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# Lignin graphenization using solar concentrated energy

Salome Rigollet, Elsa Weiss-Hortala, Gilles Flamant, Ange Nzihou

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Salome Rigollet, Elsa Weiss-Hortala, Gilles Flamant, Ange Nzihou. Lignin graphenization using solar concentrated energy. HeteroNanoCarb 2025, Jan 2025, Benasque, Spain. hal-04987431

HAL Id: hal-04987431

https://imt-mines-albi.hal.science/hal-04987431v1

Submitted on 12 Mar 2025

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# Lignin graphenization using solar concentrated energy

S. RIGOLLET<fnref n="1" />, E. WEISS-HORTALA<fnref n="1" />, G. FLAMANT<fnref n="2" />, A. NZIHOU<fnref n="1" />,³

¹ Université de Toulouse, Mines Albi, CNRS UMR 5302, Centre RAPSODEE, Albi, France.

² Processes, Materials and Solar Energy Laboratory, PROMES-CNRS, Font-Romeu Odeillo, France.

³ Princeton University, Andlinger Center for Energy and the Environment, Princeton, NJ 08544, USA.

Biomass and biowastes can be used to produce graphitic composite materials using a high temperature process<fnref n="1" />. Graphitic biocomposites are promising materials in many fields (batteries, energy storage, pollution control sensors) thanks to their tunable electrical and thermal conductivity and mechanical properties. The thermal treatment is however quite energy-intensive since it requires temperatures higher than 2000°C. The purpose of this study is thus to produce graphitic biocarbons from biomass using solar carbonization<fnref n="2" />. Lignin (macopolymer of lignocellulosic biomass) is selected as feedstock in this study since its structure is partially aromatic. The sample is placed in a transparent reactor swept by N₂, at the focus point of a parabola concentrating the solar radiation on the sample's surface.

The graphitization efficiency is studied at temperatures between 1000 °C and 2000 °C using structural, textural and nanotextural analysis. X-ray diffraction analysis showed an increase in graphenic content in biocarbon with the increase of treatment temperature. Commercial graphite diffractogram is used as reference and shows a sharp peak at 2θ=26.5° of indices 002 from hexagonal carbon layer's basal reflection. For solar-biocarbons treated at 1000 °C and 1400 °C this peak is wide and shifted (2θ=24°) indicating turbostratic and amorphous content. At 1800 °C and 2000 °C, the peak gets sharper and a shoulder forms. This is explained by the presence of both well-organized graphitic structures and turbostratic structures. This composite nature is further seen using high-resolution Transmission Electron Microscopy (HRTEM). Graphene-like materials are successfully obtained from lignin using a solar carbonization.

<figure><img src="image_3.png" /><figcaption>Figure 1: a) XRD profiles of solar biocarbons from kraft lignin (KL) treated at different temperature. Commercial graphite profile (black) for comparison. b) HRTEM image of kraft lignin treated at 1800 °C in solar carbonization (x400 000). Scale is 20 nm.</figcaption></figure>

<footnote n="1">¹ Prekodravac et al., 'A Comprehensive Review on Selected Graphene Synthesis Methods'.</footnote>

<footnote n="2">² Rigollet et al., 'Biocarbon Graphenization Processes and Energy Assessment. A Review'; Zeng et al., 'Solar Pyrolysis of Carbonaceous Feedstocks'.</footnote>