A non-additive repulsive contribution in an equation of state: The development for homonuclear square well chains equation of state validated against Monte Carlo simulation

International audienceThis work consists of the adaptation of a non-additive hard sphere theory inspired by Malakhov and Volkov, Polym. Sci. Ser. A. 2007;49(6):745-756 to a square-well chain. Using the thermodynamic perturbation theory, an additional term is proposed that describes the effect of perturbing the chain of square well spheres by a non-additive parameter. In order to validate this development, NPT Monte Carlo simulations of thermodynamic and structural properties of the non-additive square well (NASW) for a pure chain and a binary mixture of chains are performed. Good agreements are observed between the compressibility factor originating from the theory and those from molecular simulations

Fast pyrolysis of Miscanthus x Giganteus in an IR heated reactor

International audienceIntensive research on Miscanthus x Giganteus (MG), a large perennial grass, has been achieved in the last ten years because of its known advantages for farmers (high yield, low input, perennial crop, easy harvesting…) [refs 1,2,3,4]. MG is often considered as a good candidate to produce renewable energy. As lignocellulosic feedstock, MG could also serve to produce chemicals. This approach is far less present in the literature. Because logistics costs could affect the attractiveness of MG, pyrolysis is an interesting technology for energy densification [ref 4]. Therefore the present work describes the pyrolysis of Miscanthus x Giganteus. It is well know that pyrolysis products are solids, liquids and gas. Low residence time, enhanced by high heating rates and high flow rates, favors the production of liquids. A temperature range between 450 and 550°C is also recommended to limit gas formation. A new pyrolysis apparatus designed to achieve fast pyrolysis via infrared heating and low residence time is described. Process conditions are varied for temperature, particle size, N 2 flow rate and preheating effect. Pyrolysis temperature should be the most influential parameter upon the yield and properties of bio-oil. Tests are performed at different levels of power and duration. Temperature is measured in the border and in the center of the reactor because of the presence of radial gradients. The highest bio-oil yield and corresponding temperature profiles are presented. The effect of process conditions on bio-oil yield is assessed. The bio-oil composition is analyzed by GCMS. The results are compared with a direct analysis of MG by Py-GCMS. The bio char is characterized in terms of calorific value with respect to the raw MG High Heating Value (HHV). Furthermore, on the one hand the outlet gas composition is analyzed by online infrared spectroscopy which gives an indication of potential use as secondary source of energy. On the other hand the porosity of the bio-solid products is estimated by BET low-temperature adsorption method for further valorization purpose of pyrolysis products. Highlights: 1) New experimental results on Miscanthus x Giganteus pyrolysis are presented. 2) Characterization of every product thus resource potential is evaluated. 3) Comparison of Py-GCMS with lab scale pyrolysis of MG is performed. References: 1) Anissa Khelfa, Victor Sharypov, Gisèle Finqueneisel, Jean Victor Weber J. Anal. Appl. Pyrolysis 84 (2009) 84–88, Catalytic pyrolysis and gasification of Miscanthus Giganteus: Haematite (Fe2O3) a versatile catalyst

Nanoparticulate ZrO2/SO42- Catalyst for Biofuel Production

This study reports on the preparation of zirconia coatings based on monodispersed zirconium-oxo-alkoxy (ZOA) nanoparticles for conversion of free fatty acid (FFA) into biofuel. Monodispersed ZOA nanoparticles of 3.6 nm size were prepared by sol-gel method in a rapid micro-mixing reactor with turbulent fluids flow at 20°C. The ZOA nanopowders obtained after precipitation and nanocoatings deposited on glass beads, after subsequent sulfatation, drying and calcinations, show high catalytic activity towards esterification process. The biofuel yield in esterification of palmitic acid in methanol reached 67% (after t=3.5 hours) on nanopowders while it increases to 98% on nonocoatings

Représentation thermodynamique des mélanges sulfonitriques en vue d’application aux cinétiques de nitration

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Modélisation Thermodynamique des systèmes H2O-HNO3- N2O5 en vue de l’optimisation de procédés de synthèse de milieux nitrants

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Mise au point d’un nouveau procédé pour la préparation de N2O5, réactif utilisé dans les synthèses de produits nitrés

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Use of a non additive GC-PPC-SAFT equation of state to model hydrogen solubility in oxygenated organic compounds

International audienceThe equation of state based on the Group Contribution – Polar Perturbed Chain – Statistical Associating Fluid Theory (GC-PPC-SAFT), which is PC-SAFT combined with the group contribution proposed by Tamouza et al., Fluid Phase Equilib. 2004;222-223:67-76 and a polar term developed by Nguyen Huynh et al., Fluid Phase Equilib. 2008;264(1-2):62-75, is employed here to model the solubility of hydrogen in oxygenated compounds mixtures such as alcohols, ethers, diols, aldehydes. Our analysis shows that in such systems, the gas solubility may be driven by available volume effects. For this reason, a modified version of this equation of state taking into account non-additive segment diameters, is used in this work. Systematic tests are performed on binary mixtures and a predictive scheme is proposed. A correlation based on the group contribution method is also suggested as a predictive way to determine the non-additive parameter (l ij). Correlations and predictions are qualitatively and quantitatively satisfactory. The deviations are within the experimental uncertainty (~10%)

Including polarizability effects in GCPPC-SAFT: application to alkyl-ether containing systems

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Simultaneous liquid–liquid and vapour–liquid equilibria predictions of selected oxygenated aromatic molecules in mixtures with alkanes, alcohols, water, using the polar GC-PC-SAFT

International audiencePhase equilibria of oxygen-bearing aromatic compounds, hydrocarbons and water mixtures are of essential interest in many processes using feeds originating from biomass. The strong non-ideal thermodynamic behavior of these systems sometimes results in immiscibility with both water and alkanes.To address this problem, the GC-PPC-SAFT equation of state [Tamouza et al., 2004; Nguyen-Huynh et al., 2008a] is extended to some selected components: phenol, alkyl-phenols, alkyl-benzoates, benzaldehyde and anisole. However, as in these multifunctional compounds, the proximity of polar functional groups may result in a lack of transferability of the parameters from the monofunctional homologous species, some parameters have been adapted in view of physical arguments. Next, liquid–vapour and liquid–liquid equilibria of mixtures with n-alkanes were evaluated, using a predictive method for the binary interaction parameters (kij) [Nguyen-Huynh et al., 2008b]. Finally, mixtures with other associating compounds, as alcohols and water have also been considered.In all cases, both correlations and predictions are qualitatively and quantitatively satisfactory. The relative deviations obtained on bubble pressure of vapor–liquid equilibria are 4–8%, that is comparable to those obtained on previously investigated systems

Vapour-liquid equilibrium (VLE) for the systems furan + n-hexane and furan + toluene. Measurements, data treatment and modeling using molecular models

International audienceIn this paper, new experimental vapour-liquid equilibrium data of the furan + n-hexane and furan + toluene binary systems are reported. The data are determined using the ebulliometric technique. The measured data are used to assess the predictions obtained with molecular simulation, a group contribution polar PC-SAFT model and the COSMO-RS and COSMO-SAC approaches. For this purpose, new force field parameters (needed in MC-simulation) are determined for furans by fitting a limited amount of saturation data. In GC-PPC-SAFT, most of the parameters were adopted from previous studies with exception of the polar moments (dipoles are taken from experimental data). The mixtures phase diagrams are predicted (without binary parameters) at atmospheric pressure using these newly determined parameters as well as those of hexane and toluene determined in earlier studies.The predicted results are consistent with the new experimental data. Nevertheless, for the furan + n-hexane binary system, it appears that a binary interaction parameter is necessary to correctly correlate the data and to satisfactory describe the literature excess enthalpy data