Reduction and metathesis activity of MoO[sub 3]/Al[sub 2]O[sub 3] catalysts: I. An XPS investigation of MoO[sub 3]/Al[sub 2]O[sub 3] catalysts

Journal Article · Fri May 01 00:00:00 EDT 1992 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(92)90285-P· OSTI ID:6975932

Gruenert, W; Feldhaus, R; Anders, K ^[1]; Stakheev, A Y; Shpiro, E S; Minachev, K M ^[2]; Moerke, W ^[3]

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1. Central Inst. of Organic Chemistry, Leipzig (Germany)
2. Academy of Sciences, Moscow (Russian Federation)
3. Technical Univ. Merseburg, Otto-Nuschke-Strasse (Germany)

MoO[sub 3]/Al[sub 2]O[sub 3] catalysts (2-13 wt% MoO[sub 3]) were investigated by XPS in the oxidized form, after thermal treatment in flowing Ar (973 K), and after reduction in H[sub 2] (673-973 K), which are conditions typically employed in the activation of these catalysts for the metathesis reaction. A new assignment of Mo 3d binding energies to Mo oxidation states was applied in the analysis of the reduced samples. During the thermal treatment in flowing Ar, part of the hexavalent Mo present in the initial samples underwent reduction to Mo(V), which could also be detected by EPR. The reduction of alumina-supported Mo(VI) in H[sub 2] was found to produce surfaces, on which Mo(VI), Mo(V), Mo(IV), Mo(II), and, at reduction temperatures above 900 K, Mo(0), coexist. For reduction temperatures of about 800 K, distributions of these Mo states, which differ from those reported in the literature by a Mo(V) contribution not exceeding 10% of the total Mo and by the presence of Mo(II), were derived. When reduced MoO[sub 3]/Al[sub 2]O[sub 3] catalysts were subsequently treated in flowing inert gas at 973 K a partial reoxidation of the surface was observed.

• OSTI ID: 6975932
• Journal Information: Journal of Catalysis; (United States), Vol. 135:1; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
02 PETROLEUM
MOLYBDENUM OXIDES
CATALYTIC EFFECTS
REDUCTION
ALKENES
ALUMINIUM OXIDES
BINDING ENERGY
CATALYST SUPPORTS
CATALYSTS
CHEMICAL ACTIVATION
ELECTRON SPIN RESONANCE
HEAT TREATMENTS
ISOMERIZATION
PHOTOELECTRON SPECTROSCOPY
X-RAY SPECTROSCOPY
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
ELECTRON SPECTROSCOPY
ENERGY
HYDROCARBONS
MAGNETIC RESONANCE
MOLYBDENUM COMPOUNDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
REFRACTORY METAL COMPOUNDS
RESONANCE
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties
020400 - Petroleum- Processing