Alexander Lopez-Urionabarrenechea

This study examines the upgrading of plastic waste pyrolysis oil (PWPO) derived from real waste electrical and electronic equipment (WEEE) and waste packaging (WP), with the objective of producing oil fractions for their valorization in material recycling strategies. The PWPO, rich in oxygen, nitrogen, sulfur, chlorine and bromine, was hydrotreated and subsequently fractionated into distillation cuts (naphtha, kerosene, atmospheric gas-oil and residue). The experiments were carried out in a continuous laboratory facility using two commercial hydrotreating catalysts: NiMo/Al₂O₃ and CoMo/Al₂O₃. These catalysts were tested in 5-day-long experiments, increasing the temperature by about 30 °C every 24 hours, from 240 °C to 360 °C. In general, the NiMo catalyst performed better, yielding a hydrotreated oil virtually free of halogens at 360 °C. The naphtha fraction, representing almost half of the hydrotreated oil, contained neither sulfur nor nitrogen, and a proportion of benzene, toluene, ethylbenzene, and xylenes (BTEX) around 75 wt.%, making it an alternative source of these valuable and widely used chemicals. In addition, naphthalene-rich kerosene and gas oil fractions were produced, with potential for use as a naphthalene oil source. The bottom residue fraction, yielding ≈ 20 wt.%, could be reintroduced into refinery processes or used as marine fuel. These exceptional results enable the design of circular strategies for the production of petrochemicals from waste materials.

Up to date, research on sodium‐ion batteries (SIBs) has primarily focused on half‐cell configurations, a crucial but preliminary step in evaluating suitable materials for full‐cell SIBs. To date, the literature on hard carbon (HC)‐based full‐cell SIBs remains limited, and the irreversibility associated with the first cycle of HC anodes presents a significant challenge for the commercialization of hard carbon‐based SIBs. This work evaluates sodium mesoxalate as a sacrificial salt (SS) in the cathode to compensate for biomass‐based hard carbon first cycle irreversibility in two full‐cell systems versus Na ₃ V ₂ (PO ₄ ) ₃ @C and Na ₃ V ₂ O ₂ (PO ₄ ) ₂ F@C. This sacrificial salt is selected due to its nonflammability, low cost, and ease of dehydration. Full‐cell studies utilizing the sacrificial salt‐containing cathodes and biomass‐derived hard carbon anodes demonstrate to achieve outstanding specific capacity and rate capability at low and moderate rates (from 9 to 130 mA g ⁻¹ ) for the fluorophosphate cell chemistry but poorer electrochemical results for the NASICON‐based system. Finally, Life Cycle Assessment methodology is applied to the sacrificial salt containing full‐cells to evaluate and compare the environmental footprint of these SS full‐cells based on a sustainable anode with polyanionic cathode chemistries.

The generation of pyrolysis liquids and gases with poor quality is a limiting factor for the development of the recycling process of fiber-reinforced plastic waste. In this article, the life cycle assessment (LCA) of an advanced two-step pyrolysis process to recycle glass fiber-reinforced polyamide waste is presented. First, the solid waste is pyrolyzed by heating up at 3 °C/min to 500 °C in a tank reactor. The generated volatiles are subsequently thermally cracked at 900 °C in a tubular packed bed reactor. The process is able to reclaim the glass fibers similarly to the conventional one reactor pyrolysis, while producing liquids and gases with better properties. The large quantity of oxygenated pyrolysis oils generated in the conventional pyrolysis are cracked into gaseous hydrocarbons, CO, CO₂ and a minor aqueous liquid. The pyrolysis gases become the main product of the process, presenting an interesting composition of hydrogen (39.9 vol.%), methane (22.5 vol.%), carbon monoxide (19.5 vol.%) and ethylene (10.8 vol.%). The LCA shows that advanced pyrolysis demonstrates better environmental performance than conventional pyrolysis, avoiding fossil resource scarcity and reducing global warming by half and human carcinogenic toxicity by one third.

Waste carbon fibre-reinforced plastics were recycled by pyrolysis followed by a thermo-catalytic treatment in order to achieve both fibre and resin recovery. The conventional pyrolysis of this waste produced unusable gas and hazardous liquid streams, which made necessary the treatment of the pyrolysis vapours. In this work, the vapours generated from pyrolysis were valorised thermochemically. The thermal treatment of the pyrolysis vapours was performed at 700 °C, 800 °C and 900 °C, and the catalytic treatment was tested at 700 °C and 800 °C with two Ni-based catalysts, one commercial and one homemade over a non-conventional olivine support. The catalysts were deeply characterised, and both had low surface area (99 m²/g and 4 m²/g, respectively) with low metal dispersion. The thermal treatment of the pyrolysis vapours at 900 °C produced high gas quantity (6.8 wt%) and quality (95.5 vol% syngas) along with lower liquid quantity (13.3 wt%) and low hazardous liquid (92.1 area% water). The Ni–olivine catalyst at the lowest temperature, 700 °C, allowed us to obtain good gas results (100% syngas), but the liquid was not as good (only 58.4 area% was water). On the other hand, the Ni commercial catalyst at 800 °C improved both the gas and liquid phases, producing 6.4 wt% of gas with 93 vol% of syngas and 13.6 wt% of liquid phase with a 97.5 area% of water. The main reaction mechanisms observed in the treatment of pyrolysis vapours were cracking, dry and wet reforming and the Boudouard reaction.

In this work, the low-temperature pyrolysis of a real plastic mixture sample collected at a WEEE-authorised recycling facility has been investigated. The sample was pyrolysed in a batch reactor in different temperature and residence time conditions and auto-generated pressure by following a factorial design, with the objective of maximising the liquid (oil) fraction. Furthermore, the main polymers constituting the real sample were also pyrolysed in order to understand their role in the generation of oil. The pyrolysis oils were characterised and compared with commercial fuel oil number 6. The results showed that in comparison to commercial fuel oil, pyrolysis oils coming from WEEE plastic waste had similar heating values, were lighter and less viscous and presented similar toxicity profiles in fumes of combustion.

Over the last years, hard carbon (HC) has been the most promising anode material for sodium‐ion batteries due to its low voltage plateau, low cost and sustainability. In this study, biomass waste (spent coffee grounds, sunflower seed shells and rose stems) was investigated as potential material for hard carbon preparation combining a two‐step method consisting of on hydrothermal carbonization (HTC), to remove the inorganic impurities and increase the carbon content, and a subsequent pyrolysis process. The use of HTC as pretreatment prior to pyrolysis improves the specific capacity in all the materials compared to the ones directly pyrolyzed by more than 100 % at high C‐rates. The obtained capacity ranging between 210 and 280 mAh g⁻¹ at C/15 is similar to the values reported in literature for biomass‐based hard carbons. Overall, HC obtained from sunflower seed shell performs better than that obtained from the other precursors with an initial Coulombic efficiency (ICE) of 76 % and capacities of 120 mAh g⁻¹ during 1000 cycles at C with a high capacity retention of 86–93 %.