Cobalt oxide particles

These results confirm that cobalt oxides particles (C03O4 and CoOx) have a very important role in the direct oxidation of methane to C02. On the other hand, at high temperature, cationic cobalt (Co2+) appears to be able to reduce NO to N2, even in the presence of an excess of oxygen. 

Jacobs G., Ji Y., Davis B.H., Cronauer D., Kropf J., and Marshall C.L. 2007. Fischer-Tropsch synthesis Temperature programmed EXAFS/XANES investigation of the influence of support type, cobalt loading and noble metal promoter addition to the reduction behaviour of cobalt oxide particles. Appl. Catal. A Gen. 333 179-91. 

Figure 6.31 Schematic of the use of SEA to achieve selective adsorption of anionic Pt onto carbon-supported cobalt oxide particles.

The extent of reduction was close to 100% in both S2 and S4 supported catalysts with the cobalt content varying Irom 5 to 50 wt %. High extent of reduction of S2 and S4 cobalt supported catalysts is likely to be attributed to the presence of relative large cobalt particles (100-200 A). Earlier reports showed that large cobalt oxide particles supported by silica could be easily reduced to metal phases [16]. 

One example is a catalyst consisting of gold on cobalt oxide particles supported on a mechanical mixture of zirconia-stabilised ceria, zirconia and titania, that survived 773 K for 157 h, with some deactivation [145]. Grisel and Nieuwenhuys [38,127] have shown that the addition of transition metal oxides to form Au/MO j/ADOs catalysts, massively suppresses Au particle sintering in methane oxidation tests up to 973 K. Also, Seker and Gulari [30] found that Au/ADOs catalysts survive rigorous pre-treatments of 873 K in air for 24 h, followed by several cycles of 423-773 K and they were then kept... 

Also, Marsh and co-workers [145] showed that gold on cobalt oxide particles, supported on a mechanical mixture of zirconia-stabilised ceria, zirconia and titania remains active in a gas stream containing 15 ppm SO2. Haruta and co-workers [207] found that although the low-temperature CO oxidation activity of Ti02-supported Au can be inhibited by exposure to SO2, the effect on the activity for the oxidation of H2 or propane is quite small. Venezia and co-workers [208] reported that bimetallic Pd-Au catalysts supported on silica/alumina are resistant to sulphur poisoning (up to 113 ppm S in the form of dibenzothiophene) in the simultaneous hydrogenation of toluene and naphthalene at 523 K. 

In these cases, the majority of the Pt metals would be deposited on to the alumina surface rather than on the top of nickel or cobalt oxide particles as mentioned by Oh and Carpenter (26). 

BCreyling WG, Godleski JJ, Kariya ST et al (1990) In-vitro dissolution of uniform cobalt oxide particles by human and canine alveolar macrophages. Am J Respir Cell Mol Biol 2 413 22... 

X-ray diffraction patterns of all catalysts confirm presence of C03O4 [23]. Apart from the peaks indicative of C03O4 and the various supports, the supported catalysts did not show any other peaks. Accordingly, C03O4 is the dominant crystalline cobalt species after calcination. The average cobalt oxide particle sizes are included in Table 3. 

Figure 9. SEM and TEM images of successively larger magnification (left to right) showing cobalt oxide agglomerates as well as individual cobalt oxide particles.

In this work, cobalt oxide particles have been deposited on the surface of the nanotubes, and have been removed after an oxidation process, leading to 4 nm-sized holes. The reversible capacity of the DMWCNT cycled between 0.02 and 3.0 V exceeded 600 mAh g remaining constant over the 20 cycles were the material has been tested. An improvement has been achieved for an interface-controlled MWCNT structure, synthesized through a two-step process of catalyst deposition and chemical vapor deposition (CVD) and directly grown on a copper current collector [127],... 

Slauson et al. (119) have studied deposition, retention, and clearance of inhaled cobalt oxide particles from the lungs of calves with acute inflammatory... 

Bailey MR, Kreyling WG, Andre S, Batchelor A, Black A, Collier CG, Drossel-meyer E, Ferron GA, Foster P, Haider B, Hodgson A, Metivier H, Moores SR, Morgan A, Muller HL, Patrick G, Pearman I, Pickering S, Ramsden D, Stirling C, Talbot RJ. An interspecies comparison of the lung clearance of inhaled monodis-perse cobalt oxide particles—part I objectives and summary of results. J Aerosol Sci 1989 20 169 188. 

Kreyling WG, Perron GA, Haider, B. An interspecies comparison of the lung clearance of inhaled monodisperse cobalt oxide particles—part IV lung clearance of inhaled cobalt oxide particles in beagle dogs. J Aerosol Sci 1989 20 219-232. 

Kreyling WG, Cox C, Ferron GA, Oberdorster G. Lung clearance in Long-Evans rats after inhalation of porous, monodisperse cobalt oxide particles. Exp Lung Res 1993 19 445-467. 

Ltidtke K-U, Forderkunz S, Neuner M,Summer K-H, Kreyling WG. Mechanisms of intracellular dissolution of cobalt oxide particles by canine alveolar macrophages. Eur Respir J 1994 7 70. 

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