Uncovering Structure–Activity Relationships in Pt/CeO₂ Catalysts for Hydrogen-Borrowing Amination

Abstract

The hydrogen-borrowing amination of alcohols is a promising route to produce amines. In this study, experimental parameters involved in the preparation of Pt/CeO2 catalysts were varied to assess how physicochemical properties influence their performance in such reactions. An amination reaction between cyclopentanol and cyclopentylamine was used as the model reaction for this study. The Pt precursor used in the catalyst synthesis and the properties of the CeO2 support were both found to strongly influence catalytic performance. Aberration corrected scanning transmission electron microscopy revealed that the most active catalyst comprised linearly structured Pt species. The formation of these features, a function result of epitaxial Pt deposition along the CeO2 [100] plane, appeared to be dependent on the properties of the CeO2 support and the Pt precursor used. Density functional theory calculations subsequently confirmed that these sites were more effective for cyclopentanol dehydrogenationconsidered to be the rate-determining step of the processthan Pt clusters and nanoparticles. This study provides insights into the desirable catalytic properties required for hydrogen-borrowing amination but has relevance to other related fields. We consider that this study will provide a foundation for further study in this atom-efficient area of chemistry.

Revealing the Size Effect of Ceria Nanocube-Supported Platinum Nanoparticles in Complete Propane Oxidation

“…Three composite models, namely Pt 5 /CeO 2 (100), Pt 9 /CeO 2 (100), and Pt 13 /CeO 2 (100), were constructed and fully optimized based on previous studies. 31,46 These models are representative of small, medium, and large Pt NPs supported on CeO 2 (100), as illustrated in Figure 7a−c.…”

“…The DFT-D3 scheme was applied throughout the calculations to take the van der Waals (vdW) interaction into account. Adopting the approach, the lattice parameter of CeO 2 unit cell was calculated to be a = b = c = 5.462 Å, well consistent with 31 and then fully optimized via both the conjugate gradient and Quasi-Newton Broyden optimization methods to determine the stable structures. The bottom two Ce-layers were kept fixed while all the other atoms were allowed to fully relax during the structural optimization, using a 2 × 2 × 1 K-point mesh for the Brillouin-zone integration.…”

Paving the Way for Reductive Amination: Boosting Catalytic Ammonolysis of Schiff Base

“…In hydrogen-borrowing amination, the production of a primary amine mainly involves three steps including dehydrogenation, condensation, and hydrogenation, with the initial dehydrogenation process as the rate-determining step. ,, Compared with reductive amination, a high reaction temperature is usually required to boost the dehydrogenation of an alcohol, which accelerates the production of an undesired secondary/tertiary amine due to the thermodynamically favored side reactions . Therefore, achieving a better balance between the dehydrogenation of an alcohol and the selectivity of a primary amine poses a key challenge in hydrogen-borrowing amination.…”

“…Amines, especially primary amines as the key intermediates in the chemical industry, have been extensively applied in the synthesis of pharmaceuticals, polymers, and others. Reductive/hydrogen-borrowing aminations − over heterogeneous catalysts are considered as green, environmentally friendly, and sustainable routes to synthesize primary amines since water is the main byproduct. The overall chemistry includes dehydrogenation (only for hydrogen-borrowing amination), amination, hydrogenation of primary imine, and the formation, ammonolysis, and hydrogenation of Schiff base.…”

Support-facet-dependent morphology of small Pt particles on ceria

“…[26][27][28][30][31][32] Recently, two-dimensional (2D) Pt particles and ways to promote their formation have been discussed in literature. 28,[33][34][35][36] These structures have been reported to have favorable catalytic properties, especially for low temperature CO oxidation, which is a reaction of high technological relevance. 28,35 The reason why 2D structures are measured to have a higher activity than 3D structures is not fully understood, however one speculation is that planar structures increase the Pt/ceria interface, which could be beneficial for low-temperature CO oxidation via a Mars-van Krevelen reaction path.…”