Process to manufacture low sulfur fuels

Abstract

The instant invention relates to a process to produce high octane, low sulfur naphtha products through the simultaneous skeletal isomerization of feed olefins and selective hydrotreating.

1 . A process for producing low sulfur naphtha products from an olefin and sulfur containing naphtha boiling range feedstream comprising: 
 a) contacting a naphtha boiling range feedstream containing organically bound sulfur and olefins in a reaction zone, operated under effective hydrotreating conditions and in the presence of hydrogen-containing treat gas, with a supported catalyst comprising at least one medium pore zeolite selected from ZSM-23, ZSM-12, ZSM-22, ZSM-57, and ZSM-48, about 0.1 to 27 wt. % of at least one Group VIII metal oxide, and about 1 to 45 wt. % of at least one Group VI metal oxide to produce a desulfurized product.    
     
     
         2 . The process according to  claim 1  wherein said naphtha boiling range feedstream boils in the range of about 50° F. (10° C.) to about 450° F. (232° C.).  
     
     
         3 . The process according to  claim 2  wherein said naphtha boiling range feedstream has an olefin content of at least about 5 wt. %.  
     
     
         4 . The process according to  claim 1  wherein said naphtha boiling range feedstream is selected from fluid catalytic cracking unit naphtha (FCC catalytic naphtha or cat naphtha), steam cracked naphtha, coker naphtha, blends of olefinic naphthas with non-olefinic naphthas wherein the blend has an olefin content of at least about 5 wt. %, based on the total weight of the naphtha boiling range feedstream.  
     
     
         5 . The process according to  claim 4  wherein said naphtha boiling range feedstream has a sulfur content of about 50 wppm to about 7000 wppm sulfur.  
     
     
         6 . The process according to  claim 1  wherein said naphtha boiling range feedstream has a nitrogen content of about 5 wppm to about 500 wppm nitrogen.  
     
     
         7 . The process according to  claim 1  wherein said reaction zone comprises one or more catalyst beds selected from fluidized beds, ebullating beds, slurry beds, fixed beds, and moving beds wherein each of said one or more catalyst beds contains a catalyst suitable for the reaction zone in which the catalyst bed is located.  
     
     
         8 . The process according to  claim 7  wherein said reaction zone comprises one or more fixed catalyst beds.  
     
     
         9 . The process according to  claim 7  wherein said process further comprises interstage cooling between catalyst beds in said reaction zone.  
     
     
         10 . The process according to  claim 9  wherein said medium pore size zeolite has an alpha value of up to about 20.  
     
     
         11 . The process according to  claim 10  wherein said medium pore size zeolite is selected from ZSM-23 and ZSM-48.  
     
     
         12 . The process according to  claim 10  wherein said medium pore zeolite is ZSM-48.  
     
     
         13 . The process according to  claim 12  wherein said catalyst comprises about 0.1 to about 10 wt. % of a Group VIII metal oxide and about 1 to about 30 wt. % of a Group VI metal oxide. 1 to 45 wt. % of at least one Group VI metal oxide.  
     
     
         14 . The process according to  claim 13  wherein said catalyst comprises about 1 to about 8 wt. % of a Group VIII metal oxide and about 1 to about 20 wt. % of a Group VI metal oxide.  
     
     
         15 . The process according to  claim 14  wherein said effective hydrotreating conditions are selected to cause skeletal isomerization of at least about 20 wt. % of the n-olefins present in said naphtha boiling range feedstream.  
     
     
         16 . The process according to  claim 15  wherein said support is a suitable binder or matrix material selected from clays, silica, and metal oxides.  
     
     
         17 . The process according to  claim 16  wherein said support is selected from alumina, silica, and silica-alumina.  
     
     
         18 . The process according to  claim 17  wherein said support is alumina.  
     
     
         19 . The process according to  claim 18  wherein said alumina is present in a ratio of less than about 15 parts zeolite to one part binder.  
     
     
         20 . The process according to  claim 19  wherein said effective hydrotreating conditions are selected in such a manner that said desulfurized naphtha product has less than 100 wppm sulfur.  
     
     
         21 . The process according to  claim 20  wherein said effective hydrotreating conditions are selective hydrotreating conditions.  
     
     
         22 . The process according to  claim 21  wherein said desulfurized naphtha product has a higher concentration of iso-paraffins than n-paraffins.  
     
     
         23 . The process according to  claim 6  wherein said process further comprises a feeds pretreatment step wherein said feed pretreatment step comprises: 
 a) contacting the naphtha boiling range feedstream containing organically bound sulfur, nitrogen-containing compounds, and olefins in a reaction zone, operated under conditions effective at removing at least a portion of said nitrogen-containing compounds, with an acidic material to produce a first reaction zone effluent having a reduced amount of nitrogen-containing compounds.    
     
     
         24 . The process according to  claim 23  wherein said acidic material is selected from Amberlyst, alumina, sulfuric acid, spent sulfuric acid obtained from an alkylation unit, and any other acidic material known to be effective at removing nitrogen compounds from a naphtha boiling range hydrocarbon stream.