Energy & Sustainability

Shikha Gupta*, Jean-Paul Lange, Frederik Wurm, Sascha R.A. Kersten, M. Pilar Ruiz

University of Twente, Drienerlolaan 5, 7522 NB Enschede

shikha.gupta@utwente.nl

The increasing demand for sustainable materials has accelerated research into the valorisation of lignocellulosic biomass, a promising renewable carbon source due to its abundance, low cost [1]. The objective of this research project is to develop sustainable, circular and cost-effective thermoplastics or composites from woody biomass [2]. This study investigates the liquefaction behaviour and product characteristics of five types of biomass: pinewood, beechwood, bagasse, oak leaves, and spent coffee grounds, as potential sources for bio-based composite and coating precursors.

Each biomass was subjected to direct liquefaction using guaiacol at 300 °C for 30 minutes in a batch autoclave reactor. After removing the solid char, the resulting bio-oils were vacuum-distilled to separate lighter fractions, yielding a high-boiling vacuum residue (VR) for each feedstock. The VRs were comprehensively characterized using elemental analysis, gas chromatography (GC) for yield determination, and gel permeation chromatography (GPC) for molecular weight profiling. To determine structural features, advanced spectroscopic techniques including FTIR, ¹H-NMR, DOSY, ¹³C-NMR, HSQC, and ³¹P-NMR were employed.

The liquefaction process resulted in bio-oil yields exceeding 85 C% (based on dry feed), of which approximately 30–40 wt% constitutes the vacuum residue (VR) fraction, as determined by GPC (Mw > 1000 Da). NMR and FTIR analyses revealed the presence of aromatic hydroxyl groups, lignin-derived structures, and aliphatic functionalities across various VR samples. These chemical features underpin their application-specific potential: VRs from pinewood and beechwood exhibit reactive aromatic hydroxyl groups suitable for use as hardeners or curing agents in thermosetting resins. Besides aromatic hydroxyl groups, presence of aliphatic chain could enhance flexibility and hydrophobicity in polymer matrices. Meanwhile, the fatty acid and nitrogen rich VR from spent coffee grounds oak leaves showed significant reduction in curing temperature as compared to the PW without affecting the thermal and mechanical properties of the coatings. This comparative study provides an initial framework for guiding the

application-driven development of bio-based materials from biomass liquefaction residues. These insights establish a foundation for ongoing efforts to tailor biomass-derived VRs into sustainable, high-performance material platforms [3].

References

[1] M. Castellví Barnés, “Liquefaction of lignocellulose : bio-crude, char and chemistry of liquefaction,” PhD, University of Twente, Enschede, The Netherlands, 2016. doi:

10.3990/1.9789036541336.

[2] M. P. Ruiz et al., “Fully Recyclable Bio‐Based Thermoplastic Materials from Liquefied

Wood,” ChemSusChem, vol. 12, no. 19, pp. 4395–4399, Oct. 2019, doi:

10.1002/cssc.201901959.

[3] Q. Hu et al., “Fully Bio‐Based Epoxy Resins from Liquefied Wood for Chemically

Recyclable Wood Coatings,” Adv. Funct. Mater., vol. 35, no. 38, p. 2502689, Sep. 2025,

doi: 10.1002/adfm.202502689.

Beyond Recovery: Monitoring PHA Extraction from Biomass with NMR

R.V. Barrulas^a,d,*, C. M. Vermeer^b, B. P. Brandt^b, J. A. B. Sousa^b, F. R. Wurm^c, J. J. L. M. Cornelissen^a, B. Schuur^d, R. P. Martinho^a

^a Department of Molecules & Materials, MESA+ Institute & Faculty of Science and Technology, University of Twente, P. O. Box 217, 7500 AE Enschede, The Netherlands.

^b Paques Biomaterials BV, Tjalke de Boerstritte 24, Balk, 8561 EL, The Netherlands.

^c Sustainable Polymer Chemistry (SPC), Department of Molecules & Materials, MESA+ Institute & Faculty of Science and Technology, University of Twente, P. O. Box 217, 7500 AE Enschede, The Netherlands.

^d Sustainable Process Technology Group (SPT), Faculty of Science and Technology, University of Twente, P. O. Box 217, 7500 AE Enschede, The Netherlands.

*Email: r.a.valadaresbarrulas@utwente.nl

Bioplastics such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) are promising alternatives to petrochemical plastics due to their biobased origin and biodegradability; however, their large-scale adoption is hindered by inefficient and poorly understood extraction processes from complex biomass matrices [1,2]. Conventional analytical techniques, including chromatography and standard NMR, provide limited access to the molecular-scale events occurring in heterogeneous systems under realistic extraction conditions [3-6].

We report for the first time the use of in situ NMR spectroscopy for real-time, spatially resolved monitoring of PHBV extraction from organic-rich residual streams. By combining chemical specificity with spatial resolution, this approach enables in situ observation of solvent diffusion, polymer dissolution, and side-product formation with or without sample homogenization [7-9]. The resulting NMR profiles provide insight into the temporal and spatial evolution of the extraction process, including solvent transport, polymer dissolution, and the emergence of soluble components. These observations provide a molecular-level perspective on extraction dynamics and polymer stability, supporting a more mechanistic understanding of PHA recovery from complex biomass. Beyond conventional recovery measurements, in situ NMR offers a powerful analytical window into the dynamic mechanisms governing biopolymer extraction and provides a basis for improving sustainable extraction processes.

Acknowledgements: This activity is partly financed by the Allowance for Top Consortia for Knowledge and Innovation (TKIs) from the Ministry of Economic Affairs and Climate, project name ExtraProp, project number: 700.001.516.51.08/CHEMIE.PGT.2024.017.

References:

1. Vermeer, C. M. et al., Journal of Environmental Chemical Engineering, 10 (2022) 108573.

2. Elhami, V. et al., Separation and Purification Technology, 299 (2022) 121773.

3. Courtier-Murias, D. et al., Journal of Magnetic Resonance, 217 (2012) 61-76.

4. Uliyanchenko, E. et al., Polymer Chemistry, 3 (2012) 2313.

5. Colachis, M. et al., Science of The Total Environment, 955 (2024) 176920.

6. Koptyug, I. et al., Magnetic Resonance Imaging (MRI), in Springer Handbook of Advanced Catalyst Characterization (I. E. Wachs and M. A. Bañares Eds., Springer, Cham, 2023).

7. García-Aparício, C. et al., Journal of Colloid and Interface Science, 368 (2012) 14-20.

8. Waschina, S. et al., Analytica Chimica Acta, 1231 (2022) 340419.

9. Gao, Y. et al., European Journal of Organic Chemistry, 27 (2024) e202400095.

Jorik Schaap¹, Yannik Haver², Bastian Mei², Guido Mul¹, Annemarie Huijser^1,3, Kasper Wenderich¹.

¹PhotoCatalytic Synthesis Group, Mesa+ Institute, University of Twente, Enschede, The Netherlands.
²Ruhr University Bochum, Bochum, Germany.
³Max Planck Institute for Polymer Research, Mainz, Germany.

The development of efficient photo-(electro)catalysts is crucial for advancing solar energy conversion and sustainable chemical synthesis. Optimizing these materials requires deep understanding of the charge carrier dynamics. Because these essential photophysical processes occur on very short timescales, highly specialized analytical techniques are required to observe them.

Ultrafast spectroscopy is a powerful toolbox for unraveling these complex kinetics. We will focus on two different techniques available at the PCS group: Transient Absorption Spectroscopy (TAS) and Time-Resolved Photoluminescence (TRPL). Using these, we can track development of the excited state, and use this to correlate the photo physics to the catalytic performance.

To illustrate the capabilities of these techniques, we will discuss two case studies. First, we will examine in-situ bias-dependent TAS measurements on plasmonic photoelectrodes. This study demonstrates how by applying a cathodic bias potential we can modulate the plasmon resonance on the ultrafast timescale. Secondly, we will explore the use of TRPL to characterize the effect of platinum loading on strontium titanate (), for the methanol oxidation reaction. By monitoring radiative recombination lifetimes, we can directly probe the role of surface trap states and interfacial charge transfer in driving the catalytic reaction.

Ultimately, this talk aims to demonstrate how ultrafast spectroscopic insights provide vital information for the design and engineering of next-generation photo-(electro)catalytic materials.

Hybrid solid electrolytes (HSEs) based on polyethylene oxide (PEO) and garnet-type Li6.24La3Zr2Al0.24O11.98 (LLAlZO) have emerged as promising candidates for room-temperature solid-state lithium metal batteries; however, their practical application remains limited by insufficient ionic conductivity and interfacial resistance. In this study, the effects of single plasticizers, dual-plasticizer systems, and ionic liquid additives on the physicochemical and electrochemical properties of PEO–LiTFSI–LLAlZO hybrid solid electrolytes were systematically investigated. Flexible electrolyte membranes were fabricated via solution casting using succinonitrile (SN), ethylene carbonate (EC), polyethylene glycol (PEG), dual SN/EC plasticizers, and three ionic liquids (EMIM-TFSI, BMIM-TFSI, and PP13-TFSI) as additives. The dual-plasticizer electrolyte containing 12 wt% LLAlZO and equal proportions (2.75 wt%) of SN and EC (PLLSE-2.75-2.75) delivered the most balanced overall performance with an ionic conductivity of 1.8 × 10-5 S cm-1 at 40 °C and a lithium-ion transference number of 0.159 at 25 °C. Li/HSE/LFP cell could operate at 25 °C with a specific capacity of 131.1 mAh g-1 at 0.1C and 83.3% capacity retention after 50 cycles. This approach enhanced the amorphous regions in the polymer, resulting in a higher degree of Li salt dissociation and a favorable Li+ coordination environment, while also ensuring interface compatibility between the electrolyte and the electrodes. As such, the study proposes a solution to improve the electrochemical performance of hybrid solid electrolytes in Li metal batteries.