Sökning: "Heterogeneous Catalysis"

Visar resultat 41 - 45 av 118 avhandlingar innehållade orden Heterogeneous Catalysis.

1. 41. Chemistry and Physics of Cu and H2O on ZnO Surfaces : Electron Transfer, Surface Triangles, and Theory

   Författare :Matti Hellström; Kersti Hermansson; Peter Broqvist; Daniel Spångbeg; Jörg Behler; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; catalysis; density functional theory; SCC-DFTB; band-filling correction;

   Sammanfattning : This thesis discusses the chemistry and physics of Cu and H2O on ZnO surfaces, based primarily on results from quantum chemical calculations. The underlying context is heterogeneous catalysis, where Cu/ZnO-mixtures are used in the industrial synthesis of methanol and in the water gas shift reaction. LÄS MER

3. 42. Controlling the Reactivity and Selectivity in Iridium- and Rhodium-Catalyzed Asymmetric Hydrogenation

   Författare :Haibo Wu; Pher Andersson; Virginie Ratovelomanana-Vidal; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Asymmetric hydrogenation; Cascade reaction; Kinetic resolution; Desymmetrization; Dearomatization; Total synthesis; Heterogeneous catalysis; organisk kemi; Organic Chemistry;

   Sammanfattning : The work presented in this thesis is mainly focused on the development of iridium- or rhodium-catalyzed asymmetric hydrogenation featuring a number of practical concepts including cascade reaction, kinetic resolution, desymmetrization, and dearomatization. The protocols rely on gaining control of the reactivity among different olefins or olefin precursor as well as maintaining chemo- and stereo-selectivity in the hydrogenation. LÄS MER

4. 43. Oxidation and Reconstructions of Alloy Model Catalysts : Platinum-Rhodium and Palladium-Gold

   Författare :Helen Edström; Synkrotronljusfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Alloying; APXPS; Bimetallic Catalysts; Heterogeneous Catalysis; HESXRD; Oxidation; Oxide Formation; Palladium-Gold; Platinum-Rhodium; Surface Reconstruction; Fysicumarkivet A:2023 Edström;

   Sammanfattning : Alloys and bimetallic systems have shown many advantages in heterogeneous catalysis, but the details of their catalytic functions are not always known. For instance, the atomic details about surface reconstructions under catalytic reaction conditions, or which phases that are high-active or low-active. LÄS MER

5. 44. Palladium-catalyzed lignin valorization : Towards a lignin-based biorefinery

   Författare :Maxim Galkin; Joseph Samec; Rafael Luque; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; Lignin; Heterogeneous Catalysis; Palladium; Biomass; Depolymerization; Reduction; Oxidation; Biorefinery; Transfer Hydrogenolysis; Organic Chemistry; Organisk kemi;

   Sammanfattning : The work described in this thesis focuses on the cleavage of the β-O-4′ bond, which is the most abundant interunit linkage in the lignin polymer.In the first part, three methods based on palladium catalysis have been developed and their applicability has been verified using lignin model compounds. LÄS MER

7. 45. Operando X-ray Absorption Spectroscopy Studies of Methane Oxidation Catalysts

   Författare :Johan Nilsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; operando spectroscopy; XAS; palladium; heterogeneous catalysis; methane oxidation; XAFS;

   Sammanfattning : Operando spectroscopy is an experimental method in catalysis that combines measurements of catalytic activity and selectivity with simultaneous in situ spectroscopic characterization of the catalyst. Since the structure and composition of the catalyst are probed under reaction conditions, the method can provide valuable information to elucidate the mechanism of the studied reaction. LÄS MER