| STUDY |
Catalytic combustion of light hydrocarbons using perovskites is one nanoparticle application studied by authors. Perovskites show promise for oxidizing methane in air at temperatures that are low enough to avoid forming harmful nitrogen oxides (NOx). Rather than preparing perovskites via conventional solid-state methods or combustion techniques, author's team uses a coprecipitation route based on reacting metal nitrate solutions with a base. The procedure leads to smaller particles and therefore to higher surface area products than other preparation methods. In addition, the method makes it straightforward to vary the metal components, leading to a large collection of perovskites--even nonstoichiometric compounds. Because of the synthesis flexibility, author's research group was able to compare the effect of various components on catalytic performance systematically. For example, authors found that lanthanum manganate is a more active methane conversion catalyst than compounds in which nickel, cobalt, or iron replace manganese. Just the same, the nickel compound was observed to be an effective catalyst. So the researchers prepared a family of LaMn1-yNiyO3- delta compounds and varied the nickel content in search of the most active catalyst. Authors reported that the optimum nickel concentration is roughly 40%. The team also prepared perovskite nanoparticles with the general formula La1-xAxMnO3 delta in which "A" represents barium, strontium, europium, gadolinium, and other elements. Author noted that compounds with group IIA elements are active methane oxidation catalysts. One example is La0.4Sr0.6-manganate, which is noteworthy because of its 370 °C light-off temperature--the temperature at which methane begins to combust catalytically. That temperature compares well with the roughly 350 °C light-off temperature of palladium-based catalysts. "But the perovskites are attractive. author noted "because they don't include expensive noble metals." Author pointed out that a related LaSr-manganate stands up to high concentrations of steam better than some supported noble metal catalysts |
| UPDATE | 09.02 |
| AUTHOR | This data is not available for free |
| LITERATURE REF. | This data is not available for free |
|
Want more information ? Interested in the hidden information ? Click here and do your request. |