Catalyst for use in the catalytic reduction of sulfur contained in a gas stream and methods 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 method for making a catalyst composition useful in the catalytic reduction of sulfur compounds contained in a gas stream, wherein said method comprises:
a) co-mulling an inorganic oxide, a first molybdenum compound, and a first cobalt compound to provide a co-mulled mixture;
b) forming said co-mulled mixture into a formed agglomerate;
c) drying and calcining said formed agglomerate under first calcination conditions to provide a calcined formed agglomerate;
d) incorporating a second molybdenum compound and a second cobalt compound into said calcined formed agglomerate to provide an impregnated formed agglomerate; and
e) drying and calcining said impregnated formed agglomerate under second calcination conditions to provide said catalyst composition,
wherein said catalyst composition includes both underbedded molybdenum and underbedded cobalt that are overlaid with both molybdenum and cobalt.
2. The method 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 a respective metal component as an oxide.
3. The method 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 method 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 method 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 a total weight of said catalyst composition.
6. The method 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 a total weight of the said catalyst composition and the respective metal component as an oxide.
7. The method as recited in claim 6 , wherein said first calcination conditions include calcining said formed agglomerate in the presence of oxygen and at a first calcination temperature in a range of from 300° C. to 800° C., and wherein said second calcination conditions include calcining said impregnated formed agglomerate in the presence of oxygen under a second calcination temperature in a range of from 300° C. to 800° C.