Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology , Daejeon 34141, Republic of Korea.
School of Chemical and Biological Engineering, Seoul National University , Seoul 08826, Republic of Korea.
J Am Chem Soc. 2017 Dec 6;139(48):17694-17699. doi: 10.1021/jacs.7b11010. Epub 2017 Nov 22.
Direct methane conversion into value-added products has become increasingly important. Because of inertness of methane, cleaving the first C-H bond has been very difficult, requiring high reaction temperature on the heterogeneous catalysts. Once the first C-H bond becomes activated, the remaining C-H bonds are successively dissociated on the metal surface, hindering the direct methane conversion into chemicals. Here, a single-atom Rh catalyst dispersed on ZrO surface has been synthesized and used for selective activation of methane. The Rh single atomic nature was confirmed by extended X-ray fine structure analysis, electron microscopy images, and diffuse reflectance infrared Fourier transform spectroscopy. A model of the single-atom Rh/ZrO catalyst was constructed by density functional theory calculations, and it was shown that CH intermediates can be energetically stabilized on the single-atom catalyst. The direct conversion of methane was performed using HO in the aqueous solution or using O in gas phase as oxidants. Whereas Rh nanoparticles produced CO only, the single-atom Rh catalyst produced methanol in aqueous phase or ethane in gas phase.
直接将甲烷转化为有价值的产品变得越来越重要。由于甲烷的惰性，要断裂第一个 C-H 键非常困难，需要在多相催化剂上使用高温。一旦第一个 C-H 键被激活，剩余的 C-H 键就会在金属表面上相继解离，阻碍了甲烷直接转化为化学品。在这里，合成了分散在 ZrO 表面上的单原子 Rh 催化剂，并将其用于选择性激活甲烷。通过扩展 X 射线精细结构分析、电子显微镜图像和漫反射红外傅里叶变换光谱证实了 Rh 单原子性质。通过密度泛函理论计算构建了单原子 Rh/ZrO 催化剂的模型，表明 CH 中间体可以在单原子催化剂上稳定下来。使用水溶液中的 HO 或气相中的 O2 作为氧化剂进行甲烷的直接转化。虽然 Rh 纳米颗粒仅产生 CO，但单原子 Rh 催化剂在水相或气相中分别产生甲醇或乙烷。
