The oxidative dehydrogenation (ODH) of propane on single-crystal V(2)O(5)(001) is studied by periodic density functional theory (DFT) calculations. The energetics and pathways for the propane to propene conversion are determined. We show that (i) the C-H bond of propane can be activated by both the terminal and the bridging lattice O atoms on the surface with similar activation energies. At the terminal O site both the radical and the oxo-insertion pathways are likely for the C-H bond activation, while only the oxo-insertion mechanism is feasible at the bridging O site. (ii) Compared to that at the terminal O site, the propene production from the propoxide at the bridging O site is much easier due to the weaker binding of propoxide at the bridging O. It is concluded that single-crystal V(2)O(5)(001) is not a good catalyst due to the terminal O being too active to release propene. It is expected that an efficient catalyst for the ODH reaction has to make a compromise between the ability to activate the C-H bond and the ability to release propene.

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In comparison to the traditional petroleum-based plastics, polylactic acid, the most popular biodegradable plastic, can be decomposed into carbon dioxide and water in the environment. However, the natural degradation of polylactic acid requires a substantial period of time and, more importantly, it is a carbon-emitting process. Therefore, it is highly desirable to develop a novel transformation process that can upcycle the plastic trash into value-added products, especially with high chemical selectivity. Here we demonstrate a one-pot catalytic method to convert polylactic acid into alanine by a simple ammonia solution treatment using a Ru/TiO2 catalyst. The process has a 77% yield of alanine at 140 °C, and an overall selectivity of 94% can be reached by recycling experiments. Importantly, no added hydrogen is used in this process. It has been verified that lactamide and ammonium lactate are the initial intermediates and that the dehydrogenation of ammonium lactate initiates the amination, while Ru nanoparticles are essential for the dehydrogenation/rehydrogenation and amination steps. The process demonstrated here could expand the application of polylactic acid waste and inspire new upcycling strategies for different plastic wastes.

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