Pinos-Vélez Verónica, Osegueda Oscar, Crivoi Dana Georgiana, Llorca Jordi, García-García F Javier, Álvarez Mayra G, Medina Francesc, Dafinov Anton
Chemical Engineering Department, Rovira i Virgili University, Av Paisos Catalans 26, 43007Tarragona, Spain.
Departamento de Recursos Hídricos y Ciencias Ambientales, Universidad de Cuenca, Av. 12 de abril,010207Cuenca, Ecuador.
Chem Mater. 2022 Oct 11;34(19):8760-8768. doi: 10.1021/acs.chemmater.2c01951. Epub 2022 Sep 28.
A key step in creating efficient and long-lasting catalysts is understanding their deactivation mechanism(s). On this basis, the behavior of a series of Pd/corundum materials during several hydrogen adsorption/desorption cycles was studied using temperature-programmed desorption coupled with mass spectrometry and aberration-corrected transmission electron microscopy. The materials, prepared by impregnation and by sputtering, presented uniform well-dispersed Pd nanoparticles. In addition, single atoms and small clusters of Pd were only detected in the materials prepared by impregnation. Upon exposure to hydrogen, the Pd nanoparticles smaller than 2 nm and the single atoms did not present any change, while the larger ones presented a core-shell morphology, where the core was Pd and the shell was PdH . The results suggest that the long-term activity of the materials prepared by impregnation can be attributed solely to the presence of small clusters and single atoms of Pd.
制备高效且持久的催化剂的关键一步是了解其失活机制。在此基础上，采用程序升温脱附结合质谱法和像差校正透射电子显微镜，研究了一系列钯/刚玉材料在多个氢吸附/脱附循环过程中的行为。通过浸渍法和溅射法制备的材料呈现出均匀分散良好的钯纳米颗粒。此外，仅在通过浸渍法制备的材料中检测到单原子和小的钯簇。暴露于氢气中时，小于2纳米的钯纳米颗粒和单原子没有任何变化，而较大的颗粒呈现出核壳形态，其中核为钯，壳为PdH。结果表明，通过浸渍法制备的材料的长期活性可完全归因于小钯簇和单原子的存在。
