Sulfide catalysts for reducing SO2 to elemental sulfur

Abstract

A highly efficient sulfide catalyst for reducing sulfur dioxide to elemental sulfur, which maximizes the selectivity of elemental sulfur over byproducts and has a high conversion efficiency. Various feed stream contaminants, such as water vapor are well tolerated. Additionally, hydrogen, carbon monoxide, or hydrogen sulfides can be employed as the reducing gases while maintaining high conversion efficiency. This allows a much wider range of uses and higher level of feed stream contaminants than prior art catalysts.

What is claimed is:  
     
         1 . A sulfide catalyst for the conversion of sulfur dioxide to elemental sulfur comprising; 
 A. Fe, Co or Ni sulfides, either singely or in combination,    B. Mo, Mn, Cu, W. V or Cr sulfides, either singly or in combination, and    C. a carrier,    the composition of said catalyst being represented by the formula:    Fe a Co b Ni c Cr d Mn e Mo f V g Cu h W i O x S y      wherein a,b,c,d,e and f are independently ranged between 0 and 30,    g and h are between 0 and 10,    i is between 0 and 5, and    x+y is determined by the charge balance of the catalyst, and    the proportion of x:y at the active surface of the catalyst is between about 0:1 and 1:0.1.    
     
     
         2 . The catalyst of    claim 1   , wherein the proportion of x:y is in the range of about 0:1 to 1:0.5.  
     
     
         3 . The catalyst of    claim 2   , wherein the proportion of x:y is in the range of about 0:1 to 1:1.  
     
     
         4 . The catalyst of    claim 1   , wherein the formulation of the catalyst is selected from Fe 4 Co 2 Ni 2 Mo 1 Mn 4 O 17.66-y S y , Fe 4 Co 1 Ni 1 Mo 1 Mn 4 O 15.33-y S y , Fe 4 Co 1 Ni 1 Mo 1 Cr 2 Mn 2 O 17.55-y S y , Fe 4 Co 2 Ni 2 Mo 1 Mn 2 S 17.66 , Fe 4 Co 1 Ni 1 Mn 1 Cu 2 V 8 O 32.33-y S y .  
     
     
         5 . The catalyst of    claim 1   , additionally comprising a rare earth metal sulfide.  
     
     
         6 . The catalyst of    claim 5   , wherein the rare earth metal sulfide comprises La, Ce, Pr, and Nd.  
     
     
         7 . The catalyst of    claim 6   , wherein the formulation of the catalyst is Fe 4 Co 1 Ni 1 Mo 1 Pr 6 Mn 2 O 26.33y S y , Fe 4 Co 1 Ni 1 Mo 1 La 6 Mn 2 O 26.33-y -S y , Fe 4 Co 1 Ni 1 Mo 1 Ce 6 Mn 2 O 26.33-y S y , Fe 4 Co 1 Ni 1 Mo 1 Nd 6 Mn 2 O 26.33-y S y , and Fe 4 Co 1 Ni 1 Mn 1 Cu 5 Pr 5 O 24.5-y S y .  
     
     
         8 . The catalyst of    claim 1   , additionally comprising an active metal sulfide.  
     
     
         9 . The catalyst of    claim 8   , wherein said active metal sulfide is selected from Zn, Mg, Ca, Se, Bi, Li, Na, K, and Cs.  
     
     
         10 . The catalyst of    claim 9   , wherein the formulation of the catalyst is selected from Fe 1 Co 1 Ni 1 Bi 5 Cu 5 O 16.33-y S y , Fe 1 Co 1 Ni 1 Zn 5 Cu 5 O 16.33-y S y , Fe 1 Co 1 Ni i Mg 5 Cu 5 O 16.33-y S y , Fe 1 Co 1 Ni 1 Ca 5 Cu 5 O 16.33-y S y , Fe 1 Co 1 Ni 1 Se 5 Cu 5 O 16.33-y S y , Fe 2 Mg 1 Li 1 Pr 2 Cu 2 Bi 2 O 12.67-y S y , Fe 4 Co 1 Ni 1 Mn 1 Cu 2 Li 8 O 15.33-y S y , Fe 2 Mg 1 Na 1 Pr 2 Cu 2 Bi 2 O 12.67-y S y , and Fe 4 Co 1 Ni 1 Mn 1 Cu 2 Na 8 O 15.33-y S y .  
     
     
         11 . A sulfide catalyst for the conversion of sulfur dioxide to elemental sulfur which has a high conversion rate in the presence of low levels or in the absence of H 2 O and H 2 , comprising; 
 A. a component selected from Li, Na, K, Cs, La, Ce, Pr, sulfides, or mixtures thereof, and    B. a carrier,    the composition of said catalyst being represented by the formula:    A a R b O x S y      where A is an alkali metal,    R is a rare earth metal,    a and b are independently ranged between 0 and 30, x+y is determined by the charge balance of the catalyst, and the proportion of x:y is between about 0:1 and 1:0.1.    
     
     
         12 . The catalyst of    claim 11   , wherein the formulation is selected from Li 2 O 1-y S y , Na 2 O 1-y S y , K 2 O 1-y S y , Cs 2 O 1-y S y , Pr 6 O 11-y S y , Ce 6 O 11-y S y , La 6 O 11-y S y    
     
     
         13 . A method of producing the catalyst of    claim 1    using sulfiding gas, comprising; 
 a) impregnating an alumina substrate with a solution of the metal nitrate salts reflecting the desired formulation,  
 b) drying said impregnated alumina substrate,  
 c) removing crystalline water from the dry impregnated alumina substrate,  
 d) decomposing the nitrate components of the impregnated alumina substrate  
 e) calcinating the impregnated substrate  
 f) gaseous sulfiding the impregnated, calcinated substrate.  
 
     
     
         14 . The method of    claim 13   , wherein in step a), the alumina substrate is select from alpha alumina, beta alumina, or gama alumina.  
     
     
         15 . The method of    claim 13   , wherein in step b), the solution is evaporated by vacuum, gentle heating, or allowing the solution to evaporate at ambient temperatures.  
     
     
         16 . The method of    claim 13   , wherein in step b), the solution is evaporated by heating to a temperature under about 200° C.  
     
     
         17 . The method of    claim 16   , wherein the solution is evaporated by heating to a temperature between about 100° C. to 150° C.  
     
     
         18 . The method of    claim 13   , wherein in step c), the crystalline water removal temperature is from 200° C. to 300° C.  
     
     
         19 . The method of    claim 18   , wherein the temperature is about 250° C.  
     
     
         20 . The method of    claim 13   , wherein in step d), the impregnated substrate is heated to between 300° C. and 450° C.  
     
     
         21 . The method of    claim 20   , wherein the substrate is heated to about 400° C.  
     
     
         22 . The method of    claim 13   , step d), wherein the substrate is heated for about 15 minutes to 6 hours.  
     
     
         23 . The method of    claim 13   , step e), wherein the calcination temperatures is from 500° C. to 700° C.  
     
     
         24 . The method of    claim 23   , wherein the calcination is at about 600° C.  
     
     
         25 . The method of    claim 23   , wherein the calcination occurs from about 2 hours to 2 days.  
     
     
         26 . The method of    claim 25   , wherein the calcination occurs for about 4 hours.  
     
     
         27 . The method of    claim 13   , wherein in step f), the sulfidation temperature is from about 200°C. to 700° C.  
     
     
         28 . The method of    claim 27   , wherein the sulfidation temperature is from about 350° C. to 650° C.  
     
     
         29 . The method of    claim 28   , wherein the sulfidation temperature is from about 500° C. to 620° C.  
     
     
         30 . The method of    claim 13   , wherein in step f) the sulfidation time is from about 10 minutes to five days.  
     
     
         31 . The method of    claim 30   , wherein the sulfidation time is from about 30 minutes to 24 hours.  
     
     
         32 . The method of    claim 31   , wherein the sulfidation time is about an hours.  
     
     
         33 . The method of    claim 13   , in step f) wherein the sulfiding gas concentration is from about 0.1% to 100%.  
     
     
         34 . The method of    claim 33   , wherein the concentration is from about 5%-40%.  
     
     
         35 . The method of    claim 34   , wherein the concentration is about 10%.  
     
     
         36 . The method of    claim 13   , wherein in step f) the gases used to treat the substrate are selected from the group of hydrogen sulfide gas, sulfur dioxide in a methane stream [SO 2 /CH 4 ], sulfur dioxide in a hydrogen stream [SO 2 /H 2 ], and sulfur dioxide in a carbon monoxide stream [SO 2 /CO] or combinations thereof.  
     
     
         37 . A method of producing the catalyst of    claim 1    using a sulfiding liquid comprising; 
 a) impregnating an alumina substrate with a solution of the metal salts reflecting the desired formulation,  
 b) drying said impregnated alumina substrate,  
 c) treating the impregnated alumina substrate with a sulfiding solution,  
 d) drying said sulfiding solution treated impregnated substrate,  
 e) removing crystalline water from the dry impregnated alumina substrate,  
 f) decomposing the nitrate components of the impregnated alumina substrate  
 g) calcinating the impregnated substrate.  
 
     
     
         38 . The method of    claim 37   , wherein in step a), the alumina substrate is select from alpha alumina, beta alumina, or gama alumina.  
     
     
         39 . The method of    claim 37   , wherein in step b), the solution is evaporated by vacuum, gentle heating, or allowing the solution to evaporate at ambient temperatures.  
     
     
         40 . The method of    claim 37   , wherein in step b) and d), the solution is evaporated by heating to a temperature under about 200° C.  
     
     
         41 . The method of    claim 40   , wherein the solution is evaporated by heating to a temperature between about 100° C. to 150° C.  
     
     
         42 . The method of    claim 37   , wherein in step c), the sulfiding solutions is provided in stoichiometric proportions to the metallic components, with an excess of sulfiding solution.  
     
     
         43 . The method of    claim 42   , wherein the excess is about 10%.  
     
     
         44 . The method of    claim 13   , wherein in step c) the sulfiding solution ranges from about 5% to 30% concentration.  
     
     
         45 . The method of    claim 44   , wherein the sulfiding solution is about a 10% concentration.  
     
     
         46 . The method of    claim 37   , wherein in step e), the crystalline water removal temperature is from 200° C. to 300° C.  
     
     
         47 . The method of    claim 46   , wherein the temperature is about 250° C.  
     
     
         48 . The method of    claim 37   , wherein in step f), the impregnated substrate is heated to between about 300° C. and 450° C.  
     
     
         49 . The method of    claim 48   , wherein the substrate is heated to about 400° C.  
     
     
         50 . The method of    claim 37   , step f), wherein the substrate is heated for about 15 minutes to 6 hours.  
     
     
         51 . The method of    claim 37   , step g), wherein the calcination temperatures is from 500° C. to 700° C.  
     
     
         52 . The method of    claim 51   , wherein the calcination is at about 600° C.  
     
     
         53 . The method of    claim 37   , wherein in step g) the calcination occurs from about 2 hours to 2 days.  
     
     
         54 . The method of    claim 53   , wherein the calcination occurs for about 4 hours.