
"Ionic liquids play a key role in the catalytic system proposed in the WASTE2H2 project"
In the WASTE2H2 project, innovative catalytic systems are being developed to transform plastic waste into clean hydrogen, paving the way for a more sustainable energy future. A key component of this approach is the use of ionic liquids (ILs), which play a crucial role in optimizing the reaction process. To understand their function, selection criteria, and characterization, we spoke with Jonatan Perez, the leader of Work Package 2 (WP2) in WASTE2H2. His insights shed light on how ILs contribute to enhancing catalytic performance, ensuring process efficiency, and supporting the overall sustainability of the technology.
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What is the role of the ionic liquids in the catalytic systems?
Ionic liquids (ILs) play a key role in the catalytic system proposed in the WASTE2H2 project. Their exceptional and tuneable properties enable a substantial reduction in the quantity of catalyst necessary for plastic fragmentation. As a reaction medium, ILs are excellent absorbing microwaves with remarkable efficiency, stabilizing at the same time the dispersion of the nanoparticles (NPs) and enabling the plastic solubilization.
During the plastic fragmentation process, ILs prevent the deactivation of nanoparticles caused by coke deposition and simplify the recovery of co-generated solid carbon. These attributes significantly enhance product separation, streamline the recovery of the catalytic system—eliminating the need for complex recovery mechanisms—and enable its reuse. Collectively, the use of ILs greatly contributes to the viability and sustainability of the plastic waste valorization.
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How are the ionic liquids selected?
The design, synthesis, and selection of ionic liquids (ILs) will be carried out to fulfil the requirements necessary for ensuring optimal reaction performance. Key criteria include high thermal stability (>300 °C), capacity to solubilize plastics along with providing a stable medium for the dispersion of NPs and chemical stability against the generated products. Additionally, the ILs will be designed to exhibit low wettability with the solid carbon byproducts, facilitating the efficient separation and recovery of both the catalytic system and the decarbonized solid materials produced.
To achieve this, a computational study will be conducted on a series of pre-selected ILs, leveraging the expertise of the project´s partners. The most promising cations and anions will be identified through molecular dynamics simulations, which will provide insights into transport and solvation phenomena and will provide the selection of the most promising ILs candidates.
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How are ILs prepared and characterized?
The commercially available ones will be selected on the bases of the reported properties from the corresponding provider while the designed ILs will be synthetized following well-known synthetic strategies such as alkylation of an organic bases or anionic exchange of the IL counter anion with the desired one.
The ILs will be characterized to evaluate their short- and long-term chemical and thermal stability under various conditions, including microwave (MW) exposure. This evaluation will be performed using a range of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), elemental analysis (EA), and contact angle measurements among others.
The thermal and chemical stability of the ILs will be also examined in a hydrogen (H₂) atmosphere, as well as their stability in the presence of nanoparticles (NPs) and reaction by-products. This detailed analysis will ensure the suitability of the selected ILs for the catalytic fragmentation of plastic waste under MW.
The research on ionic liquids within the WASTE2H2 project showcases their immense potential in advancing plastic waste valorization. By fine-tuning their properties, the project aims to develop a highly efficient and sustainable catalytic system that facilitates the conversion of plastic into clean hydrogen, while ensuring catalyst longevity and reusability. As we move forward, the knowledge gained from this work will not only contribute to the success of WASTE2H2 but also open new pathways for greener industrial processes, reinforcing the role of innovative chemistry in the circular economy.