Process for increasing the concentration of normal hydrocarbons in a stream

Abstract

A process increases the concentration of normal paraffins in a feed stream comprising separating a naphtha feed stream into a normal paraffin rich stream and a non-normal paraffin rich stream. The non-normal paraffin rich stream is isomerized over a first isomerization catalyst to convert non-normal paraffins to normal paraffins and produce a first isomerization effluent stream. An iso-C4 stream is separated from the first isomerization effluent stream and isomerized over a second isomerization catalyst to convert iso-C4 hydrocarbons to normal C4 hydrocarbons and produce a second isomerization effluent stream. The normal paraffin rich stream, the normal paraffins in the first isomerization effluent stream and/or the second isomerization effluent stream may be fed to a steam cracker.

1 . A process for increasing the concentration of normal paraffins in a feed stream comprising:
 separating a naphtha feed stream into a normal paraffin rich stream and a non-normal paraffin rich stream;   isomerizing the non-normal paraffin rich stream over a first isomerization catalyst to convert non-normal paraffins to normal paraffins and produce a first isomerization effluent stream;   separating an iso-C4 stream from said first isomerization effluent stream;   isomerizing said iso-C4 stream over a second isomerization catalyst to convert iso-C4 hydrocarbons to normal C4 hydrocarbons and produce a second isomerization effluent stream; and   feeding said second isomerization effluent stream to a steam cracker.   
     
     
         2 . The process of  claim 1  further comprising separating a C4 stream from said first isomerization effluent stream and separating said C4 stream into said iso-C4 stream and a normal C4 stream. 
     
     
         3 . The process of  claim 2  further comprising feeding said normal C4 stream to said steam cracker. 
     
     
         4 . The process of  claim 2  further comprising feeding said normal C4 stream to the step of separating a normal paraffins stream from non-normal paraffins stream and desorbing normal paraffins from an adsorbent. 
     
     
         5 . The process of  claim 2  further comprising feeding said normal-C4 stream and said desorbed normal paraffins to a steam cracker together. 
     
     
         6 . The process of  claim 2  further comprising feeding said second isomerization effluent stream to the step of separating said C4 stream into an iso-C4 stream and a normal C4 stream. 
     
     
         7 . The process of  claim 1  further comprising: separating said first isomerization effluent stream to produce a C3 stream and further converting said C3 stream into an olefinic stream. 
     
     
         8 . The process of  claim 1  further comprising separating a C5 and C6 paraffins stream from said first isomerization effluent stream and recycling the C5 and C6 paraffins stream to the step of separating the naphtha feed stream into the normal paraffin rich stream and the non-normal paraffin rich stream. 
     
     
         9 . The process of  claim 1  wherein the step of separating the naphtha feed stream into the normal paraffins stream from the non-normal paraffins stream comprises extracting said normal paraffins by use of an adsorbent. 
     
     
         10 . The process of  claim 1  further comprising separating cyclic hydrocarbons from said non-normal paraffin stream before isomerizing the non-normal paraffins stream. 
     
     
         11 . A process for increasing the concentration of normal paraffins in a feed stream comprising:
 separating a naphtha feed stream into a normal paraffin rich stream and a non-normal paraffin rich stream;   separating the non-normal paraffin rich stream to provide an iso-C6 paraffin rich stream and C6 cyclics rich stream; and   isomerizing the iso-C6 paraffin rich stream over a first isomerization catalyst to convert non-normal paraffins to normal paraffins and produce an isomerization effluent stream.   
     
     
         12 . The process of  claim 11  further comprising separating a C4 paraffin rich stream from said first isomerization effluent stream and separating said C4 paraffin rich stream into said iso-C4 paraffin rich stream and a normal C4 paraffin rich stream;
 separating an iso-C4 paraffin rich stream from said first isomerization effluent stream; 
 isomerizing said iso-C4 paraffin stream over a second isomerization catalyst to convert iso-C4 paraffins to normal C4 paraffins and produce a second isomerization effluent stream; and 
 feeding said second isomerization effluent stream to a steam cracker. 
 
     
     
         13 . The process of  claim 11  further comprising separating a C5 and C6 paraffin stream from said first isomerization effluent stream and recycling the C5 and C6 paraffin stream to the step of separating the naphtha feed stream into the normal paraffin rich stream and the non-normal paraffin rich stream. 
     
     
         14 . The process of  claim 11  further comprising feeding said normal paraffin rich stream to a steam cracker. 
     
     
         15 . The process of  claim 12  further comprising separating a C4 paraffin rich stream from said first isomerization effluent stream and separating said C4 paraffin rich stream into said iso-C4 paraffin rich stream and a normal C4 paraffin rich stream. 
     
     
         16 . The process of  claim 15  further comprising feeding said normal C4 paraffin rich stream to said steam cracker. 
     
     
         17 . The process of  claim 12  further comprising feeding said normal C4 paraffin rich stream to the step of separating the naphtha feed stream into the normal paraffin stream and the non-normal paraffin stream and desorbing normal paraffins from an adsorbent and feeding said normal-C4 paraffin rich stream and said desorbed normal paraffin stream to a steam cracker together. 
     
     
         18 . The process of  claim 12  further comprising: separating said first isomerization effluent stream into a C3 paraffin rich stream and further converting said C3 stream into an olefinic stream. 
     
     
         19 . The process of  claim 12  wherein the step of separating the normal paraffins stream from the non-normal paraffins stream comprises extracting said normal paraffins by use of an adsorbent. 
     
     
         20 . A process for increasing the concentration of normal hydrocarbons in a feed stream comprising:
 separating a naphtha feed stream into a normal paraffins stream and a non-normal paraffins stream;   isomerizing an iso-C4 paraffin rich stream over an isomerization catalyst to convert iso-C4 paraffins to normal C4 paraffins and produce an isomerization effluent stream;   separating a normal C4 paraffin rich stream from said isomerization effluent stream; and   feeding said normal C4 paraffin rich stream to the step of separating a normal paraffins stream from non-normal paraffins stream and desorbing normal paraffins from an adsorbent.