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Innovative membrane Crystallization contactor: Applications to diffusion / REaction processes – ICARE


Innovative membrane Crystallization contactor : Applications to diffusion/REaction processes.

Project challenges & Objectives

The scientific challenges and key questions that will be addressed through the work program can be summarized as follows:<br />1. Identification of the set of conditions and material properties which lead to surface or intramembrane crystallization for the model system BaCO3 ;<br />2. Is it possible to quantitatively predict crystallization behaviour in a dense polymeric matrix by a coupled diffusion mass transfer / crystallization kinetics model ?<br />3. Do the molecular dynamics and continuous medium mass transfer modelling offer consistent predictions for a dense membrane crystallization system (a typical multiscale approach challenge) ?<br />4. What is the prediction efficiency of chemical engineering models (balances, mass transfer, hydrodynamics and nucleation kinetics) when applied to a dense polymer hollow fiber crystallization module ? For instance, is it possible to precisely predict the influence of fluid flow on crystallizer productivity and crystal quality (CSD) ?<br />5. How do the reference technology (CSTR) and the dense membrane hollow fiber crystallizer concept compare in terms of productivity (intensification factor) and solid quality ?<br />6. What is the long time scale performance stability of the dense membrane hollow fiber crystallizer (surface deposit, crystals adhesion effects leading to gradual fouling) ?

WP1 : This WP intends to analyse local phenomena in order to understand and explain how, where, when and why the crystallization takes place in or on the polymer material. Experiments are performed at lab-scale, in static mode, on several dense polymer materials commercially available. The aim is to investigate the influence of the polymer material properties (nature, permeability, mechanical resistance), the surface properties (polymer surface energy, rugosity), the membrane thickness and the water rate of the polymer on the crystallization location of a model compound (BaCO3).
WP2 : A modelling approach combining mass transfer in a resistance-in-series approach, and chemical reaction leading to the solid formation is developped. This sub-task aims to simulate the dissolution/precipitation front in the membrane module. Experimental results from WP1 are used to validate the numerical results. Several approaches, from the simplest to the more complex, will be compared. The robustness of the model will be investigated by comparing the experimental results obtained.
In addition, a molecular dynamics simulation will be proposed to depict the crystals formation mechanism (at the surface or in the membrane). The aim is to better understand the mechanisms, from a molecular point of view, occurring between the membrane and the crystals.
WP3 : The process performances will be investigated through the study of the influence of the operating conditions (fluid velocity, concentration or temperature) and the geometric conditions (filling rate). The process performances will be investigated on short but also on long time scale through crystallization / cleaning cycles in order to evaluate the lifetime of the membrane module. At the same time, BaCO3 will be precipitated in a CSTR and the results obtained will be compared to the results obtained on membrane contactors. The crystallization front will be studied in situ in continuous by using a non-invasive technique.

Results were obtained under the WP1. Severals polymers materials were studied in order to scan the main properties : hydrophobicity, permeability, nature of polymer. In addition, the influence of the membrane thickness and of the membrane moisture were also studied. Two systems are concerned : Liquid-Liquid and Gas-Liquid.
Results obtained in WP1 have clearly highlighted the key role of the membrane’s permeability to the solute on the crystallization location and have allow selecting two polymer materials for the next step of the project.

Task 1 is achieved and results obtained allow selecting two polymers materials which will be investigate in hollow fiber membrane contactors in task 3 in order to study the influence of hydrodynamics. These membranes contactors are now under production.
Task 2 has begun and mathematical approachs are under construction.

Publications : In progress
Patents : not planned to date

Crystallization/precipitation is one of the major unit operations of chemicals process industries to produce, purify or separate solid compounds or products. Until now, the stirred tank reactor is the reference process for industrial crystallization applications, but there is a strong need for breakthrough technologies, highlighted by numerous authors and prospective reports. Amongst the breakthrough technologies candidates, membrane processes are considered as one of the most promising because they can possibly ensure an intensified, continuous, easy to scale-up process together with a fine local control of hydrodynamics and mass/heat transfer characteristics. Several attempts for novel crystallization processes based on microporous membranes have been recently reported in publications and patents, but microporous materials have shown serious limitations due to surface fouling and pore blocking by crystals. The resulting process performances decrease makes this crystallization strategy largely hypothetical.
The membrane fouling and pore blocking deadlock could possibly be circumvented through the use of dense (i.e. non porous) materials and hollow fiber modules, while keeping the continuous, ease of scale up, intensification and local control key advantages of membrane processes. This strategy remains however essentially unexplored up to now and it addresses a major scientific challenge, namely the possibility to predict the crystallization mechanisms and location in (or at the surface of) a dense polymeric material under continuous operation.
ICARE project intends to address this scientific challenge based on a set of 3 workpackages combining investigations and imaging techniques on different dense membrane crystallization systems, mass transfer and crystallization experiments in batch cells (WP1), modelling and simulation of the crystallization processes (WP2), and proof of concept of the technological feasibility on tailor made lab scale hollow fiber modules based the most promising dense polymeric membranes (WP3). Barium carbonate (BaCO3) has been selected as a model system in order to precisely evaluate the possibility to predict the crystallization behaviour depending on the dense polymer mass transfer properties, reactants concentrations and process operating conditions. More specifically, a comparison between crystallization mechanisms from gaseous or dissolved CO2 feed through a dense polymeric film will be performed in order to test the robustness of the modelling strategy and simulation package (WP2). A subtask (WP 2.2), performed through an international partnership, will be dedicated to the challenging problem of molecular modelling of crystallization phenomena in (or at the surface of) a dense polymer. A comparison of the modelling prediction performances between the molecular (WP 2.2) and continuous medium (WP 2.1) scales will thus be achieved.
ICARE project aims to perform an exploratory investigation of diffusion / reaction systems in dense polymeric materials, including crystallization phase transitions. The ultimate target is to develop in 4 years a core fundamental knowledge on the crystallization processes into or on the surface of dense polymers, through a pluridisciplinary approach (chemical engineering, materials science, molecular modelling) and a combined experimental and modelling strategy. Major outcomes are expected both in terms of scientific developments and for industrial crystallization processes. Additionally, the possibility to select the system and operating conditions leading to surface or intramembrane crystallization offers attracting potentialities in materials science (e.g. hybrid material production through in-situ solid filler synthesis), separation processes (e.g. fouling of reverse osmosis membranes or ion exchange resins) or pharmaceutical applications (e.g. production of controlled release systems for drug delivery from a solid form dispersed in a polymeric matrix).

Project coordination

Elodie CHABANON (Laboratoire d'Automatique et de Génie des Procédés)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


LAGEP - UCBL Laboratoire d'Automatique et de Génie des Procédés

Help of the ANR 277,820 euros
Beginning and duration of the scientific project: December 2016 - 48 Months

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