Platinum/ceria/alumina catalysts on microstructures for carbon monoxide conversion

Platinum/ceria/alumina catalysts have been prepared by a sol–gel method and coated in the microchannels of stainless steel platelets. These catalysts are very active for the water-gas shift reaction between 300 and 400°C. Moreover, they are non-pyrophoric and thus well suited for the purification of hydrogen for PEM fuel cells. The obtained coatings show good adherence and catalytic activity. The influence of the amount of platinum and ceria as well as the effect of a binder on the catalytic performance has been investigated. The samples have been characterized before reaction by XRD, SEM and by N2 adsorption measurements. The kinetics, free from internal diffusion limitations, over these thin films have been described by a power law rate equation. An activation energy of 86 kJ/mol has been found and at 260 °C the TOF corresponds to 0.6 ± 0.1 s−1 for all investigated samples. The superior activity of the platelets compared to the powder samples is attributed to the diffusion limitations inside the powder pellets. Thus catalysts deposited on microstructured platelets lead to a better platinum utilization

The formation of agricultural governance: the interplay between state and civil society in European agriculture, 1870-1940

In this paper, we focus on the relationship between state and agriculture in Europe in the period roughly from 1870 to 1940. Since the crisis of the late nineteenth-century, state intervention had increased into many areas of agricultural markets, and a growing social mobilization within the countryside had also made its mark, with the diffusion of agricultural associations (landowners associations, farmers unions, specialized crop producers’ associations, co-operatives, ...) that led to a much more organized rural society. Already prior to the 1930s, the state had become involved, one way or another, with the development of agriculture, such as the promotion of technical advancement, in the regulation of agricultural markets, and in the development of farm supportive policies. Throughout this period, agricultural associations played a growing role as intermediary institutions, and it is this period that we consider to be the formative period of this interplay between the state and agricultural civil society. The result was a metamorphosis from the mobilization of the peasantry and the representation of agrarian interests to a form of selfgovernment or co-government of the agricultural sector at the national level, which reached its highest point only after the Second World War.En este artículo, centramos nuestra atención en la relación entre el Estado y la agricultura en Europa en el período aproximadamente de 1870 a 1940. Desde la crisis de fines del siglo XIX, el intervencionismo estatal aumentó en muchas áreas de los mercados agrícolas, al mismo tiempo que se producía una creciente movilización social en el mundo rural, con el desarrollo de asociaciones agrarias de muy diversos tipos (asociaciones de propietarios, sindicatos de agricultores, asociaciones de productores de cultivos especializados, cooperativas,...) que dieron lugar a una sociedad rural mucho más organizada. Ya antes de la década de 1930, el Estado se había involucrado, de una forma u otra, con el desarrollo de la agricultura, como por ejemplo en la promoción del cambio técnico, en la regulación de los mercados agrícolas y con políticas de apoyo a la agricultura. A lo largo de este período, las asociaciones agrarias desempeñaron un papel creciente como instituciones intermediarias, y es este período el que consideramos como el período formativo de esta interacción entre el Estado y la sociedad civil en el mundo rural europeo. El resultado fue una metamorfosis desde la movilización del campesinado y la representación de los intereses agrarios hacia una forma de autogobierno o cogobierno del sector agrario a nivel nacional, que alcanzaría su punto más alto después de la Segunda Guerra Mundial

Kinetic Study of the Selective Hydrogenation of Acetylene over Supported Palladium under Tail-End Conditions

International audienceThe 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-Al 2 O 3 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

Co-pyrolysis of beech wood and polyamide-6: Effect of HZSM-5 catalyst and of plastic concentration on the properties of pyrolysis oils

Please click Additional Files below to see the full abstrac

Biofuels from waste to road transport

Biofuels from Waste to Road (WASTE2ROAD) is an EU funded project under the Grant Agreement No. 818120 within the LC-SC3-RES-21-2018 call, “Development of next generation biofuels and alternative renewable fuel technologies for road transport”, as a Research and Innovation Action of the European Union’s Horizon 2020 Programme. The project started in the fall 2018 and will run for 4 years. In 2014, total waste production in the EU amounted to 2.5 billion tons. From this total only a limited (albeit increasing) share (36%) was recycled, while the rest was landfilled or burned, of which some 600 million tons could have been recycled or reused. Conversion of all sustainably available biogenic wastes and residues to biofuels could provide 27% of total transport fuel by 2050, achieving around 2.1 gigatons of CO2 emission reductions per year. The increasing demand for biofuels[1] implies the need for the transformation of diverse bio-resources into liquid fuels, and includes transformation of the biogenic part of municipal and industrial wastes into such biofuels. This clearly is a stepping stone to achieve the European goals[2] but it also poses challenges, such as 1) diversity and inhomogeneity of wastes throughout Europe (variable composition depending on the type of waste and geographical location), 2) the complexity of the conversion of wastes compared to fossil oils, 3) the technological aspects of co-refining and 4) high overall costs with moderate process performance. [1] https://www.iea.org/publications/freepublications/publication/Biofuels_Roadmap_WEB.pdf [2] https://europeanclimate.org/wp-content/uploads/2014/02/WASTED-final.pdf Please click Additional Files below to see the full abstract

Periodic reactor operation for parameter estimation in catalytic heterogeneous kinetics. Case study for ethylene adsorption on Ni/Al2O3

Periodic operation of chemical reactors has usually been analyzed for a potential gain in performance. However, at the laboratory scale, periodic operation of a catalytic reactor can be used for kinetic studies with better parameter estimation, which is inherent to transient kinetic studies. Different mathematical methods are developed and compared in this study to simulate and model concentration cycling in a fixed bed catalytic reactor. Different cases including dissociative and molecular adsorption are considered with or without external and internal mass transfer limitations. The analysis of these cases gives information on the contribution of the different parameters on the phase lag and gain loss. This information can be used to better plan experimental kinetic studies. Ethylene adsorption over a Ni/Al2O3 catalyst has been studied experimentally in a dedicated set-up with a high-speed Infrared analyzer capable of analyzing the outlet gas mixture with a data acquisition frequency up to 30 Hz. The data are modeled with one of the analytical expressions developed in this work to estimate the equilibrium adsorption constant

Purifaction de l'hydrogène sur catalyseurs microstructuré pour une application embarquée

Les véhicules à pile à combustible, alimentée par de l'hydrogène, représentent une solution prometteuse pour limiter la pollution urbaine. L'hydrogène présentant des risques de stockage et de distribution, il semble intéressant de le produire à bord de la voiture, à partir d'un autre carburant tel que l'essence. Cette transformation se fait dans une succession d'unités. L'objectif est d'obtenir un mélange de gaz à forte teneur en hydrogène mais à très faible teneur en CO car le CO empoisonne la pile. La réaction de water-gas shift est une étape clé du procédé ; elle convertit CO en CO2 par réaction avec l'eau et fournit une quantité d'hydrogène supplémentaire. Des catalyseurs CuO/ZnO/Al2O3 et Pt/CeO2/Al2O3 ont été préparés sur microstructures par imprégnation d'une couche d'alumine et par déposition d'une barbotine préparée à partir d'un catalyseur industriel. Des préparations avec des liants différents ont été comparées par rapport à l'adhérence de la couche et à l'activité catalytique. Une étude cinétique a été menée sur le catalyseur micro structuré Pt/CeO2/Al2O3 en ajustant les données expérimentales à différentes équations de vitesseLYON1-BU.Sciences (692662101) / SudocSudocFranceF

La microbalance inertielle (étude et modélisation cinétique de la désactivation par le coke en reformage catalytique des hydrocarbures sur catalyseur Pt-Sn/AL2O3)

LYON-ENS Sciences (693872304) / SudocSudocFranceF

CO dissociation on Pt-Sn nanoparticles as the unexpected trigger for alloy oxidation and segregation under O2-free conditions.

+ING+FRM:LCS:YSCInternational audienceThis communication describes a yet unreported mode of alloy segregation upon exposure to CO. In situ IR studies indicated that the alloy Pt-Sn nanoparticles were not stable under (i) H2-free CO at any temperature or (ii) CO/H2 mixtures at temperatures below 175°C. This was rationalized by the known, albeit slow, ability of Pt to dissociate CO. The oxygen atoms formed readily reacted with metallic Sn to form a SnOx species, leading to Pt-Sn segregation, alongside carbon deposition. In situ XPS and XANES analyses confirmed Sn reoxidation. An activation energy of 36 kJ/mol was estimated for the oxidation step of Sn surface atoms by adsorbed CO. These data highlight an important phenomenon affecting metal and alloy stability under CO, which is of major importance in heterogeneous catalysis and electrochemistry

CO dissociation on Pt-Sn nanoparticles as the unexpected trigger for alloy oxidation and segregation under O2-free conditions.

+ING+FRM:LCS:YSCInternational audienceThis communication describes a yet unreported mode of alloy segregation upon exposure to CO. In situ IR studies indicated that the alloy Pt-Sn nanoparticles were not stable under (i) H2-free CO at any temperature or (ii) CO/H2 mixtures at temperatures below 175°C. This was rationalized by the known, albeit slow, ability of Pt to dissociate CO. The oxygen atoms formed readily reacted with metallic Sn to form a SnOx species, leading to Pt-Sn segregation, alongside carbon deposition. In situ XPS and XANES analyses confirmed Sn reoxidation. An activation energy of 36 kJ/mol was estimated for the oxidation step of Sn surface atoms by adsorbed CO. These data highlight an important phenomenon affecting metal and alloy stability under CO, which is of major importance in heterogeneous catalysis and electrochemistry