Reverse micelle synthesis of nanoscale metal containing catalysts. [Nickel metal (with a nickel oxide surface layer) and iron oxyhydroxide nanoscale powders]

Conference · Mon Mar 01 04:00:00 EST 1993

OSTI ID:6567932

Darab, J G; Fulton, J L; Linehan, J C

The need for morphological control during the synthesis of catalyst precursor powders is generally accepted to be important. In the liquefaction of coal, for example, iron-bearing catalyst precursor particles containing individual crystallites with diameters in the 1-100 nanometer range are believed to achieve good dispersion through out the coal-solvent slurry during liquefaction 2 runs and to undergo chemical transformations to catalytically active iron sulfide phases. The production of the nanoscale powders described here employs the confining spherical microdomains comprising the aqueous phase of a modified reverse micelle (MRM) microemulsion system as nanoscale reaction vessels in which polymerization, electrochemical reduction and precipitation of solvated salts can occur. The goal is to take advantage of the confining nature of micelles to kinetically hinder transformation processes which readily occur in bulk aqueous solution in order to control the morphology and phase of the resulting powder. We have prepared a variety of metal, alloy, and metal- and mixed metal-oxide nanoscale powders from appropriate MRM systems. Examples of nanoscale powders produced include Co, Mo-Co, Ni[sub 3]Fe, Ni, and various oxides and oxyhydroxides of iron. Here, we discuss the preparation and characterization of nickel metal (with a nickel oxide surface layer) and iron oxyhydroxide MRM nanoscale powders. We have used extended x-ray absorption fine structure (EXAFS) spectroscopy to study the chemical polymerization process in situ, x-ray diffraction (XRD), scanning and transmission electron microcroscopies (SEM and TEM), elemental analysis and structural modelling to characterize the nanoscale powders produced. The catalytic activity of these powders is currently being studied.

• Research Organization: Pacific Northwest Lab., Richland, WA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 6567932
• Report Number(s): PNL-SA-21663; CONF-930304--19; ON: DE93012869
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CATALYSTS
CHALCOGENIDES
COHERENT SCATTERING
COLLOIDS
DIFFRACTION
DISPERSIONS
ELECTRON MICROSCOPY
ELEMENTS
EMULSIONS
GOETHITE
IRON COMPOUNDS
IRON OXIDES
METALS
MICROEMULSIONS
MICROSCOPY
MINERALS
NICKEL
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
POWDERS
SCANNING ELECTRON MICROSCOPY
SCATTERING
STRUCTURAL CHEMICAL ANALYSIS
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION