1,721,122 research outputs found
Holistic development of chemical and biological catalysis approaches for the conversion of waste renewable resources into high value-added molecules
No full textThe intensive exploitation of fossil raw materials to produce fuels and building blocks of current
industrial production has determined several critical issues. Biomass represents a promising
alternative to fossil sources and biorefineries assume a central role, leading to the conversion of
biomass into chemicals, intermediates, materials and fuels. Third-generation biomasses and wastes,
mainly composed of cellulose, hemicellulose, lignin and bioactive compounds, can be converted
into valuable bio-products and bio-fuels. The exploitation of each fraction of the feedstock is
fundamental to increase the sustainability. Since cellulose, hemicellulose, lignin and exctratives
require specific reaction conditions for their conversion into bio-products and bio-fuels, the cascade
multi-step approach could ensure the highest valorisation of each biomass component.
The main purpose of this research project is to design, investigate and optimise the conversion of
different wastes, such as defatted wheat bran, pine nut shells and sewage scum to triglycerides,
citric acid and carotenoids through an innovative approach based on the synergistic combination
of chemical and biological catalysis.
Firstly, the chemical characterisation of each biomass will be carried out. Tailored pretreatment
and/or fractionation approaches will be investigated to extract bioactive compounds for
subsequent exploitation. Chemical and enzymatic catalysis will be optimised to valorise both
polisaccarides and lignin. Homogeneous acids and cellulolytic mixtures will be evaluated for the
hydrolysis reaction. The main reaction parameters will be optimised by a chemometric approach.
The obtained hydrolysates will be used as a substrate for the fermentation of oleaginous
microorganisms to produce target molecules and the process parameters will be optimised. Ligninrich
residues collected after the pretreatment or the hydrolysis will be valorised through the
synthesis of aromatics, activated carbons, resins or functionalised materials by implementing
(thermo)chemical or biological approaches. The project involves the implementation of LCA studies
to evaluate the environmental and economic sustainability of the optimised processes
Complete valorisation of giant reed: integrated exploitation of hemicellulose, cellulose and lignin fractions towards valuable bio-based products adopting green process conditions
No full textThe economic sustainability of modern industrial-scale biorefinery models is strongly affected by the cost and the availability of raw materials. In this perspective, the exploitation of low or negative value biomasses, such as agro-industrial wastes and non-food crops, and the complete valorisation of all the fractions of the starting material represent crucial strategies to favour the development of 2nd- and 3rd-generation biorefineries. Biorefining of lignocellulosic biomass, containing hemicellulose, cellulose and lignin, generates hexose/pentose sugars and aromatic compounds which are versatile platform chemicals as they can be converted into fuels, solvents, materials and fine chemicals. Moreover, lignin-rich residues can be converted into activated carbon which presents many applications as an adsorbent biomaterial. The present study developed an innovative and integrated biorefinery process based on the complete and sustainable valorisation of cellulose, hemicellulose and lignin fractions of the non-food crop giant reed (Arundo donax L.). Giant reed is a promising low-cost and perennial biomass able to grow on marginal, contaminated or underutilised lands and it is characterised by high production yield (35-40 ton/h/y), high carbohydrates content (55-65 wt%) and low input management systems [1]. Different chemo- and bio-catalytic approaches were optimised in order to develop a cascade conversion of hemicellulose, cellulose and lignin to various marketable bioproducts [1], according to Figure 1.
Figure 1 – Integrated biorefinery scheme for the full exploitation of giant reed.
In the first step, microwave-assisted FeCl3- or Amberlyst-70-catalysed hemicellulose conversion to xylose or furfural was performed and optimised. In the second step, microwave-assisted FeCl3- or recycled Amberlyst-70-catalysed cellulose conversion to glucose or levulinic and formic acids was tested and optimised. As an alternative, the enzymatic hydrolysis of cellulose to glucose was studied. The final lignin-rich solid residue was used to produce activated carbon for the CO2 adsorption. In the last step, xylose- and glucose-rich hydrolysates were converted by fermentation to single cell oil which was used to produce new generation biodiesel
Screening of oleaginous yeasts for the valorization of sewage scum polysaccharides through the production of Single Cell Oil
No full textAmong renewable energy sources, biodiesel is one of the most promising bio-fuels in the transportation sector. Biodiesel is composed of long-chain alkyl esters of fatty acids (FAMEs), which can be obtained from various renewable raw materials, mainly from oilseed crops. Recently, microbial lipids, namely single cell oils (SCOs), have received great interest as feedstocks for biodiesel production, due to the advantages given by their use over the vegetable oils, including the overcoming of the concerns about the competition with the food supply chain [1] and the seasonality of crops. Among the oleaginous microorganisms, yeasts are the most promising lipid- accumulating microbes due to their ability of growing faster, independently from environmental conditions, and utilizing a wide range of carbon sources. Moreover, the economic and ecological feasibility of the yeast lipids production process can be enhanced by using low-cost raw materials [2], for examples sewage scum (SS), a special waste obtained from urban wastewater treatment plants. SS is composed of a polysaccharide fraction [3], which can be used as potential source of fermentable sugars for the bioaccumulation of lipids, and a lipidic fraction, which can be directly used for trans- esterification reaction to produce FAMEs. The aim of this work was to identify an efficient commercial oleaginous yeast strain able to utilize glucose and xylose contained into the SS enzymatic hydrolysate to produce SCOs. The species Cryptococcus curvatus, Rhodosporidium toruloides and Trichosporon oleaginosus were compared in terms of microbial growth and lipid accumulation and productivity. Considering the estimated concentration of the main monosaccharides present in the undetoxified SS hydrolysate, the screening of the three different oleaginous yeasts was carried out using an equivalent synthetic medium containing glucose and xylose as carbon source. In addition, optimal C/N ratio, pH, type and concentration of micronutrients were formulated for each yeast to ensure its best performance. After fermentation, standard acidic cell lysis and liquid-to-liquid extraction of SCO were carried out. Triglycerides were subjected to hydrolysis and esterification reactions, yielding FAMEs, whose profile was characterized. Finally, the main outputs of the bioprocess were calculated for the three selected yeasts, such as cellular lipid content and productivity. The results indicated T. oleaginosus as the best oleaginous yeast, due to its high lipid cell content (55 wt%) and productivity (71 (mg/L)/h): this species will be subsequently tested on the real hydrolysate obtained from SS
Catalytic transformation of lignocellulosic platform chemicals
Full text linkEditorial. This article belongs to the Special Issue Catalytic Transformation of Lignocellulosic Platform Chemical
5 Biomass pretreatment: separation of cellulose , hemicellulose, and lignin – existing technologies and perspectives
No full textBiomasse Lignocellulosiche
No full textAttualmente oltre l’80% dell’energia mondiale proviene da fonti
energetiche fossili quali carbone, petrolio e gas naturale (BP Statistical Review of World Energy 2019, 68th edition1), sebbene il progressivo incremento del consumo di queste fonti energetiche abbia causato un significativo impatto ambientale. Negli ultimi anni si è osservata una sempre maggiore presa di consapevolezza dei rischi climatici connessi con l’uso delle risorse fossili non solo in ambito tecnico-scientifico ma anche nella cultura di massa, e questo ha motivato la ricerca di nuove fonti energetiche rinnovabili. In questo contesto una delle opzioni più interessanti è la possibilità di utilizzare le biomasse per la produzione di prodotti chimici di base, intermedi e biofuels, in sostituzione delle tradizionali materie prime di origine fossile
Biomass pretreatment: separation of cellulose, hemicellulose, and lignin – existing technologies and perspectives
No full textTitanium Complexes Bearing Carbamato Ligands as Catalytic Precursorsfor Propylene Polymerization Reactions
Full text linkThis report describes propylene polymerization
reactions with titanium complexes bearing carbamato ligands,Ti(O2CNMe2)Cl2 (I) and Ti(O2CR2)4 [R25NMe2 (II), NEt2 (III) and(IV)]. Combinations of these complexes and MAOform catalysts for the synthesis of atactic polypropylene, as confirmed by FT-IR, DSC and 13C NMR analysis. Effects of main reaction parameters on the catalyst activity were studied including the type of complex, solvent, temperature, and the
[Al]/[Ti] molar ratio. The highest activity was observed when chlorobenzene was used as a solvent and AlMe3-
depleted MAO was employed as a cocatalys
A hybrid polyketone–SiO2 support for palladium catalysts and their applications in cinnamaldehyde hydrogenation and in 1-phenylethanol oxidation
No full textAn organic-inorganic hybrid material, PK-SiO2 (PK = polyketone), was employed as support for Pd catalysts. Their synthesis was carried out by MW irradiation of an ethanol solution of Pd(OAc)(2) in the presence of the support. The obtained systems were characterized by solid state NMR, SEM, TEM, ICP, XPS, BET, gas porosimetry and tested in two probe reactions: the selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde carried out in decalin and the oxidation of 1-phenylethanol to acetophenone in water. For comparison, Pd/PK and Pd/SiO2 catalysts were also prepared by using the same procedure, characterized and tested in the same reactions. On the hybrid support the Pd nanoparticles resulted significantly smaller and with a more homogeneous size distribution compared to those on bare SiO2 or PK. The catalysts on the hybrid support allowed a higher performance and could be recycled up to five.times without loss of activity and metal leaching. These results were related to the improved surface area of the hybrid material (compared to the low surface area of bare PK) ascribable to silica introduction, combined with the stabilizing effect of the polymeric counterpart against Pd nanoparticles agglomeratio
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