Pascal Fongarland

Selective catalytic oxidation of glycerol: perspectives for high value chemicals

Due to its three hydroxyl groups, glycerol is a potential starting material for various high value fine chemicals such as dihydroxyacetone, tartronic acid and mesoxalic acid. The corresponding oxidation reactions are catalysed by various metals such as palladium, platinum, bismuth or gold. Nevertheless, the selectivity not only depends on the type of the active phase, but is also influenced by numerous parameters such as the metal particles size, the pore size of the support and the pH of the reaction medium. This review not only describes the recent developments in the field of research for new catalysts but also spotlights the role of the reaction conditions as well as the possible transport limitations in this tri-phasic system. Furthermore, an economical analysis of some processes is given, which shows that this is realistic to envision sustainable production of, e.g., dihydroxyacetone.

Hydrogen solubility in straight run gasoil

AbstractThe solubility of hydrogen in a straight run gasoil is measured using a chromatographic method, which is rst validated with aknown organic liquid (cyclohexane). Under the experimental conditions (up to 4MPa, temperatures from 298 to 675K), these resultsarebestdescribedbyChao–SeaderandimprovedZudkevitch–Joe(withadjustmentparameter b 0 =0:6)models.Henry’slawconstantisdeterminedatfourtemperatures.? 2002ElsevierScienceLtd.Allrightsreserved. Keywords: Hydrogen;Cyclohexane;Solubility;Gasoil;Vaporpressure; Equation of state; Multiphase reactor 1. IntroductionIn many industrial processes of oil rening (hydro-genation, hydrotreatments such as hydrodesulfurization,hydrodenitrogenation, ...), kinetics is often related to thehydrogenpressure.However,intheseprocessesthecatalystisincontactonlywiththeliquidphasecontainingthedis-solvedhydrogen;therefore,thekineticratewouldinvolvethe hydrogen concentration in the liquid phase. If masstransfers are not limiting (as expectedin the Mahoney–Robinson reactor), hydrogen solubility in the conditionsof reaction is a way to access a goodestimation of thehydrogen concentration in the liquid phase; on the otherhand,ifamasstransferlimitationoccurs,adiusionmodelmay be used, implying the knowledge of the liquid-phasehydrogen concentration. In both cases, the knowledge ofhydrogen solubility is of interest for studying the kineticsofhydrotreatments.Whereas many data are available for hydrogen solu-bility in pure components (Young, 1981), only few re-searchers have workedwith complex mixtures, especiallywith petroleum products (Harrison, Scheppele, Sturm, G the methodis validatedby measure-mentsoncyclohexane(inwhichthehydrogensolubilityhas

Direct conversion of methanol into 1,1-dimethoxymethane: remarkably high productivity over an FeMo catalyst placed under unusual conditions

We report here the highest productivity ever observed in the direct conversion of methanol into 1,1-dimethoxymethane (ca. 4.6 kgDMM h−1 kgcat−1 at 553 K), this result being obtained over an FeMo catalyst. This catalyst is industrially used to selectively convert methanol into formaldehyde but has never before been applied to the present reaction. Placing this FeMo catalyst under unusual reaction conditions, i.e., using a feed rich in methanol, completely changed its behaviour in terms of selectivity: the massive production of 1,1-dimethoxymethane, instead of formaldehyde, was observed.

Al-modified mesoporous silica for efficient conversion of methanol to dimethyl ether

The aim of this work was to design efficient mesoporous heterogeneous catalysts for the reaction of conversion of methanol to dimethyl ether (DME). Mesostructured silica and aluminosilicate solids were synthesized using an original synthesis procedure enabling the elaboration of structurally homogeneous solids at atmospheric pressure and using a food grade templating agent. The prepared solids consisted of mesoporous silica and aluminosilicates with aluminium contents of 0.76, 1.11 and 1.60 wt%. These solids were characterized by XRD, N2-physisorption and TEM. Their efficiency in the catalytic reaction of conversion of methanol to DME was subsequently correlated with their structural and acidic properties. The sample exhibiting a pore diameter of 2.2 nm for a Si/Al ratio of 27 showed remarkable performances with a methanol conversion as high as 80% at 598 K (7.5 vol% MeOH; 50 mg of catalyst; GHSV = 26,000 cm3 h−1 g−1) and a total selectivity to DME.

Measurement of the Influence of the Microstructure of Alumina‐Supported Cobalt Catalysts on their Activity and Selectivity in Fischer–Tropsch Synthesis by using Steady‐State and Transient Kinetics

Five alumina‐supported Co catalysts with different particle sizes and structures were synthesized. The catalysts showed different activities during long‐term Fischer–Tropsch experiments. Steady‐state isotopic transient kinetic analysis (SSITKA) 12CO/H2→13CO/H2 experiments were performed during these long‐term runs. The number of active sites for CO adsorption and activation was estimated through the summation of all surface intermediates derived from the SSITKA results. Rather than comparing turnover frequencies, a kinetic analysis was performed. A simple kinetic rate equation based on the in situ number of active sites described the steady‐state CO conversion over the five catalysts adequately. Thus the difference in the catalytic performance could not be attributed to a difference in particle size, phase orientation (face‐centered cubic or hexagonal close packed), or Pt‐promotion effect but instead was only because of the number of reduced Co atoms exposed during the reaction. Similarly, the selectivity depended on the CO conversion level and temperature and not on the catalyst structure.