http://ntur.lib.ntu.edu.tw/bitstream/246246/172223/1/23.pdf

Characterization of cobalt oxides studied by FT-IR, Raman, TPR and TG-MS

Photoemission studies of adsorbed oxygen and oxide layers

X-ray photoelectron spectroscopy of Co3O4, Fe3O4, Mn3O4, and related compounds

A combined X-Ray photoelectron and Mössbauer emission spectroscopy study of the state of cobalt in sulfided, supported, and unsupported CoMo catalysts

Silica supported cobalt catalysts have been prepared by a new method combining the precipitation of the metal precursor (cobalt nitrate) by oxalic acid with the hydrolysis and condensation of the silicium precursor (tetraethoxysilane). Depending on the pH during preparation, the textural properties (BET specific surface area, porosity) of the Co/SiO 2 catalysts can be modified. In an acid medium (pathway A), the resulting silica is constituted by a polymeric net with few branchings, the catalysts are microporous. In basic medium (pathway B) silica is composed of more branched polymers leading to mesoporous catalytic systems. After calcination, the only crystallized phase detected by XRD is the Co 3 O 4 spinel. At 773 K, the surface degrees of reduction of the catalysts at cobalt isocontent (25 wt.% Co) as determined by XPS is of 81% and 69% for systems prepared by pathways A and B, respectively. The presence of small unreduced Co II suggests the existence of non-crystallized cobalt silicate formed during the reduction by reaction of CoO with silica. The activity for the CO + H 2 reaction for the 25 wt.% catalysts prepared by pathway A increased with the specific surface area which can be controlled by the preparation parameters. The reduction degree has a direct influence on the selectivity for the Co/SiO 2 catalysts. The presence of a part of unreduced cobalt (in interaction with the support) results in a better selectivity to the C 5 –C 13 fraction (gasoline), whereas a higher reduction degree of cobalt favors the production of higher molecular weight hydrocarbons (waxes) (C 22 + selectivity > 40%).

Preparation and characterization of Fischer-Tropsch active Co/SiO2 catalysts

XPS techniques were used to clarify the state of supported cobalt catalysts. In order to characterize Co2+ and Co3+, the spin-orbit splitting of the 2p level, which is considered to be affected by the exchange interaction between the unpaired 3d electrons and 2p electrons, was found to be very useful. The interaction between catalyst and support was investigated. The state of supported cobalt was determined: Co2O3 on SiO2, Co2O3+ CoAl2O4 on γ-Al2O3, and LaCoO3 on La2O3. The order of the strength of the chemical interaction between cobalt and support is as follows: La_2O_3>γ-Al_2O_3>SiO_2. This fact was also confirmed by reduction experiments.

X-Ray Photoelectron Spectroscopic Studies of Catalysts — Supported Cobalt Catalysts —

In the catalytic NO–CO reaction over metal oxide catalysts, the surface states of reduced metal oxides were studied with ESCA, and the correlation of the activities of the reduced metal oxide catalysts for the NO–CO reaction with their surface states was investigated. The surfaces of the catalysts were studied with ESCA after treatments in situ. It was revealed that the surface states of the metal oxides did not always agree with their bulk constituents. For example, it was found that the oxygen in the surface layer of the cobalt oxide after a proper reduction treatment by CO was richer than in its bulk. Moreover, the correlation between the surface states and the activities of those oxides was successfully explained. It was also concluded that, in the NO–CO reaction, the metal states were most active for the cobalt, iron, and nickel oxides, while the Cu+ state was more active than the Gu metal state for the copper oxide.

The Catalytic Reduction of Nitrogen Oxide by Carbon Monoxide over Metal Oxide Catalysts —The Correlation of the Activities with the Surface States of Metal Oxides—

Substrate dependent ligand acceleration in enantioselective hydrogenation of (E)-2,3-diarylpropenoic acid on cinchonidine-modified Pd/C

Chiral (R,R)-tartaric acid and NaBr-doubly modified Raney nickel (TA-MRNi) is a promising heterogeneous catalyst for enantioselective hydrogenation of prochiral β-keto esters. To obtain deeper insi...

Enantioselective Hydrogenation of Ketones over a Tartaric Acid-Modified Raney Nickel Catalyst: Substrate-Modifier Interaction Strength and Enantioselectivity

In the enantioselecitve hydrogenation of (E)-2-methyl-2-butenoic acid (1) over a cinchonidine-modified Pd/C catalyst, the addition of hydrogen preferentially proceeds from the Re-Si enantioface of ...

Hydrogen/Deuterium Isotopic Labeling Study of Enantioselective Hydrogenation of (E)-2-Methyl-2-butenoic Acid over a Cinchonidine-Modified Pd/C Catalyst

Yasuaki Okamoto

Papers

X-Ray Photoelectron Spectroscopic Studies of Catalysts — Supported Cobalt Catalysts —

The Catalytic Reduction of Nitrogen Oxide by Carbon Monoxide over Metal Oxide Catalysts —The Correlation of the Activities with the Surface States of Metal Oxides—

Substrate dependent ligand acceleration in enantioselective hydrogenation of (E)-2,3-diarylpropenoic acid on cinchonidine-modified Pd/C

Enantioselective Hydrogenation of Ketones over a Tartaric Acid-Modified Raney Nickel Catalyst: Substrate-Modifier Interaction Strength and Enantioselectivity

Hydrogen/Deuterium Isotopic Labeling Study of Enantioselective Hydrogenation of (E)-2-Methyl-2-butenoic Acid over a Cinchonidine-Modified Pd/C Catalyst