Chemistry of phosphomolybdate adsorption on alumina surfaces. 1. The molybdate/alumina system
- Shell Research B.V., Amsterdam (Netherlands)
The adsorption of ammonium heptamolybdate (AHM) on {gamma}-Al{sub 2}O{sub 3} and {alpha}-AlOOH has been studied by using FTIR and Raman spectroscopies, TPR, and EXAFS. It is shown that molybdate adsorption on alumina cannot be explained in terms of electrostatic binding to protonated surface hydroxyls but can be rationalized by assuming (i) a reaction between the molybdate and basic surface OH groups, leading to the decomposition of the adsorbing molecule/ion, and (ii) physisorption on coordinatively unsaturated (cus) Al{sup 3+} sites. In the AHM/{alpha}-AlOOH case, surface precipitation, presumably of (NH{sub 4}){sub 2}Mo{sub 3}O{sub 10}, takes place at surprisingly low initial AHM concentrations. The presence of (divalent) cations can influence the shape of the AHM/{gamma}-Al{sub 2}O{sub 3} isotherm but does not affect the ultimate loadings that can be achieved through processes (i) and (ii).
- OSTI ID:
- 6519262
- Journal Information:
- Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 94:13; ISSN JPCHA; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
Similar Records
Time differential perturbed angular correlation of. gamma. -rays emitted from sup 99 Mo yields sup 99 Tc in molybdenum-based catalysts: The nature of molybdate species in molybdena/alumina catalysts
Interaction chemistry between molybdena and alumina: infrared studies of surface hydroxyl groups and adsorbed carbon dioxide on aluminas modified with molybdate, sulfate, or fluorine anions
Related Subjects
400201* -- Chemical & Physicochemical Properties
ADSORPTION
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CATALYSTS
CHALCOGENIDES
DATA
DATA ANALYSIS
EXPERIMENTAL DATA
INFORMATION
MEASURING INSTRUMENTS
MEASURING METHODS
MOLYBDATES
MOLYBDENUM COMPOUNDS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PETROCHEMISTRY
REFRACTORY METAL COMPOUNDS
SORPTION
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS