A5039229575- Catalysis and Oxidation Reactions
- Catalytic Processes in Materials Science
- Catalysis and Hydrodesulfurization Studies
- Electrocatalysts for Energy Conversion
- Zeolite Catalysis and Synthesis
- Asymmetric Hydrogenation and Catalysis
- Metal-Organic Frameworks: Synthesis and Applications
- Nanomaterials for catalytic reactions
- Polyoxometalates: Synthesis and Applications
- Advanced Chemical Physics Studies
- Catalysts for Methane Reforming
- Catalysis for Biomass Conversion
- Carbon dioxide utilization in catalysis
- Surface Chemistry and Catalysis
- Covalent Organic Framework Applications
- Oxidative Organic Chemistry Reactions
- CO2 Reduction Techniques and Catalysts
- Ionic liquids properties and applications
- Mesoporous Materials and Catalysis
- Machine Learning in Materials Science
- Chemical Synthesis and Reactions
- Chemical Reaction Mechanisms
- Advanced Data Processing Techniques
- Supercapacitor Materials and Fabrication
- Chemistry and Chemical Engineering
University of Toronto
2016-2025
University of California, Berkeley
2011-2016
University of Oklahoma
1998
This study describes an instantaneously gas-induced dynamic transition of industrial Cu/ZnO/Al2O3 catalyst. Cu/ZnO clusters become "alive" and lead to a promotion in reaction rate by almost one magnitude, response the variation reactant components. The promotional changes are functions either CO2-to-CO or H2O-to-H2 ratio which determines oxygen chemical potential thus drives undergo reconstruction allows maximum formation Cu-Zn2+ sites for CH3OH synthesis.
Methane oxidation rates uncorrupted by nonchemical effects of transport, taken together with stoichiometric oxygen uptake (oxidation cycle) and evolution (decomposition data, are used to establish for the first time a set conditions required true thermodynamic equilibrium during metal-to-oxide interconversions in small Pd clusters (1.8–8.8 nm). These allow us assess intrinsic thermodynamics their catalytic CH4 oxidation. PdO decomposition absence deviates from equilibrium, as this step is...
Ethane turnovers to ethylene in either oxidehydrogenation with diverse oxidants (O2, CO2, H2O) or dehydrogenation (without an oxidant) over two-dimensional MoOx dispersed on Al2O3 catalyst occur via a generalized mechanistic framework encompassing ternary catalytic cycles of C2H6 activation, oxidant and carbon removal. This is confirmed from rate assessments, detailed kinetic analysis accounting for active site loss, isotopic tracer studies, spectroscopic characterization. Irrespective the...
A 3D linear scaling relation─connecting elementary 2-butanol C–O bond activation enthalpy, pyridine adsorption and the affinity of metal–oxygen site pairs to hydroxyls as reflected in interaction enthalpy difference─is established here with combined kinetic chemical titration techniques, allowing for accurate quantitative assessments Lewis acid strength even at low densities structurally complex metal oxides nitrides. This construction is a kinetic-thermodynamic free energy relation─using...
Kinetic and isotopic data effects of cluster size are used to probe elementary steps their kinetic relevance in CH4–O2 reactions on Pd clusters that retain a metallic bulk during catalysis. CO2 H2O were the only products detected, except when O2 was nearly depleted, which trace CO amounts formed. 13CH4–12CO–O2 showed reacts with chemisorbed oxygen (O*) much faster than CH4 reactive collision probability ratios for proportional O2/CO via constant exceeding 500. Thus, even if desorbed before...
We study 14 atomically dispersed transition metals on halite-type oxides (MeO, Me = Fe, Mg, Mn, and Ni) using periodic density functional theory calculations probe structure activity toward CO oxidation for a subset of these systems experimentally. Pd Pt can form stable negatively charged species upon binding to oxygen vacancies; the magnitude metal atom energy depends O vacancy formation energies supporting oxide lattice match between support. The resulting oxide-supported single-atom...
Kinetic measurements, competitive hydrogenation, and H–D kinetic isotopic studies confirm the prevalence of proton–electron transfer events during catalytic reduction aliphatic carbonyls (C3–C6) at protic solvent transition-metal (Ru, Pt, Pd) interfaces. Polar solvents assist with initial, rapid H-adatom ionization, which forms a proton an electron pair. The shuffles through matrix attacks carbonyl oxygen in quasi-equilibrated step, resulting formation charged hydroxy intermediate as most...
This study unravels the diverse sizes and chemical compositions of various nanostructures, from single atoms to monometallic clusters bimetallic particles in realistic, supported Pt–Pd catalysts. Aberration-corrected scanning transmission electron microscopy, CO infrared spectroscopy, oxygen uptake-titration studies probe structural dynamics these nanocreatures response changing gas-phase potentials, whereas rate assessments kinetically controlled regime under differential fuel-lean...
Abstract The connection of active site structures and their catalytic chemistry during butanal deoxygenation on polyoxometalate clusters with varying H + densities identity central atoms [H x Na 4− SiW 12 O 40 ( =0–4) y 3− PW =0–3)] was established rate assessment, IR spectroscopic, chemical titration methods. Butanal adsorbs the or ions forms RC=O⋅⋅⋅H RC=O⋅⋅⋅Na complexes at 348 K. A portion adsorbed butanals sites converts to surface acetates through reactions vicinal framework oxygen...
The mechanistic roles of free hydronium ions, surface hydrides, and interfacial protons during guaiacol hydrodeoxygenation (HDO) on ruthenium nanoparticles have been established. As adsorbs Ru, it loses its strong aromaticity undergoes a rapid H-shift from hydroxyl to meta carbons (in relation group), causing adsorbed enol keto isomers exist in chemical equilibrium. HDO occurs via hydridic H-adatom (H*) attack the enol, followed by kinetically relevant C–O bond rupture step, which water...
Kinetic, isotopic, and spectroscopic studies establish the active site requirements for three kinetically coupled catalytic cycles catalyzed by redox, Brønsted, Lewis acid–base sites, which occur during methanol oxygen reactions on titania-supported vanadium oxide catalysts. The initial activation of its oxidative dehydrogenation to formaldehyde restricts overall turnovers─this reaction proceeds via CH3OH dissociative adsorption followed a relevant C–H bond scission CH3O intermediate V–O...
Metal oxides have structurally complex surfaces on which a variety of adsorption site types can occur, including cation sites, anion oxygen vacancy and Brønsted acid sites. These sites catalyze the catalytic transformation organic molecules via diverse routes, thus enabling H abstraction, O C–C bond formation, other reactions. This Perspective provides an update recent advances future directions for various reactions metal oxide catalyst surfaces, particularly C–H activation alkanes...
This study unravels the catalytic effects of adjacent protons in redox catalysis bifunctional Keggin-type phosphomolybdic acid clusters (H3PMo12O40). Isolated sites (O*) and Brønsted acid-redox site pairs (OH/O*) catalyze methanol oxidative dehydrogenation (ODH), a reaction, via identical elementary steps formation kinetically relevant [HOCH2···H···O*]‡ [OH···HOCH2···H···O*]‡ transition states, but with different kinetic requirements, established from selective inactivation, product...
Kinetic assessments of cyclohexene and pyridine hydrogenation on metallic Pd Pt surfaces covered with chemisorbed sulfur species (H2S*, HS*, S*) at controlled chemical potentials probe quantitatively two distinct types their catalytic involvements in H-addition events. Irreversible (Sir,T*) are not chemically equilibrated H2S(g) remain surfaces, even after the complete removal. Reversible (Sr,T*) those dynamic equilibrium desorb completely upon Structure-insensitive shows higher Sir,T*...
This study reports the discovery of CoMoOx moieties with synergistic catalytic roles in C2H6–CO2 catalysis. catalysis occurs through multiple, concomitant cycles, initiated by dual cycles C2H6 activation and CO2 activation, together an undesired coke deposition cycle. requires reactive oxygen species that assist kinetically relevant C–H bond activation; these are generated from cycle within reverse water-gas shift (RWGS) reaction. An efficient RWGS reaction would retain higher O contents...