Since the first discovery in 1995, data for over 5300 exoplanets have been documented in the NASA archive, revealing a vast diversity. Identifying life-enabling analogs of the Earth among this rapidly expanding catalog is of major interest. The stability of liquid water at the planetary surface defining the concept of the habitable zone (HZ) around the host star, may be necessary for the emergence of life as we know it but not sufficient. The practically constant atomic ratio nitrogen:phosphorous = 16:1 in oceanic surface layers of our planet Earth was discovered by Redfield in 1934. It corresponds to phytoplanktonic biomass in suspension and appears optimal to fertilize phytoplankton development and therefore the food pyramid of marine life. Loladze and Elser have shown that it corresponds to a homeostatic protein:RNA ratio and is therefore “rooted in the stoichiometry of the foundational structures of life.” I show that according to the recent theory of the chemical differentiation of planets, this optimal ratio is also an intrinsic chemical property of our planet Earth uniquely determined in the solar system by its average orbital radius. On that basis, I propose a criterion of fertility within the HZ of a stellar system, which when applied to screen the public database allows us to sort out an extended list of up to 74 Earth analogs. The latter and its future extensions could provide priority targets for focused detection techniques.

By plotting empirical chemical element abundances on Earth relative to the Sun and normalized to silicon versus their first ionization potentials, we confirm the existence of a correlation reported earlier. To explain this, we develop a model based on principles of statistical physics that predicts differentiated relative abundances for any planetary body in a solar system as a function of its orbital distance. This simple model is successfully tested against available chemical composition data from CI chondrites and surface compositional data of Mars, Earth, the Moon, Venus, and Mercury. We show, moreover, that deviations from the proposed law for a given planet correspond to later surface segregation of elements driven both by gravity and chemical reactions. We thus provide a new picture for the distribution of elements in the solar system and inside planets, with important consequences for their chemical composition. Particularly, a 4 wt% initial hydrogen content is predicted for bulk early Earth. This converges with other works suggesting that the interior of the Earth could be enriched with hydrogen.

I show that experimental Turn Over Frequencies published by Wachs et al. for acid-base and redox reactions of isopropyl-alcohol and methanol catalyzed by solid binary oxides can be organized into seven distinct volcano curves when described by a metal-oxygen bond strength E-MO computed by DFT for the oxide unit-cell. Similarly to previously shown, the optimal E-MO is interpreted as proportional to the gas phase enthalpy change of the reaction, now augmented by the enthalpic balance of proton exchanges occurring in adsorbed phase, i.e. the difference of Proton Affinities of the reactant and surface hydroxyls. The oxides surface proton affinities (SPA) are thus indirectly determined for the optimal descriptors E-MO. The relationship SPA = f(E-MO) is found to follow exactly the Shustorovich UBI-QEP version of the Bond Order Conservation Principle for Morse Potentials. The DFT descriptor E-MO provides therefore a quantitative scale for oxides SPA, useful to predict the optimal catalysts for other acid-base or redox reactions catalyzed by oxides. An example of application is shown. Finally, a first extension of the theory to molecular catalysis is demonstrated. (C) 2022 Elsevier Inc. All rights reserved.

Understanding solvation interactions is a key problem for many industrial fields: from pharmaceutical to material sciences. From a quantum mechanical viewpoint, two main difficulties arise: firstly, solvation takes place through weak interactions (hydrogen bonds, van der Waals interactions), which are inherently difficult to describe. Secondly, solvation properties are dynamic in nature, which means a proper statistical averaging is required to reproduce experimental properties. In this contribution, we dwell on the analysis of solutesolvent interactions by means of the averaged-NCI index, derived from an MD averaged picture of the electron density in the system. Firstly, we show how the approach enables to distinguish static vs labile and strong vs weak hydrogen bonds. Then, by means of this approach we are able to characterize the fact that the strength of hydrogen bonds with water solvent remains similar upon branching for aliphatic alcohols. On the contrary large differences have been observed between aliphatic alcohols and phenol derivatives. This statistical analysis of interactions is expected to be useful in the derivation of microscopic parameters for solute/solvent interactions.

Hydrogenation of aromatics by catalytic hydroprocessing is necessary in the upgrading of fossil hydrocarbons into fuels and bases for petrochemistry. In this paper the meaning and applicability are discussed of the "rim-edge" model, the outstanding hydrogenation activities of NiMoS supported on NiSx, and the effect of doping by the hard anion-forming elements phosphorous, boron, and fluorine. (C) 2021 Elsevier Inc. All rights reserved.

This special Issue of the Journal of Catalysis pays tribute to Professor Michel Che. In addition to the Editorial Preface, colleagues share their recollections of the vigorous endeavour he displayed throughout his scientific life to promote efficient international collaborations, as well as to bridge fundamental science and its applications. His human qualities are unanimously valued, which has left a trail marked with friendship.

We reveal a correlation between the M-X bond energy descriptor EMX for the optimal catalyst in a family of stoichiometry MiXj, and an intensive quantity defined as the standard enthalpy of the catalyzed reaction normalized to one mole of element X transferred by this reaction from reactants to products. M is a transition element, and the stoichiometry MiXj is fixed at the solid/fluid interface by the reaction conditions. We illustrate this for a relevant set of reactions involved in solar energy and industrial applications such as oxygen evolution, oxygen reduction and hydrogen evolution in electrolysis, hydrodesulfurization of thiophene, methanation of CO, hydrogenations of aromatics and alkenes, selective oxidation of methane, and ammonia synthesis and decomposition. We propose a quantitative model to explain this unexpected connection: this key finding and its interpretation should accelerate in silico discovery of catalysts.

The morphology, surface speciation, NMR, and IR spectroscopic properties of nanosized layered magnesium silicate isostructural to talc at equilibrium in an aqueous environment were computed from first principles. The theoretical predictions were successfully compared with experimental results obtained on a commercial magnesium silicate hydrate, revealing insights relevant for understanding the catalytic and other surface properties of such materials of promising industrial applications.

By combining experimental, spectroscopic, structural, and physical characterizations and extensive density functional theory simulations, unprecedented insight is gained on the local surface properties of synthetic talc nanoparticles, their structure, morphology and particle size distribution. Basically, the nuclear magnetic resonance (NMR) chemical shifts profiles of these nano-layered silicates were dissected thoroughly and revealed the existence of bulk and surface contributions in the H-1 and Si-29 spectra. Beyond the fact that significant knowledge has been acquired on the overall structure of the synthetic talc nanoparticles (mixture of defective and non-defective layers, with defects rejected on the external interfaces), the highlighting of these signals enabled us to access the average morphologies and particle sizes of the samples by decomposing the Si-29 NMR profiles into Lorentzian contributions. Finally, the particle size distributions in number were also described in terms of a log-normal law. These distributions were compared to the particle sizes obtained from X-ray diffraction (XRD), Brunauer-Emmett-Teller measurements (BET), and dynamic light scattering (DLS) methods. The distributions of gyration radii determined by DLS are shown to match the distributions in size consistent with the same morphology.

A kinetic model predicts the experimental activity and selectivity patterns obtained in oxidation of methane for (m(3)(II)(PO4)(2), (MPO4)-P-III,) and pyrophosphate ((M2P2O7)-P-II, (MP2O7)-P-IV) catalysts spanning extended ranges of M-O bond strength (calculated from first principles) and specific total acidity H-0. A volcano curve is obtained when total methane oxidation rates are plotted against M-O bond strength. (MP2O7)-P-IV pyrophosphates are the most acidic catalysts (H-0 > 10 mu mol m(-2)) and are remarkably selective to formaldehyde (>90%). For this subset of catalysts, however, experimental oxidation rates deviate from predictions in correlation with their acidity, suggesting a significant deactivation phenomenon. H-0 is shown to be described, and therefore predictable for these phosphates, by a structural parameter, the average P-Oa bond length, Oa being a bridging atom between M and P. Differences in acidity are interpreted as a consequence of the compression or elongation of the Oa-P bond inside the M-Oa-P bridges.

A computational study within the framework of density functional theory is presented on the oligomerization of ethylene to yield 1-hexene using [(eta(5)-C5H4CMe2C6H5)]TiCl3/MAO] catalyst. This study explicitly takes into account a methylaluminoxane (MAO) cocatalyst model, where the MAO cluster has become an anionic species after having abstracted one chloride anion, yielding a cationic activated catalyst. Hence, the reaction profile was calculated using the zwitterionic system, and the potential energy surface has been compared to the cationic catalytic system. Modest differences were found between the two free energy profiles. However, we show for the first time that the use of a realistic zwitterionic model is required to obtain a Bronsted-Evans-Polanyi relationship between the energy barriers and reaction energies.

In a combined experimental and theoretical study, the activation process of a single site ethylene oligomerization catalyst with aluminum-based activators has been studied. The results put forward a plausible deactivation reaction path of the catalyst for trimethylaluminum, while for methylaluminoxane and a novel phenoxyaluminum-based activator, the experimental catalyst's activity correlates with the energy barrier for the ethylene insertion. (C) 2014 Elsevier Inc. All rights reserved.

We have performed a molecular-simulation-based study to explore some of the underlying mechanisms of asphaltene aggregation. The daunting complexity of the crude oil + asphaltene system precludes any type of meaningful molecular simulation unless some assumptions are made with respect to the key physical and chemical properties that must be explicitly described. In the present work, we focus on molecular simulations of a coarse-grained model of asphaltene molecules in pure solvents, which are based on the assumption that the general size asymmetry and asphaltene morphology play a key role in the aggregation process. We use simple single isotropic Lennard-Jones sites to represent paraffinic and aromatic C6 segments, which are used as building blocks for the description of continental asphaltene models and solvent moieties. The energy and size parameters for the intermolecular models (e and s) for solute and solvent molecules are chosen to reproduce the experimental density of the liquid phase for different mixtures. An explicit pure solvent is considered, and the relationship between the aggregation mechanism and the solvent nature is investigated through direct simulation of the aggregation process. The results reproduce accurately expected trends observed for more-complex models as well as experiments, for example, strong aggregation of asphaltene molecules in n-heptane and high solubility in toluene. Different asphaltene models based on different geometries reveal that even at this level of simplification the topology of the molecules (number and position of aliphatic branches) does affect the way molecules aggregate.

A model is presented that correlates the measured electric capacitance with the energy that comprises the desolvation, dissociation and adsorption energy of an ionic liquid into carbonaceous electrode (represented by single-wall carbon nanotubes). An original methodology is presented that allows for the calculation of the adsorption energy of ions in a host system that does not necessarily compensate the total charge of the adsorbed ions, leaving an overall net charge. To obtain overall negative (favorable) energies, adsorption energies need to overcome the energy cost for desolvation of the ion pair and its dissociation into individual ions. Smaller ions, such as BF4-, generally show larger dissociation energies than anions such as PF6- or TESI-. Adsorption energies gradually increase with decreasing pore size of the CNT and show a maximum when the pore size is slightly greater than the dimensions of the adsorbed ion and the attractive van der Waals forces dominate the interaction. At smaller pore diameters, the adsorption energy sharply declines and becomes repulsive as a result of geometry deformations of the ion. Only for those diameters where the adsorption reaches maximum values is the adsorption energy sufficiently negative to balance the positive and desolvation energies. We present for each ion (and ionic liquid) what the most adequate electrode pore size should be for maximum capacitance.

The Round Table had been prepared with the aim to collect the views of both the suppliers of new simulation methods (academic researchers) than industrial users or facilitators (distributors codes and computing platforms) on a few key issues: - what boundary mark to the implementation of the multi-scale simulation to innovate in processes? - for what? (design of materials, reactors, integrated schemas, performance prediction, real-time control, etc.); - what locks will be met on this path? (representation of physical phenomena, computing capacity, creation of multidisciplinary teams, experimental validation of the predictions, etc.). This report attempts to highlight synthetic most discussions and responses.