Spectroscopic characterization of hydrotreating catalysts containing cobalt, nickel, and molybdenum
The interactions of Co, Ni, and Mo with a ..gamma..-Al/sub 2/O/sub 3/ support were studied as a function of metal loading, calcination temperature, and order of impregnation by employing electron spectroscopy for chemical analysis (ESCA), ion scattering spectroscopy (ISS), Raman spectroscopy (LRS), diffuse reflectance spectroscopy (DRS), and x-ray diffraction (XRD). Information concerning the speciation and dispersion of the supported metals was obtained by studying the catalysts in their oxidic, reduced, and sulfided states. A method employing Raman spectroscopy is presented for quantitation of crystalline phases commonly found in commercial hydrodesulfurization catalysts. The method is based on the use of an internal standard and is accurate to within +/-6% (relative) for MoO/sub 3/ and WO/sub 3/ concentrations greater than 0.1%. A comparative study of the speciation and dispersion of Ni/Al/sub 2/O/sub 3/ and Co/Al/sub 2/O/sub 3/ catalysts has shown that Ni is better dispersed on the alumina support than Co above a metal loading of 3%. Addition of Mo to Ni/Al/sub 2/O/sub 3/ and Co/Al/sub 2/O/sub 3/ catalysts does little to alter the dispersion of the promoter phases. Significant changes in Ni and Co speciation on Mo addition include evidence for formation of a Ni (or Co)-Mo interaction species and a decrease in the amount of the aluminate-like phases. A study of the speciation and dispersion of Ni-Mo/Al/sub 2/O/sub 3/ catalysts has shown that the interaction between Ni and the support, and to a lesser extent between Mo and the support, is influenced by Ni loading, Mo loading, and the order of impregnation.
- Research Organization:
- Pittsburgh Univ., PA (USA)
- OSTI ID:
- 6932555
- Country of Publication:
- United States
- Language:
- English
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ALUMINIUM OXIDES
CARBONACEOUS MATERIALS
CATALYSIS
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
COAL
COBALT
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ELEMENTS
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HYDROGEN
MATERIALS
METALS
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NONMETALS
OXIDES
OXYGEN COMPOUNDS
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TRANSITION ELEMENTS