SiC Catalyzed CO
2Hydrogenation reaction diagram
Recently, the University of Science and Technology of China Hefei Microscale National Research Center for Physical Sciences and the School of Chemistry and Materials Science Professor Zeng Jie's team took silicon carbide as the research object and found that the hydrophilicity and hydrophobicity play an important role in the catalytic reaction process, and from the atomic scale The 'source' of this effect is explained: Hydrophilic silicon carbide QDs have a hydroxyl-rich structure on the surface, which can effectively promote the activation of carbon dioxide molecules. Research results with Molecular-Level Insight into How Hydroxyl Groups Boost Catalytic Activity in CO 2 Hydrogenation into Methanol is published online on Chem. The author's co-first author is PhD student Peng Yaohan, Ph.D. student Wang Liangbing and special associate researcher Luo Qiquan.
Catalytic reactions occur on the surface of the catalyst and can often regulate the surface properties of the catalyst to increase the activity of the catalytic reaction, selectivity and stability. Hydrophobicity is an important surface property parameter. In the past, the understanding of the nature of hydrophilicity and hydrophobicity basically stayed in the past. For the enrichment of substrate molecules, for example, the surface of a hydrophilic catalyst can easily adsorb alcohols and other species, while the hydrophobic surface can easily adsorb esters, ketones, and other species. However, this understanding is relatively macroscopic, and therefore from the atomic scale. It reveals that the nature of the catalytic reaction is influenced by the hydrophilicity and hydrophobicity of the catalyst surface, which is of great significance for the design of high-efficiency catalysts.
The researchers compared the activity of carbon dioxide hydrogenation of commercial silicon carbide and quantum dot silicon carbide. It was found that the hydrophilic quantum dot silicon carbide has a mass activity lower than that of hydrophobic commercial silicon carbide under the conditions of 32 atm and 150oC. Three orders of magnitude higher. The apparent activation energy of QD silicon carbide is (48.6 kJ mol-1), which is only about half of that of commercial silicon carbide (94.7 kJ mol-1). Using in-situ synchrotron X-ray photoelectron spectroscopy and Near-edge X-ray absorption spectroscopy and other technical means, the researchers found that the hydrophilic quantum dots silicon carbide surface is rich in hydroxyl groups, H atoms on the hydroxyl group can directly interact with carbon dioxide to form HCOO* intermediate species, and thus directly participate in the catalytic reaction process Medium. This special reaction path reduces the activation energy of HCOO* formation and thus promotes the activation of carbon dioxide. Based on this knowledge, the researchers constructed a series of surface-enriched catalysts that are 2The activity in the hydrogenation reaction is an order of magnitude higher than the hydroxyl-free structure. 2The understanding of the role of hydrogenation reaction has broken through the traditional understanding of hydrophilicity and hydrophobicity, and has sought for more efficient CO in the future. 2Hydrogenation catalysts open up new ideas.
The research work was supported by the Frontier Science Key Research Project of the Chinese Academy of Sciences, the National Major Scientific Research Project, and the National Natural Science Foundation.
