The present investigation represents a concrete example of complete valorization of Eucalyptus nitens biomass, in the framework of the circular economy. Autohydrolyzed-delignified Eucalyptus nitens was employed as a cheap cellulose-rich feedstock in the direct alcoholysis to n-butyl levulinate, adopting n-butanol as green reagent/reaction medium, very dilute sulfuric acid as a homogeneous catalyst, and different heating systems. The effect of the main reaction parameters to give n-butyl levulinate was investigated to check the feasibility of this reaction and identify the coarse ranges of the main operating variables of greater relevance. High n-butyl levulinate molar yields (35–40 mol%) were achieved under microwave and traditional heating, even using a very high biomass loading (20 wt%), an eligible aspect from the perspective of the high gravity approach. The possibility of reprocessing the reaction mixture deriving from the optimized experiment by the addition of fresh biomass was evaluated, achieving the maximum n-butyl levulinate concentration of about 85 g/L after only one microwave reprocessing of the mother liquor, the highest value hitherto reported starting from real biomass. The alcoholysis reaction was further optimized by Response Surface Methodology, setting a Face-Centered Central Composite Design, which was experimentally validated at the optimal operating conditions for the n-butyl levulinate production. Finally, a preliminary study of diesel engine performances and emissions for a model mixture with analogous composition to that produced from the butanolysis reaction was performed, confirming its potential application as an additive for diesel fuel, without separation of each component.

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Underground Hydrogen Storage (UHS) is a method to store a large amount of energy to manage its seasonal fluctuations. The selection of proper well materials is a critical aspect, considering the small size of the molecule of H2 and its strong diffusivity. Its impact on materials shall be deeply evaluated and investigated. The work described in this document analyzes the interaction of standard cement slurries used in oil and gas fields with hydrogen at standard reservoir conditions. The cement-hydrogen interaction tests were designed and conducted using the methodological approach typical of the materials/fluids compatibility tests; an autoclave was used as key instrumentation to simulate reservoir temperature and pressure conditions. The samples were left inside the autoclave in contact with hydrogen, at reservoir temperature and pressure condition (90 °C and 150 bar), for 8 weeks. In parallel to the aging in hydrogen, twin samples were aged in an inert atmosphere (nitrogen) for comparison. The effects of the long exposure of the cement to H2 have been analyzed by observing the changes in the chemical-physical properties of the cement itself. To give evidence of the goodness of the cement as a well sealant material in the UHS, compressive strength, saturation and permeability, chemistry of the cement were measured/analyzed pre- and post-hydrogen exposure. In addition to the tests, a theoretical analysis performed using thermodynamic modeling software was also conducted to validate test results. The thermodynamic analysis was focused on the specific interaction of the species, hydrate and not-, constituting the cement and the hydrogen, investigating the spontaneity of the redox reactions that could take place. Preliminary autoclave experimentation results show that hydrogen does not alter overly chemical and physical characteristics of cement samples. This compatibility study of Hydrogen with cement is the first important step to further de-risk any UHS activity. The engineered and adopted testing protocol reported in this paper proved to be effective for the purpose of the study and could be applied for the validation of specific cement slurries in the UHS contexts.