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Dynamic reactor operations will gain interest with the increase of intermittent electricity from renewable sources. Periodic operation of catalytic reactors can also be used for kinetic studies with better parameter estimation than steady‐state operation. This methodology is exemplified for the case of acetylene hydrogenation over Pd/α‐Al2O3 using small amplitude flow oscillations. It allows the evaluation of several elementary kinetic parameters from one set of dynamic data for a reaction mechanism based on a single catalytic site. The optimized transient model is able to reproduce the time‐evolution of the reactant and product molar fractions at the outlet of a fixed bed operated with modulations of different amplitudes and frequencies. It further shows that the acetylene conversion is controlled by two steps, the hydrogen adsorption step and the hydrogenation of the surface vinyl intermediate into adsorbed ethylene. [ABSTRACT FROM AUTHOR]

Sorbitol can be selectively transformed into liquid alkanes over a bifunctional catalytic system Pt/ZrO 2 + TiO 2 –WO x . In this paper, we investigated the reaction mechanism by carefully analyzing the numerous products issued from sorbitol and by studying the reactivity of some identified intermediates (1-hexanol 2-hexanol, 2-hexanone, 2,5-dimethyltetrahydrofuran, 1,2-hexanediol and 1,2,6-hexanetriol). This led us to propose that C C cleavage reactions occur on terminal C C bonds and mainly consist of dehydrogenation–decarbonylation reactions. The limiting steps of the sorbitol transformation are the isosorbide and mono-oxygenated intermediate transformations, especially the hydrogenation of ketones. It is also assessed that diols or triols with n carbon atoms are mainly converted in compounds with n − 1 carbon atoms. Short compounds (1 to 3 carbon atoms) are obtained via a dehydrogenation-retro-aldol reaction pathway and not from isosorbide conversion. [ABSTRACT FROM AUTHOR]

Supported noble-metal catalysts (Ru, Pd or Pt) and the corresponding Re-promoted catalysts exhibit a high activity for the hydrogenation of biobased carboxylic acids. Levulinic acid and succinic acid are converted into the lactones or the diols depending on the nature of the catalyst and the reaction conditions. The highest selectivity to 1,4-pentanediol of 82 % is achieved at 140 °C in the presence of the 1.9 % Ru-3.6 % Re/C catalyst. [ABSTRACT FROM AUTHOR]

Abstract: A set of microporous carbons have been used to prepare Pd/carbon catalysts. The properties of the raw materials have been determined in terms of texture and surface chemistry. A deposition precipitation method has been employed to prepare the final catalysts, leading to well-dispersed palladium particles. The influence of the textural properties as well as the surface chemistry properties has been studied and a correlation was found between the surface in the pores of the support and the Pd dispersion. The chemistry surface properties of the Pd/carbon catalysts were found similar, despite differences in the case of the starting raw materials. The hydrogenation of cinnamaldehyde has been studied and the results obtained favourably compare with those already published. Turnover frequencies were similar whatever the catalyst. High selectivities close to 90% in hydrocinnamaldehyde were obtained at 90% conversion. [Copyright &y& Elsevier]

Abstract: Carbon-supported palladium catalysts were prepared by ion-exchange and precipitation/deposition methods on various activated carbons. Pd/carbon catalysts with Pd particles ranging from 1.5 to 10nm were thus obtained. The liquid phase hydrogenation of c,t,t-1,5,9-cyclododecatriene was carried out on these catalysts. A structure-sensitivity was observed with a decrease of TOF on smallest Pd particles. The highest yield to half-hydrogenated cyclododecene was observed on large Pd particles (∼10nm). [Copyright &y& Elsevier]

Corrections to the article "Heterogenous Catalytic Hydrogenation of Biobased Levulini and Succinic Acids in Aqueous Solutions," by L. Corbel-Dermailly and colleagues publised in a 2013 issue of "Chemistry & Susceptibility" are presented.

The kinetics of the selective hydrogenation of acetylene in the presence of an excess of ethylene has been studied over a 0.05 wt. % Pd/α-Al2O3 catalyst. The experimental reaction conditions were chosen to operate under intrinsic kinetic conditions, free from heat and mass transfer limitations. The data could be described adequately by a Langmuir–Hinshelwood rate-equation based on a series of sequential hydrogen additions according to the Horiuti–Polanyi mechanism. The mechanism involves a single active site on which both the conversion of acetylene and ethylene take place. [ABSTRACT FROM AUTHOR]

Highlights: [•] Tungstated oxides acidity in water was evaluated. [•] Tungstated oxides in mechanical mixture with Pt/ZrO2 are able to transform sorbitol into hydrocarbons and/or mono-alcohols. [•] TiO2–WO x is the most acid in water and leads to an increased hydrocarbons yield. [•] Al2O3–WO x is not acid in water but produces short alcohols by C C cleavage. [ABSTRACT FROM AUTHOR]

Abstract: Pt/C catalysts were prepared by impregnation of carbon xerogels with H2PtCl6 aqueous solutions. Three supports with various pore textures were used: two micro-mesoporous (maximum pore size = 10 and 40 nm, respectively) and one micro-macroporous (maximum pore size = 70 nm). After impregnation, drying and reduction, the metal particles were at most 1–1.5 nm in diameter. The Pt dispersion was close to 100% in the case of the xerogel with large mesopores. For the two other supports, a small fraction of Pt was trapped in blocked micropores. The specific catalytic activity obtained for benzene hydrogenation was 4–10 times higher than that obtained with active charcoal-supported catalysts prepared by a similar method. The high dispersion of Pt was attributed to the presence in the xerogel of large mesopore or macropore volumes, which facilitates impregnation, and a low amount of oxygenated surface groups. [Copyright &y& Elsevier]