Interaction of nickel deposits with catalytic metals on CoMo/Al[sub 2]O[sub 3] hydrometallation catalysts
- Massachusetts Institute of Technology, Cambridge, MA (United States)
Deactivation of hydrometallation catalyst has been studied extensively due to the demand for the processing of increasing amounts of resid and low quality crude oils. However, the interaction between metal deposits and the catalyst are not well understood. In this regard, the structures of nickel deposits on sulfided CoMo/Al[sub 2]O[sub 3] hydrodemetallation catalyst surface were characterized by using scanning transmission electron microscopy and high-resolution transmission electron microscopy techniques to study the interaction between the deposits and catalytic components. The deposits were found in crystallite form of nickel sulfide (Ni[sub 7]S[sub 6]) on the catalyst surface. Within the crystallites cobalt is uniformly distributed. Molybdenum is only partially associated with the nickel deposits as a segregated surface layer of molybdenum sulfide (MoS[sub 2]). For crystallites smaller than about 15 nm, the extent of segregation decreases. About 75% of the molybdenum is not directly associated with nickel deposits. Extensive cover-up of molybdenum by nickel deposits was not observed, and is not the main reason of catalyst deactivation. It was found that nickel deposits migrated towards cobalt sites even though molybdenum sites were the active sites for the hydrometallation reaction. Structure affinity favored the formation of solid solution between cobalt and nickel sulfides, which was the driving force for the association between nickel and cobalt on the catalyst surface. Microscopic characterization showed that deposition of nickel sulfide on the catalyst surface enhanced the mobility of the catalytic components MoS[sub 2]. Coalescence of MoS[sub 2] leads to significant reduction of accessible molybdenum sulfide sites, and is the main reason for the deactivation of hydrodemetallation catalyst. 29 refs., 14 figs., 3 tabs.
- OSTI ID:
- 7275833
- Journal Information:
- Journal of Catalysis; (United States), Vol. 147:2; ISSN 0021-9517
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
02 PETROLEUM
ALUMINIUM OXIDES
STRUCTURAL CHEMICAL ANALYSIS
CATALYSTS
DEACTIVATION
COBALT ALLOYS
MOLYBDENUM ALLOYS
NICKEL SULFIDES
CATALYST SUPPORTS
CATALYTIC EFFECTS
TRANSMISSION ELECTRON MICROSCOPY
ALLOYS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
ELECTRON MICROSCOPY
MICROSCOPY
NICKEL COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties
020400 - Petroleum- Processing