Copper-Manganese Spinel Catalysts and Methods of Making Same
Disclosed here are material formulations of use in the conversion of exhaust gases, where the formulations may include Copper (Cu), Manganese (Mn) and combinations thereof. Combinations of use may include Cu—Mn Spinels. Catalysts including these materials may be synthesized by methods including co-precipitation, co-milling, templating, and the sol-gel method, using any suitable carrier material oxide and any suitable oxygen storage material. The properties of the catalysts disclosed may vary according to the calcining temperature, where stoichiometric and non-stoichiometric Cu—Mn Spinels may form when calcining suitable formulations at suitable temperatures.
1 . A catalyst system, comprising:
a substrate;
a washcoat suitable for deposition on the substrate, comprising at least one oxide solid selected from the group consisting of at least one of a carrier metal oxide, and a catalyst; and
an overcoat suitable for deposition on the substrate, comprising at least one overcoat oxide solid selected from the group consisting of at least one of a carrier metal oxide, and a catalyst;
wherein at least one of the catalysts comprises at least one spinel structured compound having the formula AB 2 O 4 , wherein each of A and B is selected from the group consisting of at least one of copper and manganese and wherein a portion of the at least one spinel structured compound is stoichiometric; and
wherein the at least one spinel structured compound is formed by calcination at a temperature in a range of about 300° C. to about 800° C.
2 . The catalyst system of claim 1 , wherein a portion of the at least one spinel structured compound is non-stoichiometric.
3 . The catalyst system of claim 2 , wherein the at least one spinel structured compound is in mixed phase with copper oxide or manganese oxide.
4 . The catalyst system of claim 3 , wherein the mixed phase has a Cu/(Cu—Mn) molar ratio of about 0.50.
5 . The catalyst system of claim 3 , wherein the mixed phase has a Cu/(Cu—Mn) molar ratio of about 0.33.
6 . The catalyst system of claim 1 , wherein the non-stoichiometric portion of the at least one spinel structured compound is formed by calcination at about 700° C.
7 . The catalyst system of claim 1 , wherein the at least one spinel structured compound is formed by calcination at a temperature in a range of about 300° C. to about 600° C.
8 . The catalyst of claim 1 , wherein the at least one carrier metal oxide is selected from the group consisting of cerium oxide, alumina, lanthanum doped alumina, titanium oxide, zirconia, ceria-zirconia, Nb 2 O 5 —ZrO 2 , and combinations thereof.
9 . The catalyst system of claim 1 , wherein the washcoat further comprises at least one oxygen storage material selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, yttrium oxide, lanthanide oxides, actinide oxides, and combinations thereof.
10 . The catalyst system of claim 1 , wherein the overcoat further comprises at least one oxygen storage material selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, yttrium oxide, lanthanide oxides, actinide oxides, and combinations thereof.
11 . The catalyst system of claim 1 , wherein the catalyst is prepared by a method selected from the group consisting of co-milling, co-precipitation, impregnation, stabilization, templating, and the sol-gel method.
12 . The catalyst system of claim 11 , wherein the method uses at least one material selected from the group consisting of copper nitrate, copper acetate, manganese nitrate, manganese acetate, and combinations thereof.
13 . The catalyst system of claim 11 , wherein a co-precipitant agent is selected from the group consisting of an NaOH solution, an Na 2 CO 3 solution, and an NH4OH solution and is aged from about 12 hours to about 36 hours.
14 . The catalyst system of claim 1 , wherein a T50 conversion temperature for the hydrocarbons is less than 500 degrees Celsius.
15 . The catalyst system of claim 1 , wherein a T50 conversion temperature for nitrogen oxide is about 350 degrees Celsius.
16 . The catalyst system of claim 1 , wherein a T50 conversion temperature for the carbon monoxide is less than about 300 degrees Celsius.
17 . The catalyst system of claim 1 , wherein the stoichiometric portion of the at least one spinel structured compound has a greater NO conversion rate compared to the non-stoichiometric portion of the at least one spinel structured compound under exhaust rich condition.