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1.
Synthesis of helional by hydrodechlorination reaction in the presence of mono- and bimetallic catalysts supported on alumina
Oreste Piccolo, Iztok Arčon, Das Gangadhar, Giuliana Aquilanti, Andrea Prai, Stefano Paganelli, Manuela Facchin, Valentina Beghetto, 2024, original scientific article

Abstract: Hydrodechlorination reaction of 3-(benzo-1,3-dioxol-5-yl)-3-chloro-2-methylacrylaldehyde in the presence of different low metal content heterogeneous mono- or bimetallic catalysts was tested for the synthesis of the fragrance Helional® (3-[3,4-methylendioxyphenyl]-2-methyl-propionaldehyde). In particular, mono Pd/Al2O3, Rh/Al2O3 or bimetallic Pd-Cu/Al2O3, Rh-Cu/Al2O3 catalysts were tested in different reaction conditions from which it emerged that mono-Rh/Al2O3 was the best performing catalyst, allowing achievement of 100% substrate conversion and 99% selectivity towards Helional® in 24 h at 80 °C, p(H2) 1.0 MPa in the presence of a base. To establish correlations between atomic structure and catalytic activity, catalysts were characterized by Cu, Rh and Pd K-edge XANES, EXAFS analysis. These characterizations allowed verification that the formation of Pd-Cu alloys and the presence of Cu oxide/hydroxide species on the surface of the Al2O3 support are responsible for the very low catalytic efficiency of bimetallic species tested.
Keywords: selective hydrodechlorination, heterogeneous catalysis, XANES analysis, EXAFS analysis
Published in RUNG: 25.04.2024; Views: 892; Downloads: 4
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2.
aInfluence of milling time and thermal treatment on catalytic activity of ▫$MoS_2$▫/graphene oxide composites
J. Rmuš Mravik, Blaž Belec, Željko Mravik, Zoran M. Jovanović, 2023, published scientific conference contribution abstract

Keywords: composites, catalysis
Published in RUNG: 13.11.2023; Views: 1074; Downloads: 1
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3.
Utilizing structurally disordered AlMg-oxide phase in Cu/ZnO catalyst for efficient ▫$CO_2$▫ hydrogenation to methanol
Andraž Mavrič, Gregor Žerjav, Blaž Belec, Matevž Roškarič, Matjaž Finšgar, Albin Pintar, Matjaž Valant, 2023, published scientific conference contribution abstract

Keywords: carbon dioxide, methanol, catalysis
Published in RUNG: 15.09.2023; Views: 1364; Downloads: 4
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4.
Structural disorder of AlMg-oxide phase supporting Cu/ZnO catalyst improves efficiency and selectivity for ▫$CO_2$▫ hydrogenation to methanol
Andraž Mavrič, Gregor Žerjav, Blaž Belec, Matevž Roškarič, Matjaž Finšgar, Albin Pintar, Matjaž Valant, 2023, original scientific article

Abstract: The performance of the Cu/ZnO catalyst system with the AlMg-oxide phase is studied for CO2 hydrogenation to methanol. The catalyst is prepared by thermal treatment of the hydrotalcite phase containing intimately mixed metal cations in the hydroxide form. CuO in the presence of ZnO and disordered AlMg-oxide phase gets easily reduced to Cu during the hydrogenation reaction. Its catalytic activity at relatively low Cu metal content (∼14 at.%) remains stable during 100 hours on stream at 260 °C with constant space-time yield for methanol (∼1.8 gMeOH gcat−1 h−1) and high methanol selectivity (>85 %) The improved performance is attributed to the neutralization of surface acidity, increased number of weak basic sites in the disordered phase, and lower tendency for coke formation.
Keywords: carbon dioxide hydrogenation, heterogenous catalysis, methanol, reducibility
Published in RUNG: 02.06.2023; Views: 1404; Downloads: 15
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5.
Alternative Recovery and Valorization of Metals from Exhausted Catalytic Converters in a New Smart Polymetallic Catalyst
Sebastiano Tieuli, Franco Baldi, Iztok Arčon, Katarina Vogel-Mikuš, Michele Gallo, Laura Sperni, Oreste Piccolo, Stefano Paganelli, 2019, original scientific article

Abstract: A new metals-polymeric composite, Metx-EPS (I), was prepared to be used as catalyst in water or in two-phase aqueous conditions. The metals source was an exhausted catalytic converter that was grinded and treated with an acidic solution at room temperature. After filtration, the solution was concentrated, neutralized and added to a broth of Klebsiella oxytoca DSM 29614 to produce (I) where metals are embedded in a peculiar polysaccharide structure (EPS). The composite was easily recovered from the fermentation broth and purified. The process protocol was verified many times and was shown to be reproducible satisfactorily. The % recovery of metals, originally present in the converter, was good as determined by atomic absorption. The morphology and the chemical state of main metals in (I) were investigated by X-ray absorption spectroscopy methods (XANES and EXAFS). No metallic alloy seems to be evident. The catalytic activity and a possible synergic effect due to the presence of the different metals was valuated in the hydrogenation of some substrates, valuable precursors for theproduction of fine chemicals.
Keywords: Biogenerated polymetallic exopolysaccharide, biphasic catalysis, hydrogenation, metals-polymeric composite, new catalyst from metallic wastes, EXAFS, XANES
Published in RUNG: 06.05.2019; Views: 3572; Downloads: 0
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6.
Synthesis of a Cu/ZnO Nanocomposite by Electroless Plating for the Catalytic Conversion of CO2 to Methanol
Maja Pori, Iztok Arčon, Damjan Lašič Jurković, Marjan Marinšek, Goran Dražić, Blaž Likozar, Zorica Crnjak Orel, 2019, original scientific article

Abstract: The process of methanol synthesis based on the hydrogenation of CO2 was investigated over binary Cu/ZnO catalyst materials, prepared by applying a novel electroless plating fabrication method. The activity of the produced catalytic samples was determined at temperature range between 200 and 300 °C and the feedstock conversion data were supplemented with a detailed microstructure analysis using high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD) and Cu and Zn K-edge, X-ray absorption near-edge structure (XANES) measurements and extended X-ray absorption fine-structure (EXAFS) measurements. It was confirmed that the disorder in the Cu crystallites created unique geometrical situations, which acted as the additional reactive centres for the adsorption of the reactant molecule species. Copper and zinc structural synergy (spill-over) was also demonstrated as being crucial for the carbon dioxide’s activation. EXAFS and XANES results provide strong evidence for surface alloying between copper and zinc and thus the present results demonstrate new approach applicable for explaining metal–support interactions.
Keywords: EXAFS, CuZn alloy, Spillover mechanism, CO2 valorization, Electroless deposition method, Heterogeneous catalysis
Published in RUNG: 12.04.2019; Views: 3948; Downloads: 0
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7.
International Conference on Functional Nanomaterials and Nanodevices
Saim Emin, Dominik Eder, Polina Mladenova, 2018, other monographs and other completed works

Keywords: energy conversion, catalysis, nanomaterials, nanobiotechnologies
Published in RUNG: 17.09.2018; Views: 4833; Downloads: 0
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