Showing papers on "Cobalt sulfide published in 2001"

CoIIIEDTA- reduction by Desulfovibrio vulgaris and propagation of reactions involving dissolved sulfide and polysulfides.

Abstract: The migration of 60Co, dominantly via transport of Co-EDTA complexes, into surface water and groundwater is a recognized concern at many nuclear production and storage sites. Reduction of CoIIIEDTA- to CoIIEDTA2- should decrease the mobility of 60Co in natural environments by stimulating ligand displacement with Fe(III) or Al(III) or by precipitation of CoSx in sulfidic environments. In this study, we examine direct (enzymatic) and indirect (metabolite) reduction processes of CoIIIEDTA- by the sulfate-reducing bacterium Desulfovibrio vulgaris. D. vulgaris reduces CoIIIEDTA- to CoIIEDTA2-, but growth using it as a terminal electron acceptor was not demonstrated. Rather than acting as a competing electron acceptor and limiting cobalt reduction, introducing sulfate with D. vulgaris enhances the reduction of CoIIIEDTA- as a result of sulfide production. Sulfide reduces CoIIIEDTA- in a pathway involving polysulfide formation and leads to a CoS precipitate. Thus, both direct and indirect (i.e., through the production of sulfide) microbial reduction pathways of CoIIIEDTA- may help to retard its migration within soils and waters.

Preparation, characterization and catalysis of intrazeolite molybdenum, cobalt and cobalt-molybdenum sulfide clusters: a molecular approach to hydrodesulfurization catalysts

Abstract: Better understandings of the nature of Co–Mo sulfide catalysts are of great importance to a rational design of highly active hydrodesulfurization catalysts on a molecular level. Synthesis of uniform binary sulfide clusters well-defined in structure and thermally stabilized on a support is desirable for such purposes. In the present study, successful preparations, using metal carbonyls as precursors, of Mo, Co and Co–Mo sulfide clusters encaged in zeolite are reported. The structure, location and catalytic properties of the clusters are described on the basis of XPS, XAFS, XRD, XRF, IR, HREM and adsorptions of benzene and NO. Implications for the generation of catalytic synergy between Co and Mo sulfides are presented in brief. It is suggested that the host–guest interactions between zeolite framework oxygens and precursor molecules and product clusters are crucial to the size and structure of the intrazeolite clusters.

Method for producing lithium cobaltate

Abstract: PROBLEM TO BE SOLVED: To establish a method for producing inexpensive lithium cobaltate by improving both quick chargeability and discharging performance at low temperatures simultaneously while reducing the expensive production cost, a defect of conventional lithium cobaltate (LiCoO2 ). SOLUTION: This method for producing lithium cobaltate is characterized by making mine-originating cobalt oxyhydroxide (CoOOH) derived from cobalt sulfide into a desired particle size, e.g. 0.6 to 8.5 micrometer range of median particles, mixing the cobalt oxyhydroxide with at least one lithium compound selected from lithium carbonate, lithium hydroxide, lithium acetate and lithium citrate, and firing in the range of 1.005 to 1.02 Li/Co mol ratio.

Titanium-Promoted Cobalt Sulfide Catalysts for NO Decomposition and Reduction by CO

Abstract: Cobalt sulfide and titanium-promoted cobalt sulfides were reported as catalysts for NO decomposition and reduction by CO. Titanium-promoted cobalt sulfides showed not only nearly complete NO removal but the simultaneous catalytic reduction of NO and SO2 by CO to N2 and elemental sulfur, respectively.