The method of  claim 1 , further comprising:
 introducing an atmospheric distillation tower bottoms, a vacuum distillation tower bottoms, or a combination thereof to a thermal cracker to produce the thermally cracked hydrocarbon product; and   separating the thermally cracked hydrocarbon product to produce a light hydrocarbon fraction, a heavy hydrocarbon fraction, and the kerosene fraction.   
   
   
       12 . A method for producing n-paraffins, comprising:
 thermally cracking a hydrocarbon feed to produce a thermally cracked hydrocarbon mixture;   selectively separating a kerosene fraction from the hydrocarbon mixture;   hydroprocessing at least a portion of the kerosene fraction to produce a hydroprocessed kerosene comprising n-paraffins, less than about 500 ppmw sulfur-containing compounds, and less than about 200 ppmw nitrogen-containing compounds; and   separating the n-paraffins from the hydroprocessed kerosene product to produce an n-paraffins product.   
   
   
       13 . The method of  claim 12 , wherein the hydroprocessed kerosene comprises at least 1 ppmw nitrogen-containing compounds and at least 1 ppmw sulfur-containing compounds. 
   
   
       14 . The method of  claim 12 , wherein the kerosene fraction has a bromine index of at least 10. 
   
   
       15 . The method of  claim 12 , wherein the hydrocarbon feed comprises atmospheric distillation tower bottoms, vacuum distillation tower bottoms, or a combination thereof. 
   
   
       16 . The method of  claim 12 , wherein separating the n-paraffins comprises an adsorption process, a solvent extraction process, a distillation process, or any combination thereof. 
   
   
       17 . A system for producing n-paraffins, comprising:
 a hydroprocessing unit for hydroprocessing at least a portion of a kerosene fraction recovered from a thermally cracked hydrocarbon product to produce a hydroprocessed kerosene product comprising n-paraffins; and   a first separation unit for separating the n-paraffins from the hydroprocessed kerosene product to produce an n-paraffins product.   
   
   
       18 . The system of  claim 17 , further comprising a thermal cracking unit for thermally cracking a hydrocarbon feed to produce the thermally cracked hydrocarbon product; and a second separation unit for separating the thermally cracked hydrocarbon product to produce a light hydrocarbon fraction, a heavy hydrocarbon fraction, and the kerosene fraction. 
   
   
       19 . The system of  claim 17 , wherein the first separation unit comprises one or more adsorption/desorption units. 
   
   
       20 . The system of  claim 17 , further comprising a third separation unit for purifying the n-paraffins product to produce an n-paraffins product comprising about 99 wt % or more n-paraffins.