Comment on "Electronic properties and charge transfer phenomena in Pt nanoparticles on γ-Al2O3: size, shape, support, and adsorbate effects" by F. Behafarid et al., Phys. Chem. Chem. Phys., 2012, 14, 11766-11779.

We show how density functional theory (DFT) calculations rationalize the origin of high H/Pt ratio and the electronic properties of γ-alumina supported Pt nanoparticles as observed in Phys. Chem. Chem. Phys., 2012, 14, 11766-11779.

The role of the extra-framework cations in the adsorption of CO(2) on faujasite Y.

A purely electrostatic picture predicts that small, more polarizing cations adsorb more strongly than the large ones. In the case of the adsorption of CO(2) on faujasite Y, however, the inverse order is found at low pressure: CsY and KY adsorb stronger than NaY and LiY. This trend cannot be explained by a simple monopole-dipole or monopole-quadrupole interaction of CO(2) with a single cation. Therefore, we have conducted a combined adsorption, IR and DFT study in order to shed light on this phenomenon. Our results show that a simultaneous interaction of CO(2) with the cations (located in the hexagonal window between supercage and sodalite cage) and framework oxygen atoms (in the 12-ring connecting two supercages) can explain the strong adsorption of CO(2) on CsY and KY. We also discuss the effect of van der Waals interactions. Although there is a redistribution of the charge of three framework oxygen atoms in the 12-ring towards the carbon atom of CO(2), the geometry of CO(2) remains almost linear. The adsorption mode can, therefore, be interpreted as a carbonate precursor. In zeolite Y, this acid-base like interaction is more important than polarization of CO(2) by the cation only. Furthermore, evidence for an adsorption mode where CO(2) binds simultaneously to two cations in the supercage was detected by DFT, as already reported for Na-ferrierite. This adsorption mode is, however, strongly dependant on the distance between two cations in the supercage and is only favorable in the case of KY.

Compensation effect and volcano curve in toluene hydrogenation catalyzed by transition metal sulfides.

Within the framework of volcano curves, a kinetic study of toluene hydrogenation catalyzed by transition metal sulfides highlights the variation of the apparent kinetic parameters as a function of the ab initio sulfur-metal bond energy descriptor and sulfo-reductive reaction conditions.

First principles surface thermodynamics of industrial supported catalysts in working conditions.

Ever stronger environmental concerns prompt the research in the area of heterogeneous catalysis to play an ever more crucial role to produce ever cleaner fuel from the refining of petroleum effluents. The catalytic active phase is often used in a dispersed state over a porous oxide material. This paper is a review of recent progress brought by periodic density functional theory (DFT) calculations in the area of two relevant industrial supported catalysts. We focus on two important supports used in the refining industry: anatase-TiO(2) and γ-alumina. According to the various reaction conditions, the presence of H(2)O, H(2) and H(2)S may change the surface states of the support. In particular, it is crucial to know and control the hydroxylation state depending on temperature and partial pressure of reactants (H(2)O, H(2), H(2)S). The support effects on the catalytic active phases are presented for MoS(2) particles, used in hydrodesulfurization catalysis, and for Pd particles, used in hydrogenation catalysis. It is shown how the wetting property and equilibrium morphology of the active phase depend on the support. A discussion on the impact for catalytic activities is provided.