A chemical-loop approach for the generation of hydrogen by means of ethanol reforming

The work investigates the feasibility of a new process aimed at the production of hydrogen with inherent separation of carbon oxides. The process consists in a cycle in which, in the first step, a mixed metal oxide is reduced by ethanol (obtained from biomasses). The reduced metal is then contacted with steam in order to split the water and sequestrating the oxygen into the looping material’s structure. The oxides used to run this thermochemical cycle, also called “steam-iron process” are mixed ferrites in the spinel structure MeFe2O4 (Me = Fe, Co, Ni or Cu). To understand the reactions involved in the anaerobic reforming of ethanol, diffuse reflectance spectroscopy (DRIFTS) was used, coupled with the mass analysis of the effluent, to study the surface composition of the ferrites during the adsorption of ethanol and its transformations during the temperature program. This study was paired with the tests on a laboratory scale plant and the characterization through various techniques such as XRD, Mössbauer spectroscopy, elemental analysis... on the materials as synthesized and at different reduction degrees In the first step it was found that besides the generation of the expected CO, CO2 and H2O, the products of ethanol anaerobic oxidation, also a large amount of H2 and coke were produced. The latter is highly undesired, since it affects the second step, during which water is fed over the pre-reduced spinel at high temperature. The behavior of the different spinels was affected by the nature of the divalent metal cation; magnetite was the oxide showing the slower rate of reduction by ethanol, but on the other hand it was that one which could perform the entire cycle of the process more efficiently. Still the problem of coke formation remains the greater challenge to solve.

Synthesis of new bioactive β-lactam compounds

New biologically active β-lactams were designed and synthesized, developing novel antibiotics and enzymatic inhibitors directed toward specific targets. Within a work directed to the synthesis of mimetics for RGD (Arg-Gly-Asp) sequence able to interact with αvβ3 and α5β1-type integrins, new activators were developed and their Structure-Activity Relationships (SAR) analysis deepened, enhancing their activity range towards the α4β1 isoform. Moreover, to synthesize novel compounds active both against bacterial infections and pulmonary conditions of cystic fibrosis patients, new β-lactam candidates were studied. Among the abundant library of β-lactams prepared, mainly with antioxidant and antibacterial double activities, it was identified a single lead to be pharmacologically tested in vivo. Its synthesis was optimized up to the gram-scale, and pretreatment method and HPLC-MS/MS analytical protocol for sub-nanomolar quantifications were developed. Furthermore, replacement of acetoxy group in 4-acetoxy-azetidinone derivatives was studied with different nucleophiles and in aqueous media. A phosphate group was introduced and the reactivity exploited using different hydroxyapatites, obtaining biomaterials with multiple biological activities. Following the same kind of reactivity, a small series of molecules with a β-lactam and retinoic hybrid structure was synthesized as epigenetic regulators. Interacting with HDACs, two compounds were respectively identified as an inhibitor of cell proliferation and a differentiating agent on steam cells. Additionally, in collaboration with Professor L. De Cola at ISIS, University of Strasbourg, some new photochemically active β-lactam Pt (II) complexes were designed and synthesized to be used as bioprobes or theranostics. Finally, it was set up and optimized the preparation of new chiral proline-derived α-aminonitriles through an enantioselective Strecker reaction, and it was developed a chemo-enzymatic oxidative method for converting alcohols to aldehydes or acid in a selective manner, and amines to relative aldehydes, amides or imines. Moreover, enzymes and other green chemistry methodologies were used to prepare Active Pharmaceutical Ingredients (APIs).

Development of an innovative pyrolysis plant for the production of secondary raw materials

This project was born with the aim of developing an environmentally and financially sustainable process to dispose of end-life tires. In this perspective was devised an innovative static bed batch pilot reactor where pyrolysis can be carried out on the whole tires in order to recover energy and materials and simultaneously save the energy costs of their shredding. The innovative plant is also able to guarantee a high safety of the process thanks to the presence of a hydraulic guard. The pilot plant was used to pyrolyze new and end-life tires at temperatures from 400 to 600°C with step of 50°C in presence of steam. The main objective of this research was to evaluate the influence of the maximum process temperature on yields and chemical-physics properties of pyrolysis products. In addition, in view of a scale-up of the plant in continuous mode, the influence of the nature of several different tires as well as the effects of the aging on the final products were studied. The same pilot plant was also used to carry out pyrolysis on polymeric matrix composites in order to obtain chemical feedstocks from the resin degradation together with the recovery of the reinforcement in the form of fibers. Carbon fibers reinforced composites ad fiberglass was treated in the 450-600°C range and the products was fully characterized. A second oxidative step was performed on the pyrolysis solid residue in order to obtain the fibers in a suitable condition for a subsequent re-impregnation in order to close the composite Life Cycle in a cradle-to-cradle approach. These investigations have demonstrated that steel wires, char, carbon and glass fibers recovered in the prototypal plant as solid residues can be a viable alternative to pristine materials, making use of them to obtain new products with a commercial added value.

1st and 2nd Generation Ethanol from Biomass Crops

In chapter 1 and 2 calcium hydroxide as impregnation agent before steam explosion of sugarcane bagasse and switchgrass, respectively, was compared with auto-hydrolysis, assessing the effects on enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) at high solid concentration of pretreated solid fraction. In addition, anaerobic digestion of pretreated liquid fraction was carried out, in order to appraise the effectiveness of calcium hydroxide before steam explosion in a more comprehensive way. In As water is an expensive input in both cultivation of biomass crops and subsequent pretreatment, Chapter 3 addressed the effects of variable soil moisture on biomass growth and composition of biomass sorghum. Moreover, the effect of water stress was related to the characteristics of stem juice for 1st generation ethanol and structural carbohydrates for 2nd generation ethanol. In the frame of chapter 1, calcium hydroxide was proven to be a suitable catalyst for sugarcane bagasse before steam explosion, in order to enhance fibre deconstruction. In chapter 2, effect of calcium hydroxide on switchgrass showed a great potential when ethanol was focused, whereas acid addition produced higher methane yield. Regarding chapter 3, during crop cycle the amount of cellulose, hemicellulose and AIL changed causing a decrease of 2G ethanol amount. Biomass physical and chemical properties involved a lower glucose yield and concentration at the end of enzymatic hydrolysis and, consequently, a lower 2G ethanol concentration at the end of simultaneous saccharification and fermentation, proving that there is strong relationship between structure, chemical composition, and fermentable sugar yield. The significantly higher concentration of ethanol at the early crop stage could be an important incentive to consider biomass sorghum as second crop in the season, to be introduced into some agricultural systems, potentially benefiting farmers and, above all, avoiding the exacerbation of the debate about fuel vs food crops.