PRIMO

Membrane processes are mixture separation processes involving the use of a polymeric or inorganic film, which may be dense or microporous, the membrane. Depending on the characteristics of the membrane, single-phase mixtures (gas or liquid) or two-phase mixtures (liquid-solid) can be separated. For the separation of single-phase mixtures, membrane processes are an alternative to conventional molecular separation processes. Their main advantages are low energy consumption, compared with distillation, and ease of implementation, compared with adsorption. Thanks to their intrinsic qualities, membrane processes are enjoying strong growth, and their use in industrial environments is constantly increasing.

Different membrane processes can be distinguished, depending on the size of the components to be separated, the physical nature of the driving force used to overcome the membrane barrier, and the physical state of the fluids circulating on either side of the membrane. Various membrane processes are studied within the PRIMO axis. The following non-exhaustive list provides an overview.

• Gas permeation for industrial gas separation in general and CO2 capture in particular.
• Gas-liquid membrane contactors for CO2 capture and the degassing and desolvation of industrial effluents.
• Liquid-liquid membrane contactors for the purification of phenolic compounds from bio-oils.
• Nanofiltration for the selective recovery of dyes in the treatment of liquid effluents from the textile industry.
• Reverse osmosis for effluent treatment in the nuclear industry.
• Membrane distillation for desalination of brackish water.

The aim of PRIMO research is to develop new membrane processes or to intensify existing ones. This involves modeling the phenomena involved at all scales, from molecular mechanisms, through hydrodynamics and transfers, right up to the architecture of the entire process. Multifunctional and hybrid processes are also envisaged.

Heterogeneous fluid-solid catalysis processes account for the majority of reactive processes in industry, and mastering them is fundamental to the successful transition to sustainable industry. The development of new processes using a multi-scale approach is a thematic priority for the PRIMO axis, especially key processes in the energy transition, such as those based on hydrogen and CO2 recovery. Applications include the use of hydrogen for mobility, micro-cogeneration or e-fuels production (Power-to-Chemicals), and the separation and recovery of CO2 as part of a circular engineering approach. Many challenges need to be met to develop these new processes: reducing their spatial and environmental footprint, increasing the modularity of equipment, the need for decentralized production and managing the intermittent nature of incoming material and energy flows.

From a methodological point of view, the work carried out on the catalyst scale consists, on the one hand, in developing kinetic models based on experimental results that can be used on larger scales, and, on the other hand, in synthesizing and characterizing these catalytic materials, in partnership with other areas of the LRGP, or even with other laboratories. As part of this project, a pilot plant to test the performance and stability of catalytic materials will be built at LRGP in 2023-2024. Reactor modeling and optimization work at equipment scale integrates kinetic, thermodynamic and hydrodynamic phenomena, as well as material and heat transfer. These models are integrated into complete process models, in order to calculate global performance indicators (production cost, energy efficiency, environmental impact, etc.) and subsequently identify the optimum process architecture, i.e. the one that minimizes/maximizes these indicators.

Intensification, defined as all the technologies and methods used to increase volume productivity, and process synthesis, seen as the optimal arrangement of unit operations, are part of the scientific methodologies of the axis. They are aimed at designing new equipment and innovative processes with a view to optimizing technical and energy efficiency.

The main intensification strategies developed within the axis are as follows.

• Geometric structuring and miniaturization of transfer and reaction equipment.
• Transition from batch to continuous processes.
• Design of multifunctional equipment, such as compact reactor-exchangers or reactor-separators, to take advantage of potential synergies.

Process synthesis is an important scientific theme of the PRIMO axis and of interest to the LRGP as a whole, given the many possible applications. On the one hand, work is carried out to determine the optimal architecture and operating conditions of a process by optimizing superstructures on the basis of performance indicators. Secondly, evolutionary methods are being developed to identify ab initio process structures. In order to limit the computation time of optimization algorithms, approaches using machine learning and graph methods are employed.