News iPRACS research group

Synthesis of platform chemicals from ground tire rubber waste by means of ozonolysis (RSC Advances)

The EU's push toward a circular bioeconomy needs carbon that is not fossil, and is not taken from food systems.

That is a very short list. Waste tires should be on it.

Our new open-access paper in RSC Advances (link) looks at a complementary option: ozonolysis on end-of-life tire rubber toward platform chemicals. We achieved complete polymer conversion, with 74 wt% of the products being biocompatible platform chemicals. The headliners are levulinic acid and succinic acid, both listed by the EU as priority biobased platform chemicals, both feeding real downstream markets in pharma, solvents, resins, and biopolymers. Today these molecules are sourced from crops or petrochemical routes. Our results add to a growing body of work exploring whether waste rubber streams could contribute to the same value chain.The paper focuses on lab-scale chemistry: reaction conditions, product distribution, and characterisation. Scale-up, techno-economic analysis, and integration with existing tire-recycling infrastructure remain open questions for future work.

This work was realized by Yanou Fishel, Sébastien Maricaux and Prof. Filip Lemiere and supervised by Prof. Pieter Billen and Prof. Christophe Vande Velde. With thanks to the support of Fonds Wetenschappelijk Onderzoek - Vlaanderen (FWO) 

Upcycling definition

Prof. Pieter Billen got frustrated with the rise of the word "upcycling" in scientific and technological reports, and especially with its uptake in offical EU policy documents. He says: "I could not get my head around this term, as it seems to violate all thermodynamic principles at the heart of our research".

In an attempt to clarify this, making the distinction with "recycling", he realized that our engineering reasoning about circular systems often implicitly assumes commodity logic. And, in commodity materials the value (market price) is almost linearly linked to energy. This allows strategic planning, and rapid screening (see the recent paper of Britt Segers) while business leaders ought to step out of the commodities game to valorize innovation efforts. Precisely this last activity is what, in my new definition, sets "upcycling" apart from "recycling", wherever one feels the need to utilize this term. Most technological reports do not report any economic or business aspects, and should therefore refrain from using "upcycling", as it is not scientifically grounded, and might indeed violate thermodynamics.

In short: let's keep this term for the business world, provided it is properly substantiated to avoid another greenwashing cycle (as per the last sentence of my paper).

Prof. Pieter Billen's opinion on this, and the introduction of new definitions, has now been published in Circular Economy and Sustainability - CIES (Springer journal). The following link provides full only-read access. 

🔬 iPRACS at 10th EuChemS Chemistry Congress (ECC10): showcasing innovation in circular chemistry

iPRACS was strongly represented at ECC10 in Antwerp (July 2026), with multiple posters and oral presentations highlighting our latest research in chemical recycling, sustainable polymers, catalysis, modelling, and circularity.

📃 Posters 

• Britt Segers – Entropy management of PLA: Novel state-based screening method for decision support from feedstock to end-of-life treatment
• Féline De Meester – Unraveling competing reactions in the synthesis of renewable α-methylene-γ-valerolactone
• Fuline MUSENGO OTOMBOY – Immobilized pincer ligand for cross-coupling reaction in flow 
• Zoë De Herdt – RENOVATE-PU: Recycle the non-recyclable by valorizing industrial chemical recycling techniques for polyurethane
• Makram Elabed – From Waste to Value-Added Polymers: Chemical Transformation of PET into Eco-Friendly Copolyesteramides 
• Christophe Vande Velde – Hydrogen bond-donating large-pore MOFs as catalysts 
• Elke Theeuwes – Getting all ducks in one row: unraveling the complexity of chemical recycling of hard-to-recycle plastics

🎤 Oral presentations

• Christophe de Graaf – Bridging molecular dynamics and COSMO-RS simulations with macroscale modelling for advancements in polyurethane post-depolymerization separation processes 
• Jonas Cassimon – Tagging for circularity: fluorescent tagging of polycondensation polymers to enable efficient sorting and enhanced recycling
• Attila Kovács – Statistical entropy analysis for the evaluation of polymer complexity and circularityWe look forward to connecting with fellow researchers, industry professionals, and innovators throughout the conference.

💡 Interested in one of these topics? Feel free to reach out to the researchers and principle investigators directly, or contact Elke Theeuwes, Business Developer at iPRACS.

Principle investigators: Pieter Billen, Christophe Vande Velde, and Yoshi Marien.

Evaluating global warming potential distributions in biomass to polylactic acid routes by a mass-distribution state-based screening method (Bioresource Technology Reports)

This publications explores how we can estimate the climate impact of PLA production at the earliest stages of process development.

Early-stage decision-making is often hindered by the lack of detailed process models. In this work, we demonstrate how a state-based screening method, based on mass distributions, can provide insights into the global warming potential of different biomass feedstocks without requiring detailed process simulations.Our goal is to contribute to practical decision-support tools for designing more sustainable biobased value chains while enabling thermodynamically grounded decision-making in emerging bioeconomy systems.

This publication was realized by Britt Segers, Attila Kovacs, Peng Xiao, Philippe Nimmegeers and Pieter Billen. 

📄 Read the full open access paper here: https://lnkd.in/eniRvNBQ

Reinventing molecular entropy for sustainable cycling of macromolecules

At the 11th International Conference on Engineering for Waste and Biomass Valorisation Conference (A Coruña, Spain), prof. Pieter Billen gave an update on our information-theoretic work on entropy management for a working circular (bio-)economy. 

Although we have excellent navigation systems to support decisions, they are data thirsty and rely on detailed maps. The final direction sometimes seems obscure. That is why thermodynamics and statistics may provide an excellent compass to direct our efforts. Oxidation state changes are worth bookkeeping in a smart way. Secondly, entropy changes matter a lot in energy expenses, when oxidation states change only slightly. 

Interested in this topic? Check the publication of Britt Segers in RSC Sustainability: Screening for carbon value in a future bioeconomy through carbon oxidation states and statistical entropy. 

Much more is yet to come!

But meanwhile, shout out to all of our collaborators who have joined Prof. Pieter Billen on this quest: Britt Segers, Cristina Moyaert, Attila Kovács, Leandro de Pinho Silva Soares, Carla Calero Pérez, Yoshi Marien, and Philippe Nimmegeers.

The Road to Molecular Circularity of Polyurethane: Quality Control on Steroids

At the latest EUROPUR conference in Antwerp, Prof. Pieter Billen was invited to speak about polyurethane recycling. The main message of his talk was: let's use circularity as a pretext to deeply understand polyurethane chemistry, and from there design comfortable, durable, desirable, AND sustainable materials.

The main takeaways are:

1. We can make a business case for polyol tagging, allowing tracing and circularity even for complex formulations. (Jonas Cassimon)
   
2. We are going to model polyurethane, ensuring consolidated knowledge on physical chemistry and polymer engineering, together with leading experts from Universiteit Gent (Dagmar D'Hooge and Paul Van Steenberge), Vrije Universiteit Brussel (Frank De Proft and Guy Van Assche), and Rijksuniversiteit Groningen (Remco Havenith). With support of these partners: Ana Cunha, Joost Brancart, Attila Kovacs, and others.
3. We need to talk about circular isocyanates. We can make them from waste, the technology is feasible and seems economic. Support our ISONEXT Moonshot project proposal, whereby the academic consortium consists of iPRACS (Pieter Billen, Christophe Vande Velde and Yoshi Marien), together with Universiteit Gent (Yi Ouyang) and Vrije Universiteit Brussel (Joost Brancart and Guy Van Assche).

Do not hesitate to reach out to Elke Theeuwes for more information. 

A special thanks to the organizers and the audience for fruitful interactions during the conference and FWO for providing the opportunity to do this research. 

Together with UCSIA an event was held to shed light on how we can kick-start chemical recycling plastic opportunities in Tunsia. To explore this topic in more depth lectures were given, as well as introductions and a panel discussion (including experts of the European Commission, University of Hasselt, Arab-Belgian-Luxembourgh Chamber of Commerce and University of Mons). 

During this event we had the opportunity to celebrate and create a basis of understanding for a new collaboration between iPRACS and the University of Sfax on the doctoral research of Makram Elabed, who received a Fonds Bruyns scholarship from UCSIA.

How do you measure how 'recycleable' a polymer is - before you've made it?

​Attila Kovács presented at the Brightland Polymer Days 2026, tackling exactly this question. 

Polymers gain performance from structural diversity - but the same diversity makes recycling harder and more energy-intensive. Current descriptors like dispersity simply do not capture this well enough to guide circular design. 

At iPRACS we propose to apply Statistical Entropy Analysis (SEA), rooted in Shannon's information theory, at the molecular level of polymers. Hereby applying a four-level model: chain length -> topology -> graft length -> monomer identity. 

Using kinetic Monte Carlo simulations of polybutadiene/styrene grafting, we showed that molecular entropy:

• Tracks complexity monotonically with conversion, where dispersity fails.
  
• Captures multimodel distributions that single-number metrics miss.
• Quantifies the complexity penalty of blending mixed polymer feedstocks.

The vision: a metric that links molecular design choices to recyclability from the earliest stages of synthesis.

Next-generation rubber recycling process using ozone

At the ETRA conference 2026 (European Tyre Recycling Association), Elke Theeuwes presented an update on the tyre recycling research performed at iPRACS by Yanou Fishel and Prof. Christophe Vande Velde. 

​During the lifetime of tyres, degradation by ozone must be avoided. However, at end-of-life, an ozone treatment can be beneficial as a recycling technique in order to obtain chemical platform molecules, oxidized carbon black, and a gaseous stream. It is a fully electrified process, thereby creating opportunities in the circular economy after successful upscaling. This ozonolysis technology could become the next-generation recycling technology after pyrolysis.

The NCO cycle: a two-step complete recycling process for polyurethanes

Marthe Nees defended successfully her PhD thesis, whereby she demonstrated an elegant approach to circularity. In order to recover isocyanates from polyurethante waste, she used a two-step apporoach consisting of:

1. Polyurethane alcoholysis to recover polyols
   
2. The remaining carbamates are thermolysed into isocyanates

Congratulations on this achievement!

Water polluted with PFAS and air with far too much CO₂. Two serious problems for which one type of substance could well be the answer: MOFs. In 2025, their discoverers won the Nobel Prize for Chemistry for this. And rightly so, according to chemist Prof. Dr. Christophe Vande Velde. He also enjoys tinkering with them at the University of Antwerp and joyfully announces the MOF era in this video!

​Pieter Billen explains in Knack how we should keep demanding more sustainable packaging materials, yet not be unrealistic about the timing, and certainly be careful when replacing plastics with other materials. (Knack)​

​Pieter Billen explains in Knack how we should keep demanding more sustainable packaging materials, yet not be unrealistic about the timing, and certainly be careful when replacing plastics with other materials. Industry is working hard on new recycling technologies, driven by upcoming legislation. We at iPRACS are doing our share to contribute to this effort. (article in Dutch)