Catalyst for use in the catalytic reduction of sulfur contained in a gas stream and method of making and using such catalyst
Presented is a catalyst composition having exceptional properties for converting sulfur, sulfur compounds, and carbon monoxide contained in gas streams by catalyzed hydrolysis, hydrogenation and water-gas shift reactions. The catalyst comprises underbedded molybdenum and cobalt with an overlayer of molybdenum and cobalt. These metals are present in the catalyst within certain concentration ranges and relative weight ratios. The underbedded metals are present in the catalyst within a specified range relative to the overlayer and total metals. The underbedded metals are formed by co-mulling an inorganic oxide with the catalytically active metals of molybdenum and cobalt. The co-mulled mixture is calcined and then impregnated with overlaid molybdenum and cobalt.
1. A catalyst composition useful in the catalytic reduction of sulfur compounds contained in a gas stream, wherein said catalyst composition comprises: a calcined co-mulled mixture of an inorganic oxide, a first molybdenum compound, and a first cobalt compound, an overlayer of a second molybdenum compound and a second cobalt compound disposed on the calcined co-mulled mixture such that the catalyst composition has underbedded molybdenum, underbedded cobalt, overlaid molybdenum, and overlaid cobalt.
2. The catalyst as recited in claim 1 , wherein said catalyst composition has a total molybdenum content of at least 7.4 wt. % and a total cobalt content of at least 2.7 wt. %, with both wt. % based on a total weight of said catalyst composition and the respective metal component as an oxide.
3. The catalyst as recited in claim 2 , wherein said catalyst composition has a molybdenum ratio of underbedded molybdenum content-to-total molybdenum content in a range of from 1:5 to 4:5, and a cobalt ratio of underbedded cobalt content-to-total cobalt content in a range of from 1:5 to 4:5.
4. The catalyst as recited in claim 3 , wherein said catalyst composition has a total metals ratio of total molybdenum content-to-total cobalt content in a range of from 1.5:1 to 6:1.
5. The catalyst as recited in claim 4 , wherein said catalyst composition has a total inorganic oxide content in a range of from 65 to 90 wt. % based on the total weight of said catalyst composition.
6. The catalyst as recited in claim 5 , wherein said underbedded molybdenum content is in a range of from 1.1 to 12.5 wt. % and said underbedded cobalt content is in a range of from 0.5 to 5 wt. % based on the total weight of the said catalyst composition and the respective metal component as an oxide.
7. A process, comprising:
introducing a gas stream, comprising a sulfur compound or carbon monoxide, or both, into a reactor that defines a reaction zone containing the catalyst composition of claim 1 ; and
contacting said gas stream with said catalyst composition under hydrolysis reaction conditions.
8. The process as recited in claim 7 , wherein said sulfur compound is present in said gas stream at a sulfur compound concentration in the range of from 0.01 volume % to 2 volume %, and wherein said sulfur compound is selected from the group of compounds consisting of carbonyl sulfide (COS), carbon disulfide (CS 2 ), sulfur dioxide (SO 2 ), and elemental sulfur (Sx).
9. The process as recited in claim 8 , wherein said hydrolysis reaction conditions include an inlet temperature to said reactor that is in a range of from 115° C. to 300° C.
10. The process as recited in claim 8 , wherein said reduced concentration of sulfur compound in said treated gas is less than 75 ppmv.