Catalytic reforming process to produce high octane gasoline

Abstract

The present invention is a multistage reforming process to produce high octane product from naphtha boiling range feed. In the process, a effluent product from a penultimate reforming stage is separated into at least a first stream and a second stream by boiling point. The lower boiling of the two streams is further reformed in a final reforming stage over a medium pore molecular sieve catalyst.

1 . A reforming process comprising:
 a. contacting a naphtha boiling range feedstock in a penultimate stage of a multi-stage reforming process at a first reforming pressure to produce a penultimate effluent;   b. separating at least a portion of the penultimate effluent into at least an intermediate reformate and a heavy reformate, wherein the intermediate reformate has a mid-boiling point that is lower than that of the heavy reformate; and   c. contacting at least a portion of the intermediate reformate in a final stage of the multi-stage reforming process at a second reforming pressure with a catalyst comprising at least one medium pore molecular sieve to produce a final effluent comprising a final reformate, wherein the first reforming pressure is greater than the second reforming pressure.   
   
   
       2 . The process of  claim 1 , wherein the naphtha boiling range feedstock boils in the range from about 50° F. to about 550° F. 
   
   
       3 . The process of  claim 1 , wherein the intermediate reformate comprises at least 70 vol % C 5 -C 8  hydrocarbons. 
   
   
       4 . The process of  claim 3 , wherein the intermediate reformate comprises at least 70 vol % C 6 -C 8  hydrocarbons. 
   
   
       5 . The process of  claim 1 , wherein the heavy reformate comprises at least 70 vol % C 9 + hydrocarbons. 
   
   
       6 . The process of  claim 1 , wherein the RON of the intermediate reformate is higher than the RON of the naphtha boiling range feedstock. 
   
   
       7 . The process of  claim 1 , wherein the intermediate reformate has an RON within the range of 65 to less than 100. 
   
   
       8 . The process of  claim 1 , wherein the heavy reformate has an RON of at least 95. 
   
   
       9 . The process of  claim 1 , wherein at least 70 vol % of the final reformate boils in the range of about 70° F. or higher. 
   
   
       10 . The process of  claim 1 , wherein the final reformate has an RON of 90 or greater. 
   
   
       11 . The process of  claim 10 , wherein the final reformate has an RON which is greater than the RON of the intermediate reformate. 
   
   
       12 . The process of  claim 1 , wherein the second reforming pressure, of the final reforming stage, is within the range of 50 psig to 250 psig. 
   
   
       13 . The process of  claim 12 , wherein the second reforming pressure, of the final reforming stage, is within the range of 50 psig to 150 psig. 
   
   
       14 . The process of  claim 1 , wherein the first reforming pressure, of the penultimate reforming stage, is within the range of 70 psig to 400 psig. 
   
   
       15 . The process of  claim 1 , wherein the first reforming pressure is within the range of 200 psig to 400 psig and within the second reforming pressure is within the range of 50 psig to 150 psig. 
   
   
       16 . The process of  claim 1 , wherein the catalyst within the penultimate stage comprises a Group VIII metal and a prompter supported on a porous refractory inorganic oxide support. 
   
   
       17 . The process of  claim 15 , wherein the Group VIII metal is platinum. 
   
   
       18 . The process of  claim 15  wherein the catalyst comprises platinum and rhenium on an alumina support. 
   
   
       19 . The process of  claim 1 , wherein the medium pore molecular sieve is selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, ZSM-38, ZSM-48 MCM-22, SSZ-20, SSZ-25, SSZ-32, SSZ-35, SSZ-37, SSZ-44, SSZ-45, SSZ-47, SSZ-57, SSZ-58, SSZ-74, SUZ-4, EU-1, NU-85, NU-87, NU-88, IM-5, TNU-9, ESR-10, TNU-10 and combinations thereof. 
   
   
       20 . The process of  claim 1 , wherein the medium pore molecular sieve comprises ZSM-5 having a silica to alumina molar ratio of at least 200:1. 
   
   
       21 . The process of  claim 1 , wherein the medium pore molecular sieve comprises ZSM-5 having a silica to alumina molar ratio of at least 500:1. 
   
   
       22 . The process of  claim 1 , wherein the medium pore molecular sieve comprises ZSM-5 having less than 5,000 ppm alkali. 
   
   
       23 . The process of  claim 1 , wherein the catalyst in the final reforming stage further comprises a Group VIII metal selected from platinum or palladium. 
   
   
       24 . The process of  claim 1 , further comprising blending the heavy reformate with the final reformate to produce a fuel or a fuel blend stock. 
   
   
       25 . A reforming process comprising:
 a. contacting a naphtha boiling range feedstock in a penultimate stage of a multi-stage reforming process at a first reforming pressure to produce an penultimate effluent;   b. separating at least a portion of the penultimate effluent into at least a light reformate, an intermediate reformate and a heavy reformate, wherein the light reformate has a mid-boiling point that is lower than that of the intermediate reformate, and wherein the intermediate reformate has a mid-boiling point that is lower than that of the heavy reformate; and   c. contacting at least a portion of the intermediate reformate in a final stage of the multi-stage reforming process at a second reforming pressure with a catalyst comprising at least one medium pore molecular sieve to produce an final effluent comprising a final reformate, wherein the first reforming pressure is greater than the second reforming pressure.   
   
   
       26 . The process of  claim 24 , wherein the light reformate comprises at least 70 vol % C 5  hydrocarbons. 
   
   
       27 . The process of  claim 24 , wherein the intermediate reformate comprises at least 70 vol % C 5 -C 8  hydrocarbons. 
   
   
       28 . The process of Claim  26 , wherein the intermediate reformate comprises at least 70 vol % C 6 -C 8  hydrocarbons. 
   
   
       29 . The process of  claim 24 , wherein the RON of the intermediate reformate is higher than the RON of the naphtha boiling range feedstock. 
   
   
       30 . The process of  claim 24 , wherein the intermediate reformate has ah RON of at least 65. 
   
   
       31 . The process of  claim 24 , wherein the heavy reformate has an RON of 95 or greater. 
   
   
       32 . The process of  claim 24 , wherein the final reformate has an RON of 90 or greater. 
   
   
       33 . The process of  claim 24 , wherein the final reformate has an RON which is greater than the RON of the intermediate reformate. 
   
   
       34 . The process of  claim 24 , further comprising:
 a. separating the final effluent into at least a final C 5  stream and a final reformate stream;   b. combining the final C 5  stream with the light reformate stream; and   c. combining the final reformate with the heavy reformate.   
   
   
       35 . The process of  claim 33 , wherein the final reformate stream comprises at least 70 vol % C 5 + hydrocarbons. 
   
   
       36 . The process of  claim 33 , wherein the final reformate stream comprises at least 70 vol % C 6 + hydrocarbons. 
   
   
       37 . The process of  claim 33 , wherein the final reformate stream comprises at least 70 vol % C 5- C 8  hydrocarbons.