Valeria La Parola

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.

The problem of microbial resistance to antibiotics makes it necessary to develop new materials capable of overcoming the resistance to the chemicals currently used. Herein, the antibacterial properties of modified bamboo powder are tested and compared with modified cellulose isolated from soybean hulls. Such biomasses are functionalized in a water solution with (3‐aminopropyl)triethoxysilane to introduce primary amino groups, and two different functionalization procedures are adopted: the first requires conventional heating steps, whereas the second implies microwave radiation use. The main outcomes from the characterizations evidence that the materials prepared with the thermal treatment are stabler than those obtained by the microwave‐assisted procedure and that bamboo‐derived samples react with the (3‐aminopropyl)triethoxysilane through different functionalities other than hydroxyl groups. Finally, the antibacterial activity measured against Escherichia coli and Staphylococcus aureus shows that all the functionalized samples could efficiently remove Gram‐positive and Gram‐negative bacteria (removal > 93%). Moreover, active filters are realized by packing the material powders: when the bacterial inoculum passes through them in a continuous flow, some differences are observed between cellulose and bamboo‐based materials, but the overall performances show that after 17 min and five recirculation cycles, both the samples reach an excellent Escherichia coli removal of about 100%.