Methane cracking has emerged as a promising route for sustainable hydrogen production because it avoids direct carbon dioxide emissions while simultaneously enabling carbon sequestration in the form of solid carbon. In this work, a comprehensive and systematic experimental investigation of catalytic methane cracking was performed by directly comparing a commercial nickel catalyst (KATALCO™ 25-4MQ), an in-house catalyst prepared by wet impregnation using Fe(NO₃)₃·9H₂O as the iron precursor and Puralox SCFa-160 Ce20 as the support, and non-catalytic thermal conditions under identical operating parameters. Experiments were carried out in a laboratory-scale fixed-bed reactor at atmospheric pressure by varying methane partial pressure (0.1–0.2 atm) and operating temperature (600–800 °C), while maintaining a constant methane-specific WHSV of 0.3 h⁻¹. Continuous online gas analysis was employed to monitor reactor performance, and a dedicated post-processing methodology, including nitrogen-tracer-based carbon balance calculations, was developed to validate the experimental results. The results demonstrated the strong beneficial effects of both temperature and catalytic materials on methane decomposition. The Fe-based catalysts exhibited the highest performance, achieving average methane conversions and hydrogen yields approaching 50%, with peak values exceeding 90% under the most favorable conditions. Commercial Ni catalysts also showed promising activity, although a more pronounced deactivation tendency was observed during prolonged operation. Conversely, non-catalytic tests resulted in substantially lower performance. Overall, this work provides an experimentally assessed and integrated methodology together with benchmark performance indicators that may serve as useful guidance for researchers, process designers, and practitioners involved in the development, optimization, and future scale-up of methane cracking technologies for turquoise hydrogen production.

In this study, an electrochemical valorization strategy on liquid byproducts from hazelnut shell gasification was developed to couple waste remediation with energy-efficient hydrogen production. The aqueous phase, rich in organic compounds, is processed in an anion exchange membrane (AEM) cell, where pure hydrogen evolved at the cathode while organic pollutants are oxidized at the anode. First, the feedstock is thoroughly characterized using gas chromatography–mass spectrometry (GC-MS), identifying a complex matrix of water-soluble aromatic compounds such as phenols, catechols, and other aromatics compounds, with concentrations reaching up to 2.9 g/kg for catechols. Then, the electro-reforming process is optimized using Nickel oxide–hydroxide (Ni(O)OH) electrodes with a loading of 0.75 mg/cm². This methodology relies on the favorable thermodynamics of organic oxidation, which requires a lower onset potential (0.4 V) compared to the oxygen evolution reaction (OER) observed in the alkaline control (0.52 V), and the low overpotential of the Nickel oxide–hydroxide electrode towards the oxidized species. Consequently, the organic load undergoes progressive oxidation into hydrophilic and less bioaccumulating species and carbon dioxide, allowing for the simultaneous generation of pure hydrogen at the cathode at a reduced cell voltage. Elevated stability was observed, with a substantial abatement—78% of the initial organic load—of organic compounds achieved over 80 h at a fixed cell voltage of 0.5 V, and a specific energy consumption for hydrogen production of $38.5 \mathrm{M}\mathrm{J}\cdot {\mathrm{k}\mathrm{g}}_{{\mathrm{H}}_2}^{-1}$. This represents a step forward in the development of technologies that reduce the energy intensity of hydrogen generation while valorizing biomass gasification residues.

The use of biochar derived from agricultural wood waste represents a promising long-term carbon storage strategy, contributing to mitigation of climate change effects while offering agronomic benefits. This residue is considered as an appropriate material since it does not compete directly with the food chain. Life Cycle Assessment (LCA) is a widely recognized methodology to evaluate the potential environmental impacts associated with all the stages of the life cycle of a product, process or service. In this study, the potential environmental impact of biochar production and its application on soil have been assessed employing a cradle-to-grave approach. The biochar was produced through the pyrogasification of residual lignocellulosic biomass in a pilot-scale plant. The LCA model has been generated employing the GaBi software (LCA for experts 10.7), in accordance with ISO LCA standards and ILCD Handbook, using the experimental results collected during the test carried out in the pilot plant. Two scenarios have been discussed: a basic scenario, involving the biochar production and application on the soil, and an improved scenario, in which by-products from biochar production are used to replace energy in thermal processes. The Global Warming Potential (GWP) of biochar production resulted in −5.52 kg CO₂ eq./kg of biochar including the sequestered carbon during plant growth and 1.81 kg CO₂ eq./kg of biochar stored in soil and the heat recovery resulted in approximately 20 MJ/kg of biochar of avoided consumption of fossil-based fuels. These findings provide additional support to evaluate biochar potential as an environmentally beneficial solution.

In this study, an electrochemical valorization strategy on liquid byproducts from hazel-nut shell gasification was developed to couple waste remediation with energy-efficient hydrogen production. The aqueous phase, rich in organic compounds, is processed in an anion exchange membrane (AEM) cell, where pure hydrogen evolved at the cathode while organic pollutants are oxidized at the anode. First, the feedstock is thoroughly charac-terized using gas chromatography-mass spectrometry (GC-MS), identifying a complex matrix of water-soluble aromatic compounds such as phenols, catechols, and other aro-matics compounds, with concentrations reaching up to 2.9 g/kg for catechols. Then, the electro-reforming process is optimized using Nickel oxide-hydroxide (Ni(O)OH) elec-trodes with a loading of 0.75 mg/cm2. This methodology relies on the favorable thermo-dynamics of organic oxidation, which requires a lower onset potential (0.4 V) compared to the oxygen evolution reaction (OER) observed in the alkaline control (0.52 V), and the low overpotential of the Nickel oxide-hydroxide electrode towards the oxidized species. Consequently, the organic load undergoes progressive oxidation into hydrophilic and less bioaccumulating species and carbon dioxide, allowing for the simultaneous genera-tion of pure hydrogen at the cathode at a reduced cell voltage. Elevated stability was observed, with a substantial abatement of organic compounds achieved over 80 hours at a fixed cell voltage of 0.5 V. This represents a step forward in the development of tech-nologies that reduces the energy intensity of hydrogen generation while valorizing bio-mass gasification residues.