Innovate contactor for CO2 recovery

Innovate contactor for CO2 recover

Numerical study of the coupling between reaction and mass transfer for liquid-liquid slug flow in square microchannels

While the benefits of miniaturisation on processes have been widely demonstrated, its impact on microfluidics and local mechanisms such as mass transfer is still little understood. The aim of this work is to simulate coupling between reaction and mass transfer in microchannels for liquid-liquid slug flow. First, the extrapolation to confined flow of the classical model used to calculate interfacial mass fluxes in reactive infinite media was studied. This model consists in estimating transferred fluxes between two phases as a function of the enhancement factor E. Its expression depends on the model used to represent interfacial mass transfer. In infinite media, Lewis and Whitman’s stagnant film theory is generally preferred for its simplicity and its reliability. In the case of confined slug flow, the limitation of such a model to predict interfacial fluxes is highlighted. Secondly, the case of liquid-liquid competitive consecutive reactions in microchannels is considered. This work emphasizes the unfavourable impact of the length between droplets on selectivity. This is a direct consequence of mass transport mechanisms in microchannels

Caractérisation tribologique de films moléculaires d'acide phosphonique déposés sur une surface de cuivre

National audienceLa surface d'un substrat de cuivre a été fonctionnalisée grâce à une technique d'auto-assemblage d'une monocouche d'acide phosphonique. Après caractérisation de ce film, un excellent comportement tribologique est noté lorsqu'aucun nettoyage ultrasonore n'est effectué, pour des conditions de sollicitation de pression de 133 MPa et de vitesse de glissement de 1mm/s sur un tribomètre alternatif linéaire utilisant un frotteur en Si3N4 (μ = 0.12, durée de vie multipliée par 100). Des espèces physisorbées, sous formes d'amas de plusieurs μm3, présentes sur la monocouche semblent responsables de ce bon comportement. De premiers essais sur un tribomètre d'étirage-plan ont montré un réel potentiel de ce type de fonctionnalisation en emboutissage

Investigation of OSN properties of PDMS membrane for the retention of dilute solutes with potential industrial applications

International audienceFew commercially available membranes can be used for organic solvent nanofiltration (OSN). Applying OSN in chemical industries is nevertheless of high interest to cut with energy consumption linked to solvent recycling and soluble catalysts recovery. A commercial membrane, PERVAP4060, was used to investigate the retention of dilute solutes in toluene feeds and to mimic metathesis medium. The studied solutes were R-BINAP a neutral polyaromatic molecule used in metathesis chemistry, tetraoctylammonium bromide (ToABr), a charged molecule used as a homogeneous catalyst and n-hexadecane. Retention of polar ToABr (95%) was higher than that of neutral R-BINAP (80%). The transfer mechanism, either pore flow or solution-diffusion, was discussed. All the results obtained suggested that the transport is governed by the solution-diffusion mechanism. The measured retentions could be explained in terms of solubility affinities and diffusion coefficients. The stability and performances of PERVAP4060 were well established, showing the strong potential for industrial applications

Intensified post-combustion CO2 capture: potential of hollow fiber membrane contactor for absorption and stripping steps

Post-combustion CO2 capture (PCC) is an important strategy in mitigating greenhouse effect. The robustness of packed columns makes it the standard technology for the gas-liquid absorption of CO2, using aqueous amine solutions as liquid absorbents. Even though it is not the best performing chemical solvent, monoethanolamine (MEA) at 30% wt. is currently considered as the benchmark solvent for PCC [1]. However, the treatment of large quantities of flue gases requires itself equipment of a large size. Hollow fibre membrane contactors (HFMC) are considered as one of the most promising strategies for intensified CO2 absorption process, due to their significantly higher interfacial area than that of packed columns, allowing to reduce the equipment size [2]. HFMC technology has been widely investigated for the absorption step under laboratory conditions (e.g. high reactant excess) [3]. However, despite the potential advantages of membrane contactors, very few investigations have studied implementing this technology within an industrial framework. The performance of CO2 absorption and stripping using HFMC under industrial conditions is still unknown. To fill this lack, adiabatic multicomponent one-dimensional models have been developed to estimate the performance of both absorption and stripping steps using HFMC and packed columns. The modelling of both technologies is based on coupled mass and heat transfer balances. Indeed, this is standard in packed columns modelling, however, neglecting the thermal effects appears to be common in HFMC modelling [4], [5]. The intensification potential of HFMC for both absorption and stripping steps was therefore estimated in industrial conditions. Please click Additional Files below to see the full abstract

Enhanced Pervaporation Properties of PVA-Based Membranes Modified with Polyelectrolytes. Application to IPA Dehydration

In this work, dense and supported pervaporation polyvinyl alcohol (PVA)-based membranes modified with poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate)(PSS)/PAH top nanolayers were synthesized. Two main points were investigated: the role of the polyelectrolyte PAH on water selectivity of the selective polymer matrix and the impact of the porous substrate based on polyacrylonitrile (PAN) and aromatic polysulfone amide (UPM-20®), used to get supported high-performance membranes. Various methods of analysis (fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), porosity, contact angles, ultrafiltration) were applied to study the developed membranes. Transport characteristics of the developed membranes were studied in isopropanol dehydration by pervaporation. Obtained results are discussed in the light of the structure and physicochemical characteristics of these PVA/PAH membranes and the types of porous substrate. It was shown that the PAN-supported membrane with the selective layer based on PVA/PAH modified by 10 polyelectrolyte PSS/PAH bilayers possessed ~4.5 times higher permeation flux with the same high selectivity level (99.9 wt % water in the permeate) for the dehydration of the isopropanol (20 wt % water) at 60 °C compared to the commercial analog PERVAPTM 1201.РНФ № 17-73-2006

Investigation of new modification strategies for PVA membranes to improve their dehydration properties by pervaporation

International audienceNovel supported membranes based on polyvinyl alcohol (PVA) were developed using two strategies: first, by the modification of the PVA network, via so-called bulk modification, with the formation of the selective layer accomplished through the introduction of fullerenol and/or poly(allylamine hydrochloride), and second, by the functionalization of the surface with successive depositions of multilayered films of polyelectrolytes, such as poly(allylamine hydrochloride) and poly(sodium 4-styrenesulfonate) on the PVA surface. The membrane surface modifications were characterized by scanning electron microscopy and contact angle measurements. The modified PVA membranes were examined for their dehydration transport properties by the perva-poration of isopropyl alcohol-water (80/20% w/w), which was chosen as a model mixture. Compared with the pristine PVA membrane, the main improvement was a marked increase in permeance. It was found that the surface modifications mainly gave rise to a higher global flux but with a strong reduction in selectivity. Only the combination of both bulk and surface modifications with PEL could significantly increase the flux with a high water content in the permeate (over 98%). Lastly, it should be noted that this study developed a green procedure to prepare innovative membrane layers for dehydration, making use of only water as a working medium

CO 2 capture by aqueous ammonia with hollow fiber membrane contactors: Gas phase reactions and performance stability

A critical challenge involved in developing membrane contactor technology for CO2 capture by aqueous ammonia is ensuring long-term performance stability in industrial application. When working at low temperatures and with dry inlet gas, this study demonstrates precipitation fouling due to crystallization of ammonium salts using a commercially produced composite membrane contactor (Oxyplus®). The fouling occurred on the lumen side of the membrane where the gas circulated. Experiments performed using a CO2/N2 mixture saturated with water vapor to mimic real flue gas, interestingly, showed stable performance and no fouling. Experiments were performed at different operating temperature. Under all conditions, with and without solid salt formation leading to fiber fouling, an aqueous solution formed inside the fiber lumen. In this solution, 76% of the ammonia leaking from the shell side and 12% of CO2 feed was captured. The aqueous solution formed in the lumen can be easily separated to recover the ammonia content, which under the tested conditions, resulted in lower ammonia loss than what would be expected in a packed column

Approche tribologique du soudage du bois par frottement

Depuis peu, la mise en évidence de la possible réalisation d'assemblages en bois soudés par frottement sans aucun apport de matière extérieur présente d'intéressantes perspectives tant d'un point de vue économique qu'environnemental. Dans ce cadre, notre étude vise à étudier l'influence des paramètres décrivant le procédé sur la qualité de l'assemblage via un couplage entre des essais instrumentés sur tribomètre et une caractérisation du cordon de soudure par microscopie électronique, rugosimétrie 3D, tomographie aux rayons X et essais mécaniques

Caractérisation tribologique de monocouches auto-assemblées

L'auto-assemblage de monocouches ou SAMs (Self-Assembled Monolayers) permet la génération d'une surface fonctionnalisée basée sur le greffage, par réaction chimique, d'un film de molécules organiques en surface. Dans ce cadre, nous avons exploré les aptitudes tribologiques de diverses SAM's en sollicitation de contact « sec » et « lubrifié » après avoir optimisé leur « qualité » : adsorption, organisation, densité et stabilité