Hydrodehalogenation process using a catalyst containing nickel

Abstract

A gas stream containing at least about 90% (vol.) hydrogen and at least one halogen-containing compound is contacted with a nickel hydrogenation catalyst. When the gas stream contacts the hydrogenation catalyst substantially all halogen-containing compounds are dehalogenated.

We claim:  
     
         1 . A process for treating a gas stream having at least about 90 volume percent of H 2 , based on the total volume of all constituents comprising said gas stream, at least one halogen-containing compound and a total concentration of S-containing compounds less than about 2 ppm by volume, based on a mono-sulfur compound equivalent, said process comprising: 
 (a) contacting said gas stream with a nickel catalyst composition at a temperature greater than 850° F. (454° C.) but less than or equal to about 1050° F. (566° C.), wherein said halogen-containing compound contacts said nickel catalyst composition so that a substantial portion of said halogen-containing compound is reduced, said catalyst composition comprising a source for nickel in a zero oxidation state, Ni 0 , selected from the group consisting of 
 (i) at least about 5 weight percent Ni 0 ,  
 (ii) a Ni 0  precursor having Ni +n , where 1≦n≦4, that can produce at least about 5 weight percent Ni 0  under substantially reducing conditions, and  
 (iii) combinations thereof, said Ni 0  weight percent being measured as a percentage of the total weight of all constituents comprising said nickel catalyst composition; and  
   (b) producing a nickel catalyst-treated gas stream, wherein substantially all halogen-containing compounds are de-halogenated.    
     
     
         2 . The process of  claim 1 , wherein the gas stream further comprises O 2 .  
     
     
         3 . The process of  claim 2 , wherein the mole ratio of H 2  to O 2  in said gas stream is at least about 10 to 1.  
     
     
         4 . The process of  claim 2 , wherein the mole ratio of H 2  to O 2  in said gas stream is in a range of from about 10 to 1 to about 100,000 to 1.  
     
     
         5 . The process of  claim 1 , wherein the total concentration of S-containing compounds is less than about 1 ppm by volume, based on a mono-sulfur compound equivalent.  
     
     
         6 . The process of  claim 1 , further comprising pre-treating said gas stream by contacting said gas stream with a pre-treatment material comprising zinc oxide so that at least a portion of any sulfur-containing compounds in said gas stream is removed.  
     
     
         7 . The process of  claim 6 , further comprising, prior to the pre-treating step, removing at least a portion of zinc oxide poisons present in said gas stream by contacting said gas stream with an adsorbent bed.  
     
     
         8 . The process of  claim 7 , wherein said zinc oxide poisons are selected from the group consisting of HCl, HF, HBr, Hl and combinations thereof.  
     
     
         9 . The process of  claim 1 , wherein the nickel catalyst-treated gas stream is substantially free of halogen-containing compounds and comprises H 2 O, a halogen-containing acid and a saturated hydrocarbon having from 1 to about 3 carbon atoms.  
     
     
         10 . The process of  claim 9 , further comprising removing said halogen-containing acid by contacting said nickel catalyst-treated gas stream with a pre-treatment bed selected from the group consisting of an adsorbent bed, a chemical neutralizing bed, and combinations thereof.  
     
     
         11 . The process of  claim 10 , wherein the adsorbent bed comprises a material selected from the group consisting of alumina, calcium oxide, and combinations thereof.  
     
     
         12 . The process of  claim 1 , wherein said gas stream further comprises oxygen-containing compounds.  
     
     
         13 . The process of  claim 12 , wherein said oxygen-containing compounds are selected from the group consisting of CO, CO 2 , O 2 , N 2 O, NO, NO 2 , HNO 3  and combinations thereof and CH 4 , H 2 O, NH 3  and combinations thereof are produced from said nickel catalyst-treatment.  
     
     
         14 . The process of  claim 1 , wherein said gas stream further comprises amines.  
     
     
         15 . The process of  claim 14 , wherein said amines are selected from the group consisting of R 1 NH 2 , R 1 R 2 NH, R 1 R 2 R 3 N, and combinations thereof and NH 3  is produced when said gas stream is contacted with said nickel catalyst composition, where R 1 , R 2  and R 3  are independently selected from the group consisting of C 1  to C 3  hydrocarbyl groups.  
     
     
         16 . The process of  claim 2 , wherein at least a portion of said halogen-containing compounds and at least a portion of said O 2  are reduced substantially concurrently.  
     
     
         17 . The process of  claim 1 , wherein said nickel catalyst composition comprises said nickel source and a support for said nickel source.  
     
     
         18 . The process of  claim 17 , wherein said support is inert with respect to hydrodehalogenation and halo-compound by-product reactions.  
     
     
         19 . The process of  claim 17 , wherein said support is selected from the group consisting of aluminum oxide, magnesium oxide, calcium oxide and combinations thereof.  
     
     
         20 . The process of  claim 19 , wherein the concentration of said support is in a range of from about 35 to about 95 wt. % in said nickel catalyst composition.  
     
     
         21 . The process of  claim 1 , wherein the concentration of H 2  in said gas stream is at least about 95 volume percent.  
     
     
         22 . The process of  claim 1 , wherein the concentration of Ni 0  or Ni 0  precursor is in a range of from about 5 to about 65 weight percent.  
     
     
         23 . The process of  claim 1 , wherein the concentration of Ni 0  or Ni 0  precursor is in a range of from about 10 to about 50 weight percent.  
     
     
         24 . The process of  claim 1 , wherein the concentration of Ni 0  or Ni 0  precursor is in a range of from about 15 to about 25 weight percent.  
     
     
         25 . The process of  claim 1 , wherein said nickel catalyst composition further comprises a promoter in a concentration of from about 0.1 to about 5 weight percent.