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Acetonylacetone
The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Maria Ziolek – One of the best experts on this subject based on the ideXlab platform.
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Catalytic properties of new ternary Nb-Sb-V oxide – A comparative study with mechanical mixture of single oxides and binary systems
Catalysis Today, 2012Co-Authors: Maria Ziolek, Hanna Golinska-mazwa, Elzbieta Filipek, Mateusz PizAbstract:Abstract The study presents a comparative analysis of catalytic properties of new Nb2SbVO10 ternary oxide against those of a mechanical mixture of single oxides and a mixture of single with binary oxide, all of the same chemical composition. Moreover, the material without antimony (Nb9VO25) was tested. Acid–base and redox properties were studied in the following test reactions: 2-propanol decomposition, Acetonylacetone (AcOAc) cyclisation and methanol oxidation. The properties of ternary oxide and the mechanical mixture of single oxides are not significantly different. The main difference is in the generation of more active Lewis acid–base pairs in ternary oxide, which is demonstrated by the higher production of ether in the intermolecular dehydration of 2-propanol. Acidic/basic and redox properties of the oxide catalysts containing Nb, Sb, V, O (atomic ratio: 2:1:1:10) strongly depend on the presence of binary oxide, which significantly enhances the basicity of the catalysts. The highest basicity was found for pure binary oxide Nb9VO25 but this catalyst without Sb exhibits much lower activity in the transformation of both alcohols.
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Vanadium and antimony supported NbSiOx—Characterisation and catalytic properties in methanol oxidation☆
Catalysis Today, 2011Co-Authors: Hanna Golinska, P. Decyk, Maria ZiolekAbstract:Abstract Niobosilica material (NbSiOx) prepared by a simple method without the use of organic template was applied as a support for SbVOx phases with high Sb and V contents. In this paper we describe the preparation of VSb/NbSiOx catalysts, their structural/textural characterisation (studied by XRD, N2 adsorption, UV–vis, ESR) and surface catalytic properties (estimated from pyridine adsorption, test reactions: Acetonylacetone cyclisation and methanol oxidation). It was found that vanadium–antimony binary oxide phase interacts with acidic hydroxyls on NbSiOx surface. Such interaction leads to the formation of Sb0.95V0.95O4 rutile phase and new OH groups exhibiting basic properties. As the strength of interaction of Sb0.95V0.95O4 phase with niobium species in NbSiOx support increases with increasing calcination temperature, the particle sizes of rutile phase are smaller for higher calcination temperatures. High calcination temperatures cause that more vanadium species are present at the +4 oxidation state, whereas after low-calcination temperatures and at high vanadium content V O species are formed and they are well visible in UV–vis spectra of the catalysts. The presence and role of different active centres on VSb/NbSiOx catalysts are discussed on the basis of results obtained in the oxidation of methanol.
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Meso–macroporous zirconia modified with niobia as support for platinum—Acidic and basic properties
Catalysis Today, 2010Co-Authors: Joanna Goscianska, Maria Ziolek, Emma K. Gibson, Marco DaturiAbstract:Abstract Meso–macroporous tetragonal zirconia synthesised hydrothermally within this work and containing ca. 60% of mesopores and a surface area of 84 m 2 /g is a highly basic material exhibiting both Bronsted and Lewis basicities (BBS and LBS). Moreover, it has Lewis acid sites and very weak BAS (bridged hydroxyls). Such ZrO 2 was used as a matrix for niobium oxide species loaded as 0.3 and 1 monolayers. NbOx loading decreases basicity (both LBS and BBS) and the number of Lewis acid sites (LAS) and leads to an increase in the number of Bronsted acid sites (BAS). The loading with a 0.3 monolayer of NbOx leads to a very attractive support/catalyst because of the generation of active oxygen atoms at the interface between the NbOx and ZrO 2 phases. Niobio-zirconia supports were modified by impregnation with chloroplatinic acid (1 wt% of Pt). Platinum modification further changes the acid–base properties of the supports, depending on the NbOx loading. The highest Pt dispersion is reached on the NbOx monolayer because of the strong metal–support interaction. Structure and surface properties (acid–base) of the supports and platinum catalysts were characterized in detail by N 2 adsorption, XRD, XPS, UV–vis, FTIR combined with the adsorption of probe molecules (pyridine, CO at room temperature and ∼100 K, CO 2 ), and by test reactions (Acetonylacetone cyclization and 2-propanol dehydration/dehydrogenation).
Antonio A. Romero – One of the best experts on this subject based on the ideXlab platform.
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Acetonylacetone conversion on AlPO_4–cesium oxide (5–30 wt%) catalysts
Catalysis Letters, 1999Co-Authors: Felipa M. Bautista, Juan M. Campelo, Angel Garcia, Raquel M. Leon, Diego Luna, Jose M. Marinas, Antonio A. RomeroAbstract:Acetonylacetone underwent both acid‐ and base‐catalyzed intramolecular cyclizations to 2,5‐dimethylfuran and 3‐methyl‐2‐cyclopenten‐1‐one, respectively, on pure AlPO_4, whereas its modification with increasing amounts of cesium oxide developed AlPO_4‐based materials with increased basic properties and, hence, higher selectivities to the base‐catalyzed cyclization process. However, the poisoning of surface acid and base sites indicated that Acetonylacetone conversion into 3‐methyl‐2‐cyclopenten‐1‐one can also be attributed to the joint participation of surface acid and base sites. So, Acetonylacetone cannot be used for the simultaneous characterization of acidic and basic surface properties of acid–base heterogeneous catalysts.
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Acetonylacetone conversion on AlPO4–cesium oxide (5–30 wt%) catalysts
Catalysis Letters, 1999Co-Authors: Felipa M. Bautista, Juan M. Campelo, Angel Garcia, Raquel M. Leon, Diego Luna, Jose M. Marinas, Antonio A. RomeroAbstract:Acetonylacetone underwent both acid‐ and base‐catalyzed intramolecular cyclizations to 2,5‐dimethylfuran and 3‐methyl‐2‐cyclopenten‐1‐one, respectively, on pure AlPO4, whereas its modification with increasing amounts of cesium oxide developed AlPO4‐based materials with increased basic properties and, hence, higher selectivities to the base‐catalyzed cyclization process. However, the poisoning of surface acid and base sites indicated that Acetonylacetone conversion into 3‐methyl‐2‐cyclopenten‐1‐one can also be attributed to the joint participation of surface acid and base sites. So, Acetonylacetone cannot be used for the simultaneous characterization of acidic and basic surface properties of acid–base heterogeneous catalysts.
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Acetonylacetone conversion on alpo4 cesium oxide 5 30 wt catalysts
Catalysis Letters, 1999Co-Authors: Felipa M. Bautista, Juan M. Campelo, Angel Garcia, Raquel M. Leon, Diego Luna, Jose M. Marinas, Antonio A. RomeroAbstract:Acetonylacetone underwent both acid‐ and base‐catalyzed intramolecular cyclizations to 2,5‐dimethylfuran and 3‐methyl‐2‐cyclopenten‐1‐one, respectively, on pure AlPO4, whereas its modification with increasing amounts of cesium oxide developed AlPO4‐based materials with increased basic properties and, hence, higher selectivities to the base‐catalyzed cyclization process. However, the poisoning of surface acid and base sites indicated that Acetonylacetone conversion into 3‐methyl‐2‐cyclopenten‐1‐one can also be attributed to the joint participation of surface acid and base sites. So, Acetonylacetone cannot be used for the simultaneous characterization of acidic and basic surface properties of acid–base heterogeneous catalysts.
Marco Daturi – One of the best experts on this subject based on the ideXlab platform.
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Meso–macroporous zirconia modified with niobia as support for platinum—Acidic and basic properties
Catalysis Today, 2010Co-Authors: Joanna Goscianska, Maria Ziolek, Emma K. Gibson, Marco DaturiAbstract:Abstract Meso–macroporous tetragonal zirconia synthesised hydrothermally within this work and containing ca. 60% of mesopores and a surface area of 84 m 2 /g is a highly basic material exhibiting both Bronsted and Lewis basicities (BBS and LBS). Moreover, it has Lewis acid sites and very weak BAS (bridged hydroxyls). Such ZrO 2 was used as a matrix for niobium oxide species loaded as 0.3 and 1 monolayers. NbOx loading decreases basicity (both LBS and BBS) and the number of Lewis acid sites (LAS) and leads to an increase in the number of Bronsted acid sites (BAS). The loading with a 0.3 monolayer of NbOx leads to a very attractive support/catalyst because of the generation of active oxygen atoms at the interface between the NbOx and ZrO 2 phases. Niobio-zirconia supports were modified by impregnation with chloroplatinic acid (1 wt% of Pt). Platinum modification further changes the acid–base properties of the supports, depending on the NbOx loading. The highest Pt dispersion is reached on the NbOx monolayer because of the strong metal–support interaction. Structure and surface properties (acid–base) of the supports and platinum catalysts were characterized in detail by N 2 adsorption, XRD, XPS, UV–vis, FTIR combined with the adsorption of probe molecules (pyridine, CO at room temperature and ∼100 K, CO 2 ), and by test reactions (Acetonylacetone cyclization and 2-propanol dehydration/dehydrogenation).
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Meso-macroporous zirconia modified with niobia as support for platinum-Acidic and basic properties
Catalysis Today, 2010Co-Authors: Joanna Goscianska, Maria Ziolek, Emma Gibson, Marco DaturiAbstract:Meso-macroporous tetragonal zirconia synthesised hydrothermally within this work and containing ca. 60% of mesopores and a surface area of 84 m(2)/g is a highly basic material exhibiting both Breasted and Lewis basicities (BBS and LBS). Moreover, it has Lewis acid sites and very weak BAS (bridged hydroxyls). Such ZrO(2) was used as a matrix for niobium oxide species loaded as 0.3 and 1 monolayers. NbOx loading decreases basicity (both LBS and BBS) and the number of Lewis acid sites (LAS) and leads to an increase in the number of Breasted acid sites (BAS). The loading with a 0.3 monolayer of NbOx leads to a very attractive support/catalyst because of the generation of active oxygen atoms at the interface between the NbOx and ZrO(2) phases. Niobio-zirconia supports were modified by impregnation with chloroplatinic acid (1 wt% of Pt). Platinum modification further changes the acid-base properties of the supports, depending on the NbOx loading. The highest Pt dispersion is reached on the NbOx monolayer because of the strong metal-support interaction. Structure and surface properties (acid-base) of the supports and platinum catalysts were characterized in detail by N(2) adsorption, XRD, XPS, UV-vis, FTIR combined with the adsorption of probe molecules (pyridine, CO at room temperature and similar to 100 K, CO(2)), and by test reactions (Acetonylacetone cyclization and 2-propanol dehydration/dehydrogenation). (C) 2009 Elsevier B.V. All rights reserved.
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The effect of the Cs introduction into Pt/NbMCM-41 and Pt/SiMCM-41 on surface properties and NO reduction with hydrocarbons
Studies in Surface Science and Catalysis, 2007Co-Authors: Izabela Sobczak, Maria Ziolek, J. Goscianska, F. Romero Sarria, Marco Daturi, J.m. JablonskiAbstract:The effect of Cs on the size and catalytic behaviour of Pt-species in Pt/Cs/NbMCM-41 and Pt/Cs/SiMCM-41 samples was studied by XRD, N 2 adsorption/desorption, HRTEM measurements and the test reaction (Acetonylacetone cyclization). Operando FTIR spectroscopy has been used to study the mechanism of the NO reduction with propene (NSR-NO x storage reduction) over Pt/Cs-containing MCM-41 materials. The results showed that the presence of Cs limits the growth of the Pt metal particles in both matrices. Nb in the mesoporous matrix protects from the destruction caused by alkaline medium. The activity in DeNO x process is determined by Pt particle sizes and is higher in the case of larger particles. Caesium enhances Pt dispersion and decreases the activity in the HC-SCR reaction. Both Nb and Cs species store nitrate species in DeNOx process, however nitrates located on Cs are more active.