Dihydroxyacetone conversion into lactic acid in an aqueous medium in the presence of metal salts: influence of the ionic thermodynamic equilibrium on the reaction performance

International audienceThe catalytic conversion of dihydroxyacetone (DHA) to lactic acid (LA) via pyruvaldehyde (PA) in aqueous media was studied using different homogeneous metal salts. A kinetic model was developed and the parameters corresponding to each reaction steps were estimated. Agreement between experiments and simulated results was excellent and the performance of the different catalysts was consistent with previous studies described in the literature. Aluminium salts, which show the best performance, were tested in a whole range of concentrations and at different pH, in order to identify the catalytically active ionic species. It was confirmed that the DHA to pyruvaldehyde (PA) dehydration step is catalyzed by both Brønsted and Lewis acids whereas the consecutive reaction of PA to LA is solely catalyzed by Lewis acids. Moreover, comparing thermodynamic analysis of the reaction media and kinetic parameters demonstrated that cationic hydroxyl-aluminium complexes [Al(OH)h] (3-h)+ formed in situ by the hydrolysis of the aluminium aqua complexes like [Al(OH2)6] 3+ are the most active Lewis acids

Influence of slow diffusing species on mixture diffusion of hexane isomers in silicalite: Characterization by a new cyclic method

International audienceThe feasibility of mono- and di-branched paraffins separation on silicalite was evaluated by performing cyclic breakthrough experiments in liquid phase with mixtures of 2-methylpentane (2MP), 3-methylpentane (3MP), 2,3-dimethylbutane (23DMB), and 2,2-dimethylbutane (22DMB). For mixtures of the faster diffusing species (2MP, 3MP, and 23DMB), cyclic steady state is obtained from the first cycle. On the other hand, when the slow diffusing species 22DMB is involved, a slow accumulation occurs from cycle to cycle, yielding a change of the breakthrough curves for all the species. Using a diffusion model especially adapted to adsorbent saturation loading, the kinetic and thermodynamic parameters of 22DMB were estimated. Influence of the cycling conditions on the separation performance were finally studied by simulatio

Consequence of structural identifiability properties on state-model formulation for linear inverse chromatography

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Separation of mono- and dibranched hydrocarbons on silicalite

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Measurement of Monobranched Alkane Mobility in the Silicalite Framework in the Presence of Dibranched and Linear Molecules

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Co-adsorption and Separation of CO2-CH4 Mixtures in the Highly Flexible MIL-53(Cr) MOF

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