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7. VOX/Al2O3Catalyzed Oxidative Dehydrogenation of Propane: Focus on Catalyst Characterization and Deactivation Behavior

Author

Passamonti, Francisco J., D’Ippolito, Silvana A., Vicerich, María A., Sanchez, María A., Bocanegra, Sonia, Guignard, Nadia, Especel, Catherine, Epron, Florence, Pieck, Carlos L., and Benítez, Viviana M.

Abstract

Oxidative dehydrogenation of hydrocarbons (ODH) converts propane and/or ethane into propylene and/or ethylene, which are important compounds in the chemical industry. Unlike steam cracking, ODH offers a high theoretical conversion to olefins and lower energy consumption. The ODH reaction of propane to propylene was studied using VOX/Al2O3catalysts prepared by wet impregnation. The reaction conditions were widely varied, with temperatures ranging from 300 to 550 °C, the C3/O2ratio from 1.6 to 3.3, and the vanadium content from 1 to 11 wt %. It was observed that these parameters are key experimental variables that influence the performance of the catalysts in ODH. Catalysts with intermediate vanadium loading exhibit an optimal amount of acidic sites due to the presence of monomeric and polymeric VOXspecies, resulting in high selectivity toward propylene. Temperature-programmed oxidation analyses showed that coke deposition is proportional to the degree of VOXpolymerization.

Published
2025
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9. DFT Atomic‐Scale Insight into Pt/Cu Single Atom Alloy Clusters Supported on γ‐Al2O3: The Effect of Hydrogen Environment.

Author

Shahrokhi, Masoud, Mineva, Tzonka, Benabbas, Abdennour, Especel, Catherine, Le Valant, Anthony, Ricolleau, Christian, Wang, Guillaume, Nelayah, Jaysen, Epron, Florence, and Guesmi, Hazar

Subjects
COPPER clusters, ATOMIC clusters, HYDROGEN atom, COPPER, DENSITY functional theory, PLATINUM
Abstract

Single atom alloy (SAA) clusters formed by anchoring single atoms in small supported host clusters are emerging as catalysts with high performance. In this work, density functional theory (DFT) calculations and ab‐initio molecular dynamics (AIMD) simulations are performed to study the stability and the structure evolution of γ‐alumina‐supported platinum/copper SAA clusters of sub‐nanometer size in hydrogen environment. Due to the strong dynamic nature of both Cu cluster and anchored Pt single atom and their evolving interaction with the support, different isomers with different geometric and energetic properties are predicted. Extensive sampling through AIMD simulations reveals strong effect of hydrogen on the location of Pt single atom and strong variation of the cluster shape, evolving from 3D to concave and planar shapes wetting the alumina support. Interfacial site location of Pt single atom is found to be hydrogen coverage dependent. When the hydrogen coverage increases, the Pt single atom located preferentially at the interfacial site is pulled up by hydrogen atoms toward the upper surface Cu layers. The interaction of Pt/Cu cluster with alumina is predicted to decrease with increasing hydrogen coverage. Finally, electronic structure analysis reveals dramatic effect of hydrogen on the metallic nature of the catalysts. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Catalytic Dehydrogenation on Ultradisperse Sn-Promoted Ir Catalysts Supported on MgAl 2 O 4 Prepared by Different Techniques.

Author

de Miguel, Sergio, Fals, Jayson, Benitez, Viviana, Especel, Catherine, Epron, Florence, and Bocanegra, Sonia

Subjects
BIMETALLIC catalysts, CATALYTIC dehydrogenation, CATALYST supports, ATOMIC clusters, HYDROGENOLYSIS, TIN, SURFACE area, DISPERSION (Chemistry)
Abstract

Ir and IrSn catalysts with different Sn contents (0.5, 0.7 and 0.9 wt%) were prepared using MgAl2O4 supports synthesized using two different techniques (the citrate–nitrate combustion and coprecipitation methods). Both supports, with a spinel structure, presented low acidity and good textural properties. However, the support prepared by coprecipitation had higher specific surface area and pore volume than the one prepared by combustion, which would favor the dispersion of the metals to be deposited. Likewise, during the preparation of the catalytic materials, a very good interaction was achieved between the metals and both supports, which was confirmed by the presence of sub-nanometer atomic clusters in the mono- and bimetallic catalysts. Regarding the catalytic properties, while the monometallic Ir/MgAl2O4 samples lead to a very low conversion of n-butane and a selectivity towards hydrogenolysis products, the addition of Sn to Ir increases the conversion, decreases hydrogenolysis and therefore sharply increases the selectivity towards the different butenes. Catalysts with higher Sn loadings present better catalytic behavior. One of the roles of the Sn promoter would be to geometrically modify the Ir clusters, drastically decreasing the hydrogenolytic activity. This effect, added to the strong electronic modification of the Ir sites by the action of Sn, with probable Ir-Sn alloy formation, is responsible for the high catalytic performance of these bimetallic catalysts. [ABSTRACT FROM AUTHOR]

Published
2024
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23. Designing CuO–SiO2 and Cu0–SiO2 Monolithic Ceramics Bearing Hierarchical Porosity Toward Robust and Cycling CO Oxidation Properties

Author

Vardon, Antoine, primary, Labarrère, Hugo, additional, Nallet, Frédéric, additional, Chanut, Nicolas, additional, Weill, François, additional, Labrugère-Sarroste, Christine, additional, Bobet, Jean-Louis, additional, Ly, Isabelle, additional, Epron, Florence, additional, Especel, Catherine, additional, and Backov, Rénal, additional

Published
2022
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37. Binary CoOx–SiO2 Porous Nanostructures for Catalytic CO Oxidation

Author

Ly, Isabelle, primary, Vardon, Antoine, additional, Chanut, Nicolas, additional, Nallet, Frédéric, additional, Pellenq, Roland J.-M., additional, Rouzières, Mathieu, additional, Clérac, Rodolphe, additional, Akil, Joudia, additional, Epron, Florence, additional, Especel, Catherine, additional, and Backov, Rénal, additional

Published
2022
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42. Influence of the Ir content and the support on the thiotolerance of the Ir/SiO2-Al2O3 catalysts for selective ring opening of decalin

Author

D'ippolito, Silvana Andrea, Ballarini, Adriana Daniela, Rosas, Santiago Miguel, Pirault Roy, Laurence, Especel, Catherine, Epron, Florence, and Pieck, Carlos Luis

Subjects
SELECTIVE RING OPENING, purl.org/becyt/ford/2.4 [https], purl.org/becyt/ford/2 [https], THIOTOLERANCE, IR/SIO2-AL2O3, DECALIN
Abstract

The influence of Ir content on sulphur tolerance for the selective ring opening of decalin was investigated. Ir/SiO2-Al2O3 catalysts (70 wt% and 80 wt% SiO2) were used. In the absence of sulphur, slight differences were observed on the yields according to the metallic content regardless of the support used. Although the results of cyclopentane hydrogenolysis showed that the metallic function acquires importance as the metal content increases, for these metal percentages the acid function limits the rate of decalin opening reaction. Products distribution are strongly modified using decalin with S content compared to pure decalin. The formation of dehydrogenated products is virtually null due to S adsorbed on the metal sites. The support has low influence on the thiotolerance. The results, related to the amount of S per Ir surface atom, showed that for a moderate S content (S/Irsurf ∼ 0.30), 1.5 Ir/Sy appears to be less poisoned than 1Ir/Sy and 2Ir/Sy. Fil: D'ippolito, Silvana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Ballarini, Adriana Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Rosas, Santiago Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Pirault Roy, Laurence. Université de Poitiers; Francia Fil: Especel, Catherine. Université de Poitiers; Francia Fil: Epron, Florence. Université de Poitiers; Francia Fil: Pieck, Carlos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina

Published
2021
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49. Binary CoOx–SiO2 Porous Nanostructures for Catalytic CO Oxidation.

Author

Ly, Isabelle, Vardon, Antoine, Chanut, Nicolas, Nallet, Frédéric, Pellenq, Roland J.-M., Rouzières, Mathieu, Clérac, Rodolphe, Akil, Joudia, Epron, Florence, Especel, Catherine, and Backov, Rénal

Abstract

Via integrative chemistry, the first CoOx–SiO2(HIPE) self-standing monoliths of cobalt nano-oxides embedded within silica macro–mesocellular hosts have been prepared. These binary CoOx–SiO2 porous nanostructure (MUB-100-(x)) materials present an average of 95% porosity. We found out that high cobalt concentration maintains the hexagonal-2D organization of the mesoscopic voids when applying the thermal treatment at 700 °C. Their specific surface areas fall between 400 and 500 m2 g–1 when assessed by Ar physisorption measurements. At the microscopic length scale, as revealed through magnetic investigations, the low cobalt content foams MUB-100(1) and MUB-100(2) are made of the amorphous β-Co-(OH)2 phase coexisting with the silica network, whereas increasing the cobalt concentration during the one-pot syntheses (MUB-100(3) and MUB-(4) materials) favors the formation of the spinel Co3O4 and olivine Co2SiO4 crystalline nanoparticles embedded within silica. When considering the CO oxidation catalytic performance, the MUB-100(4) is able to totally convert the CO flow before 200 °C (starting at 125 °C) while achieving 50% conversion for a light-off temperature (T50) of 145 °C, revealing the good efficiency of the MUB-100(4) in CO oxidation with which up to 4 catalytic cycles have been performed without disrupting drastically the catalytic performance and reaching thermodynamic stability from cycle 2 to cycle 4. [ABSTRACT FROM AUTHOR]

Published
2022
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50. Ru‐Pt catalysts supported on Al2O3 and SiO2─Al2O3 for the selective ring opening of naphthenes

Author

Vicerich, Maria Ana, Benitez, Viviana Monica, Sánchez, María Amparo, Especel, Catherine, Epron, Florence, and Pieck, Carlos Luis

Subjects
Ingeniería Química, SELECTIVE RING OPENING, Ingeniería de Procesos Químicos, RU-PT CATALYSTS, INGENIERÍAS Y TECNOLOGÍAS, DECALIN
Abstract

Alumina and silica-alumina supported Ru-Pt catalysts were evaluated for the ring opening of naphthenes. Pt, Ru and Ru-Pt catalysts were prepared by impregnation of inorganic precursors over γ-alumina and silica-alumina supports. The catalysts were evaluated by temperature programmed reduction (TPR), pyridine temperature programmed desorption (TPD), CO-FTIR and by test reactions of 33DM1B isomerization, cyclohexane dehydrogenation, cyclopentane hydrogenolysis and ring opening of decalin. The strong interaction between the metals (Pt-Ru) was attributed to their reduction occurring simultaneously. The acidity and strength of the acid sites of the monometallic Ru catalyst were higher than those of the monometallic Pt catalyst. Total acidity (Lewis and Brønsted) and strength of the acid sites were higher for the silica-alumina supported catalysts. The silica-alumina catalysts had ten times more Brønsted acidity than the γ-alumina ones and an increased activity and selectivity to decalin ring opening products. Supported monometallic Ru had the best performance for the ring opening reaction Fil: Vicerich, Maria Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Benitez, Viviana Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Sánchez, María Amparo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Especel, Catherine. Universite de Poitiers. Laboratoire de Catalyse En Chimie Oranique; Francia Fil: Epron, Florence. Universite de Poitiers. Laboratoire de Catalyse En Chimie Oranique; Francia Fil: Pieck, Carlos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina

Published
2019

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