Abstract
Direct methane conversion (DMC) to high value-added products is of significant importance for the effective utilization of CH4 to combat the energy crisis. However, there are ongoing challenges in DMC associated with the selective C−H activation of CH4. The quest for high-efficiency catalysts for this process is limited by the current drawbacks including poor activity and low selectivity. Here we show a cerium dioxide (CeO2) nanowires supported rhodium (Rh) single-atom (SAs Rh-CeO2 NWs) that can serve as a high-efficiency catalyst for DMC to oxygenates (i.e., CH3OH and CH3OOH) under mild conditions. Compared to Rh/CeO2 nanowires (Rh clusters) prepared by a conventional wet-impregnation method, CeO2 nanowires supported Rh single-atom exhibits 6.5 times higher of the oxygenates yield (1231.7 vs. 189.4 mmol gRh−1 h−1), which largely outperforms that of the reported catalysts in the same class. This work demonstrates a highly efficient DMC process and promotes the research on Rh single-atom catalysts in heterogeneous catalysis.
Highlights
Direct methane conversion (DMC) to high value-added products is of significant importance for the effective utilization of CH4 to combat the energy crisis
Transmission electron microscopy (TEM) image shows that uniform CeO2 NWs with a diameter and length of ~ 6.2 nm and ~ 260 nm are obtained (Supplementary Fig. 1)
No Rh nanoparticles are observed in TEM image, indicating that Rh atoms are well dispersed in SAs RhCeO2 NWs (Fig. 1a)
Summary
Direct methane conversion (DMC) to high value-added products is of significant importance for the effective utilization of CH4 to combat the energy crisis. We show a cerium dioxide (CeO2) nanowires supported rhodium (Rh) single-atom (SAs Rh-CeO2 NWs) that can serve as a high-efficiency catalyst for DMC to oxygenates (i.e., CH3OH and CH3OOH) under mild conditions. Noble metals-based single-atom catalysts (SACs) have emerged as a new frontier in heterogenous catalysis because of large ratio of surface atoms, low-coordination environment of metal centers, and strong metal–support interactions[11,12,13] They have been widely studied in diverse processes with superior catalytic performance, including CO oxidation, CH4 conversion, oxygen reduction, water gas shift reaction, and so on[14,15,16]. The Rh/CeO2 NWs tend to overoxidize CH4 to COx species with the assistance of ∙OH, leading to a low oxygenates’ yield and selectivity (189.4 mmol gRh−1 h−1 and 56.4%)
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