Abstract
The electronic metal-support interaction (EMSI) is one of most intriguing phenomena in heterogeneous catalysis. In this work, this subtle effect is clearly demonstrated by density functional theory (DFT) calculations of single Pt atom supported on vacancies in a boron nitride nanosheet. Moreover, the relation between the EMSI and the performance of Pt in propane direct dehydrogenation (PDH) is investigated in detail. The charge state and partial density of states of single Pt atom show distinct features at different anchoring positions, such as boron and nitrogen vacancies (Bvac and Nvac respectively). Single Pt atom become positively and negatively charged on Bvac and Nvac, respectively. Therefore, the electronic structure of Pt can be adjusted by rational deposition on the support. Moreover, Pt atoms in different charge states have been shown to have different catalytic abilities in PDH. The DFT calculations reveal that Pt atoms on Bvac (Pt-Bvac) have much higher reactivity towards reactant/product adsorption and C–H bond activation than Pt supported on Nvac (Pt-Nvac), with larger adsorption energy and lower barrier along the reaction pathway. However, the high reactivity of Pt-Bvac also hinders propene desorption, which could lead to unwanted deep dehydrogenation. Therefore, the results obtained herein suggest that a balanced reactivity for C–H activation in propane and propene desorption is required to achieve optimum yields. Based on this descriptor, a single Pt atom on a nitrogen vacancy is considered an effective catalyst for PDH. Furthermore, the deep dehydrogenation of the formed propene is significantly suppressed, owing to the large barrier on Pt-Nvac. The current work demonstrates that the catalytic properties of supported single Pt atoms can be tuned by rationally depositing them on a boron nitride nanosheet and highlights the great potential of single-atom catalysis in the PDH reaction.
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