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Research Interests: Chemistry, Catalysis, Catalysts, Nuclear Chemistry, Glycerol, and 3 moreMolar Ratio, BASE, and Selectivity
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Research Interests: Materials Science, Chemistry, Catalysis, Catalysts, Nanoparticle, and 2 morePhotocatalysis and Metal(Photocatalysis and Metal)
(Photocatalysis and Metal)
The limited fossil resources availability and the climate change are raising wide interest between the scientific researchers and the civil community. Among the several subjects, the production of bulk chemicals from renewable sources is... more
The limited fossil resources availability and the climate change are raising wide interest between the scientific researchers and the civil community. Among the several subjects, the production of bulk chemicals from renewable sources is one of the great challenge that researchers are facing. Concerning this theme, adipic acid (AdA) production from wood biomass is one of the most important topic due to the large amount of AdA consumed and the market growth, in particular for the production of polyamides (Nylon 6,6). Bio-AdA can be produced from t,t-muconic acid (MA), a metabolic intermediate of the catechol ortho-cleavage pathway.1 In nature, microorganisms displaying this pathway are quite common and they can accumulate at least 13.5 g/l of MA as sodium muconate2. The so produced sodium muconate is then converted to AdA with a heterogeneous hydrogenation chemical reaction. Using mild operating conditions (70\ub0C and hydrogen pressure 4 bar) and commercial catalyst (Pt/AC 5% wt or Pd/AC 5% wt) in 1 hour a full conversion and a complete selectivity toward AdA is achieved3. MA coming from the fermenter needs a purification step due to the high purity grade required for the market. The purification process consists in an acidification and crystallization steps, that transform sodium muconate into muconic acid, separating this chemical from all the compounds used in the fermenter. Considering water as hydrogenation reaction media, unfortunately MA is less soluble than sodium muconate. On the basis of these considerations different hydrogenation reactions were performed varying the operating conditions both on muconic acid and sodium muconate. The results reveal a different behavior during hydrogenation reaction performed at 70\ub0C at different hydrogen pressures. Pd/AC 5%wt commercial catalyst was used, maintaining the catalyst/substrate ratio equal to 200:1 (mol basis). The results are reported in Fig.1. Using t,t-MA than Na-muconate a higher activity and selectivity to AdA have been observed. Moreover, the effect of reaction conditions, such as reaction temperature, hydrogen pressure and catalyst amount have been investigated
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Herein, we investigated the effect of the support modification (Sibunit carbon) with diazonium salts of Pd and Pd-Au catalysts on furfural hydrogenation under 5 bars of H2 and 50 °C. To this end, the surface of Sibunit (Cp) was modified... more
Herein, we investigated the effect of the support modification (Sibunit carbon) with diazonium salts of Pd and Pd-Au catalysts on furfural hydrogenation under 5 bars of H2 and 50 °C. To this end, the surface of Sibunit (Cp) was modified with butyl (Cp-Butyl), carboxyl (Cp-COOH) and amino groups (Cp-NH2) using corresponding diazonium salts. The catalysts were synthesized by the sol immobilization method. The catalysts as well as the corresponding supports were characterized by Fourier transform infrared spectroscopy, N2 adsorption-desorption, inductively coupled plasma atomic emission spectroscopy, high resolution transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Hammet indicator method and X-ray photoelectron spectroscopy. The analysis of the results allowed us to determine the crucial influence of surface chemistry on the catalytic behavior of the studied catalysts, especially regarding selectivity. At the same time, the structural, textural, elec...
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Oxidation of 5-hydroxymethylfurfural (HMF), a major feedstock derived from waste/fresh biomass, into 2,5-furandicarboxylic acid (FDCA) is an important transformation for the production of biodegradable plastics. Herein, we investigated... more
Oxidation of 5-hydroxymethylfurfural (HMF), a major feedstock derived from waste/fresh biomass, into 2,5-furandicarboxylic acid (FDCA) is an important transformation for the production of biodegradable plastics. Herein, we investigated the effect of the support (unmodified and modified titania, commercial alumina, and untreated and treated Sibunit carbon) of mono- and bimetallic catalysts based on noble metals (Ag, Au, Pd) on selective HMF oxidation with molecular oxygen to FDCA under mild and basic reaction conditions. The higher selectivity to FDCA was obtained when metals were supported on Sibunit carbon (Cp). The order of noble metal in terms of catalyst selectivity was: Ag < Au < Pd < PdAu. Finally, FDCA production on the most efficient PdAu NPs catalysts supported on Sibunit depended on the treatment applied to this carbon support in the order: PdAu/Cp < PdAu/Cp-HNO3 < PdAu/Cp-NH4OH. These bimetallic catalysts were characterized by nitrogen adsorption-desorption...
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The selective oxidation of veratryl alcohol as lignin-derived compound was studied under mild conditions, using Au-Cu catalysts synthesized from pre-formed nanoparticles with different Au:Cu molar ratios. Bimetallic catalysts show higher... more
The selective oxidation of veratryl alcohol as lignin-derived compound was studied under mild conditions, using Au-Cu catalysts synthesized from pre-formed nanoparticles with different Au:Cu molar ratios. Bimetallic catalysts show higher activity compared to monometallic counterparts, highlighting a clear synergistic effect. By comparing the physico-chemical surface properties of catalysts supported on carbon and Al2O3, we were able to establish a strong support effect, with alumina-based catalysts being more active than carbon-supported ones. Moreover, TEM and X-ray photoelectron spectroscopy (XPS) analyses showed a different composition of nanoparticles (NPs) and metal exposure, and we established that Au is the active phase of the reaction. The co-presence of Au and Cu species, and their different interaction with the support, enabled obtaining more than 70% conversion of veratryl alcohol to veratryl aldehyde as a unique product. Moreover, the Au1Cu1 supported on alumina catalyst...
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Ru and AuRu nanoparticles were prepared by a sol-immobilization methodology and deposited on different doped zirconia supports (ZrO2, Y–ZrO2 and La–ZrO2).
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Three types of carbon nanofibers (pyrolytically stripped carbon nanofibers (PS), low-temperature heat treated carbon nanofibers (LHT), and high-temperature heat treated carbon nanofibers (HHT)) with different graphitization degrees and... more
Three types of carbon nanofibers (pyrolytically stripped carbon nanofibers (PS), low-temperature heat treated carbon nanofibers (LHT), and high-temperature heat treated carbon nanofibers (HHT)) with different graphitization degrees and surface chemistry have been used as support for Au, Pd, or bimetallic AuPd alloy nanoparticles (NPs). The carbon supports have been characterized using Raman, X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). Moreover, the morphology of the metal nanoparticles was investigated using transmission electron microscopy (TEM) and CV. The different properties of the carbon-based supports (particularly the graphitization degree) yield different electrochemical behaviors, in terms of potential window widths and electrocatalytic effects. Comparing the electrochemical behavior of monometallic Au and Pd and bimetallic AuPd, it is possible to observe the interaction of the two metals when alloyed. Moreover, we demonstrate that carbon surface ha...
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DPU and SOL immobilisation have been used to prepare 1 %AuAg/TiO2 with internal ratio 1 : 1 and 4 : 1 which have been studied as fresh, calcined in air at 300 °C and reduced at 550 °C in H2. TEM‐EDS, XPS, UV‐Vis and CO‐DRIFT allowed to... more
DPU and SOL immobilisation have been used to prepare 1 %AuAg/TiO2 with internal ratio 1 : 1 and 4 : 1 which have been studied as fresh, calcined in air at 300 °C and reduced at 550 °C in H2. TEM‐EDS, XPS, UV‐Vis and CO‐DRIFT allowed to characterize the samples in terms of particle size, particle composition, exposure and oxidation state of metals. Correlating these characteristics to the catalytic behaviour we concluded that only Au‐rich catalysts show synergistic effect, silver in bimetallic systems appears more resistant to oxidation than in monometallic one, thermal treatment enhances the SMSI thus producing (regardless to the post‐treatment) almost the same amount of Auδ+ and also Agδ+. Catalysts prepared by DPU (calcined in air or reduced in H2) are more active than SOL (fresh or calcined) probably due to the higher presence of gold at the surface.
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Research Interests: Materials Science, Organic Chemistry, Electrochemistry, Catalysis, Nanoparticle, and 15 moreMedicine, Metal Nanoparticles, Electrochemical Impedance Spectroscopy, Gold, Dielectric Spectroscopy, Platinum, Metal, Palladium, Glycerol, Cyclovoltammetry, Molecules, Particle Size, Redox, Oxidation-Reduction, and Synergistic effect
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CO2 capture and storage is a fundamental research topic in order to decrease the concentration of such greenhouse gas. A new and challenging procedure is the CO2 photoreduction to alcohols and alkanes in the presence of a semiconductor.... more
CO2 capture and storage is a fundamental research topic in order to decrease the concentration of such greenhouse gas. A new and challenging procedure is the CO2 photoreduction to alcohols and alkanes in the presence of a semiconductor. In this research, we tested a novel concept of photoreactor developed by our group1,2 able to operate under high pressure (up to 20 bar) and to explore different temperature ranges. Unconventional operating conditions were explored through this set up, so overcoming the key limitation of CO2 solubility in water and increasing the operating temperature, to improve the overall mass transfer inside the reactor. Na2SO3 was employed as inorganic hole scavenger. Besides reactor engineering optimization, several photocatalysts were investigated in order to solve the two main limitations of semiconductor application in photocatalysis: i) the inadequate visible light absorption of the UV-active catalysts; ii) the high electron-hole recombination rate. Au/TiO2 and CuO/TiO2 with different loadings (0.1-0.5 wt.%), preparation methods (deposition/precipitation, impregnation and Flame Spray Pyrolysis), and polymorphs (anatase, rutile) were chosen as photocatalysts. Characterization of fresh and spent samples was carried out by traditional techniques (XRD, BET, TEM, UV) combined with specific in situ analysis (DRIFTS). The operating conditions (pressure, temperature, pH, irradiation power) and photocatalysts have been varied allowing the investigation of the whole process several possible applications of this reactor. In particular focusing on the maximization of gas (H2 and CH4) and liquid (CH3OH, HCHO, HCOOH) products. Keywords: CO2 photoconversion, gold photocatalysts, copper oxide photocatalysts, high pressure photocatalysis. References (1) Rossetti, I.; Villa, A.; Pirola, C.; Prati, L.; Ramis, G. A Novel High-Pressure Photoreactor for CO2 Photoconversion to Fuels. RSC Adv. 2014, 4 (55), 28883\u201328885. (2) Rossetti, I.; Villa, A.; Compagnoni, M.; Prati, L.; Ramis, G.; Pirola, C.; Bianchi, C. L.; Wang, W.; Wang, D. CO2 Photoconversion to Fuels under High Pressure: Effect of TiO2 Phase and of Unconventional Reaction Conditions. Catal. Sci. Technol. 2015, 5, 4481\u20134487
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t,t-muconic acid (MA) is a metabolic intermediate of the catechol ortho-cleavage pathway. This pathway allows the degradation of many aromatic compounds, such as benzoate, toluene, benzene, phenol, aniline, and salicylate. All these... more
t,t-muconic acid (MA) is a metabolic intermediate of the catechol ortho-cleavage pathway. This pathway allows the degradation of many aromatic compounds, such as benzoate, toluene, benzene, phenol, aniline, and salicylate. All these intermediates require the synthesis of catechol as central aromatic intermediate (Harwood, 1996). In nature, microorganisms displaying this pathway are quite common and they can accumulate at least 0.5 g/l of MA (Mizuno, 1988). The so produced MA is then converted to adipic acid (AA) with a heterogeneous hydrogenation chemical reaction; this particular reaction is only partially reported and discussed in literature, in fact articles often describe mainly the bio-process for the production and recovery of the muconic acid (Vardon, 2015). Currently there are not detailed studies of kinetic hydrogenation of muconic acid to adipic acid in water, because all the research groups analyzed only few catalysts in limited pressure and temperature ranges. Draths and Frost (1994) obtain high yield (90%) at low pressure and temperature (3.5 bar, 25 \ub0C) with Pt/C using alcoholic solvents as reaction medium. Due to the low solubility of the muconic acid in this type of solvents, we will take into account to lead the hydrogenation reaction directly on the muconate salt recovered from the biological conversion reactor. The sodium muconate salt is widely more soluble in water (the green solvent par excellence) than in alcohols and the possibility to work at higher muconic acid concentration open the possibility to increase a lot the productivity of the plants. Different hydrogenation reactions monitoring the conversion of MA and the selectivity to AA on Pt/C catalyst 5% were conducted. The reaction on the sodium muconate salt took place at 40\ub0C and 4 bar of hydrogen. The main results are reported in Fig. 1. Figure 1: (\u25ca) MA conversion and (\u25a0) AA selectivity selectivity at 40\ub0C, 4 bar, 7 10-2M of sodium muconate
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Muconic acid is a polyunsaturated dicarboxylic acid that can be produced from wood biomass-derived aromatic compounds and sugars through biological production. This intermediate is particularly relevant, because it can be chemically... more
Muconic acid is a polyunsaturated dicarboxylic acid that can be produced from wood biomass-derived aromatic compounds and sugars through biological production. This intermediate is particularly relevant, because it can be chemically converted to adipic acid through a catalytic hydrogenation reaction, fostering the shift to a green industry. Adipic acid is one of the most commercially important dicarboxylic acid, as feedstock for the production of PA-6,6, and currently is entirely manufactured from oil. If muconic acid production is widely study, the subsequent hydrogenation to adipic acid is far from being optimized. The purpose of working with model solutions of muconic acid was to performed the hydrogenation reaction in the mildest conditions, compatible with an industrial economic scale up. Moreover, we hypothesized a reaction pathway useful to understand the mechanism and to regress the kinetic parameters
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Glycerol solutions deriving from the transesterification of different kinds of not-refined oils have been directly oxidized in the presence of O2 without any purification step. As glycerol is one of the molecules indicated to be a... more
Glycerol solutions deriving from the transesterification of different kinds of not-refined oils have been directly oxidized in the presence of O2 without any purification step. As glycerol is one of the molecules indicated to be a potential starting material for a new chemical platform based on renewables, this could represent an important step for the cost abatement of biodiesel production. Different catalytic systems have been evaluated in terms of productivity of single product and resistance to impurities deriving from raw materials. Gold and palladium catalysts have been particularly studied and gold based ones revealed an improved resistance to impurities with respect to palladium, especially when alloye
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Herein, we report the synthesis of preformed bimetallic Pd‐Au nanoparticles supported on carbon nanofibers with different Pd : Au atomic ratio (nominal molar ratio: 8–2, 6–4, 4–6, 2–8) and the corresponding Pd and Au monometallic... more
Herein, we report the synthesis of preformed bimetallic Pd‐Au nanoparticles supported on carbon nanofibers with different Pd : Au atomic ratio (nominal molar ratio: 8–2, 6–4, 4–6, 2–8) and the corresponding Pd and Au monometallic catalysts by sol immobilization method. The obtained materials were characterized thoroughly by Transmission Electron Microscopy (TEM), X‐ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectroscopy (ICP‐OES). The catalytic performances of the Pd‐Au catalysts were evaluated in the aqueous phase dehydrogenation of formic acid (FA) at room temperature obtaining enhanced activity, stability and selectivity compared to the monometallic systems. In particular, Pd6Au4 and Pd8Au2 showed the best combination of catalytic properties, i. e., high selectivity to H2 and improved catalytic stability. Density functional theory (DFT) calculations on Pd15, Au15 and Pd9Au6 clusters supported on a carbon sheet were then simulated to provi...
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AuPd nanoparticles supported on NiO exhibit high activity and stability in the base free oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA).
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The selective transformation of biomass-derived compounds to useful fine chemicals and fuels has developed rapidly in recent years, and biomass compounds will soon become one of the main resource contributors for the production of... more
The selective transformation of biomass-derived compounds to useful fine chemicals and fuels has developed rapidly in recent years, and biomass compounds will soon become one of the main resource contributors for the production of chemicals. In the near future, it is expected that biomass derived compounds will contribute substantially to global chemical production along with fossil-based analogues. Although, there is still debate about the sustainability of the usage of biomass-derived molecules, it is important to emphasise that effort has been made to use biomass in the most efficient way, and that the biomass resources used are not suitable for food purposes. In this review we will focus to present selected examples on the transformation of glycerol in three distinct areas; (i) glycerol oxidation, (ii) glycerol hydrogenolysis and (iii) glycerol aqueous reforming, using supported metal nanoparticles as the chosen catalysts.
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The introduction of oxygen functionalities to the surface of CNFs depressed the hydrogenation and decomposition reaction during the synthesis of H2O2.
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Pt nanoparticles were prepared by a sol immobilization route, deposited on supports with different acid/base properties (MgO, activated carbon, TiO2, Al2O3, H‐Mordenite), and tested in the selective oxidation of sorbose to 2‐keto‐gulonic... more
Pt nanoparticles were prepared by a sol immobilization route, deposited on supports with different acid/base properties (MgO, activated carbon, TiO2, Al2O3, H‐Mordenite), and tested in the selective oxidation of sorbose to 2‐keto‐gulonic acid (2‐KGUA), an important precursor for vitamin C. In general, as the basicity of the support increased, a higher catalytic activity occurred. However, in most cases, a strong deactivation was observed. The best selectivity to 2‐KGUA was observed with acidic supports (TiO2 and H‐Mordenite) that were able to minimize the formation of C1/C2 products. We also demonstrated that, by alloying Pt to Au, it is possible to enhance significantly the selectivity of Pt‐based catalysts. Moreover, the AuPt catalyst, unlike monometallic Pt, showed good stability in recycling because of the prevention of metal leaching during the reaction.
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Effect of CO2 saturation and reactor pressure on H2 (full triangles) and CH4 (circles) productivity at pH = 11.4, T = 65 °C. H2 productivity (empty triangles) at pH 5.5, T = 65 °C. Sample 0.1 wt% Au/P25.