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Piccolo L.,CNRS Research on Catalysis and Environment in Lyon
Chemical Communications | Year: 2013

The hydrogenation of butadiene has been investigated for the first time on Al13Fe4. The model (010) surface of this non-noble metal combination appears to be both active and selective under mild reaction conditions. The performances of Al13Fe4 for CC bond hydrogenation are compared with those of the reference noble metal, palladium. © 2013 The Royal Society of Chemistry. Source


Gallezot P.,CNRS Research on Catalysis and Environment in Lyon
Chemical Society Reviews | Year: 2012

This critical review provides a survey illustrated by recent references of different strategies to achieve a sustainable conversion of biomass to bioproducts. Because of the huge number of chemical products that can be potentially manufactured, a selection of starting materials and targeted chemicals has been done. Also, thermochemical conversion processes such as biomass pyrolysis or gasification as well as the synthesis of biofuels were not considered. The synthesis of chemicals by conversion of platform molecules obtained by depolymerisation and fermentation of biopolymers is presently the most widely envisioned approach. Successful catalytic conversion of these building blocks into intermediates, specialties and fine chemicals will be examined. However, the platform molecule value chain is in competition with well-optimised, cost-effective synthesis routes from fossil resources to produce chemicals that have already a market. The literature covering alternative value chains whereby biopolymers are converted in one or few steps to functional materials will be analysed. This approach which does not require the use of isolated, pure chemicals is well adapted to produce high tonnage products, such as paper additives, paints, resins, foams, surfactants, lubricants, and plasticisers. Another objective of the review was to examine critically the green character of conversion processes because using renewables as raw materials does not exempt from abiding by green chemistry principles (368 references). © 2012 The Royal Society of Chemistry. Source


Platon M.,CNRS Molecular Chemistry Institute of Burgundy University | Amardeil R.,CNRS Molecular Chemistry Institute of Burgundy University | Djakovitch L.,CNRS Research on Catalysis and Environment in Lyon | Hierso J.-C.,CNRS Molecular Chemistry Institute of Burgundy University
Chemical Society Reviews | Year: 2012

A survey highlighting the most recent palladium catalytic systems produced and their performances for progress in direct synthesis of indole backbones by heterocarbocyclization of reactive substrates is provided. The discussion is developed in relation with the principles of sustainable chemistry concerning atom and mass economy. In this respect, the general convergent character of the syntheses is of particular interest (one-pot, domino, cascade or tandem reactions), and the substrates accessibility and reactivity, together with the final waste production, are also important. This critical review clearly indicates that the development of ligand chemistry, mainly phosphines and carbenes, in the last few decades gave a significant impetus to powerful functionalization of indoles at virtually all positions of this ubiquitous backbone (118 references). © 2012 The Royal Society of Chemistry. Source


Herrmann J.-M.,CNRS Research on Catalysis and Environment in Lyon
Applied Catalysis B: Environmental | Year: 2010

Photocatalysis has presently become a major discipline owing to two factors: (i) the intuition of the pioneers of last 20th century and (ii) the mutual enrichment of scientists arising from different fields: photochemistry, electrochemistry, analytical chemistry, radiochemistry, material chemistry, surface science, electronics, and hopefully catalysis. Since heterogeneous photocatalysis belongs to catalysis, all the bases of this discipline must be respected: (i) proportionality of the reaction rate to the mass of catalyst (below the plateau due to a full absorption of photons); (ii) implication of the Langmuir-Hinshelwood mechanism of kinetics with the initial rate being proportional to the coverages θ in reactants;(iii) conversions obtained above the stoichiometric threshold defined as the maximum number of potential active sites initially present at the surface of a mass m of titania used in the reaction. In addition, one should respect photonics, with the photocatalytic activity, i.e. the reaction rate being (i) parallel to the absorbance of the photocatalyst and (ii) proportional to the radiant flux Φ. In every study, one should determine the quantum yield (QY) (or efficiency), which, although dimensionless, is a "doubly kinetic" magnitude defined as the ratio of the reaction rate r (in molecules converted/second) to the efficient photonic flux (in photons/second) received by the solid. This is an instantaneous magnitude directly linked to the parameters mentioned above, in particular to the concentration. It can vary from a maximum value of ca. 40% in pure liquid phase to very low values (10-2%) in diluted media (pollutants trace eliminations). To establish true photocatalytic normalized tests, the above recommendations must be observed with a real catalytic activity independent of non-catalytic side-reaction. In particular, dye decolorization, especially in the visible, provides an apparent "disappearance" of the dye, due to a limited stoichiometric electron transfer from the photo-excited dye molecule to titania, subsequently compensated by an additional ionosorption of molecular oxygen. The energetics of photocatalysis on TiO2, being based on the energy E of the photons, i.e. E≥3.2eV, enables one to produce OH radicals, the second best oxidizing agent. The decrease of energy E to the visible may be thermodynamically detrimental for the generation of such highly cracking and degrading species. Concerning solid state chemistry, it is now finally admitted that cationic doping is detrimental for photocatalysis. In conclusion, all these recommendations have to be addressed and experiments have to be operated in suitable conditions before claiming that one deals with a true photocatalytic reaction. © 2010 Elsevier B.V. Source


Sorokin A.B.,CNRS Research on Catalysis and Environment in Lyon
Chemical Reviews | Year: 2013

Phthalocyanine metal complexes are structurally related to porphyrin complexes. The principal motivation for the preparation of heterogeneous catalysts is the possibility of their easy separation from the reaction mixture and their reuse for successive reactions, provided that the catalysts retain their catalytic properties. However, too few papers focus on rigorous studies of the catalysts' stability and recycle. Both organic polymers and inorganic materials can be used as supports. More robust inorganic solids are more suitable, in particular, for oxidation reactions and should be preferred. Several factors should be considered for the appropriate choice of the support: stability of the support under reaction conditions, possible involvement with the reaction, capacity to readily introduce functionality for covalent anchoring, degree of functionalization, and availability and cost of the support. Source

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