Strong metal-support interaction between palladium and gallium oxide within monodisperse nanoparticles: self-supported catalysts for propyne semi-hydrogenation

The strong metal-support interaction (SMSI) between metals and reducible supports (e.g., CeO2, TiO2, and SnO2), which has been widely investigated, plays a very important role in heterogeneous catalysis. We report the first example of SMSI between palladium (Pd) and gallium oxide (Ga2O3) within a PdGa nanoparticle (denoted as PdxGay NP, where x:y is the atomic ratio of Pd and Ga). The typical features of classic SMSI, such as electron transfer between Ga2O3 and Pd and suppression of H-2 and CO adsorption, are successfully observed on PdxGay NPs. Detailed characterizations and control experiments demonstrate that the coexistence of PdGa alloy and Ga2O3 in PdxGay NPs plays a vital role in the formation of SMSI. To systematically study the effects of SMSI on catalytic performance, PdxGay NPs were used as self-supported catalysts for propyne semi-hydrogenation (PSH), a critical process for removing trace propyne from propylene in industry. It is shown that optimized Pd0.34Ga1 NPs give a propylene selectivity of 98.2% at a propyne conversion of 96.6% at 30 degrees C and atmospheric pressure, which is much higher than that of pure Pd NPs and Pd/Ga2O3 catalysts prepared by a conventional wet-impregnation method. The reaction paths of PSH on PdxGay NPs have been further revealed by density functional theory (DFT) calculations. This work may not only deepen the basic understanding of SMSI, but also promote the design and application of heterogeneous catalysts. (C) 2020 Elsevier Inc. All rights reserved.

Automated summary

This study reports the first example of strong metal-support interaction (SMSI) between palladium and gallium oxide within PdGa nanoparticles, demonstrating the important role of PdGa alloy and Ga2O3 coexistence in the formation of SMSI. The PdxGay NPs used as catalysts show higher catalytic performance for propyne semi-hydrogenation compared to conventional catalysts, indicating their potential in catalyst design and application. The reaction pathways of PSH on PdxGay NPs have been further elucidated by density functional theory calculations, providing a deeper understanding of SMSI and its implications for heterogeneous catalysis.