Sulfur-resistant catalyst support material
A catalyst support material and a catalyst system incorporating said support material along with a method of making the same is provided for use in applications in which the support material is exposed to sulfur-containing impurities. The catalyst support material generally comprises an inorganic oxide base material having a surface and pores of predetermined size; and a zirconium layer adapted to interact with the surface and sized to be received by the pores of the base material. The catalyst support material being prepared by applying a layer of a zirconium compound to the surface and pores of an inorganic oxide base material followed by calcination in order to convert the zirconium compound to a metal, a metal oxide, or a mixture thereof.
1. A catalyst support material for use in applications in which the support material is exposed to sulfur-containing impurities in an exhaust gas, the catalyst support material comprising:
an inorganic oxide base material having a BET surface area in the range of 20 to 400 m 2 /g and pores defined by a pore volume in the range of 0.1 cc/g to 2 cc/g and a pore diameter between 25 angstroms to 1000 angstroms; the inorganic oxide base material being alumina, silica, titania, or combinations thereof; and
a zirconium layer derived from a coating of a zirconium compound, applied to the surface and drawn into the pores of the base material by capillary action; the amount of zirconium in the zirconium layer ranges between about 5% and 20% by weight;
wherein the catalyst support material exhibits a resistance to the absorption of the sulfur-containing impurities.
2. The catalyst support material of claim 1 , wherein the zirconium layer is zirconium metal, zirconium oxide, or a mixture thereof.
3. The catalyst support material of claim 1 , wherein the surface of the base material has a size given as a BET surface area in the range of 75 to 300 m 2 /g.
4. The catalyst support material of claim 1 , wherein the inorganic oxide base material is one selected from the group of γ-alumina, δ-alumina, θ-alumina, a-alumina, aluminum monohydrate, fumed silica, precipitated silica, silica gel, rutile TiO 2 , anatase TiO 2 , brookite TiO 2 , cubic forms of titania, and combinations thereof.
5. The catalyst support material of claim 1 , wherein the catalyst support material has the shape of a powder, beads, or pellets.
6. A supported catalyst system for use in catalyzing reactions subjected to the presence of sulfur-containing impurities in an exhaust gas, the catalyst system comprising a catalyst and a catalyst support material; the catalyst support material comprising:
an inorganic oxide base material having a BET surface area in the range of 20 to 400 m 2 /g and pores defined by a pore volume in the range of 0.1 cc/g to 2 cc/g and a pore diameter between 25 angstroms to 1000 angstroms; the inorganic oxide base material being alumina, silica, titania, or combinations thereof; and
a zirconium layer derived from a coating of a zirconium compound, applied to the surface and drawn into the pores of the base material by capillary action; the amount of zirconium in the zirconium layer ranges between about 5% and 20% by weight;
wherein the catalyst support material exhibits a resistance to the absorption of the sulfur-containing impurities.
7. The supported catalyst system of claim 6 , wherein the catalyst is one selected from the group of transition metals, transition metal oxides, alkaline earth metal oxides, rare-earth oxides, and mixtures thereof.
8. The supported catalyst system of claim 6 , wherein the catalyst is incorporated in an amount ranging from about 0.1 to 10 wt. %.
9. A method of preparing a catalyst support material for use in a supported catalyst system that is exposed to the presence of sulfur-containing impurities in an exhaust gas, the method comprising the steps of:
providing an inorganic oxide base material having a BET surface area in the range of 20 to 400 m2/g and pores defined by a pore volume in the range of 0.1 cc/g to 2 cc/g and a pore diameter between 25 angstroms to 1000 angstroms; the inorganic oxide base material being alumina, silica, titania, or combinations thereof;
providing a zirconium compound;
applying a coating of the zirconium compound to at least a portion of the surface and drawn into the pores by capillary action of the base material to form a coated base material; and
converting the coating of the zirconium compound into a layer of zirconium metal, zirconium oxide, or a mixture thereof;
wherein the amount of zirconium in the zirconium layer ranges between about 5% and 20% by weight;
wherein the catalyst support material exhibits a resistance to the absorption of the sulfur-containing impurities.
10. The method of claim 9 , wherein forming a coated base material by applying a coating of the zirconium compound to at least a portion of the surface and drawn into the pores of the base material is done using a process selected from the group of impregnation, co-precipitation, and spray drying (SD).
11. The method of claim 9 , wherein the zirconium compound that is applied to the surface and into the pores of the base material is selected from the group of zirconium acetate, zirconium citrate, and zirconium oxalate.
12. The method of claim 9 , wherein converting the coating of zirconium compound into the zirconium metal, zirconium oxide, or mixture thereof is accomplished by calcining the coated base material at a temperature in the range of 500 to 1200° C.
13. The supported catalyst system of claim 6 , wherein the zirconium layer in the catalyst support material is zirconium metal, zirconium oxide, or a mixture thereof.
14. The supported catalyst system of claim 6 , wherein the surface of the base material in the catalyst support material has a size given as a BET surface area in the range of about 75 to 300 m 2 /g.
15. The supported catalyst system of claim 6 , wherein the inorganic oxide base material in the catalyst support material is one selected from the group of γ-alumina, δ-alumina, θ-alumina, a-alumina, aluminum monohydrate, fumed silica, precipitated silica, silica gel, rutile TiO 2 , anatase TiO 2 , brookite TiO 2 , cubic forms of titania, and combinations thereof.
16. The supported catalyst system of claim 6 , wherein the catalyst support material has the shape of a powder, beads, or pellets.
17. The catalyst support material of claim 1 , wherein the catalyst support material exhibits at least a 0.2% decrease in the amount of sulfur-containing impurities that are absorbed onto the surface or within the pores as compared to the same inorganic oxide base material in the absence of the zirconium layer as determined by thermogravimetric analysis.
18. The catalyst support material of claim 1 , wherein the catalyst support material comprises about 84% of the inorganic oxide base material and about 16% of the zirconium layer.