Nanostellar Inc., 3696 Haven Avenue, Redwood City, CA 94063, USA.
Science. 2012 Aug 17;337(6096):832-5. doi: 10.1126/science.1225091.
Oxidation of nitric oxide (NO) for subsequent efficient reduction in selective catalytic reduction or lean NO(x) trap devices continues to be a challenge in diesel engines because of the low efficiency and high cost of the currently used platinum (Pt)-based catalysts. We show that mixed-phase oxide materials based on Mn-mullite (Sm, Gd)Mn(2)O(5) are an efficient substitute for the current commercial Pt-based catalysts. Under laboratory-simulated diesel exhaust conditions, this mixed-phase oxide material was superior to Pt in terms of cost, thermal durability, and catalytic activity for NO oxidation. This oxide material is active at temperatures as low as 120°C with conversion maxima of ~45% higher than that achieved with Pt. Density functional theory and diffuse reflectance infrared Fourier transform spectroscopy provide insights into the NO-to-NO(2) reaction mechanism on catalytically active Mn-Mn sites via the intermediate nitrate species.
一氧化氮（NO）的氧化对于随后在选择性催化还原或贫 NO(x) 陷阱装置中的有效还原仍然是柴油发动机中的一个挑战，因为目前使用的基于铂（Pt）的催化剂效率低且成本高。我们表明，基于锰莫来石（Sm、Gd）Mn(2)O(5)的混合相氧化物材料是当前商业 Pt 基催化剂的有效替代品。在实验室模拟的柴油废气条件下，这种混合相氧化物材料在成本、热耐久性和 NO 氧化的催化活性方面优于 Pt。该氧化物材料在低至 120°C 的温度下具有活性，转化率最大值比 Pt 高约 45%。密度泛函理论和漫反射红外傅里叶变换光谱通过中间硝酸盐物种为通过催化活性 Mn-Mn 位的 NO 到 NO(2)反应机制提供了深入了解。
