Preparational factors and characterization of Ni-Mo/Al sub 2 O sub 3 hydrotreating catalysts
The purpose of this work is to (1) provide a better fundamental understanding of the relationships between preparation and structure of Ni-Mo/Al{sub 2}O{sub 3} catalysts and process performance, (2) develop simple characterization tests useful in quality control and in screening potential exploratory catalysts, and (3) establish improved design principles. Commercial production routes were used to produce a catalysts series with systematic variations in both MoO{sub 3} (10-20 wt.%) and NiO (0-7 wt.%) contents and calcination temperature (300-600 C). Catalysts characterization was accomplished through combined magnetic susceptibility, acid extraction, nitric oxide chemisorption, infrared spectroscopy, and thiophene HDS kinetic measurements. Several oxidic Ni phases were identified: bulk NiO, surface or subsurface NiAl{sub 2}O{sub 4}, and octahedral and tetrahedral Ni associated with Mo. Tetrahedral Ni was found to promote both HDS and hydrogenation activities of two types of sites. A sulfided catalyst structural model describing all identified Ni and Mo species and structures was proposed. Tetrahedral Ni occupies edge substitutional positions for Mo on the periphery of NoS{sub 2}-like domains, anchored via oxide bonds to the alumina support. Improved hydrotreating catalysts are believed possible through incorporation of phosphorus pentaoxide, P{sub 2}O{sub 5}, during catalyst preparation. The large phosphate anions force restricted growth of Mo domains, creating small, multilayered Mo structures containing more edge sites for tetrahedral Ni occupation. Magnetic susceptibility, which directly measures tetrahedral Ni content, is recommended as a useful characterization for screening catalysts.
- Research Organization:
- Houston Univ., TX (USA)
- OSTI ID:
- 7025779
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CATALYSTS
CHEMICAL PREPARATION
MOLYBDENUM OXIDES
SURFACE PROPERTIES
NICKEL OXIDES
ALUMINIUM OXIDES
CALCINATION
CATALYSIS
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHEMISORPTION
CORRELATIONS
CRYSTAL STRUCTURE
DESULFURIZATION
HYDROGENATION
INFRARED SPECTRA
MAGNETIC SUSCEPTIBILITY
MEASURING METHODS
MICROSTRUCTURE
NITRIC OXIDE
PHOSPHORUS OXIDES
PROMOTERS
QUALITY CONTROL
RECOMMENDATIONS
REFINING
REGENERATION
SOLVENT EXTRACTION
SPECTROSCOPY
THIOPHENE
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
CONTROL
DECOMPOSITION
EXTRACTION
HETEROCYCLIC COMPOUNDS
MAGNETIC PROPERTIES
MOLYBDENUM COMPOUNDS
NICKEL COMPOUNDS
NITROGEN COMPOUNDS
NITROGEN OXIDES
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PHYSICAL PROPERTIES
PROCESSING
PYROLYSIS
REFRACTORY METAL COMPOUNDS
SEPARATION PROCESSES
SORPTION
SPECTRA
SYNTHESIS
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
020400* - Petroleum- Processing