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Shaped metal particles are known to possess distinct catalytic properties, which is often attributed to the catalytic activities of different particle facets. In this contribution, propane dehydrogenation on Pt particles of different shapes is investigated by a combination of experiments and DFT calculations. The selectivity toward propylene and catalyst stability in propane dehydrogenation can be enhanced by shaping Pt nanoparticles under industrially relevant conditions. Octahedral particles (12.0 nm) dominated by the Pt(1 1 1) surface have higher selectivity toward propylene production and better stability than cubic particles (11.5 nm) that are dominated by the Pt(1 0 0) surface. Combined experiments and DFT calculations suggest that the weakened binding strength of propylene and increased energy barrier for the C–H bond cleavage in propylene dehydrogenation on Pt(1 1 1) compared to Pt(1 0 0) and Pt(2 1 1) contribute to the higher selectivity toward propylene by lowering the formation possibility of the deeply dehydrogenated intermediates. When coke is formed on the Pt surface, the d -band of surrounding Pt atoms is shifted farther below the Fermi level, leading to the deactivation of Pt catalyst. Our DFT calculations provide a rational interpretation of the experimental observations regarding the shape effects on propane dehydrogenation. [ABSTRACT FROM AUTHOR]

Abstract: DFT–GGA calculations have been used to study the chemisorption of CH x (x =0–3), C2H y (y =3–5) and C3H z (z =3–8) on Pt(111) at the coverage of 1/9 ML. The adsorption energies, favored binding sites and geometric parameters of adsorption configurations are determined. All the carbonaceous species are found to be adsorbed on Pt(111) with C atoms sp3-hybridized. The geometries of adsorption configurations have been compared with published experimental data to evaluate the reliability of our calculation method. The calculated adsorption energies of C1 species, ranked in descending order, are as follows, C>CH>CH2 >CH3, and the similar trend has been observed with respect to the chemisorption of C2 species. As for the C3 species, propylene prefers binding to the surface in the di-σ mode and the adsorption energy is calculated to be −0.93eV. The stepwise dehydrogenation of propane to propynyl (CCCH3) is investigated by calculating the change of reaction heat, which suggests that propylidyne (CCH2CH3) is the most stable species on Pt(111). Based on the adsorption energies and Brønsted–Evans–Polanyi (BEP) analysis, propyne is predicted to be the most likely starting point for the C–C scission. [Copyright &y& Elsevier]