Deep desulfurization process

Abstract

Methods for producing a substantially desulfurized hydrocarbon fuel stream, using no substantial amount of hydrogen, at pressures less than 125 psig are described. The process uses two fixed beds in series to remove sulfur and/or other heteroatoms to produce a substantially desulfurized (less than 1 ppm sulfur) hydrocarbon fuel stream. The first fixed bed uses a transition metal catalyst dispersed on an inorganic oxide matrix and the second bed uses a high surface area, porous, amorphous inorganic oxide catalyst or a high surface area porous carbonaceous catalyst. The second fixed bed can additionally comprise one or more metals.

1 . A process comprising the steps of:
 a) contacting a hydrocarbon feed stream, which comprises heteroatom containing compounds, in a first adsorption zone with a first adsorbent comprising at least one transition metal and at least one inorganic oxide at a first pressure and a first temperature, in the absence of any substantial amounts of added hydrogen, to form a first effluent wherein the first effluent has a heteroatom content lower than the heteroatom content of the hydrocarbon feedstream and;   b) contacting at least a portion of the first effluent, in a second adsorption zone, with a second adsorbent comprising an amorphous inorganic oxide, a porous carbonaceous material, or combinations thereof, at a second reaction pressure and a second reaction temperature, in the absence of any substantial amounts of added hydrogen, to form a second effluent, wherein the second effluent has a heteroatom content lower than the heteroatom content of the first effluent.   
     
     
         2 . The process of  claim 1 , wherein the first pressure is between about 25 psig to about 125 psig. 
     
     
         3 . The process of  claim 1 , wherein the second pressure is between about 0 psig to about 50 psig. 
     
     
         4 . The process of  claim 1 , wherein the first temperature is between about 100° C. to about 500° C. 
     
     
         5 . The process of  claim 1 , wherein the second temperature is between about 0° C. to about 150° C. 
     
     
         6 . The process of  claim 1 , wherein the first effluent has a sulfur content of less than about 50 ppm. 
     
     
         7 . The process of  claim 1 , wherein the second effluent has a sulfur content of less than about 1 ppm. 
     
     
         8 . The process of  claim 1 , further comprising the step of regenerating the second adsorbent by passing a desorbing liquid through said second adsorbent. 
     
     
         9 . The process of  claim 8 , wherein the desorbing liquid is selected from the group consisting of aromatic solvents, paraffinic solvents, polar solvents, and combinations thereof. 
     
     
         10 . The process of  claim 9 , wherein the desorbing liquid is toluene. 
     
     
         11 . A process for desulfurizing a hydrocarbon feedstream in continuous adsorption mode in the absence of any substantial amount of added hydrogen comprising the steps of:
 (a) contacting a hydrocarbon feed stream, which comprises heteroatom containing compounds, in a first adsorption zone wherein the first adsorption zone comprises at least two adsorption beds in parallel, in the absence of any substantial amounts of added hydrogen, to form a first effluent wherein the first effluent has a heteroatom content lower than the heteroatom content of the hydrocarbon feedstream and;   (b) contacting at least a portion of the first effluent, in a second adsorption zone, wherein the second adsorption zone comprises at least 2 adsorption beds in parallel, at a second reaction pressure and a second reaction temperature, in the absence of any substantial amounts of added hydrogen, to form a second effluent, wherein the second effluent has a heteroatom content lower than the heteroatom content of the first effluent.   
     
     
         12 . The process of  claim 11 , wherein the first adsorbent comprising at least one transition metal and at least one inorganic oxide. 
     
     
         13 . The process of  claim 12 , wherein the inorganic oxide is silica, alumina, or combinations thereof. 
     
     
         14 . The process of  claim 12 , wherein the transition metal is nickel, molybdenum, or combinations thereof. 
     
     
         15 . The process of  claim 11 , wherein the second adsorbent comprises an amorphous inorganic oxide, a porous carbonaceous material, or combinations thereof. 
     
     
         16 . The process of  claim 15 , wherein the porous carbonaceous material is activated charcoal. 
     
     
         17 . The process of  claim 16 , wherein the activated charcoal has a surface area of at least 1000 m 2 g. 
     
     
         18 . The process of  claim 11 , wherein the hydrocarbon feedstream is selectively directed by at least one valve to one of the two or more adsorption beds of the first adsorption zone. 
     
     
         19 . The process of  claim 11 , wherein at least a portion of the first effluent is selectively directed by at least one valve to one of the two or more adsorption beds of the second adsorption zone.