Carla Calabrese

Dry reforming of methane (DRM) represents a promising route for the valorization of CO₂ captured from industrial emissions through high-temperature catalytic conversion. In this work, a LaMn_1−xNi_xO₃ perovskite catalyst (x = 0.25, 6 wt% Ni) was synthesized as a powder by solution combustion synthesis and subsequently deposited onto γ-alumina supports to obtain a structured catalyst. X-ray diffraction confirmed the formation of the perovskite structure, characterized by corner-sharing BO₆ octahedra with Ni substitution at the B-site. H₂-temperature-programmed reduction (H₂-TPR) revealed the reduction of Mn⁴⁺ and Mn³⁺ species to MnO, accompanied by the complete reduction of oxidized Ni species to metallic Ni over the investigated temperature range. Raman spectroscopy of the spent catalyst indicated negligible carbon deposition after DRM. Moreover, the Mn–O stretching band shifted from 657 cm⁻¹ in the fresh catalyst to 643 cm⁻¹ after reaction, consistent with changes in the manganese oxidation state associated with the collapse of the perovskite structure and the formation of MnO. During a 25 h stability test at 700 °C, the powdered LaMn_1−xNi_xO₃ catalyst achieved a CH₄ conversion of 75% at a WHSV of 60 L g⁻¹ h⁻¹. DRM tests performed with the structured catalyst confirmed the catalytic performance under larger-scale operating conditions and different reaction parameters, including temperature, residence time, and CH₄/CO₂ feed ratio, reaching CH₄ conversions of up to 94% at 800 °C.

Dry reforming of methane represents a promising approach for the valorization of CO₂ captured from industrial emissions via a high-temperature catalytic process. To this aim, a LaMn1-xNixO3 catalyst with a perovskite structure (x=0.25) for dry reforming was obtained as ultrafine powder by solution combustion synthesis and then softly deposited over -alumina supports as structured catalyst. X-ray diffraction proved that the fresh catalyst exhibits the characteristic framework of corner-sharing BO6 oc-tahedra and Mn substitution in B site. Temperature programmed reduction in H2 showed two main peaks between 200 and 400 °C and between 700 and 900 °C, proving the strong reduction of Mn oxides in different oxidation states and Ni oxide even to the elemental state. Raman spectroscopy on fresh and spent catalyst showed that carbon deposition during reforming was negligible and lattice distortion occurred associated to oxygen vacancies or partial reduction. A 25-hour reforming test with LaMn1-xNixO3 proved conversion of CH4 equal to 75% at 700°C. Dry reforming tests with the struc-tured catalyst confirmed the results obtained with the catalyst powder on a larger scale and different conditions, such as temperature, residence time and CH4/CO2 feed ratio, achieving CH4 conversion of up to 94% at 800 °C.

Nickel-supported catalysts over SiO₂-CeO₂ mixed oxides were investigated as catalysts for syngas production via dry reforming of methane. SiO₂-CeO₂ supports were optimized by varying the preparation method and ceria loading with the aim of stabilizing nickel nanoparticles, enhancing the catalytic performance, and improving the resistance to coke formation under high-temperature reforming conditions. To investigate the effect of support composition, SiO₂-CeO₂ mixed oxides with ceria contents ranging from 5 to 30 wt% were prepared using two synthesis routes: sol–gel and wetness impregnation methods. A nickel loading of 5 wt% was deposited on the resulting supports. The catalysts were characterized by XRD, N₂ physisorption, temperature-programmed reduction (TPR), and Raman spectroscopy. Catalytic activity tests were carried out over reduced catalysts in an H₂-He stream at 750 °C, using a feed mixture containing 15 vol% CH₄ and 15 vol% CO₂ in He. The effect of temperature on catalytic performance was evaluated in the range of 450–750 °C. Thermogravimetric, XRD and Raman analyses of spent catalysts were used to assess carbon deposition and the nature of crystalline phases. The results highlight the role of CeO₂ content and preparation method in determining nickel dispersion, reducibility, catalytic performance in DRM, and coke resistance.

Nickel-supported over SiO₂-CeO₂ mixed oxides were investigated as catalysts for syngas production via the dry reforming of methane. The SiO₂-CeO₂ supports were optimized, playing on the preparation method and ceria loading with the aim of stabilizing nickel nanoparticles, enhancing the catalytic performance, and improving the resistance to coke formation under high-temperature reforming conditions. To investigate the effect of support composition, SiO₂-CeO₂ mixed oxides with ceria contents ranging from 5 to 30 wt% were prepared using two synthesis routes: sol-gel and wetness impregnation methods. A nickel loading of 5 wt% was deposited on the resulting supports. The catalysts were characterized by XRD, N₂ physisorption, temperature-programmed reduction, and Raman spectroscopy. Catalytic activity tests were conducted over reduced catalysts in an H₂-He stream at 750 °C, using a feed mixture containing 15 vol% CH₄ and 15 vol% CO₂ in He. The effect of temperature on catalytic performance was evaluated in the range of 450–800 °C. Thermogravimetric, XRD and Raman analyses of spent catalysts were used to assess carbon deposition and the nature of crystalline phases. The results highlight the role of CeO₂ content and preparation method in determining nickel dispersion, reducibility, catalytic performance in DRM, and coke resistance.

The development of eco-friendly paint formulations is part of the transition process to more sustainable materials, which involves many industries such as offshore and shipbuilding, where the deterioration of steel in seawater is a key factor. This article aims to produce innovative coatings and test their protective action on DH 36 steel plates. SiO₂ and TiO₂ were modified with amino groups and iron sites to be used as filler for the design of ecological paint formulations The antimicrobial features of both NH₂ groups and iron ionic species were combined with the chemical and mechanical stability of silica and titania, with silica-based powders showing increased efficacy. The surface properties of the resulting coatings were examined by determination of thickness, water wettability, roughness, and cross-cut adhesion tests (before and after a degradation test in seawater according to ASTM D870-97 standards). Preliminary tests of the microbiological activity of the iron amino functionalized materials were carried out to monitor, as proof of concept, the growth of some bacterial strains through measurements of optical density. The findings indicate that these coatings not only provide effective corrosion protection but are promising for enhancing the durability and environmental performance of steel surfaces exposed to marine environments.

Nowadays, the development of eco-friendly paint formulations is part of the transition process to more sustainable materials, which involves many industrial fields such as offshore and shipbuilding where the deterioration of steel in seawater is a key factor. This article aims to produce suitable innovative coatings and test their protective action on DH 36 steel plates. Commercially available SiO2 and TiO2 were covalently modified with amino groups allowing two organic-inorganic hybrid materials for the immobilization of iron sites. The obtained powders were characterized by thermogravimetric analysis, N2 physisorption, X-ray diffraction, and X-ray photoelectron spectroscopy. Fe-based solids were used as filler for the design of ecological paint formulations which, in turn, were applied on the surface of metal prototype plates. The surface properties of the resulting coatings were examined by determination of thickness, water wettability, roughness, and cross-cut adhesion tests (before and after degradation test in seawater according to ASTM D 870-97 standard). Preliminary tests of the microbiological activity of the iron amino functionalized materials were carried out monitoring, as proof of concept, the growth of some bacterial strains through measurements of optical density.

Cu (10 wt%) materials on silica nanotubes were prepared via two different synthetic approaches, co-synthesis and wetness impregnation on preformed SiO₂ nanotubes, both as dried or calcined materials, with Cu(NO₃)2.5H₂O as a material precursor. The obtained silica and the Cu samples, after calcination at 550 °C for 5 h, were characterized by several techniques, such as TEM, N₂ physisorption, XRD, Raman, H₂-TPR and XPS, and tested for toluene oxidation in the 20–450 °C temperature range. A reference sample, Cu(10 wt%) over commercial silica, was also prepared. The copper-based silica nanotubes exhibited the best performances with respect to toluene oxidation. The Cu-based catalyst using dried silica nanotubes has the lowest T₅₀ (306 °C), the temperature required for 50% toluene conversion, compared with a T₅₀ of 345 °C obtained for the reference catalyst. The excellent catalytic properties of this catalyst were ascribed to the presence of easy copper (II) species finely dispersed (crystallite size of 13 nm) on the surface of silica nanotubes. The present data underlined the impact of the synthetic method on the catalyst properties and oxidation activity.

For this study, the synthesis of TiO₂ nanomaterials was performed via a novel sol-gel method employing titanium butoxide as a metal precursor, Pluronic F127 as a templating agent, toluene as a swelling agent, and acidic water or ethanol as the reaction solvents. The method was designed by tailoring certain reaction parameters, such as the sequence of toluene addition, magnetic stirring, the type of reaction solvent, and the calcination conditions. Analysis of the specific surface area and porosity was carried out via N₂ physisorption, whereas the morphological features of the solids were investigated via transmission electron microscopy. The crystalline structure of both the dried powders and the calcined materials was evaluated using X-ray diffraction analysis. It transpired that the different phase compositions of the solids are related to the specific synthesis medium employed. Under the adopted reaction conditions, ethanol, which was used as a reaction solvent, promoted the local arrangement of dispersed anatase particles, the specific arrangement of which does not lead to rutile transformation. Conversely, the use of water alone supported high-particle packing, evolving into a rutile phase. The photodegradation of Rhodamine B was used as a target reaction for testing the photocatalytic activity of the selected samples.

In this work, formulations of “environmentally compatible” silicone-based antifouling, synthesized in the laboratory and based on copper and silver on silica/titania oxides, have been characterized. These formulations are capable of replacing the non-ecological antifouling paints currently available on the market. The texture properties and the morphological analysis of these powders with an antifouling action indicate that their activity is linked to the nanometric size of the particles and to the homogeneous dispersion of the metal on the substrate. The presence of two metal species on the same support limits the formation of nanometric species and, therefore, the formation of homogeneous compounds. The presence of the antifouling filler, specifically the one based on titania (TiO₂) and silver (Ag), facilitates the achievement of a higher degree of cross-linking of the resin, and therefore, a better compactness and completeness of the coating than that attained with the pure resin. Thus, a high degree of adhesion to the tie-coat and, consequently, to the steel support used for the construction of the boats was achieved in the presence of the silver–titania antifouling.

In this work formulations of "environmentally compatible" silicone-based antifouling synthesized in the laboratory and based on copper and silver on silica/titania oxides have been characterized, capable of replacing the non-ecological antifouling paints currently on the market. The texture properties and the morphological analysis of these powders with an antifouling action indicate that their activity is linked to the nanometric size of the particles and to the homogeneous dispersion of the metal on the substrate. The presence of two metal species on the same support limits the for-mation of nanometric species and therefore the formation of homogeneous compounds. The presence of the antifouling filler (specifically the one based on TiO2 and Ag) facilitates the achievement of a higher degree of cross-linking of the pure resin, and therefore a better compactness and completeness of the coating. This leads to a consequent better degree of adhesion to the tie-coat and therefore to the steel support used for the construction of the boats.