Hydrothermally stable methane oxidation catalyst
A method of manufacturing a methane oxidation catalyst and methane oxidation catalysts formed by the method are provided. The method includes providing a palladium (Pd)-based catalyst including Pd dispersed onto a support. A magnesium (Mg) precursor is introduced to the Pd-based catalyst by one of ion exchange or incipient wetness impregnation. After introducing the magnesium precursor to the Pd-based catalyst, the catalyst is dried and subjected to a final heat treatment that includes hydrothermal calcination. A method of methane oxidation in a lean exhaust environment via the methane oxidation catalyst is also provided.
1. A method of manufacturing a methane oxidation catalyst, the method comprising:
providing a palladium (Pd)-based catalyst including Pd dispersed onto a support;
introducing a magnesium (Mg) precursor to the Pd-based catalyst by one of ion exchange or incipient wetness impregnation; and
after introducing the magnesium precursor to the Pd-based catalyst, drying the catalyst and subjecting the catalyst to a final heat treatment;
wherein the final heat treatment is hydrothermal calcination performed at a temperature in the range of 400 to 800° C. for a time period of 4 hours or more in the presence of water, oxygen, and nitrogen.
2. The method of claim 1 , wherein the step of providing a Pd-based catalyst includes introducing a Pd precursor to the support.
3. The method of claim 2 , wherein the Pd precursor is Pd(NO 3 ) 2 .2H 2 O.
4. The method of claim 2 , wherein the support is a small-pore zeolite having a SiO 2 :Al 2 O 3 ratio of 10:1 or greater.
5. The method of claim 2 , wherein the Pd precursor is introduced to the support by one of ion exchange or incipient wetness impregnation.
6. The method of claim 5 , wherein the Pd precursor is dispersed onto the support in an amount in the range of 1 to 5 wt. % based on the weight of the support.
7. The method of claim 5 , wherein the Pd precursor and Mg precursor are added sequentially, in that order.
8. The method of claim 1 , wherein the support is a high surface area Al 2 O 3 having a surface area greater than 90 m 2 /g.
9. The method of claim 1 , wherein the Mg precursor is Mg(NO 3 ) 2 .6H 2 O.
10. The method of claim 1 , wherein the molar ratio of Mg:Pd in the catalyst is in the range of 1:1 to 3:1.
11. The method of claim 1 , wherein the step of drying the catalyst is performed at a temperature in the range of 100 to 140° C. for a time period of between 2 and 5 hours.
12. A method of manufacturing a methane oxidation catalyst, the method comprising:
providing a palladium (Pd)-based catalyst including Pd dispersed onto a support;
introducing a magnesium (Mg) precursor to the Pd-based catalyst by one of ion exchange or incipient wetness impregnation; and
after introducing the magnesium precursor to the Pd-based catalyst, drying the catalyst and subjecting the catalyst to a final heat treatment;
wherein the step of providing a Pd-based catalyst includes introducing a Pd precursor to the support;
wherein the Pd precursor is introduced to the support by one of ion exchange or incipient wetness impregnation;
wherein the Pd precursor and Mg precursor are added sequentially, in that order;
wherein prior to the addition of the Mg precursor, the Pd-based catalyst is subjected to an intermediate heat treatment that is hydrothermal calcination performed at a temperature in the range of 400 to 800° C. for a time period of 4 hours or more in the presence of water, oxygen, and nitrogen.