Catalytic sulfur removal from a hydrocarbon stream

Abstract

A process for the catalytic removal of sulfur from a hydrocarbon stream such as gasoline comprising an organo-sulfur compound such as a mercaptan or thiol. The catalyst is a silica based zeolite such as ZSM-5. The process is preferably performed in a downer reactor with a residence time of between 7 and 30 seconds and a volumetric particle concentration of between 15 and 40%. Preferably, substantially all of the sulfur that is removed from the organo-sulfur compound is in the form of hydrogen sulfide.

1 . A process for removing sulfur from a hydrocarbon stream comprising an organo-sulfur compound, the process comprising: 
 a) providing a downer reactor;    b) providing a hydrocarbon stream comprising an organo-sulfur compound in the downer reactor at a temperature in the range of 300 to 500° C.;    c) providing a catalyst comprising a zeolite that promotes removal of sulfur from the organo-sulfur compound in the downer reactor;    d) contacting the hydrocarbon stream with the catalyst; and,    e) converting at least 70% of the organo-sulfur compound to hydrogen sulfide in the downer reactor.    
   
   
       2 . A process according to  claim 1 , wherein the catalyst has a residence time in the downer reactor and wherein the residence time is from 7 second to 30 seconds.  
   
   
       3 . A process according to  claim 1 , wherein at least 75% of the organo-sulfur compound is converted to hydrogen sulfide in the downer reactor.  
   
   
       4 . A process according to  claim 1 , wherein the temperature is from about 375° C. to about 500° C.  
   
   
       5 . A process according to  claim 1 , wherein the catalyst is present in the downer reactor in a volumetric particle concentration and wherein the volumetric particle concentration is from about 5 to about 40%.  
   
   
       6 . A process according to  claim 1 , wherein the hydrocarbon stream has a fluid velocity in the downer reactor and wherein the fluid velocity is between 0.5 and 4.0 m/s.  
   
   
       7 . A process according to  claim 1 , wherein the downer reactor has a length of between 5 and 40 meters.  
   
   
       8 . A process according to  claim 1 , wherein the downer is operated such that the product of catalyst reactor density and residence time is between 0.30 and 1.44 g cryst ·s·cm −3 .  
   
   
       9 . A process according to  claim 1 , wherein the catalyst is a microporous hydrophobic zeolite having acidic sites and a tortuous pore path.  
   
   
       10 . A process according to  claim 1 , wherein the catalyst comprises ZSM-5.  
   
   
       11 . A process according to  claim 1 , wherein the organo-sulfur compound is present in the hydrocarbon stream at a concentration of between 10 and 10000 ppm.  
   
   
       12 . A process according to  claim 1 , wherein the organo-sulfur compound comprises one or more sulfur atoms and from 1 to 12 carbon atoms.  
   
   
       13 . A process according to  claim 1 , wherein the organo-sulfur compound comprises a mercaptan, a thio-ether, a thio-ketone, a thio-aromatic, a thio-paraffin, or a combination thereof.  
   
   
       14 . A process according to  claim 1 , wherein the organo-sulfur compound comprises methyl mercaptan, ethyl mercaptan, or diethyl sulfide.  
   
   
       15 . A process according to  claim 1 , wherein the hydrocarbon stream comprises a hydrocarbon having from 1 to 20 carbon atoms.  
   
   
       16 . A process according to  claim 1 , wherein the hydrocarbon stream comprises n-octane.  
   
   
       17 . A process according to  claim 1 , wherein the hydrocarbon stream is gasoline.  
   
   
       18 . A process according to  claim 1 , wherein the process further comprises circulating the catalyst between the downer reactor and a regenerator.  
   
   
       19 . A process for removing sulfur from a hydrocarbon stream comprising an organo-sulfur compound, the process comprising: 
 a) providing a solids transport reactor;    b) providing a hydrocarbon stream comprising an organo-sulfur compound in the solids transport reactor at a temperature in the range of 300 to 500° C.;    c) providing a catalyst comprising a zeolite that promotes removal of sulfur from the organo-sulfur compound in the solids transport reactor; the catalyst having a catalyst reactor density from 0.02 to 0.12 g cryst ·cm −3 ;    d) contacting the hydrocarbon stream with the catalyst; and,    e) converting at least 70% of the organo-sulfur compound to hydrogen sulfide in the solids transport reactor in a residence time from 7 to 20 seconds, wherein the product of catalyst reactor density and residence time is from 0.30 to 1.44 g cryst ·s·cm −3 .    
   
   
       20 . A process for removing sulfur from a hydrocarbon stream comprising an organo-sulfur compound, the process comprising: 
 a) providing a downer reactor having a length of from 10 to 36 meters;    b) providing a hydrocarbon stream comprising gasoline and comprising 10 to 10000 ppm of an organo-sulfur compound comprising a mercaptan in the downer reactor at a temperature in the range of 300 to 500° C.;    c) providing a catalyst comprising zeolite ZSM-5 in the downer reactor at a volumetric particle concentration of from 5% to 40%;    d) contacting the hydrocarbon stream with the catalyst; and,    e) converting at least 90% of the organo-sulfur compound to hydrogen sulfide in the downer reactor in a residence time of between 7 and 20 seconds.