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Guesmi H.,National Graduate School of Chemistry, Montpellier | Grybos R.,Jerzy Haber Institute of Catalysis and Surface Chemistry | Handzlik J.,Cracow University of Technology | Tielens F.,CNRS Laboratory of Condensed Matter Chemistry, Paris
RSC Advances | Year: 2016

A DFT based characterization of tungsten oxide supported on amorphous hydroxylated silica is presented. The different molecular organizations are investigated on the surface topology and tungsten oxygen coordination. The presence of mono- and di-grafted species is discussed and rationalized, using an atomistic thermodynamic approach. The presence of W O groups are preferred over W-OH groups and the grafting coordination is dominated by the degree of hydration of the silica surface. At room temperature di-oxo digrafted and mono-oxo-tetragrafted species are in competition regulated by the ambient degree of hydration which also affects the silanol density of the silica support. A comparison between tungsten and the other group VI elements confirms a greater chemical difference with Cr than with Mo. © The Royal Society of Chemistry 2016. Source

Majda D.,Jagiellonian University | Zimowska M.,Jerzy Haber Institute of Catalysis and Surface Chemistry | Tarach K.,Jagiellonian University | Gora-Marek K.,Jagiellonian University | And 2 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2016

Water thermoporosimetry (TPM) is a powerful method for studying the properties of porous materials, devoted especially for investigation of the samples that can be destroyed in drying process. However, this method is not very popular and relatively rarely used because of problems with proper measurement procedure and choosing correct equation for the result interpretation. This report focused on refinement of general experimental protocols for water TPM. For the first time, the role of various parameters on the TPM outcomes was deeply investigated and simple and fast experimental mode was proposed. Additionally, based on the series of mesoporous silica SBA-15, the calibration procedure was employed and the reliable calibration equations were established. © 2016 The Author(s) Source

IBM, Conpart AS, Intrinsiq Materials and Jerzy Haber Institute Of Catalysis And Surface Chemistry | Date: 2015-10-12

A bridging arrangement includes a first and a second surface defining a gap therebetween. At least one surface of the first and second surface has an anisotropic energy landscape. A plurality of particles defines a path between the first and second surface bridging the gap.

Kolodziej M.,Jerzy Haber Institute of Catalysis and Surface Chemistry | Drelinkiewicz A.,Jerzy Haber Institute of Catalysis and Surface Chemistry | Lalik E.,Jerzy Haber Institute of Catalysis and Surface Chemistry | Gurgul J.,Jerzy Haber Institute of Catalysis and Surface Chemistry | And 2 more authors.
Applied Catalysis A: General | Year: 2016

Liquid phase hydrogenation of cinnamaldehyde (CAL) is studied at mild conditions (50 °C, atmospheric pressure) on molybdena-supported Pd catalysts (0.5-4 wt% Pd) to elucidate an effect of hydrogen bronzes in controlling the selectivity to C=C/C=O hydrogenation. The Pd/SiO2 catalyst is used as a reference, because SiO2 is known to be an "inert" support. Additional information on the interaction of Pd/MoO3 catalysts with hydrogen is provided by the microcalorimetric measurements. The impregnation of MoO3 with palladium acetate followed by hydrogen reduction (250 °C) produces Pd/MoO3 catalysts containing Pd particles ca. 8-10 nm, regardless of the metal loading. The XRD, XPS, SEM, TEM, and HRTEM techniques have been employed to characterize the catalysts. The metal particles are nearly monodispersed and well distributed at low Pd-loading, 0.5%Pd/MoO3. As the content of Pd increases the agglomeration of Pd particles occurs. All the Pd/MoO3 catalysts display higher selectivity to C=O hydrogenation compared to Pd/SiO2. The content of Pd has an impact on activity and selectivity. The activity normalized to the Pd mass decreases with growing Pd-loading in Pd/MoO3. The C=C group of CAL was preferentially hydrogenated compared to the carbonyl (C=O) group at low (0.5%Pd) and high (4%Pd) Pd content pointing out to an effect of optimum Pd-loading in the selectivity of CAL hydrogenation. The activity/selectivity behavior of Pd/MoO3 catalysts is related to an effect of hydrogen bronzes existing during the catalytic tests. They could provide additional active sites efficient for the activation of CAL resulting in promotion of C=C hydrogenation. Hydrogen species in the bronzes could also have a beneficial effect on palladium crystallites formation upon reduction of palladium ions. High mobility of hydrogen species in the bronzes structure assisted by easy migration of palladium ions facilitated by MoO3 layered morphology and structural changes during the reduction could promote the Pd crystallites of tetrahedral shape. © 2016 Elsevier B.V. All rights reserved. Source

Tokarz-Sobieraj R.,Jerzy Haber Institute of Catalysis and Surface Chemistry | Grybos R.,Jerzy Haber Institute of Catalysis and Surface Chemistry | Filek U.,Jerzy Haber Institute of Catalysis and Surface Chemistry | Micek-Ilnicka A.,Jerzy Haber Institute of Catalysis and Surface Chemistry | And 3 more authors.
Catalysis Today | Year: 2015

The catalytic properties, both redox and acidic, of 12-tungsto- and 12-molybdo-phosphoric Al3+, Ga3+, In3+ salts were studied. As a model reaction the gas phase ethanol conversion was used. On different sites (redox and acidic) various products are obtained (acetaldehyde and diethyl ether/ethylene respectively). Catalytic activity of MePW and MePMo salts was theoretically predicted, using both periodic and cluster models. Performed experiments confirm the theoretical prediction concerning the influence of addenda atoms (W and Mo) and various counter-cations (Al3+, Ga3+, In3+) on the catalytic properties of studied systems. © 2015 Elsevier B.V. All rights reserved. Source

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