Silvia Spera

Characterization of Bio‐oil from Hydrothermal Liquefaction of Organic Waste by NMR Spectroscopy and FTICR Mass Spectrometry

Solid wastes of organic origins are potential feedstocks for the production of liquid biofuels, which could be suitable alternatives to fossil fuels for the transport and heating sectors, as well as for industrial use. By hydrothermal liquefaction, the wet biomass is partially transformed into a water-immiscible, oil-like organic matter called bio-oil. In this study, an integrated NMR spectroscopy/mass spectrometry approach has been developed for the characterization of the hydrothermal liquefaction of bio-oil at the molecular level. (1)H and (13)C NMR spectroscopy were used for the identification of functional groups and gauging the aromatic carbon content in the mixture. GC-MS analysis revealed that the volatile fraction was rich in fatty acids, as well as in amides and esters. High-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) has been applied in a systematic way to fully categorize the bio-oil in terms of different classes of components, according to their molecular formulas. Most importantly, for the first time, by using this technique, and for the liquefaction bio-oil characterization in particular, FT-MS data have been used to develop a methodology for the determination of the aromatic versus aliphatic carbon and nitrogen content. It is well known that, because they resist hydrogenation and represent sources of polluting species, both aromatic molecules and nitrogen-containing species raise concerns for subsequent upgrading of bio-oil into a diesel-like fuel.

Polymerization of styrene with nickel complex/methylaluminoxane catalytic systems

Polymerization of styrene using catalytic systems based on nickel derivatives and methylaluminoxane (MAO) was studied. Among tested catalysts, nickel bis(acetylacetonate) and nickel dichloride show the maximum activity. Bis(phosphine)nickel dichlorides exhibit lower activity, depending on the nature of the phosphine ligand. Polymer yields decrease by lowering the catalyst concentration, by increasing the reaction temperature, or by carrying out the polymerization in a polar donor solvent. Weight average molecular weight of most of the prepared polystyrenes ranges from 9000 to 25,000, with polydispersity indexes of 1.6–3.8. However, polystyrene prepared in dioxane solvent exhibits a small fraction of very high molecular weight (about 140,000). From NMR analysis, the products seem generally to be constituted of two polymers with different steric microstructure: atactic polystyrene and partially isotactic polystyrene (ca. 75–85% meso diads). Catalytic site specificity is correlated with the type of nickel ligand, while the effect of reaction temperature is less defined.

Synthesis of phosphatidylcholines containing ricinoleic acid

Abstract 1,2-Diricinoleoyl- and 1-ricinoleoyl-2-oleoyl-sn-glycero-3-phosphocholine were synthesised with good yields. The synthesis started with the preparation of ricinoleic acid from castor oil. The choice of a suitable agent to protect the –OH group of ricinoleic acid was a key factor to afford the final products. Several protecting groups were assayed but only β-methoxyethoxymethyl chloride (MEMCl) and 2,2,2-trichloroethyl chloroformate (TRECCl) gave reasonable yields and good optical purities of the final products. The overall yields for 1,2-diricinoleoyl-sn-glycero-3-phosphocholine and 1-ricinoleoyl-2-oleoyl-sn-glycero-3-phosphocholine were 32.1% (with respect to ricinoleic acid methyl ester using TREC as protecting group) and 10.3% (with respect to 1-trityl-glycero-3-phosphocholine), respectively.

13C and 1H nuclear magnetic resonance relaxation of poly(ethylene terephthalate), poly(ethylene isophthalate) and their copolyester in solution: a molecular motion study

Abstract 13 C nuclear magnetic resonance spin—lattice relaxation times ( T 1 ) and nuclear Overhauser enhancement factors 13 C{ 1 H} ( NOEf ) have been measured on solutions of poly(ethylene terephthalate) (PET), poly(ethylene isophthalate) (PEI) and poly(ethylene isophthalate- co -terephthalate) (PEIT) in d 2 -tetrachloroethane. The T 1 and NOEf values are well described by a log X 2 distribution of correlation times, while the isotropic model appears to be inadequate. The average correlation times (τ 0 ) and the distribution parameters ( p ) of carbons and protons show features that are explained by invoking rotations and/or oscillations of terephthalic and isophthalic rings around the C1—C4 axis.

Unusual Catalysts from Molasses: Synthesis, Properties and Application in Obtaining Biofuels from Algae

Acid catalysts were prepared by sulfonation of carbon materials obtained from the pyrolysis of sugar beet molasses, a cheap, viscous byproduct in the processing of sugar beets into sugar. Conditions for the pyrolysis of molasses (temperature and time) influenced catalyst performance; the best combination came from pyrolysis at low temperature (420 °C) for a relatively long time (8-15 h), which ensured better stability of the final material. The most effective molasses catalyst was highly active in the esterification of fatty acids with methanol (100 % yield after 3 h) and more active than common solid acidic catalysts in the transesterification of vegetable oils with 25-75 wt % of acid content (55-96 % yield after 8 h). A tandem process using a solid acid molasses catalyst and potassium hydroxide in methanol was developed to de-acidificate and transesterificate algal oils from Chlamydomonas reinhardtii, Nannochloropsis gaditana, and Phaeodactylum tricornutum, which contain high amounts of free fatty acids. The amount of catalyst required for the de-acidification step was influenced by the chemical composition of the algal oil, thus operational conditions were determined not only in relation to free fatty acids content in the oil, but according to the composition of the lipid extract of each algal species.

Functionalization of poly(organophosphazenes), 10. Thermally induced grafting reactions of maleates containing oxazoline groups onto aryloxy-substituted poly(organophosphazenes)†

The functionalization reaction of aryloxy-substituted poly(organophosphazenes) with variable amounts of oxazoline groups is described as a function of different experimental parameters, such as the reaction time and temperature, the concentration of the peroxide initiator and of the oxazoline-containing maleate group, the solvent used to run the process and the type of substituents attached to the polyphosphazene skeleton. The resulting phosphazene grafted copolymers were characterized by IR and NMR ( 1 H, 13 C and 31 P) spectroscopy and by thin layer chromatography. These materials are successively reacted with poly(methacrylic acid) due to the well known reactivity of the oxazoline residues with carboxylic functions, to form new materials in which the inorganic and the organic macromolecules are linked together through genuine covalent bonds formed by ester-amide structures.

Conformational analysis of some aromatic copolyesters in solution by means of 1H1H nuclear Overhauser effect experiments

Abstract Conformational analysis was performed on some aromatic copolyesters in solution by means of 1H1H nuclear Overhauser effect (NOE) measurements, using the cyclic dimer of isophthalic acid and ethylene glycol (DIMIS) as the model compound. From the observed NOE, a folding of the ethylene glycol towards the aromatic ring can be assumed for all the polyesters containing an isophthalic ring. In addition, the spatial interaction between adjacent aromatic rings, put forward in order to explain the chemical shift distribution observed in the 1H n.m.r. spectra of these copolymers, has been demonstrated with steady-state NOE experiments. The average distance between protons on adjacent aromatic rings has been calculated by means of dynamic NOE measurements. The most probable conformation, giving rise to these NOE effects, has been postulated on the basis of a formalism introduced in a previous work.

NMR investigation of UV-cured vinyl ether networks

The structure of the networks obtained by UV curing of the triethylene-glycol divinyl ether (DVE3) and its mixtures with diethylene-glycol monovinyl ether (HDVE2) was investigated by high resolution 1 H and 13 C NMR spectroscopy. By working in swelled systems, signals with good resolution were obtained and were assigned to the different structures. The signals attribulable to the CH 3 end groups of the poly(vinyl ether) together with the CH 2 and CH groups of the chain could be distinguished. The CH 3 groups signal is stronger in the case of the DVE3/HDVE2 mixture as a consequence of the chain transfer reaction. Hydrolysis reactions occur in the systems giving rise to the formation of acetaldehyde and aldehydic end groups.

A Model Study to Unravel the Complexity of Bio-Oil from Organic Wastes.

Binary and ternary mixtures of cellulose, bovine serum albumin (BSA) and tripalmitin, as biomass reference compounds for carbohydrates, proteins and triglycerides, respectively, were treated under hydrothermal liquefaction (HTL) conditions to describe the main reaction pathways involved in the process of bio-oil production from municipal organic wastes. Several analytical techniques (elemental analysis, GC-MS, atmospheric-pressure photo-ionisation high-resolution Fourier transform ion cyclotron resonance mass spectrometry, and 13 C cross-polarisation magic-angle spinning NMR spectroscopy) were used for the molecular-level characterisation of the resulting aqueous phase, solid residue and bio-oil, in particular. The main reaction pathways led to free fatty acids, fatty acid amides, 2,5-diketopiperazines and Maillard-type compounds as the main components of the bio-oil. The relationship of such compounds to the original components of the biomass was thus determined, which highlights the fate of the heteroatom-containing molecules in particular. Finally, the molecular composition of the bio-oils from our reference compounds was matched with that of the bio-oil from municipal organic waste biomass by comparing their high-resolution Fourier transform ion cyclotron resonance mass spectra, and we obtained a surprisingly high similarity. Hence, the ternary mixture acts as a reliable biomass model and is a powerful tool to clarify the degradation mechanisms that occur in the biomass under HTL treatment, with the ultimate goal to improve the HTL process itself by modulating the input of the organic starting matter and then the upgrading steps to bio-fuels.

Poly(Organophosphazenes) Containing Oxazoline Groups

The synthesis, the characterization and the utilization of cyclo- and poly-phosphazenes functionalized with oxazoline residues are discussed.