scholarly journals A unified view on heterogeneous and homogeneous catalysts through a combination of spectroscopy and quantum chemistry

2016 ◽  
Vol 188 ◽  
pp. 181-197 ◽  
Author(s):  
Dimitrios Maganas ◽  
Annette Trunschke ◽  
Robert Schlögl ◽  
Frank Neese
Keyword(s):  
Heterogeneous Catalysis ◽  
Quantum Chemistry ◽  
Resonance Raman Spectroscopy ◽  
Electronic Spectroscopy ◽  
Open Shell ◽  
Active Species ◽  
Spectroscopic Techniques ◽  
Formidable Challenge ◽  
Catalytically Active ◽  
Unified View

Identifying catalytically active structures or intermediates in homogeneous and heterogeneous catalysis is a formidable challenge. However, obtaining experimentally verified insight into the active species in heterogeneous catalysis is a tremendously challenging problem. Many highly advanced spectroscopic and microscopic methods have been developed to probe surfaces. In this discussion we employ a combination of spectroscopic methods to study two closely related systems from the heterogeneous (the silica-supported vanadium oxide VOx/SBA-15) and homogeneous (the complex K[VO(O2)Hheida]) domains. Spectroscopic measurements were conducted strictly in parallel for both systems and consisted of oxygen K-edge and vanadium L-edge X-ray absorption measurements in conjunction with resonance Raman spectroscopy. It is shown that the full information content of the spectra can be developed through advanced quantum chemical calculations that directly address the sought after structure–spectra relationships. To this end we employ the recently developed restricted open shell configuration interaction theory together with the time-dependent theory of electronic spectroscopy to calculate XAS and rR spectra respectively. The results of the study demonstrate that: (a) a combination of several spectroscopic techniques is of paramount importance in identifying signature structural motifs and (b) quantum chemistry is an extremely powerful guide in cross connecting theory and experiment as well as the homogeneous and heterogeneous catalysis fields. It is emphasized that the calculation of spectroscopic observables provides an excellent way for the critical experimental validation of theoretical results.

Single molecule study of samarium oxide nanoparticles as a purely heterogeneous catalyst for one-pot aldehyde chemistry

2016 ◽  
Vol 6 (19) ◽  
pp. 7113-7121 ◽  
Author(s):  
Gregory K. Hodgson ◽  
Stefania Impellizzeri ◽  
Juan C. Scaiano
Keyword(s):  
Heterogeneous Catalysis ◽  
Homogeneous Catalysis ◽  
Single Molecule ◽  
Metal Ion ◽  
Active Species ◽  
Oxide Nanoparticles ◽  
Samarium Oxide ◽  
One Pot ◽  
Catalytically Active

Heterogeneous catalysis holds distinct advantages over homogeneous catalysis; however, it is only truly advantageous if unaffected by metal ion leaching or in situ formation of a soluble catalytically active species.

Metallic palladium, PdO, and palladium supported on metal oxides for the Suzuki–Miyaura cross-coupling reaction: a unified view of the process of formation of the catalytically active species in solution

2017 ◽  
Vol 7 (18) ◽  
pp. 3934-3951 ◽  
Author(s):  
Alessandro Del Zotto ◽  
Daniele Zuccaccia
Keyword(s):  
Metal Oxide ◽  
Metal Oxides ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Active Species ◽  
Cross Coupling Reaction ◽  
Metallic Palladium ◽  
Catalytically Active ◽  
Unified View ◽  
Supported Pd

The nature of the true catalytic species in the Suzuki–Miyaura coupling starting from metallic palladium, PdO, and metal oxide-supported Pd is critically reviewed.

Sewage sludge as a precursor of adsorbents/catalysts for environmental applications

2007 ◽  
Vol 2 (1) ◽  
Author(s):  
A. Ros ◽  
C. Canals-Batlle ◽  
M.A. Lillo-Ródenas ◽  
E. Fuente ◽  
M. A. Montes-Morán ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Room Temperature ◽  
Waste Water Treatment ◽  
Textural Properties ◽  
Active Species ◽  
Elemental Sulphur ◽  
Gaseous Emissions ◽  
Removal Experiments ◽  
Catalytically Active

This paper focuses on the valorisation of solid residues obtained from the thermal treatment of sewage sludge. In particular, sewage sludge samples were collected from two waste water treatment plants (WWTPs) with different sludge line basic operations. After drying, sludges were heated up to 700 °C in appropriate ovens under diluted air (gasification) and inert (pyrolysis) atmospheres. The solids obtained, as well as the dried (raw) sludges, were characterised to determine their textural properties and chemical composition, including the speciation of their inorganic fraction. All the materials under study were employed as adsorbents/catalysts in H2S removal experiments at room temperature. It was found that, depending on the particular sludge characteristics, outstanding results can be achieved both in terms of retention capacities and selectivity. Some of the solids outperform commercially available sorbents specially designed for gaseous emissions control. In these adsorbents/catalysts, H2S is selectively oxidised to elemental sulphur most likely due to the presence of inorganic, catalytically active species. The role of the carbon-enriched part on these solids is also remarked.

Probing the Catalytically Active Species in POM‐catalysed DNA‐model Hydrolysis

2021 ◽  
Author(s):  
Frederico F Martins ◽  
Ángel Sánchez-González ◽  
Jose Lanuza ◽  
Haralampos N. Miras ◽  
Xabier Lopez ◽  
...  
Keyword(s):  
Active Species ◽  
Catalytically Active

scholarly journals Shedding light on the nature of the catalytically active species in photocatalytic reactions using Bi2O3 semiconductor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Paola Riente ◽  
Mauro Fianchini ◽  
Patricia Llanes ◽  
Miquel A. Pericàs ◽  
Timothy Noël
Keyword(s):  
Experimental Studies ◽  
Heterogeneous Photocatalysis ◽  
Active Species ◽  
Organic Transformations ◽  
Alkyl Bromides ◽  
Catalytically Active ◽  
Visible Light Driven ◽  
Photocatalytic Reactions ◽  
Insight Into ◽  
Photocatalytic Processes

AbstractThe importance of discovering the true catalytically active species involved in photocatalytic systems allows for a better and more general understanding of photocatalytic processes, which eventually may help to improve their efficiency. Bi2O3 has been used as a heterogeneous photocatalyst and is able to catalyze several synthetically important visible-light-driven organic transformations. However, insight into the operative catalyst involved in the photocatalytic process is hitherto missing. Herein, we show through a combination of theoretical and experimental studies that the perceived heterogeneous photocatalysis with Bi2O3 in the presence of alkyl bromides involves a homogeneous BinBrm species, which is the true photocatalyst operative in the reaction. Hence, Bi2O3 can be regarded as a precatalyst which is slowly converted in an active homogeneous photocatalyst. This work can also be of importance to mechanistic studies involving other semiconductor-based photocatalytic processes.

In Search of Catalytically Active Species in the Surfactant-Mediated Biphasic Alkene Epoxidation with Mimoun-Type Complexes

2001 ◽  
Vol 3 (3) ◽  
pp. 329-332 ◽  
Author(s):  
Dirk V. Deubel ◽  
Jörg Sundermeyer ◽  
Gernot Frenking
Keyword(s):  
Active Species ◽  
Catalytically Active

scholarly journals Surprisingly high sensitivity of copper nanoparticles toward coordinating ligands: consequences for the hydride reduction of benzaldehyde

2018 ◽  
Vol 8 (19) ◽  
pp. 5073-5080 ◽  
Author(s):  
Xavier Frogneux ◽  
Ferenc Borondics ◽  
Stéphane Lefrançois ◽  
Florian D'Accriscio ◽  
Clément Sanchez ◽  
...  
Keyword(s):  
Copper Nanoparticles ◽  
High Sensitivity ◽  
Active Species ◽  
Hydride Reduction ◽  
Catalytically Active

Depending on the ligand, ligand-induced leaching of copper nanoparticles may produce catalytically active species for the reduction of benzaldehyde.

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