Selection of extraction solvents for chemical processes: ReSolv, our solution for process innovation

The choice of solvent in an extraction process is often perceived as a secondary parameter… until it becomes necessary to replace it. Changing regulations, increasing safety requirements and the desire to reduce environmental impact are causing manufacturers to rethink tried-and-tested solutions. This is the case, for example, with MIBK – a historically effective solvent, now suspected of being CMR, and gradually phased out of use.

But changing solvent doesn’t simply mean replacing one molecule with another: it can involve a complete overhaul of the process, with major consequences for costs, delivery times and technical viability. That’s why it’s essential to anticipate these constraints as far upstream as possible, right from the design phases (TRL 2 to 4), when there’s still plenty of room for manoeuvre and reasonable adaptation costs.

A solution born of an industrial need

Faced with these challenges, Processium decided in 2013 to develop ReSolv, a software package dedicated to the search and selection of extraction solvents. The project arose from the need of an industrial client to quickly identify viable alternatives to solvents that had become obsolete, banned or simply sub-optimal.

Initially simple, ReSolv evolved through successive iterations, driven by customer projects and R&D work. With each new project, the tool was enriched and adapted to meet the requirements of the specifications more effectively. Today, Resolv is robust, reliable and used whenever a solvent selection or replacement need arises.

A proprietary database at the heart of the tool

From the outset, ReSolv was conceived as an extension of our in-house physico-chemical database, e-thermo, which we have been enriching for over ten years. Indeed, this database constitutes the technical heart of the tool, providing the essential properties (solubility, thermodynamics, safety, regulations) that feed the ReSolv selection algorithm.

ReSolv is more than just software: it’s a method combining algorithmic intelligence and process expertise, designed for process engineers in the field.

Criteria defined with the customer

ReSolv’s solvent selection algorithm works by successive filters, based on criteria set at the start of the project:

• Selectivity (ability to extract only the target molecule)
• Solvent recyclability
• Cost and availability
• HSE criteria (health, safety and environment)
• Regulatory constraints (REACH, restrictions)
• Performance compared to reference solvent

After querying e-thermo, ReSolv applies classification rules based on real experimental data, as previously mentioned, along with predictive methods to calculate missing properties to produce a short-list of 5 to 15 relevant solvents.

Coupling with Processium expertise and experimental validation

Beyond the algorithm, the final choice of solvent is based on Processium’s recognized expertise, which considers the entire process: not only the extraction efficiency of the product, but also the ability to regenerate and recycle the solvent under optimal conditions. This global vision guarantees a pragmatic selection adapted to actual industrial constraints.

The ReSolv approach is always complemented by experimental laboratory tests carried out in our own facilities. This dual level of validation – algorithmic and experimental – reduces the need for costly empirical testing, while speeding up development.

Compared with a more conventional method, this approach:

• Significantly reduces R&D time and costs
• Reduces technical uncertainties
• Reinforces the robustness of choice under real-life conditions

• As part of a long-term R&D strategy, a manufacturer asked us to help them identify an extraction solvent that could be more easily recycled. The objective: to reduce material losses and limit the costs associated with the purchase and processing of used solvents. Thanks to ReSolv, we quickly identified a more sustainable alternative, compatible with a closed-loop recycling circuit. This solution, although requiring initial investment, is now delivering significant economies of scale, while reducing the environmental footprint of the process.
• For one of our customers, whose initial solvent was classified as CMR (carcinogenic, mutagenic or toxic to reproduction), a complete overhaul of the process was required. ReSolv, which systematically eliminates CMR substances from its selection process, first identified a replacement solvent that was both efficient, sustainable and economically viable. However, this new solvent, although more competitive, was not compatible with the existing process. Our teams of process engineers therefore supported the customer in the design and implementation of a suitable process, ensuring optimal integration of this safer, more sustainable solution.

For more than a decade, ReSolv has been helping our customers to make a more informed selection of extraction solvents, based on a multi-criteria analysis that considers technical performance, as well as regulatory, economic and environmental issues. By structuring a process that is often guided by experience or common sense, our tool makes choices more reliable right from the early stages of development. It helps to secure processes, anticipate future constraints, and considerably reduce the time and resources devoted to experimental R&D. Compared with a more empirical approach, ReSolv limits iterations, reinforces the consistency of decisions and accelerates the transition to industrialization.

With ReSolv, solvent selection is no longer based on costly empirical tests or fragmented approaches. It becomes a structured process, based on reliable data, objective criteria and systematic experimental validation in our own laboratories.

But it’s not just the software that makes our method so effective. What makes the difference is Processium’s complete process integration: from thermodynamic modeling to process engineering. This one-stop-shop approach guarantees seamless continuity, which is crucial when a change of solvent involves profound modifications to the existing process.

By limiting the number of interfaces and roundtrips between different service providers, we enable our customers to gain speed, reliability and consistency, in an industrial context where choices have to be made quickly, well and sustainably.

ReSolv illustrates Processium’s ability to anticipate changes in the industrial sector. In the context of ecological transition and increasing regulatory pressure, having an agile, continuously improving tool developed in-house is a real competitive advantage.

Beyond the algorithm, it’s our ability to couple numerical approaches with experimental validation that makes the difference. ReSolv is not an end in itself: it is the catalyst for an integrated, rigorous and efficient approach to process design, one that can also be adapted to other applications involving solvents.