Desulfurization and novel sorbents for same

Abstract

Particulate sorbent compositions comprising zinc titanate support having thereon a substantially reduced valence promotor metal selected from the group consisting of cobalt, nickel, iron, manganese, copper, molybdenum, tungsten, silver, tin and vanadium or mixtures thereof provide a system for the desulfurization of a feed stream of cracked-gasolines or diesel fuels in a desulfurization zone by a process which comprises contacting such feed streams in a desulfurization zone with a particulate sorbent composition followed by separation of the resulting low sulfur-containing steam and sulfurized sorbent and thereafter regenerating and activating the separated sorbent before recycle of same to the desulfurization zone.

That which is claimed is:  
     
         1 . A sorbent composition suitable for removal of sulfur from cracked-gasolines and diesel fuels which is comprised of: 
 (a) a zinc titanate support and    (b) a metal, metal oxide or metal oxide precursor promotor wherein said metal is selected from the group consisting of cobalt, nickel, iron, manganese, copper, molybdenum, tungsten, silver, tin and vanadium and mixtures thereof, wherein said promotor metal is present in a substantially reduced valence state and in an amount which will effect the removal of sulfur from a stream of cracked-gasoline or diesel fuel when contacted with said sorbent composition under desulfurization conditions.    
     
     
         2 . A sorbent composition in accordance with  claim 1  wherein said reduced valence state metal is present in an amount in the range of about 5 to about 50 weight percent of the total weight of the sorbent composition.  
     
     
         3 . A sorbent composition in accordance with  claim 1  wherein said reduced valence state metal is present in an amount in the range of about 15 to about 40 weight percent of the total weight of the sorbent composition.  
     
     
         4 . A sorbent composition in accordance with  claim 1  wherein said reduced valence state metal is present in an amount in the range of about 10 to 30 weight percent of the total weight of the sorbent composition.  
     
     
         5 . A sorbent composition in accordance with  claim 1  wherein the ratio of zinc to titanium in said support is in the range of about 0.2 to about 3.  
     
     
         6 . A sorbent composition in accordance with  claim 5  wherein said promotor metal is nickel.  
     
     
         7 . A sorbent composition in accordance with  claim 6  wherein the valence of said nickel has been substantially reduced to zero.  
     
     
         8 . A sorbent composition in accordance with  claim 1  having additionally present therein an inorganic binder.  
     
     
         9 . A sorbent composition in accordance with  claim 1  wherein said composition is a particulate in the form of one of granule, extrudate, tablet, sphere, pellet or microsphere.  
     
     
         10 . A process for the production of a sorbent composition suitable for the removal of sulfur from a cracked-gasoline or diesel fuel which comprises: 
 (a) impregnating a solid particulate of zinc titanate with a metal, metal oxide or metal oxide promotor wherein the metal is selected from the group consisting of cobalt, nickel, iron, manganese, copper, molybdenum, tungsten, silver, tin and vanadium and combinations thereof:    (b) drying the resulting impregnated solid particulate composition;    (c) calcining the dried particulate composition; and    (d) reducing the calcined particulate product with a suitable reducing agent so as to produce a sorbent composition having a reduced promotor metal content in an amount which is sufficient to permit the removal with same of sulfur from a crack-gasoline or diesel fuel stream when contacted with same.    
     
     
         11 . A process in accordance with  claim 10  wherein said solid particulate of zinc titanate is prepared by a process which comprises: 
 (a) forming a dry blend of zinc oxide and titanium oxide;  
 (b) preparing an aqueous slurry comprising said zinc oxide-titanium dioxide dry blend;  
 (c) spray drying said aqueous slurry to produce substantially spherical particles; and thereafter (d) calcining said spherical particles under conditions to convert at least a portion of the zinc oxide and titanium dioxide to zinc titanate.  
 
     
     
         12 . A process in accordance with  claim 10  wherein said reducing agent is hydrogen.  
     
     
         13 . A process in accordance with  claim 10  wherein said dried particulate is calcined at a temperature in the range of from about 400° F. to about 1500° F.  
     
     
         14 . A process in accordance with  claim 10  wherein said calcined, impregnated particulated mix is reduced in a reduction zone with a reducing agent under conditions suitable to effect a substantial reduction of the valance of said promotor metal such that the resulting composition will effect the removal of sulfur from a cracked-gasoline or diesel fuel when treated with same under desulfurization conditions.  
     
     
         15 . A process in accordance with  claim 10  wherein said reduced valence metal is present in an amount in the range of about 5 to about 50 weight percent, based on the total weight of the sorbent composition.  
     
     
         16 . A process in accordance with  claim 15  wherein said promotor metal is nickel.  
     
     
         17 . A process in accordance with  claim 16  wherein the reduction of nickel is carried out at a temperature in the range of about 100° F. to about 1500° F. and at a pressure of about 15 to about 1500 psia for a time sufficient to permit the formation of the desired reduced valence nickel component.  
     
     
         18 . The sorbent product of the process of  claim 10 .  
     
     
         19 . The sorbent product of the process of  claim 11 .  
     
     
         20 . The sorbent product of the process of  claim 15 .  
     
     
         21 . A process for the removal of sulfur from a stream of a cracked-gasoline or diesel fuel which comprises: 
 (a) contacting said stream with a sorbent composition comprising zinc titanate, and a metal, metal oxide or metal oxide precursor promotor wherein said metal is selected from the group consisting of cobalt, nickel, iron, manganese, copper, molybdenum, tungsten, silver, tin and vanadium and mixtures thereof and wherein said promotor metal is present in a substantially reduced valence state and in an amount which will effect the removal of sulfur from a stream of cracked-gasoline or diesel fuel when contacted with said sorbent composition under desulfurization conditions, such contacting being carried out in a desulfurization zone under conditions such that there is formed a desulfurized fluid stream of cracked-gasoline or diesel fuel and a sulfurized sorbent;    (b) separating the resulting desulfurized fluid stream from said sulfurized sorbent;    (c) regenerating at least a portion of the separated sulfurized sorbent in a regeneration zone so as to remove at least a portion of the sulfur absorbed thereon;    (d) reducing the resulting desulfurized sorbent in an activation zone so as to provide a reduced valence metal promotor content therein which will affect the removal of sulfur from a stream of a cracked-gasoline or diesel fuel when contacted with same; and thereafter.    (e) returning at least a portion of the resulting desulfurized, reduced sorbent to said desulfurization zone.    
     
     
         22 . A process in accordance to  claim 21  wherein said desulfurization is carried out at a temperature in the range of about 100° F. to about 1000° F. and a pressure in the range of about 15 to about 1500 psia for a time sufficient to effect the removal of sulfur from said stream.  
     
     
         23 . A process in accordance to  claim 22  wherein said regeneration is carried out at a temperature in the range of about 100° F. to about 1500° F. and a pressure in the range of about 10 to about 1500 psia for a time sufficient to effect the removal of at least a portion of sulfur from the sulfurized sorbent.  
     
     
         24 . A process in accordance with  claim 23  wherein there is employed air as a regeneration agent in said regeneration zone.  
     
     
         25 . A process in accordance with  claim 22  wherein said regenerated sorbent is subjected to reduction with hydrogen in a hydrogenation zone which is maintained at a temperature in the range of about 100° F. to about 1500° F. and at a pressure in the range of about 15 to about 1500 psia and for a period of time to effect a substantial reduction of said promotor metal of said sorbent.  
     
     
         26 . A process in accordance with  claim 25  wherein said promotor metal is nickel.  
     
     
         27 . A process in accordance with  claim 25  wherein said separated sulfurized sorbent is stripped prior to introduction into said regeneration zone.  
     
     
         28 . A process in accordance with  claim 27  wherein said regenerated sorbent is stripped prior to introduction into said activation zone.  
     
     
         29 . The cracked-gasoline product of the process of  claim 20 .  
     
     
         30 . The diesel fuel product of the process of claim  20 .