Gonçalves Renato V, Wojcieszak Robert, Wender Heberton, Sato B Dias Carlos, Vono Lucas L R, Eberhardt Dario, Teixeira Sergio R, Rossi Liane M
†Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Avenida Prof. Lineu Prestes 748, São Paulo 05508-000, São Paulo, Brazil.
§Unité de Catalyse et Chimie du Solide, UCCS, UMR CNRS 8181, F-59655 Villeneuve d'Ascq, France.
ACS Appl Mater Interfaces. 2015 Apr 22;7(15):7987-94. doi: 10.1021/acsami.5b00129. Epub 2015 Apr 7.
Copper catalysts are very promising, affordable alternatives for noble metals in CO oxidation; however, the nature of the active species remains unclear and differs throughout previous reports. Here, we report the preparation of 8 nm copper nanoparticles (Cu NPs), with high metallic content, directly deposited onto the surface of silica nanopowders by magnetron sputtering deposition. The as-prepared Cu/SiO2 contains 85% Cu0 and 15% Cu2+ and was enriched in the Cu0 phase by H2 soft pretreatment (96% Cu0 and 4% Cu2+) or further oxidized after treatment with O2 (33% Cu0 and 67% Cu2+). These catalysts were studied in the catalytic oxidation of CO under dry and humid conditions. Higher activity was observed for the sample previously reduced with H2, suggesting that the presence of Cu-metal species enhances CO oxidation performance. Inversely, a poorer performance was observed for the sample previously oxidized with O2. The presence of water vapor caused only a small increase in the temperature require for the reaction to reach 100% conversion. Under dry conditions, the Cu NP catalyst was able to maintain full conversion for up to 45 h at 350 °C, but it deactivated with time on stream in the presence of water vapor.
铜催化剂是一氧化碳氧化反应中替代贵金属的非常有前景且价格低廉的选择；然而，活性物种的性质仍不明确，并且在以往的报道中各不相同。在此，我们报告了通过磁控溅射沉积直接将高金属含量的8纳米铜纳米颗粒（Cu NPs）沉积在二氧化硅纳米粉末表面的制备方法。所制备的Cu/SiO₂含有85%的Cu⁰和15%的Cu²⁺，通过氢气软预处理使其富含Cu⁰相（96% Cu⁰和4% Cu²⁺），或者在用氧气处理后进一步氧化（33% Cu⁰和67% Cu²⁺）。对这些催化剂在干燥和潮湿条件下的一氧化碳催化氧化反应进行了研究。观察到先前用氢气还原的样品具有更高的活性，这表明铜金属物种的存在增强了一氧化碳氧化性能。相反，先前用氧气氧化的样品表现出较差的性能。水蒸气的存在仅使反应达到100%转化率所需的温度略有升高。在干燥条件下，Cu NP催化剂在350℃下能够保持高达45小时的完全转化，但在有水蒸气存在的情况下，它会随着反应时间的延长而失活。
