Desulfurization and novel sorbents for same

Abstract

Particulate sorbent compositions comprising a mixture of zinc oxide, silica, alumina and a substantially reduced valence cobalt are provided for the desulfurization of a feedstream of cracked-gasoline or diesel fuels in a desulfurization zone by a process which comprises the contacting of such feedstreams in a desulfurization zone followed by separation of the resulting low sulfur-containing stream 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) zinc oxide;    (b) silica;    (c) alumina; and    (d) cobalt    wherein said cobalt is present in a substantially reduced valence state and in an amount which effects the removal of sulfur from a stream of cracked-gasoline or diesel fuel when contacted with same under desulfurization conditions.    
     
     
         2 . A sorbent composition in accordance with  claim 1  wherein said cobalt is present in an amount in the range of about 5 to about 50 weight percent.  
     
     
         3 . A sorbent composition in accordance with  claim 2  wherein said zinc oxide is present in an amount in the range of about 10 to about 90 weight percent.  
     
     
         4 . A sorbent composition in accordance with  claim 3  wherein said silica is present in an amount in the range of about 5 to about 85 weight percent.  
     
     
         5 . A sorbent composition in accordance with  claim 4  wherein said alumina is present in an amount in the range of from about 5 to about 30 weight percent.  
     
     
         6 . A sorbent composition in accordance with  claim 1  wherein said zinc oxide is present in an amount in the range of about 45 to about 60 weight percent, said silica is present in an amount in the range of about 15 to 60 weight percent, said alumina is present in an amount of 5.0 to about 15 weight percent and said cobalt is present in an amount in the range of about 15 toabout 40 weight percent.  
     
     
         7 . A sorbent composition in accordance with  claim 6  wherein said zinc oxide is present in an amount of about 38 weight percent, said silica is present in an amount in the range of about 31 weight percent, said alumina is present in an amount of about 8 weight percent and said cobalt is present in an amount of about 30 weight percent.  
     
     
         8 . A sorbent composition in accordance to  claim 1  wherein said composition is a particulate in the form of one of granule, extrudate, tablet, sphere, pellet or microsphere.  
     
     
         9 . process for the production of a sorbent composition suitable for the removal of sulfur from a cracked-gasoline or diesel fuel stream which comprises: 
 (a) admixing of zinc oxide, silica and alumina so as to form a mix thereof;    (b) particulating the resulting mix so as to form particles thereof;    (c) drying the particulate of step (b);    (d) calcining the dried particulate of step (c);    (e) impregnating the resulting calcined particulate of step (d) with cobalt or a cobalt-containing compound;    (f) drying the impregnated particulate of step (e);    (g) calcining the dried particulate of step (f); and thereafter    (h) reducing the resulting calcined particulate of step (g) with a suitable reducing agent under suitable conditions to produce a particulate composition having a substantial zero valence cobalt content therein such that the reduced cobalt-containing composition will affect the removal of sulfur from a stream of cracked-gasoline or diesel fuel when said stream is contacted with same under desulfurization conditions.    
     
     
         10 . A process in accordance with  claim 9  wherein said mix is in the form of one of a wet mix, dough, paste or slurry.  
     
     
         11 . A process in accordance with  claim 9  wherein said particles are in the form of one of granules, extrudates, tablets, spheres, pellets or microspheres.  
     
     
         12 . A process in accordance with  claim 9  wherein said zinc oxide is present in an amount in the range of from about 10 to about 90 weight percent, said silica is present in an amount in the range of about 5 to about 85 weight percent and said alumina is present in an amount in the range of from about 5 to about 30 weight percent.  
     
     
         13 . A process in accordance with  claim 12  wherein said particulate is impregnated with cobalt or a cobalt compound in an amount to provide a cobalt content therein in an amount in the range of from about 5 to about 50 weight percent.  
     
     
         14 . A process in accordance with  claim 9  wherein said particulate is dried in steps (c) and (f) at a temperature in the range of about 150° F. to about 350° F.  
     
     
         15 . A process in accordance with  claim 9  wherein said dried particulate is calcined in steps (d) and (g) at a temperature in the range of about 400° F. to about 1500° F.  
     
     
         16 . A process in accordance with  claim 10  wherein said zinc oxide is present in an amount in the range of about 45 to 60 weight percent, said silica is present in an amount in the range of about 15 to 60 weight percent, said alumina is present in an amount in the range of about 5.0 to about 15 weight percent and said cobalt is present in an amount in the range of about 15 to about 40 weight percent.  
     
     
         17 . A process in accordance with  claim 9  wherein said calcined, impregnated particulated mix is reduced in a reduction zone with a reducing agent under suitable conditions to effect a substantial reduction of the valence of the cobalt content so as to provide an amount of reduced valence cobalt 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.  
     
     
         18 . A process in accordance with  claim 17  wherein said reduced valence cobalt is present in an amount in the range of about 5 to about 40 weight percent, based on the total weight of the sorbent composition.  
     
     
         19 . A process in accordance with  claim 17  wherein the reduction of cobalt is carried out 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 for a time sufficient to permit the formation of the desired reduced valence cobalt component.  
     
     
         20 . The sorbent product of the process of  claim 9 .  
     
     
         21 . The sorbent product of the process of  claim 10 .  
     
     
         22 . The sorbent product of the process of  claim 16 .  
     
     
         23 . A process for the removal of sulfur from a stream of a cracked-gasoline or a diesel fuel which comprises: 
 (a) contacting said stream with a sorbent composition comprising zinc oxide, silica, alumina and cobalt wherein said cobalt is present in a substantially reduced valence state and in amount which will effect the removal of sulfur from said stream 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 cobalt 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.    
     
     
         24 . A process in accordance to  claim 23  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 psia to about 1500 psia for a time sufficient to affect the removal of sulfur from said stream.  
     
     
         25 . A process in accordance to  claim 23  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.  
     
     
         26 . A process in accordance with  claim 25  wherein there is employed air as a regeneration agent in said regeneration zone.  
     
     
         27 . A process in accordance with  claim 23  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 affect a substantial reduction of the valence of the cobalt content of said sorbent.  
     
     
         28 . A process in accordance with  claim 23  wherein said separated sulfurized sorbent is stripped prior to introduction to said regeneration zone.  
     
     
         29 . A process in accordance with  claim 23  wherein the regenerated sorbent is stripped prior to introduction into said activation zone.  
     
     
         30 . The cracked-gasoline product of the process of  claim 23 .  
     
     
         31 . The diesel fuel product of the process of  claim 23.