salvatore abate | University of Messina (original) (raw)

Papers by salvatore abate

Research paper thumbnail of Graphitic Layered Structures Enhancing TiNT Catalyst Photo-Electrochemical Behaviour

Coatings

The increasing knowledge in nanoscience and materials technology promoted the development of adva... more The increasing knowledge in nanoscience and materials technology promoted the development of advanced materials with enhanced and unusual properties suitable for sustainable applications ranging from energy to environmental purposes. Here are presented some results from our current investigations on composite semiconducting materials. The investigated composites have been prepared from different nitrogen precursors and thin films of TiO2 nanotubes. The synergy between hetero-structures based on graphitic-C3N4 and thin films of titania nanotubes obtained by anodisation was studied. The composites have been characterised with several complementary techniques to evidence the relation between photo-behaviour and the composition of the samples. This study allows new insights into the nature of the specific enhanced properties due to this synergy among the two compounds. The g-C3N4/TiNT heterojunctions showed enhanced photo-electrochemical properties observed from the photocurrent measure...

Research paper thumbnail of Hydrogenation of dimethyl oxalate to ethylene glycol on Cu/SiO2 catalysts prepared by a deposition-decomposition method: Optimization of the operating conditions and pre-reduction procedure

Catalysis Today, May 1, 2022

Cu/SiO2 catalysts prepared by a deposition-decomposition (DD) method using ammonium hydroxide are... more Cu/SiO2 catalysts prepared by a deposition-decomposition (DD) method using ammonium hydroxide are currently among the most promising catalysts for oxalates hydrogenation to ethylene glycol (EG). Here, a Cu/SiO2 catalyst prepared by the DD method was pre-reduced at a) 200-350 °C in 100% H2, and 2) 200°C in a 50% H2/N2 mixture. Then, it was tested at 200 °C, and 25 barg, while EG yields were optimized, with H2-GHSV and H2/DMO ratios in the ranges 1000-4000 h-1 and 30-200 mol/mol. The calcined catalyst presents an XRD amorphous Cu phyllosilicate phase. After pre-reduction in pure H2 at 200 to 250°C (Tred), the Cu metallic surface area increased from 6 to 12 m 2 /gcat and slightly decreased at 350°C. Simultaneously, the silanol's band, measured by DRIFT experiments, increased with Tred. The highest ethylene glycol yield (91 %) was achieved after pre-reduction at 200 °C in pure hydrogen, working with an H2-GHSV and H2/DMO of 1050 h-1 and 68 mol/mol, respectively. The catalyst was stable for more than 36 h after a 20 h induction period. Catalyst characterization results as a function of Tred confirm that mixed-valence copper nanoparticles favor the EG selective formation, while side reactions leading to ethanol and 1,2-butanediol are related to exposed acidic and basic sites due to decreased Cu/support interactions.

Research paper thumbnail of Zeolite templated carbon from Beta replica as metal-free electrocatalyst for CO2 reduction

Applied Materials Today, Mar 1, 2022

Zeolite Templated Carbons (ZTCs) are a class of materials that feature the textural properties of... more Zeolite Templated Carbons (ZTCs) are a class of materials that feature the textural properties of the template zeolites and the high conductivity of graphene-like structures. These characteristics make ZTCs a valuable candidate for CO 2 catalytic reduction. We report here for the first time that metal-free ZTCs obtained from Beta zeolite are a novel valuable energy material for the reduction of CO 2 to formic acid, about 10 times better than a reference reduced graphene oxide catalyst. In addition, it is evidenced that the pristine ZTC contains a large amount of oxygen, an aspect largely underestimated in literature. A specific method to reduce this oxygen content was developed, that coupled to an in-depth characterization by multiple techniques of these materials, allows to understand the nature of the oxygen functionalities on ZTCs surface. Moreover, it was evidenced that the change of oxygenated species by combined thermal and NaBH 4 treatment of ZTCs affects the catalytic behavior, leading to a remarkable increase in the performances compared to the pristine one. The comparison of the performances and characteristics of two ZTCs, obtained by different BEA nanostructures, allow to correlate better the modification of the type of oxygen species present in ZTCs to the catalytic behavior. The results open new perspectives for the catalytic application of deoxygenated ZTCs.

Research paper thumbnail of Pd nanoparticles supported on N-doped nanocarbon for the direct synthesis of H2O2 from H2 and O2

Catalysis Today, Nov 17, 2010

Pd nanoparticles deposited by sol-immobilization on N-doped nanocarbon (carbon nanotube-like from... more Pd nanoparticles deposited by sol-immobilization on N-doped nanocarbon (carbon nanotube-like from Pyrograf Products; N-CNT-like) is studied in the direct synthesis of H2O2 and compared with those of the undoped catalysts or prepared by the same Pd deposition method on active carbon (Vulcan XC-72) as the support. The catalytic tests were carried out using a slurry batch-or semi-continuous reactor at room temperature and a total pressure of 10 bar using CO2-expanded methanol as the solvent. The Pd on N-CNT-like gives high productivities to H2O2, comparable to the best literature results, while the selectivity to H2O2 is low due to the low oxygen partial pressure and likely low oxygen coverage on Pd particles. The introducing of nitrogen in the CNT-like material favors not only the dispersion of Pd (with a consequent improvement of the activity), but also the specific turnover, due to probably the electronic effect of pyridine-like nitrogen sites present in the N-CNT-like support favoring the O2 surface coverage. However, the introduction of these N functionalities on the surface has also a negative effect on the rate of H2O2 consecutive conversion to water.

Research paper thumbnail of Exploring the hydrogenation of furfural in the liquid phase by high-throughput screening of commercial catalysts: Effects of temperature, solvents, and promoters on the production of 2-methylfuran

Chemical Engineering Research and Design

Research paper thumbnail of Metal-Free Electrodes Based on Tio2 Nanotube Arrays for the Selective Electro-Reduction of Oxalic Acid: The Relations between Nanostructure and Performances

Research paper thumbnail of Transparent Nanostructured Titania Coatings with Self- cleaning and Antireflective Properties for Photovoltaic Glass Surfaces

Chemical engineering transactions, 2015

Transparent titania (TiO2) coatings having self-cleaning and antireflection (AR) properties, for ... more Transparent titania (TiO2) coatings having self-cleaning and antireflection (AR) properties, for application as surface functional layer in cover glasses of photovoltaic (PV) devices, were prepared, characterized and tested. The coating preparation is made by forming first a nanosol through controlled hydrolysis of a tetraisopropyl orthotitanate (TIPT) precursor. The nanosol is then deposited on the glass substrates by dip- coating with a subsequent step of calcination. This work reports the effect of the preparation parameters on both optical and morphological properties of the obtained coatings. The nanostructure and texture of the samples were characterized by X-ray diffraction, UV-vis spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM), while transmittance measurements were carried out to assess the AR properties. Self-cleaning properties were investigated by water contact angle measurements and photocatalytic activity tests. Films with good optica...

Research paper thumbnail of Direct synthesis of H2O2 on Pd/Al2O3 contactors: Understanding the effect of Pd particle size and calcination through kinetic analysis

Chemical engineering transactions, 2021

The direct synthesis of H2O2 on Pd-based catalysts, although recognized as a potential route for ... more The direct synthesis of H2O2 on Pd-based catalysts, although recognized as a potential route for the sustainable production of H2O2, is still limited by the low catalytic selectivity and safety concerns. Here, the calcination treatment effect, with the dispersion of Pd NPs and its interaction with Al2O3, is investigated. Catalysts have been prepared by the sol-immobilization procedure (SI) on Al2O3 as asymmetric alumina membranes (AAS) and tested in both reduced and calcined form (450°C, 1°C/min, 8 h) for the direct synthesis of H2O2. Finally, the catalytic performance was compared with other catalysts, prepared by hydrazine-reduction (NRC) and impregnation-decomposition (IDC) already reported in a previous paper and calcined for a shorter time (450°C, 1°C/min, 6 h).TEM micrographs showed the formation of Pd NPs with average diameters of 12 (NR), 3.8 (IDC), and 3.3 nm (SI), respectively. The reduced SI catalyst has shown a 2-4% selectivity. However, after calcination (SIC), a 69 % s...

Research paper thumbnail of Effect of the Solvent in Enhancing the Selectivity to Furan Derivatives in the Catalytic Hydrogenation of Furfural

ACS Sustainable Chemistry & Engineering, 2018

The catalytic hydrogenation of furfural, particularly to methyl-furan, is studied on four commerc... more The catalytic hydrogenation of furfural, particularly to methyl-furan, is studied on four commercial catalysts (based on Ni and Cu and alumina or silica as supports) in different aprotic solvents (n-heptane, diisopropyl ether and ethyl acetate) and two Cl-containing solvents (chlorobenzene and n-heptane containing 0.5% wt. CHCl3). The catalytic data are complemented by the estimated solvent characteristics, activity coefficients of reactants (including H2) and products, and energy stability by the solvent on reactants and main products of reaction. The results show that the solvent plays a major role in the modification of selectivity, but strongly depending on the catalyst. In low polar solvent (n-heptane) yield up to about 50% can be obtained to methyl-furan using Cu/Al2O3, but yields nearly halve using Cu/SiO2 catalysts and become very low for Ni-based catalysts. The latter, on the contrary, show high selectivity to methyl-furan (up to about 70-80%) using n-heptane containing small amounts of CHCl3. There is a double role of the solvent, both in the stabilization of the reaction products and minor of the reactants, and in interacting with the catalyst, modifying its intrinsic reactivity, both aspects scarcely investigated, but representing a valuable option to control the selectivity in the valorization of biomass byproducts.

Research paper thumbnail of Bimetallische Ni‐Fe‐Hydrotalcit‐Katalysatoren für die effektive Umsetzung von CO2 zu Erdgas

Chemie Ingenieur Technik, 2016

Research paper thumbnail of Role of size and pretreatment of Pd particles on their behaviour in the direct synthesis of H2O2

Journal of Energy Chemistry, 2016

Abstract Two families of catalysts, based on Pd nanoparticles supported on ceramic asymmetric tub... more Abstract Two families of catalysts, based on Pd nanoparticles supported on ceramic asymmetric tubular alumina membranes, are studies in the direct synthesis of H 2 O 2 . They are prepared by depositing Pd in two ways: (i) reduction with N 2 H 4 in an ultrasonic bath and (ii) by impregnation-deposition. The first preparation leads to larger particles, with average size of around 11 nm, while the second preparation leads to smaller particles, with average size around 4 nm. The catalytic membranes were tested as prepared, after thermal treatment in air and after further pre-reduction with H 2 in mild (100 °C) conditions. Samples were characterized by TEM, CO-chemisorption monitored by DRIFTS method and TPR, while catalytic tests have been performed in a semi-batch recirculation membrane reactor. Experimental catalytic results were analysed using two kinetics models to derive the reaction constants for the parallel and consecutive reactions of the kinetic network. Smaller particles of Pd show lower selectivity due to the higher rate of parallel combustion, even if the better dispersion of Pd and thus higher metal surface area in the sample lead to a productivity in H 2 O 2 similar or even higher than the sample with the larger Pd particles. Independently on the presence of smaller or larger Pd nanoparticles, an oxidation treatment leads to a significant enhancement in the productivity, although the catalyst progressively reduces during the catalytic process. The inhibition of the parallel combustion reaction (to water) induced from the calcination treatment remains after the in-situ reduction of the oxidized Pd species formed during the pre-treatment. This is likely due to the elimination of defect sites which dissociatively activate oxygen, and tentatively attributed to Pd sites able to give three- and four-fold coordination of CO.

Research paper thumbnail of Synthesis, characterization and activity pattern of Cu–ZnO/ZrO2 catalysts in the hydrogenation of carbon dioxide to methanol

Journal of Catalysis, 2007

A novel synthesis route based on reverse co-precipitation under ultrasound irradiation has led to... more A novel synthesis route based on reverse co-precipitation under ultrasound irradiation has led to Cu–ZnO/ZrO2 catalysts (Znat/Cuat, 0–3; ZrO2, 42–44 wt%) with a remarkable development of total surface area (SABET, 120–180 m2/g) and very high dispersion (3–58 ...

Research paper thumbnail of Enhanced performance in the direct electrocatalytic synthesis of ammonia from N2 and H2O by an in-situ electrochemical activation of CNT-supported iron oxide nanoparticles

Journal of Energy Chemistry, 2020

The direct electrocatalytic synthesis of ammonia from N 2 and H 2 O by using renewable energy sou... more The direct electrocatalytic synthesis of ammonia from N 2 and H 2 O by using renewable energy sources and ambient pressure/temperature operations is a breakthrough technology, which can reduce by over 90% the greenhouse gas emissions of this chemical and energy storage process. We report here an in-situ electrochemical activation method to prepare Fe 2 O 3-CNT (iron oxide on carbon nanotubes) electrocatalysts for the direct ammonia synthesis from N 2 and H 2 O. The in-situ electrochemical activation leads to a large increase of the ammonia formation rate and Faradaic efficiency which reach the surprising high values of 41.6 μg mg cat −1 h − 1 and 17%, respectively, for an in-situ activation of 3 h, among the highest values reported so far for non-precious metal catalysts that use a continuous-flow polymer-electrolytemembrane cell and gas-phase operations for the ammonia synthesis hemicell. The electrocatalyst was stable at least 12 h at the working conditions. Tests by switching N 2 to Ar evidence that ammonia was formed from the gas-phase nitrogen. The analysis of the changes of reactivity and of the electrocatalyst characteristics as a function of the time of activation indicates a linear relationship between the ammonia formation rate and a specific XPS (X-ray-photoelectron spectroscopy) oxygen signal related to O 2 − in iron-oxide species. This results together with characterization data by TEM and XRD suggest that the iron species active in the direct and selective synthesis of ammonia is a maghemite-type iron oxide, and this transformation from the initial hematite is responsible for the in-situ enhancement of 3-4 times of the TOF (turnover frequency) and NH 3 Faradaic efficiency. This transformation is likely related to the stabilization of the maghemite species at CNT defect sites, although for longer times of preactivation a sintering occurs with a loss of performances.

Research paper thumbnail of Insights by in-situ studies on the nature of highly-active hydrotalcite-based Ni-Fe catalysts for CO2 methanation

Chemical Engineering Research and Design

Research paper thumbnail of Orange Peel Biomass‐derived Carbon Supported Cu Electrocatalysts Active in the CO <sub>2</sub> ‐Reduction to Formic Acid

ChemPhysChem, Jan 9, 2023

Research paper thumbnail of Multifunctional HDO/Selective Cracking Ni/HBEA Catalysts to Produce Jet Fuel and Diesel from Bio-oils

Chemical Engineering Transactions, 2016

The development of multifunctional catalysts to selectively produce in one-step processes jet fue... more The development of multifunctional catalysts to selectively produce in one-step processes jet fuels (around C12) and diesel (around C16-C18) from bio-oils (vegetable and especially algal oil) is still a challenge to produce next-generation biofuels. This topic is addressed here by investigating the activity of Ni based catalysts in the methyl palmitate conversion, as model test reaction. The performance of Ni/HBEA (8%wt Ni) catalysts, where mesoporosity was introduced by desilication, were compared with those of mesoporous SBA-15. It is evidenced that desilication allows to introduce selective hydrocracking functionality together with HDO (hydrodeoxygenation), the latter prevailing occurring through hydrogenation of the acid group rather than via hydrodecarboxylation.

Research paper thumbnail of Electrocatalytic production of glycolic acid via oxalic acid reduction on titania debris supported on a TiO2 nanotube array

Journal of Energy Chemistry, 2021

Electrodes prepared by anodic oxidation of Ti foils are robust and not toxic materials for the el... more Electrodes prepared by anodic oxidation of Ti foils are robust and not toxic materials for the electrocatalytic reduction of oxalic acid to glycolic acid allowing to develop a renewable energy driven process for the production of an alcoholic compound from an organic acid at low potential and room temperature. Coupled with an electrochemical synthesis of the oxalic acid from CO2 the process represents a new green and low-carbon path to produce added value chemicals from CO2. Various electrodes prepared by anodic oxidation of Ti foils were investigated. They were characterized by the presence of a TiO2 nanotube array together with the presence of small patches, debris or TiO2 nanoparticles. A series of relationships between the characteristics of these samples, in particular the concentration of oxygen vacancies and the amount of Ti 3+ detected by XPS or the intensity of the anodic peak in cyclic voltammetry tests, and the catalytic behavior (oxalic acid conversion and yield of glycolic acid) evidence the relation between these aspects. The analysis of the results indicate in small amorphous TiO2 nanoparticles (or surface pathces or debris) stabilized by interaction with TiO2 nanotubes the sites responsible for the conversion of oxalic acid and glycolic acid yield. By varying this structural characteristic of the electrodes, it is possible to tune the glycolic acid to glyoxylic acid relative ratio. A best cumulative Faradaic efficiency of about 84% with selectivity to glycolic acid around 60% and oxalic conversion about 30% was obserbed.

Research paper thumbnail of Investigations of Carbon Nitride-Supported Mn3O4 Oxide Nanoparticles for ORR

Catalysts, 2020

Earth-abundant Mn-based oxide nanoparticles are supported on carbon nitride using two different i... more Earth-abundant Mn-based oxide nanoparticles are supported on carbon nitride using two different immobilization methods and tested for the oxygen reduction reaction. Compared to the metal free CN, the immobilization of Mn oxide enhances not only the electrocatalytic activity but also the selectivity towards the 4e- reduction reaction of O2 to H2O. The XPS analysis reveals the interaction of the pyridine N species with Mn3O4 nanoparticles being particularly beneficial. This interaction is realized—although to a limited extent—when preparing the catalysts via impregnation; via the oleic acid route it is not observed. Whilst this work shows the potential of these systems to catalyze the ORR, the main limiting factor is still the poor conductivity of the support which leads to overpotential.

Research paper thumbnail of g-C3N4 Decorated TiO2 Nanotube Ordered Thin Films as Cathodic Electrodes for the Selective Reduction of Oxalic Acid

Paper Received: 21 May 2020; Revised: 23 December 2020; Accepted: 19 February 2021 Please cite th... more Paper Received: 21 May 2020; Revised: 23 December 2020; Accepted: 19 February 2021 Please cite this article as: De Luca F., Passalacqua R., Abramo F.P., Perathoner S., Centi G., Abate S., 2021, G-c3n4 Decorated Tio2 Nanotube Ordered Thin Films as Cathodic Elctrodes for the Selective Reduction of Oxalic Acid, Chemical Engineering Transactions, 84, 37-42 DOI:10.3303/CET2184007 CHEMICAL ENGINEERING TRANSACTIONS

Research paper thumbnail of Catalytic Performance of Ni-based Catalysts Supported on γ-Al2O3-ZrO2-TiO2-CeO2 Composite Oxide for CO2 Methanation

Increasing emissions of carbon dioxide arising from the widespread production of energy from foss... more Increasing emissions of carbon dioxide arising from the widespread production of energy from fossil fuels is a critical matter regarding the global warming. The hydrogenation of CO2 into oxygenates and/or hydrocarbons have been the most investigated reactions to obtain fuels [1]. Among several hydrogenation reactions, methanation of carbon dioxide following the Sabatier reaction is the most advantageous one regarding thermodynamics. Nickel based catalysts are the most studied materials for the latter reaction, because of their high activity and low price, but metal sintering at reaction conditions diminishes their industrial viability [2]. The type of support used for heterogeneous catalysts is an important factor to consider on solving such problems. Metal-support interactions play a role on catalyst performance in terms of the active site dispersion, activity and stability of the catalysts [3]. In this work, we focused our attention on the selection of different supports for Ni-ba...

Research paper thumbnail of Graphitic Layered Structures Enhancing TiNT Catalyst Photo-Electrochemical Behaviour

Coatings

The increasing knowledge in nanoscience and materials technology promoted the development of adva... more The increasing knowledge in nanoscience and materials technology promoted the development of advanced materials with enhanced and unusual properties suitable for sustainable applications ranging from energy to environmental purposes. Here are presented some results from our current investigations on composite semiconducting materials. The investigated composites have been prepared from different nitrogen precursors and thin films of TiO2 nanotubes. The synergy between hetero-structures based on graphitic-C3N4 and thin films of titania nanotubes obtained by anodisation was studied. The composites have been characterised with several complementary techniques to evidence the relation between photo-behaviour and the composition of the samples. This study allows new insights into the nature of the specific enhanced properties due to this synergy among the two compounds. The g-C3N4/TiNT heterojunctions showed enhanced photo-electrochemical properties observed from the photocurrent measure...

Research paper thumbnail of Hydrogenation of dimethyl oxalate to ethylene glycol on Cu/SiO2 catalysts prepared by a deposition-decomposition method: Optimization of the operating conditions and pre-reduction procedure

Catalysis Today, May 1, 2022

Cu/SiO2 catalysts prepared by a deposition-decomposition (DD) method using ammonium hydroxide are... more Cu/SiO2 catalysts prepared by a deposition-decomposition (DD) method using ammonium hydroxide are currently among the most promising catalysts for oxalates hydrogenation to ethylene glycol (EG). Here, a Cu/SiO2 catalyst prepared by the DD method was pre-reduced at a) 200-350 °C in 100% H2, and 2) 200°C in a 50% H2/N2 mixture. Then, it was tested at 200 °C, and 25 barg, while EG yields were optimized, with H2-GHSV and H2/DMO ratios in the ranges 1000-4000 h-1 and 30-200 mol/mol. The calcined catalyst presents an XRD amorphous Cu phyllosilicate phase. After pre-reduction in pure H2 at 200 to 250°C (Tred), the Cu metallic surface area increased from 6 to 12 m 2 /gcat and slightly decreased at 350°C. Simultaneously, the silanol's band, measured by DRIFT experiments, increased with Tred. The highest ethylene glycol yield (91 %) was achieved after pre-reduction at 200 °C in pure hydrogen, working with an H2-GHSV and H2/DMO of 1050 h-1 and 68 mol/mol, respectively. The catalyst was stable for more than 36 h after a 20 h induction period. Catalyst characterization results as a function of Tred confirm that mixed-valence copper nanoparticles favor the EG selective formation, while side reactions leading to ethanol and 1,2-butanediol are related to exposed acidic and basic sites due to decreased Cu/support interactions.

Research paper thumbnail of Zeolite templated carbon from Beta replica as metal-free electrocatalyst for CO2 reduction

Applied Materials Today, Mar 1, 2022

Zeolite Templated Carbons (ZTCs) are a class of materials that feature the textural properties of... more Zeolite Templated Carbons (ZTCs) are a class of materials that feature the textural properties of the template zeolites and the high conductivity of graphene-like structures. These characteristics make ZTCs a valuable candidate for CO 2 catalytic reduction. We report here for the first time that metal-free ZTCs obtained from Beta zeolite are a novel valuable energy material for the reduction of CO 2 to formic acid, about 10 times better than a reference reduced graphene oxide catalyst. In addition, it is evidenced that the pristine ZTC contains a large amount of oxygen, an aspect largely underestimated in literature. A specific method to reduce this oxygen content was developed, that coupled to an in-depth characterization by multiple techniques of these materials, allows to understand the nature of the oxygen functionalities on ZTCs surface. Moreover, it was evidenced that the change of oxygenated species by combined thermal and NaBH 4 treatment of ZTCs affects the catalytic behavior, leading to a remarkable increase in the performances compared to the pristine one. The comparison of the performances and characteristics of two ZTCs, obtained by different BEA nanostructures, allow to correlate better the modification of the type of oxygen species present in ZTCs to the catalytic behavior. The results open new perspectives for the catalytic application of deoxygenated ZTCs.

Research paper thumbnail of Pd nanoparticles supported on N-doped nanocarbon for the direct synthesis of H2O2 from H2 and O2

Catalysis Today, Nov 17, 2010

Pd nanoparticles deposited by sol-immobilization on N-doped nanocarbon (carbon nanotube-like from... more Pd nanoparticles deposited by sol-immobilization on N-doped nanocarbon (carbon nanotube-like from Pyrograf Products; N-CNT-like) is studied in the direct synthesis of H2O2 and compared with those of the undoped catalysts or prepared by the same Pd deposition method on active carbon (Vulcan XC-72) as the support. The catalytic tests were carried out using a slurry batch-or semi-continuous reactor at room temperature and a total pressure of 10 bar using CO2-expanded methanol as the solvent. The Pd on N-CNT-like gives high productivities to H2O2, comparable to the best literature results, while the selectivity to H2O2 is low due to the low oxygen partial pressure and likely low oxygen coverage on Pd particles. The introducing of nitrogen in the CNT-like material favors not only the dispersion of Pd (with a consequent improvement of the activity), but also the specific turnover, due to probably the electronic effect of pyridine-like nitrogen sites present in the N-CNT-like support favoring the O2 surface coverage. However, the introduction of these N functionalities on the surface has also a negative effect on the rate of H2O2 consecutive conversion to water.

Research paper thumbnail of Exploring the hydrogenation of furfural in the liquid phase by high-throughput screening of commercial catalysts: Effects of temperature, solvents, and promoters on the production of 2-methylfuran

Chemical Engineering Research and Design

Research paper thumbnail of Metal-Free Electrodes Based on Tio2 Nanotube Arrays for the Selective Electro-Reduction of Oxalic Acid: The Relations between Nanostructure and Performances

Research paper thumbnail of Transparent Nanostructured Titania Coatings with Self- cleaning and Antireflective Properties for Photovoltaic Glass Surfaces

Chemical engineering transactions, 2015

Transparent titania (TiO2) coatings having self-cleaning and antireflection (AR) properties, for ... more Transparent titania (TiO2) coatings having self-cleaning and antireflection (AR) properties, for application as surface functional layer in cover glasses of photovoltaic (PV) devices, were prepared, characterized and tested. The coating preparation is made by forming first a nanosol through controlled hydrolysis of a tetraisopropyl orthotitanate (TIPT) precursor. The nanosol is then deposited on the glass substrates by dip- coating with a subsequent step of calcination. This work reports the effect of the preparation parameters on both optical and morphological properties of the obtained coatings. The nanostructure and texture of the samples were characterized by X-ray diffraction, UV-vis spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM), while transmittance measurements were carried out to assess the AR properties. Self-cleaning properties were investigated by water contact angle measurements and photocatalytic activity tests. Films with good optica...

Research paper thumbnail of Direct synthesis of H2O2 on Pd/Al2O3 contactors: Understanding the effect of Pd particle size and calcination through kinetic analysis

Chemical engineering transactions, 2021

The direct synthesis of H2O2 on Pd-based catalysts, although recognized as a potential route for ... more The direct synthesis of H2O2 on Pd-based catalysts, although recognized as a potential route for the sustainable production of H2O2, is still limited by the low catalytic selectivity and safety concerns. Here, the calcination treatment effect, with the dispersion of Pd NPs and its interaction with Al2O3, is investigated. Catalysts have been prepared by the sol-immobilization procedure (SI) on Al2O3 as asymmetric alumina membranes (AAS) and tested in both reduced and calcined form (450°C, 1°C/min, 8 h) for the direct synthesis of H2O2. Finally, the catalytic performance was compared with other catalysts, prepared by hydrazine-reduction (NRC) and impregnation-decomposition (IDC) already reported in a previous paper and calcined for a shorter time (450°C, 1°C/min, 6 h).TEM micrographs showed the formation of Pd NPs with average diameters of 12 (NR), 3.8 (IDC), and 3.3 nm (SI), respectively. The reduced SI catalyst has shown a 2-4% selectivity. However, after calcination (SIC), a 69 % s...

Research paper thumbnail of Effect of the Solvent in Enhancing the Selectivity to Furan Derivatives in the Catalytic Hydrogenation of Furfural

ACS Sustainable Chemistry & Engineering, 2018

The catalytic hydrogenation of furfural, particularly to methyl-furan, is studied on four commerc... more The catalytic hydrogenation of furfural, particularly to methyl-furan, is studied on four commercial catalysts (based on Ni and Cu and alumina or silica as supports) in different aprotic solvents (n-heptane, diisopropyl ether and ethyl acetate) and two Cl-containing solvents (chlorobenzene and n-heptane containing 0.5% wt. CHCl3). The catalytic data are complemented by the estimated solvent characteristics, activity coefficients of reactants (including H2) and products, and energy stability by the solvent on reactants and main products of reaction. The results show that the solvent plays a major role in the modification of selectivity, but strongly depending on the catalyst. In low polar solvent (n-heptane) yield up to about 50% can be obtained to methyl-furan using Cu/Al2O3, but yields nearly halve using Cu/SiO2 catalysts and become very low for Ni-based catalysts. The latter, on the contrary, show high selectivity to methyl-furan (up to about 70-80%) using n-heptane containing small amounts of CHCl3. There is a double role of the solvent, both in the stabilization of the reaction products and minor of the reactants, and in interacting with the catalyst, modifying its intrinsic reactivity, both aspects scarcely investigated, but representing a valuable option to control the selectivity in the valorization of biomass byproducts.

Research paper thumbnail of Bimetallische Ni‐Fe‐Hydrotalcit‐Katalysatoren für die effektive Umsetzung von CO2 zu Erdgas

Chemie Ingenieur Technik, 2016

Research paper thumbnail of Role of size and pretreatment of Pd particles on their behaviour in the direct synthesis of H2O2

Journal of Energy Chemistry, 2016

Abstract Two families of catalysts, based on Pd nanoparticles supported on ceramic asymmetric tub... more Abstract Two families of catalysts, based on Pd nanoparticles supported on ceramic asymmetric tubular alumina membranes, are studies in the direct synthesis of H 2 O 2 . They are prepared by depositing Pd in two ways: (i) reduction with N 2 H 4 in an ultrasonic bath and (ii) by impregnation-deposition. The first preparation leads to larger particles, with average size of around 11 nm, while the second preparation leads to smaller particles, with average size around 4 nm. The catalytic membranes were tested as prepared, after thermal treatment in air and after further pre-reduction with H 2 in mild (100 °C) conditions. Samples were characterized by TEM, CO-chemisorption monitored by DRIFTS method and TPR, while catalytic tests have been performed in a semi-batch recirculation membrane reactor. Experimental catalytic results were analysed using two kinetics models to derive the reaction constants for the parallel and consecutive reactions of the kinetic network. Smaller particles of Pd show lower selectivity due to the higher rate of parallel combustion, even if the better dispersion of Pd and thus higher metal surface area in the sample lead to a productivity in H 2 O 2 similar or even higher than the sample with the larger Pd particles. Independently on the presence of smaller or larger Pd nanoparticles, an oxidation treatment leads to a significant enhancement in the productivity, although the catalyst progressively reduces during the catalytic process. The inhibition of the parallel combustion reaction (to water) induced from the calcination treatment remains after the in-situ reduction of the oxidized Pd species formed during the pre-treatment. This is likely due to the elimination of defect sites which dissociatively activate oxygen, and tentatively attributed to Pd sites able to give three- and four-fold coordination of CO.

Research paper thumbnail of Synthesis, characterization and activity pattern of Cu–ZnO/ZrO2 catalysts in the hydrogenation of carbon dioxide to methanol

Journal of Catalysis, 2007

A novel synthesis route based on reverse co-precipitation under ultrasound irradiation has led to... more A novel synthesis route based on reverse co-precipitation under ultrasound irradiation has led to Cu–ZnO/ZrO2 catalysts (Znat/Cuat, 0–3; ZrO2, 42–44 wt%) with a remarkable development of total surface area (SABET, 120–180 m2/g) and very high dispersion (3–58 ...

Research paper thumbnail of Enhanced performance in the direct electrocatalytic synthesis of ammonia from N2 and H2O by an in-situ electrochemical activation of CNT-supported iron oxide nanoparticles

Journal of Energy Chemistry, 2020

The direct electrocatalytic synthesis of ammonia from N 2 and H 2 O by using renewable energy sou... more The direct electrocatalytic synthesis of ammonia from N 2 and H 2 O by using renewable energy sources and ambient pressure/temperature operations is a breakthrough technology, which can reduce by over 90% the greenhouse gas emissions of this chemical and energy storage process. We report here an in-situ electrochemical activation method to prepare Fe 2 O 3-CNT (iron oxide on carbon nanotubes) electrocatalysts for the direct ammonia synthesis from N 2 and H 2 O. The in-situ electrochemical activation leads to a large increase of the ammonia formation rate and Faradaic efficiency which reach the surprising high values of 41.6 μg mg cat −1 h − 1 and 17%, respectively, for an in-situ activation of 3 h, among the highest values reported so far for non-precious metal catalysts that use a continuous-flow polymer-electrolytemembrane cell and gas-phase operations for the ammonia synthesis hemicell. The electrocatalyst was stable at least 12 h at the working conditions. Tests by switching N 2 to Ar evidence that ammonia was formed from the gas-phase nitrogen. The analysis of the changes of reactivity and of the electrocatalyst characteristics as a function of the time of activation indicates a linear relationship between the ammonia formation rate and a specific XPS (X-ray-photoelectron spectroscopy) oxygen signal related to O 2 − in iron-oxide species. This results together with characterization data by TEM and XRD suggest that the iron species active in the direct and selective synthesis of ammonia is a maghemite-type iron oxide, and this transformation from the initial hematite is responsible for the in-situ enhancement of 3-4 times of the TOF (turnover frequency) and NH 3 Faradaic efficiency. This transformation is likely related to the stabilization of the maghemite species at CNT defect sites, although for longer times of preactivation a sintering occurs with a loss of performances.

Research paper thumbnail of Insights by in-situ studies on the nature of highly-active hydrotalcite-based Ni-Fe catalysts for CO2 methanation

Chemical Engineering Research and Design

Research paper thumbnail of Orange Peel Biomass‐derived Carbon Supported Cu Electrocatalysts Active in the CO <sub>2</sub> ‐Reduction to Formic Acid

ChemPhysChem, Jan 9, 2023

Research paper thumbnail of Multifunctional HDO/Selective Cracking Ni/HBEA Catalysts to Produce Jet Fuel and Diesel from Bio-oils

Chemical Engineering Transactions, 2016

The development of multifunctional catalysts to selectively produce in one-step processes jet fue... more The development of multifunctional catalysts to selectively produce in one-step processes jet fuels (around C12) and diesel (around C16-C18) from bio-oils (vegetable and especially algal oil) is still a challenge to produce next-generation biofuels. This topic is addressed here by investigating the activity of Ni based catalysts in the methyl palmitate conversion, as model test reaction. The performance of Ni/HBEA (8%wt Ni) catalysts, where mesoporosity was introduced by desilication, were compared with those of mesoporous SBA-15. It is evidenced that desilication allows to introduce selective hydrocracking functionality together with HDO (hydrodeoxygenation), the latter prevailing occurring through hydrogenation of the acid group rather than via hydrodecarboxylation.

Research paper thumbnail of Electrocatalytic production of glycolic acid via oxalic acid reduction on titania debris supported on a TiO2 nanotube array

Journal of Energy Chemistry, 2021

Electrodes prepared by anodic oxidation of Ti foils are robust and not toxic materials for the el... more Electrodes prepared by anodic oxidation of Ti foils are robust and not toxic materials for the electrocatalytic reduction of oxalic acid to glycolic acid allowing to develop a renewable energy driven process for the production of an alcoholic compound from an organic acid at low potential and room temperature. Coupled with an electrochemical synthesis of the oxalic acid from CO2 the process represents a new green and low-carbon path to produce added value chemicals from CO2. Various electrodes prepared by anodic oxidation of Ti foils were investigated. They were characterized by the presence of a TiO2 nanotube array together with the presence of small patches, debris or TiO2 nanoparticles. A series of relationships between the characteristics of these samples, in particular the concentration of oxygen vacancies and the amount of Ti 3+ detected by XPS or the intensity of the anodic peak in cyclic voltammetry tests, and the catalytic behavior (oxalic acid conversion and yield of glycolic acid) evidence the relation between these aspects. The analysis of the results indicate in small amorphous TiO2 nanoparticles (or surface pathces or debris) stabilized by interaction with TiO2 nanotubes the sites responsible for the conversion of oxalic acid and glycolic acid yield. By varying this structural characteristic of the electrodes, it is possible to tune the glycolic acid to glyoxylic acid relative ratio. A best cumulative Faradaic efficiency of about 84% with selectivity to glycolic acid around 60% and oxalic conversion about 30% was obserbed.

Research paper thumbnail of Investigations of Carbon Nitride-Supported Mn3O4 Oxide Nanoparticles for ORR

Catalysts, 2020

Earth-abundant Mn-based oxide nanoparticles are supported on carbon nitride using two different i... more Earth-abundant Mn-based oxide nanoparticles are supported on carbon nitride using two different immobilization methods and tested for the oxygen reduction reaction. Compared to the metal free CN, the immobilization of Mn oxide enhances not only the electrocatalytic activity but also the selectivity towards the 4e- reduction reaction of O2 to H2O. The XPS analysis reveals the interaction of the pyridine N species with Mn3O4 nanoparticles being particularly beneficial. This interaction is realized—although to a limited extent—when preparing the catalysts via impregnation; via the oleic acid route it is not observed. Whilst this work shows the potential of these systems to catalyze the ORR, the main limiting factor is still the poor conductivity of the support which leads to overpotential.

Research paper thumbnail of g-C3N4 Decorated TiO2 Nanotube Ordered Thin Films as Cathodic Electrodes for the Selective Reduction of Oxalic Acid

Paper Received: 21 May 2020; Revised: 23 December 2020; Accepted: 19 February 2021 Please cite th... more Paper Received: 21 May 2020; Revised: 23 December 2020; Accepted: 19 February 2021 Please cite this article as: De Luca F., Passalacqua R., Abramo F.P., Perathoner S., Centi G., Abate S., 2021, G-c3n4 Decorated Tio2 Nanotube Ordered Thin Films as Cathodic Elctrodes for the Selective Reduction of Oxalic Acid, Chemical Engineering Transactions, 84, 37-42 DOI:10.3303/CET2184007 CHEMICAL ENGINEERING TRANSACTIONS

Research paper thumbnail of Catalytic Performance of Ni-based Catalysts Supported on γ-Al2O3-ZrO2-TiO2-CeO2 Composite Oxide for CO2 Methanation

Increasing emissions of carbon dioxide arising from the widespread production of energy from foss... more Increasing emissions of carbon dioxide arising from the widespread production of energy from fossil fuels is a critical matter regarding the global warming. The hydrogenation of CO2 into oxygenates and/or hydrocarbons have been the most investigated reactions to obtain fuels [1]. Among several hydrogenation reactions, methanation of carbon dioxide following the Sabatier reaction is the most advantageous one regarding thermodynamics. Nickel based catalysts are the most studied materials for the latter reaction, because of their high activity and low price, but metal sintering at reaction conditions diminishes their industrial viability [2]. The type of support used for heterogeneous catalysts is an important factor to consider on solving such problems. Metal-support interactions play a role on catalyst performance in terms of the active site dispersion, activity and stability of the catalysts [3]. In this work, we focused our attention on the selection of different supports for Ni-ba...