Desulfurization of a naphtha boiling range feed

Abstract

Processes for desulfurizing a fluid catalytic cracker (FCC) naphtha feedstock, straight run naphtha feedstocks and combinations thereof are provided herein. Naphtha boiling range feed is passed over a silicon trap prior to being hydrodesulfurized in an olefin-retentive, catalytic naphtha hydrodesulfurization process. Processes for removing silicon from FCC naphtha feedstock, straight run naphtha feedstock and combinations thereof are also provided herein.

1 . A process for desulfurizing a naphtha boiling range feed comprising:
 contacting the naphtha boiling range feed consisting essentially of fluid catalytic cracker naphtha, straight run naphtha, or a combination thereof with a silicon trap comprising inert alumina to remove silicon from the naphtha boiling range feed to form a naphtha boiling range effluent; and   hydrodesulfurizing at least a portion of the naphtha boiling range effluent.   
     
     
         2 . The process of  claim 1 , wherein the naphtha boiling range feed does not include delayed coker naphtha. 
     
     
         3 . The process of  claim 1 , wherein the naphtha boiling range feed has one or more of the following:
 (i) an API gravity of at least about 50 as measured according to ASTM D4052;   (ii) a Bromine number of about 50 to about 75 as measured according to ASTM D1159; and   (iii) a sulfur content of at least about 300 ppmw as measured according to ASTM D4294.   
     
     
         4 . The process of  claim 1 , wherein the fluid catalytic cracker naphtha, the straight run naphtha, or the combination thereof comprises at least about 90 wt % of the silicon present in the naphtha boiling range feed. 
     
     
         5 . The process of  claim 1 , wherein the fluid catalytic cracker naphtha, the straight run naphtha, or the combination thereof comprises about 100 wt % of the silicon present in the naphtha boiling range feed. 
     
     
         6 . The process of  claim 1 , wherein the fluid catalytic cracker naphtha, the straight run naphtha, or the combination thereof comprises about 0.25 ppmw to about 10.0 ppmw of silicon. 
     
     
         7 . The process of  claim 1 , wherein the silicon trap has a surface area of at least about 250 m 2 /g. 
     
     
         8 . The process of  claim 1 , wherein the silicon trap has a surface area of at least about 300 m 2 /g. 
     
     
         9 . The process of  claim 1 , wherein the silicon trap has a metal content of not more than about 1.0 wt % Group 8, 9 or 10 metals and not more than about 5.0 wt % Group 6 metals. 
     
     
         10 . The process of  claim 1 , wherein the silicon trap has a metal content of not more than about 1.0 wt % nickel or cobalt and not more than about 5.0 wt % molybdenum. 
     
     
         11 . The process of  claim 1 , wherein the silicon trap comprises inert alumina particles having an average particle diameter of less than about 1.6 mm. 
     
     
         12 . The process of  claim 1 , wherein the hydrodesulfurization is carried out at a temperature of about 250° C. to about 325° C., a total system pressure of about 1000 kPag to about 3500 kPag, a hydrogen partial pressure of about 600 kPa to about 2500 kPa and a liquid hourly space velocity (LHSV) of about 1.0 hr −1  to about 10 hr −1 . 
     
     
         13 . The process of  claim 1 , wherein the hydrodesulfurization comprises contacting the naphtha boiling range effluent with a catalyst comprising:
 about 1.0 wt % to about 10 wt % MoO 3 ; and   about 0.1 to 5 wt. % CoO;   wherein the catalyst has one or more of the following:
 (i) a Co/Mo atomic ratio of about 0.1 to about 1.0, 
 (ii) a median pore diameter of about 6 nm to about 20 nm; 
 (iii) a MoO 3  surface concentration of about 0.5×10 −4  g MoO 3 /m 2  to about 3×10 −4  g MoO 3 /m 2 ; and 
 (iv) an average particle size diameter of less than about 2.0 mm. 
   
     
     
         14 . The process of  claim 1 , wherein the hydrodesulfurization is performed in a two stage process comprising:
 (i) contacting the naphtha boiling range effluent with hydrogen and a hydrotreating catalyst in a first vapor reaction stage to remove at least about 70 wt % of sulfur present in the naphtha boiling range effluent to produce a first stage effluent comprising a mixture of reduced sulfur naphtha and H 2 S; and separating the reduced sulfur naphtha and H 2 S; and   (ii) contacting the reduced sulfur naphtha and hydrogen with a hydrodesulfurization catalyst in a second vapor reaction stage having a temperature at least about 10° C. greater than in the first vapor reaction stage and a space velocity at least about 1.5 times greater than in the first vapor reaction stage to remove at least about 80 wt % of remaining sulfur from the reduced sulfur naphtha to form a desulfurized naphtha product.   
     
     
         15 . The process of  claim 14 , wherein the naphtha boiling range effluent comprises at least about 300 wppm sulfur. 
     
     
         16 . The process of  claim 14 , wherein the desulfurized naphtha product comprises less than about 5.0 wt % of the amount of sulfur present in the naphtha boiling range effluent but retains at least 40 vol % of the olefin content of the naphtha boiling range effluent. 
     
     
         17 . The process of  claim 14 , wherein both the hydrotreating catalyst and the hydrodesulfurization catalyst comprise Co and Mo on a support in an amount of less than a total of about 12 wt % calculated as the respective metal oxides CoO and MoO 3  with a Co/Mo atomic ratio from 0.1 to 1.0. 
     
     
         18 . The process of  claim 14 , wherein the reaction conditions in each stage have a temperature from about 230° C. to about 400° C., a pressure from about 400 KPag to about 34000 kPag, and a space velocity from about 1 v/v/hr to about 10 v/v/hr, wherein a space velocity in the second vapor reaction stage is greater than that in the first vapor reaction stage. 
     
     
         19 . The process of  claim 18 , wherein the percent desulfurization in the second vapor reaction stage is at least about 90%. 
     
     
         20 . A process for removing silicon from a naphtha boiling range feed comprising:
 contacting the naphtha boiling range feed consisting essentially of fluid catalytic cracker naphtha, straight run naphtha or a combination thereof with a silicon trap comprising inert alumina to remove silicon from the naphtha boiling range feed to form a naphtha boiling range effluent,   wherein the inert alumina has:
 a surface area of at least about 250 m 2 /g; 
 an average particle diameter of less than about 1.6 mm; and 
 a metal content of not more than about 1.0 wt % Group 8, 9 or 10 metals and not more than about 5.0 wt % Group 6 metals. 
   
     
     
         21 . The process of  claim 20 , wherein the naphtha boiling range feed does not include delayed coker naphtha. 
     
     
         22 . The process of  claim 20 , wherein the naphtha boiling range feed has one or more of the following:
 (i) an API gravity of at least about 50 as measured according to ASTM D4052;   (ii) a Bromine number of about 50 to about 75 as measured according to ASTM D1159; and   (iii) a sulfur content of at least about 300 ppmw as measured according to ASTM D4294.   
     
     
         23 . The process of  claim 20 , wherein the fluid catalytic cracker naphtha, the straight run naphtha, or the combination thereof comprises as least about 90 wt % of the silicon present in the naphtha boiling range feed. 
     
     
         24 . The process of  claim 20 , wherein the fluid catalytic cracker naphtha, the straight run naphtha, or the combination thereof comprises about 0.25 ppmw to about 10 ppmw of silicon. 
     
     
         25 . The process of  claim 20 , wherein the silicon trap has a metal content of not more than about 1.0 wt % nickel or cobalt and not more than about 5.0 wt % molybdenum. 
     
     
         26 . A process for desulfurizing a naphtha boiling range feed comprising:
 contacting the naphtha boiling range feed comprising fluid catalytic cracker naphtha, straight run naphtha, coker naphtha or a combination thereof with a silicon trap comprising inert alumina to remove silicon from the naphtha boiling range feed to form a naphtha boiling range effluent; and   hydrodesulfurizing at least a portion of the naphtha boiling range effluent.