Multi-stage reforming process with final stage catalyst regeneration

Abstract

The present invention relates to a multistage reforming process to produce a high octane product. A naphtha boiling range feedstock is processed in a multi-stage reforming process, in which said process involves at least 1) a penultimate stage for reforming the naphtha feedstock to produce a penultimate effluent 2) a final stage for further reforming at least a portion of the penultimate effluent 3) a regeneration step for the final stage catalyst. The severity of the penultimate stage can be increased during final stage catalyst regeneration in order to maintain the target RON of the reformate product and avoid reactor downtime.

1 . A reforming process comprising:
 a. providing a naphtha to a multi-stage reforming system that includes a penultimate reforming stage containing a first reforming catalyst and a final reforming stage containing a second reforming catalyst;   b. contacting the naphtha at a first reforming temperature with the first reforming catalyst and producing a penultimate effluent;   c. contacting at least a portion of the penultimate effluent at a second reforming temperature with the second reforming catalyst and producing a final reformate having an RON of greater than 90; and   d. regenerating the second reforming catalyst in the final reforming stage while reforming the naphtha in the penultimate reforming stage and producing a third reformate from the penultimate reforming stage that has an RON of at least 90.   
     
     
         2 . The process of  claim 1 , wherein step (b) comprises contacting the naphtha at a first reforming temperature in the range of from 800° F. to 1100° F. (427° C. to 593° C.). 
     
     
         3 . The process of  claim 1 , wherein step (b) comprises contacting the naphtha at a first reforming pressure in the range of from 200 psig (1380 kPa) to 400 psig (2760 kPa). 
     
     
         4 . The process of  claim 1 , wherein step (b) comprises contacting the naphtha with the first reforming catalyst, which comprises platinum and rhenium on an alumina support. 
     
     
         5 . The process of  claim 1 , wherein step (c) comprises contacting at least a portion of the penultimate effluent at a second reforming temperature in the range of from 800° F. to 1100° F. (427° C. to 593° C.). 
     
     
         6 . The process of  claim 1 , wherein step (c) comprises contacting at least a portion of the penultimate effluent at a second reforming pressure in the range of from 40 psig (276 kPa) to 200 psig (1480 kPa). 
     
     
         7 . The process of  claim 1 , wherein step (c) comprising contacting at least a portion of the penultimate effluent with the second reforming catalyst comprising silicalite having a silica to alumina molar ratio of at least 200, a crystallite size of less than 10 microns and an alkali content of less than 5,000 ppm. 
     
     
         8 . The process of  claim 7 , wherein step (c) comprises contacting at least a portion of the penultimate effluent with the second reforming catalyst comprising iridium, platinum, palladium or a combination thereof. 
     
     
         9 . The process of  claim 1 , wherein step (a) comprises providing the naphtha having an RON of less than 75. 
     
     
         10 . The process of  claim 1 , wherein step (c) further comprises:
 a. isolating an intermediate reformate from the penultimate effluent, the intermediate reformate having an RON within the range of 75 to 90; and   b. contacting the intermediate reformate at the second reforming temperature with the second reforming catalyst and producing the final reformate having an RON of greater than 90.   
     
     
         11 . The process of  claim 1 , wherein step (c) comprises producing a final reformate having an RON of at least 95. 
     
     
         12 . The process of  claim 1 , wherein step (d) comprises producing a third reformate having an RON of at least 95. 
     
     
         13 . The process of  claim 1 , wherein step (d) comprises reforming the naphtha in the penultimate reforming stage at a temperature that is at least 5° F. higher than the first reforming temperature. 
     
     
         14 . The process of  claim 1 , wherein regenerating the second reforming catalyst in step (d) comprises:
 a. ceasing the flow of intermediate reformate to the final reforming stage;   b. increasing the reforming temperature in the penultimate reforming stage by at least 5° F. (2.8° C.) to produce a third reformate having an RON of at least 90; and   c. regenerating the second reforming catalyst in the final reforming stage.   
     
     
         15 . The process of  claim 14 , wherein regenerating the second reforming catalyst in step (d) comprises:
 a. passing a nitrogen containing stream through the second reforming stage to remove at least a portion of the naphtha contained therein;   b. passing an oxygen containing stream through the final reforming stage to remove at least a portion of the carbon deposited on the second reforming catalyst contained within the final reforming stage;   c. passing a nitrogen containing stream through the second reforming catalyst to remove at least a portion of the oxygen contained therein;   d. reducing the temperature of the second reforming catalyst within the final reforming stage to a temperature of less than the second reforming temperature;   e. introducing at least a portion of the penultimate effluent to the final reforming stage; and   f. increasing the temperature of the second reforming catalyst to a temperature in the range of 800° F. to 1100° F. (427° C.-593° C.).   
     
     
         16 . The process of  claim 15 , further comprising:
 h. reducing the reforming temperature in the penultimate reforming stage by at least 5° F. (2.8° C.).