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First principles calculations have been used to calculate the interlayer binding energy, the phonons frequencies, and the electronic structure of the In3X4 layered systems, with X = Se or Te. Using density functional theory corrected to take into account van der Waals interactions, the binding energy was found to be ∼ 41-44 meV for In3Se4 and ∼ 53-58 meV for In3Te4. Moreover, the absence of imaginary frequencies in the phonons bandstructures demonstrates the dynamical stability of the isolated layers. These facts suggest that isolated layers of In3Se4 and In3Te4 could be obtained by means of exfoliation from the bulk. [ABSTRACT FROM AUTHOR]

The catalytic hydrodeoxygenation (HDO) of lignin is an important route to produce green aromatics. Herein we study the adsorption of key phenolic molecules (phenol, catechol, guaiacol, anisole) over various metallic nanoparticles (NP) (Ni, Cu, Co, Fe) supported over amorphous silica, by the periodic spin polarized density functional theory (DFT). CO and water are potential inhibiting molecules present in the lignin pyrolysis gas. Therefore their competing adsorption is also studied in details. Our calculations show that the oxygenated compounds have a stronger interaction at the interface between the NP cluster and the silica for all the studied metals. By comparing the resulting adsorption energies, we found that the Ni 13 @silica catalyst is the most attractive one for oxygenated molecules. The most stable configuration is a phenol adsorption at the interface through the OH group with the silica surface and the aromatic ring with the transition metal cluster. In addition, we show that the adsorption of the oxygenated compounds is not impacted by the presence of inhibiting molecules on Fe 13 @silica, Co 13 @silica and Ni 13 @silica catalysts. This type of DFT investigation appears to be useful to suggest suitable formulations for an optimal HDO of lignin. [Display omitted] • Potential of metallic nanoparticle@amorphous silica for HDO investigated by DFT. • Phenolic compounds preferentially adsorbed on the NP/support interface. • No inhibiting effect of H 2 O and CO expected on Fe,Ni,Co@amorphous silica. [ABSTRACT FROM AUTHOR]

• NP/silica catalysts are potentially active and selective for a large panel of applications. • Grafting mechanisms of transition metal species (Co, Ni, Cu) under various forms on amorphous silica surfaces. • Transition metal clusters are strongly bonded to the surface through M-O-Si and M-OH-Si bonds. • A Large charge transfer due to the strong effect of the transition metal cluster on the silica surface. Transition metals (Co, Ni, or Cu) systems supported on amorphous silica are promising materials for their unique surface chemical reactivity. Despite many investigations, the transition metal-support interactions for this type of materials are not yet well understood at the molecular level. In this work, periodic density functional theory calculations, were performed to investigate systematically the interaction between Co, Ni, or Cu species (monomers and clusters) and amorphous silica surfaces with densities of 3.3 and 4.6 OH/nm2. It is shown that the geometry, energetic stability, and magnetic properties of transition metal species deposited on amorphous silica surfaces depend strongly of the number of M-O-Si groups and, in few cases, of the number of M-OH-Si groups, with sometimes a strong effect on the silica surface that induces a reorganization of the silanol groups. Among monomers, cobalt is found to be the most stable on the silica surface while among clusters, the Ni cluster is the most strongly adsorbed. The magnetic moments of the adsorbed transition metal clusters on silica surface are found to be reduced with respect to their corresponding free clusters for Co and Ni. [ABSTRACT FROM AUTHOR]

Theoretical and experimental assessments for the selective removal of phenol from synthetic 2nd generation biofuels. Investigation of the different structural interaction modes, their interaction energies, and vibrational frequencies. • Biofuels purification using zeolites was followed by experimental and theoretical approaches. • H+ and Na+ exchanged zeolites were compared for removing phenol from toluene. • DFT calculation combined with IR spectroscopy revealed the adsorption modes. • Multi-component breakthrough was conducted to investigate the adsorbents selectivity. • Astonishing performance of HY zeolite to remove phenol from a synthetic biofuel was shown. The purification of second-generation biofuels is becoming an urgent issue due to the toxicity of the combustion products of residual phenol in these biofuels. The use of solid sorbents such as zeolites appears as a promising solution for ensuring the selective sorption of phenol towards aromatics (the main components of biofuel). In the present work, we have adopted a bottom-up approach for removing phenol from a synthetic biofuel feed containing isooctane, phenol (1 wt.%), n-nonane (1 wt.%) and toluene (40 wt.%), using faujasite-type Y zeolites with Si/Al ratio = 2.5. The astonishing performance of HY zeolite to treat the synthetic biofuel has been highlighted by assessing the interaction modes of the molecules involved over the structural sites via the combination of theoretical molecular modeling and experimental adsorption experiments. [ABSTRACT FROM AUTHOR]

The compound Ba 3 ThSe 3 (Se 2 ) 2 has been synthesized by solid-state methods at 1173 K. Its crystal structure features one-dimensional chains of 1 ∞ [Th(Se) 3 (Se 2 ) 2 6− ] separated by Ba 2+ cations. Each Th atom in these chains is coordinated to two Se–Se single-bonded pairs and four Se atoms to give rise to a pseudooctahedral geometry around Th. The Th–Se distances are consistent with Th 4+ and hence charge balance of Ba 3 ThSe 3 (Se 2 ) 2 is achieved as 3×Ba 2+ , 1×Th 4+ , 3×Se 2− , and 2×Se 2 2− . From optical measurements the band gap of Ba 3 ThSe 3 (Se 2 ) 2 is 1.96(2) eV. DFT calculations indicate that the compound is a semiconductor. [ABSTRACT FROM AUTHOR]

Magnesite (MgCO 3) and dolomite [(Mg,Ca)(CO 3) 2 ] are the main minerals involved in the production of magnesium metal, which is considered as a critical raw material in the EU and USA. In this study, we investigated the hydration mechanisms of (10 1 ̅ 4) magnesite and dolomite surface by static density functional theory relaxations and ab initio molecular dynamics simulations. For both minerals, the dissociative adsorption of water was unfavored compared to the molecular adsorption, which displayed an adsorption energy of −101.2 kJ mol−1 and −94.2 kJ mol−1 for magnesite and dolomite, respectively. In the case of dolomite, the adsorption of water was slightly favored on the surface calcium ions compared to magnesium ions, which was attributed to stronger interactions between the hydrogen atoms of water and the oxygen atoms of the surface. Then, the coverage was gradually increased to reach a monolayer: the adsorption energies for magnesite displayed a slight increase with increasing coverage, whereas dolomite exhibited no sensitivity to water coverage. Using ab initio molecular dynamics simulations conducted at 300 K, we showed that, beyond the first layer, water displayed a clustering behavior induced by the intermolecular interactions, while the isosteric enthalpies of adsorption continuously decreased with increasing coverage, due to the screening effect of deeper water layers. When more water molecules were added, until reaching the complete hydration of magnesite and dolomite surfaces, a refined water structuration emerged: a significant layering effect was exhibited, due to highly-organized layers, until 8–10 Å from the surface, which therefore corresponded to the distance at which the surface had no more effect on water layers. Overall, magnesite exhibited a larger affinity for water than dolomite, including adsorption energies and structuration of water, which provides new insights in the understanding of the fine surface mechanisms involved in the subsequent flotation process. [Display omitted] • Water adsorbs under molecular form on magnesite and dolomite surfaces. • ΔE ads of a water molecule is − 101.2 on magnesite and − 94.2 kJ·mol−1 on dolomite. • Higher coverage studies confirm that magnesite is more hydrophilic than dolomite. • Better structuration of water above magnesite compared to dolomite. • Reverse flotation recommended for the dolomite/magnesite separation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Adsorption of glucose and itaconic acid on amorphous silica surfaces studied by DFT. • Several geometrical configurations and silanol densities considered. • The amorphous silica surfaces are potentially selective toward glucose adsorption. • Silica materials can be helpful for the purification process of organic acids. A better separation and purification of organic acids in liquid phase is a key for a more performing biorefinery industry. Herein, amorphous silica surfaces with a density of silanol ranging between 1.1 and 7.2 OH · nm−2 are investigated to separate glucose molecules from the fermentation broths. Different interaction modes of glucose and itaconic acid on the considered silica surfaces at various silanol sites are systematically investigated using periodic density functional theory. Our results show that the surfaces with a silanol density of 2.0 to 7.2 OH · nm−2 are potentially selective for glucose adsorption in comparison with itaconic acid. [ABSTRACT FROM AUTHOR]