Reduction and metathesis activity of MoO[sub 3]/Al[sub 2]O[sub 3] catalysts. II. The activation 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)90286-Q· OSTI ID:6975923

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

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1. Central Inst. of Organic Chemistry, Leipzig (Germany)
2. Academy of Sciences, Moscow (Russian Federation)

MoO[sub 3]/Al[sub 2]O[sub 3] catalysts (0.5-13 wt% MoO[sub 3]) were activated for the metathesis of propene by thermal treatment in flowing inert gas and by reduction in H[sub 2] (reaction conditions: 473 K, 0.1 MPa). Temperatures between 900 and 1140 K were applied for the activation of the catalysts in inert atmosphere. The activity of the supported Mo (molecules/s Mo) increased with decreasing MoO[sub 3] content, which is opposite to the well-known trends for the reducibility of Mo(VI)/Al[sub 2]O[sub 3]. The kinetic reaction order of the propene metathesis was found to be 0.8 at 473 K. The apparent activation energy was 30-37 kJ/mole, with a slight decrease at increasing MoO[sub 3] content. The response of the activity to the extent of reduction was investigated at different reduction temperatures and MoO[sub 3] contents. From these observations and the results of the thermal activation study, it has been concluded that the active sites of metathesis can be formed from both Mo(VI) and Mo(IV) precursors. These precursors coexist on reduced surfaces, while the activity attained after thermal activation in inert gas is due exclusively to sites originating from mo(VI) species. Other Mo states (Mo(V), and Mo(II), and MO(0)) do not contribute to the metathesis activity.

• OSTI ID: 6975923
• 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
CHEMICAL ACTIVATION
PROPYLENE
ISOMERIZATION
ACTIVATION ENERGY
ALUMINIUM OXIDES
CATALYST SUPPORTS
CATALYSTS
CHEMICAL REACTION KINETICS
HEAT TREATMENTS
PRECURSOR
REDUCTION
SURFACE PROPERTIES
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
VALENCE
ALKENES
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
ENERGY
HYDROCARBONS
KINETICS
MOLYBDENUM COMPOUNDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties
020400 - Petroleum- Processing