Dave C. Swalm School of Chemical Engineering and ‡Bagley College of Engineering, Mississippi State University , Mississippi State, Mississippi 39762, United States.
ACS Appl Mater Interfaces. 2018 Feb 7;10(5):4776-4785. doi: 10.1021/acsami.7b19299. Epub 2018 Jan 24.
A novel gold-copper-based silica-encapsulated mixed metal oxide (MMO) core-shell catalyst-with sub-5 nm MMO particles-was successfully synthesized via a reverse micelle process. The SiO-encapsulated MMO catalyst was reduced under hydrogen flow to produce an Au-Cu@SiO catalyst. X-ray diffraction and X-ray photoelectron spectroscopy characterization confirmed the presence of Au-Cu nanocomposites in the catalyst, while transmission electron microscopy characterization revealed the core-shell structure of the catalyst with the presence of sub-5 nm Au-Cu nanoparticle cores inside SiO shells. Brunauer-Emmett-Teller surface characterization identified that the catalyst is porous and bimodal in nature. The effects of promoter metal ion, catalyst pretreatment (calcination), and the presence of CO in the feed stream on carbon monoxide (CO) oxidation over the Au-Cu@SiO catalyst were examined in the temperature range of 50-400 °C. A catalyst stability test was performed at 300 °C by conducting a CO oxidation reaction for 116 h on stream. The catalyst exhibited excellent efficacy for CO oxidation, with ∼100% conversion to CO achieved at 400 °C. While the presence of Cu enhanced the CO conversion at low to intermediate temperatures (50-300 °C), silica encapsulation of the Au-Cu nanocomposites facilitated remarkable stability of the catalyst. The activity of the Au-Cu@SiO catalyst is suitable for its application in automotive after-treatment devices, especially in low-temperature combustion engine exhausts.
一种新型的金-铜基二氧化硅包裹的混合金属氧化物（MMO）核壳催化剂-具有亚 5nm 的 MMO 颗粒-通过反胶束法成功合成。SiO2 包裹的 MMO 催化剂在氢气流下还原，生成 Au-Cu@SiO 催化剂。X 射线衍射和 X 射线光电子能谱表征证实了催化剂中存在 Au-Cu 纳米复合材料，而透射电子显微镜表征则揭示了催化剂的核壳结构，其中存在亚 5nm 的 Au-Cu 纳米颗粒核包裹在 SiO2 壳内。Brunauer-Emmett-Teller 表面特性表明，该催化剂具有多孔性和双峰特性。考察了促进金属离子、催化剂预处理（煅烧）以及进料流中 CO 的存在对 Au-Cu@SiO 催化剂上一氧化碳（CO）氧化的影响，反应温度范围为 50-400°C。在 300°C 下进行了 CO 氧化反应 116 小时的催化剂稳定性测试。该催化剂在 CO 氧化方面表现出优异的效果，在 400°C 下达到了约 100%的 CO 转化率。虽然 Cu 的存在提高了 CO 在低温到中温（50-300°C）下的转化率，但 Au-Cu 纳米复合材料的 SiO2 包裹提高了催化剂的显著稳定性。Au-Cu@SiO 催化剂的活性适合用于汽车尾气后处理装置，特别是在低温燃烧发动机尾气中。
