76 research outputs found
Novel Catalytic Strategies for the Synthesis of Furans and Their Derivatives
No full textEditorial to the special issue "Novel Catalytic Strategies for the Synthesis of Furans and Their Derivatives
Amberlyst A-70: A surprisingly active catalyst for the MW-assisted dehydration of fructose and inulin to HMF in water
No full text5-Hydroxymethyl-2-furaldehyde (HMF) is a biomass-derived intermediate for the sustainable production of monomers and biofuels. However, most of its syntheses are performed under not environmentally and/or economically green conditions. In this work, the dehydration of fructose/inulin to HMF was optimized, employing aqueous medium, high substrate concentrations (10 and 20 wt%), low loading of commercial acid resin (Amberlyst-70) and microwave heating. The influence of substrate/catalyst ratio, time and temperature on the products yields was investigated. Amberlyst-70 resulted a very active and recyclable system: HMF yields up to 46 mol% were ascertained, the best result up to now reached under these reaction conditions
Della biomassa lignocellulosica non si butta via niente: esempi di valorizzazione integrale di biomasse diverse
No full textNegli ultimi anni è stata studiata la valorizzazione integrale di diversi tipi di biomasse, quali le erbacee da colture dedicate ed anche di biomasse per uso alimentare quali il mais, gli agrumi e la nocciola. Le biomasse erbacee, quali canna comune (Arundo Donax L.), miscanto (Miscanthus x Giganteus) e sorgo (Sorghum Bicolor), sono abbondanti nel nostro territorio, facilmente coltivabili e a basso costo di produzione. Per la loro idrolisi è stata utilizzata acqua come solvente di reazione, in modo tale da avere un approccio verde e sostenibile, e acido cloridrico come catalizzatore. Il residuo solido proveniente dall’idrolisi è stato caratterizzato ed impiegato per la sintesi di schiume poliuretaniche flessibili. La valorizzazione integrale è stata perseguita anche per le biomasse parzialmente edibili, come la nocciola e la buccia esausta degli agrumi. Dalla cuticola della nocciola sono stati estratti in alta resa e caratterizzati importantissimi agenti antiossidanti polifenolici. Il guscio e la buccia esausta degli agrumi sono stati idrolizzati ad acido levulinico ed il residuo di idrolisi convertito in carboni attivi che si sono dimostrati molto efficienti in processi di adsorbimento in fase liquida ed in fase gas
BIOFUELS FROM WASTE BIOMASS: A CASCADE STRATEGY FOR THE SUSTAINABLE PRODUCTION OF 2-METHYL-TETRAHYDROFURAN AND 2-BUTANOL
No full text2-methyltetrahydrofuran and 2-butanol are two very promising biofuels: in this work, a cascade strategy for their synthesis has been investigated through hydrolysis and hydrogenation reactions starting from waste biomass. The exhausted cellulose powder, an abundant industrial by-product of the paper manufacture, was employed as feedstock for the production of levulinic acid in aqueous medium under sustainable reaction conditions, adopting microwave irradiation, dilute HCl as catalyst and high biomass/water weight ratio. The highest levulinic acid yield, 38 wt% calculated respect to the starting biomass, was ascertained, and then the obtained raw hydrolyzate was employed as substrate for the synthesis of the two targeted biofuels. The reaction was carried out in the presence of 5 wt% Ru/C and the effect of several reaction parameters, such as the amount and properties of the acid co-catalyst (niobium phosphate and HY zeolite), temperature, H2 pressure and the presence of 10 wt% Re/C, was investigated. The selectivity of the reaction strongly depends on the presence of rhenium and on the type of co-catalyst. In fact, niobium phosphate preferentially promoted the 2-methyltetrahydrofuran synthesis, leading to a yield of 21.3 mol%, calculated respect to initial moles of levulinic acid in the raw hydrolyzate, whereas HY zeolite resulted to be more active in the hydrogenation/decarboxylation reaction to 2-butanol, which was obtained with yield of 65.1 mol%, calculated respect to initial moles of levulinic acid in the raw hydrolyzate
New Frontiers in the Catalytic Synthesis of Levulinic Acid: From Sugars to Raw and Waste Biomass as Starting Feedstock
No full textLevulinic acid (LA) is one of the top bio-based platform molecules that can be converted into many valuable chemicals. It can be produced by acid catalysis from renewable resources, such as sugars, lignocellulosic biomass and waste materials, attractive candidates due to their abundance and environmentally benign nature. The LA transition from niche product to mass-produced chemical, however, requires its production from sustainable biomass feedstocks at low costs, adopting environment-friendly techniques. This review is an up-to-date discussion of the literature on the several catalytic systems that have been developed to produce LA from the different substrates. Special attention has been paid to the recent advancements on starting materials, moving from simple sugars to raw and waste biomasses. This aspect is of paramount importance from a sustainability point of view, transforming wastes needing to be disposed into starting materials for value-added products. This review also discusses the strategies to exploit the solid residues always obtained in the LA production processes, in order to attain a circular economy approac
Novel Challenges on the Catalytic Synthesis of 5-Hydroxymethylfurfural (HMF) from Real Feedstocks
No full textThe depletion of fossil resources makes the transition towards renewable ones more urgent. For this purpose, the synthesis of strategic platform-chemicals, such as 5-hydroxymethylfurfural (HMF), represents a fundamental challenge for the development of a feasible bio-refinery. HMF perfectly deals with this necessity, because it can be obtained from the hexose fraction of biomass. Thanks to its high reactivity, it can be exploited for the synthesis of renewable monomers, solvents, and bio-fuels. Sustainable HMF synthesis requires the use of waste biomasses, rather than model compounds such as monosaccharides or polysaccharides, making its production more economically advantageous from an industrial perspective. However, the production of HMF from real feedstocks generally suffers from scarce selectivity, due to their complex chemical composition and HMF instability. On this basis, different strategies have been adopted to maximize the HMF yield. Under this perspective, the properties of the catalytic system, as well as the choice of a suitable solvent and the addition of an eventual pretreatment of the biomass, represent key aspects of the optimization of HMF synthesis. On this basis, the present review summarizes and critically discusses the most recent and attractive strategies for HMF production from real feedstocks, focusing on the smartest catalytic systems and the overall sustainability of the adopted reaction conditions
Integrated Cascade Process for the Catalytic Conversion of 5‐Hydroxymethylfurfural to Furanic and TetrahydrofuranicDiethers as Potential Biofuels
No full textThe depletion of fossil resources is driving the research towards alternative renewable ones. Under this perspective, 5‐hydroxymethylfurfural (HMF) represents a key molecule deriving from biomass characterized by remarkable potential as platform chemical. In this work, for the first time, the hydrogenation of HMF in ethanol was selectively addressed towards 2,5‐bis(hydroxymethyl)furan (BHMF) or 2,5‐bis(hydroxymethyl)tetrahydrofuran (BHMTHF) by properly tuning the reaction conditions in the presence of the same commercial catalyst (Ru/C), reaching the highest yields of 80 and 93 mol%, respectively. These diols represent not only interesting monomers but strategic precursors for two scarcely investigated ethoxylated biofuels, 2,5‐bis(ethoxymethyl)furan (BEMF) and 2,5‐bis(ethoxymethyl)tetrahydrofuran (BEMTHF). Therefore, the etherification with ethanol of pure BHMF and BHMTHF and of crude BHMF, as obtained from hydrogenation step, substrates scarcely investigated in the literature, was performed with several commercial heterogeneous acid catalysts. Among them, the zeolite HZSM‐5 (Si/Al=25) was the most promising system, achieving the highest BEMF yield of 74 mol%. In particular, for the first time, the synthesis of the fully hydrogenated diether BEMTHF was thoroughly studied, and a novel cascade process for the tailored conversion of HMF to the diethyl ethers BEMF and BEMTHF was proposed
Cascade strategy for the tunable catalytic valorization of levulinic acid and γ-valerolactone to 2-methyltetrahydrofuran and alcohols
No full textA cascade strategy for the catalytic valorization of aqueous solutions of levulinic acid as well as of γ-valerolactone to 2-methyltetrahydrofuran or to monoalcohols, 2-butanol and 2-pentanol, has been studied and optimized. Only commercial catalytic systems have been employed, adopting sustainable reaction conditions. For the first time, the combined use of ruthenium and rhenium catalysts supported on carbon, with niobium phosphate as acid co-catalyst, has been claimed for the hydrogenation of γ-valerolactone and levulinic acid, addressing the selectivity to 2-methyltetrahydrofuran. On the other hand, the use of zeolite HY with commercial Ru/C catalyst favors the selective production of 2-butanol, starting again from γ-valerolactone and levulinic acid, with selectivities up to 80 and 70 mol %, respectively. Both levulinic acid and γ-valerolactone hydrogenation reactions have been optimized, investigating the effect of the main reaction parameters, to properly tune the catalytic performances towards the desired products. The proper choice of both the catalytic system and the reaction conditions can smartly switch the process towards the selective production of 2-methyltetrahydrofuran or monoalcohols. The catalytic system [Ru/C + zeolite HY] at 200 °C and 3 MPa H2is able to completely convert both γ-valerolactone and levulinic acid, with overall yields to monoalcohols of 100 mol % and 88.8 mol %, respectively
Synthesis of the bio-blendstock butyl levulinate: from model sugars to a real waste
No full textAlkyl levulinates (ALs) are strategic bio-products within the bio-refinery process, finding applications
as fragrances, plasticizers, intermediate for chemicals and oxygenated bio-fuels. In particular for the
latter application, butyl levulinate (BL) represents an interesting compound, thanks to its promising
fuel properties (low solubility in water, good solubility in Diesel fuel, contribution to the reduction of CO
and soot emission) and its feasible synthesis. In the present work, the BL synthesis has been carried out starting directly from model sugars
(glucose and microcrystalline cellulose) and a waste cellulosic biomass, namely a paper powder (PP)
produced downstream of a papermill process. For this purpose, cheap diluted sulfuric acid has been
used as catalyst, working at high substrate loading (high-gravity approach), aiming at the realisation
of an economically sustainable process that allows the achievement of high BL concentration. Yields up to about
40 mol% have been achieved, working at the optimum feedstock loading of 14 wt%, which is higher
than the majority of the values reported up to now
A novel strategy for syngas production through the oxy-gasification of pulp and paper mill sludge
No full textPulp and paper mill sludge (PPMS) is the main organic residual generated from the wastewater treatments of the pulp and paper industry. It is generally divided into primary sludge, characterised by cellulosic-rich fibre and ash, and secondary sludge, primarily composed of organic matter with a high microbial content. Due to the huge production of the paper-making industry, around 400 million wet tons of PPMS are produced annually. Nowadays, the management and disposal of PPMS are landfilling and/or incineration, incurring economic, environmental and social costs. The present work concerns the use of the gasification process as a promising valorisation method of primary and secondary PPMS, with the goal of the production of syngas. The syngas obtained by gasification is generally composed by CO, CO2, H2 and CH4, and it is commonly used as feedstock for the synthesis of key molecules within the chemical industry, such as methanol and hydrocarbons, or for plant energy recovery (heat or electricity generation). The composition of PPMS depends on several factors, however, due to the biological activity of secondary PPMS, only primary PPMS has been characterised, highlighting a total amount of 70 wt% of CaCO3 and 25 wt% of cellulosic fibre. The experimental activity has mainly focused on an oxy-gasification strategy. Initially, fir pellets were used as a benchmark, followed by experimentation with a blend of PPMS and wood pellets in a 1:4 wt/wt ratio. The gasification attempts have been conducted in a downdraft fixed bed reactor (≈100 KwTH) by adopting a mixture of O2/H2O as a gasifying agent. Notably, the co-gasification with both primary and secondary PPMS resulted in obtaining nitrogen-free syngas characterized by a high H2 content (40 mol%) and CO (21 mol%). However, only the syngas composition derived from primary PPMS has shown to be stable over time, displaying high values (≈80%) of Cold Gas Efficiency (CGE), which is an indicator of gasification effectiveness. Finally, the characterization of the side products, such as ash and tar (condensable hydrocarbon and aromatic molecules) has been also performed. In particular, FT-IR analysis revealed that the primary PPMS ash predominantly consisted of CaO. In conclusion, this work proposes the integrated valorization of PPMS through gasification, leading to a promising syngas composition for energy recovery and a high CaO content in gasification ash primary PPMS, which opened up possible strategies for its recovery and recycling
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