Studies of MoO3-Al2O3 catalyst in ethylene polymerization. III. The nature of Mo(V) and its relation with activity.

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概要

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• In order to determine the active center of ethylene polymerization over MoO<SUB>3</SUB>–Al<SUB>2</SUB>O<SUB>3</SUB>, the <I>g</I>-tensor and the amount of molybdenum(V) in each chemical state were determined by means of ESR measurement. The anisotropy of the <I>g</I>-tensor revealed the strength of the crystal field in the state; the decreasing order of the strengths was as follows: state(S)>state(M)>state(W)>MoO<SUB>3</SUB>–SiO<SUB>2</SUB>\fallingdotseqfree MoO<SUB>3</SUB>. In the state(S) molybdenum oxide is insoluble in aq.10M–NH<SUB>3</SUB>, in the state(M) it is soluble in aq. NH<SUB>3</SUB> but insoluble in water, and in the state(W) it is soluble in water. The amount of molybdenum(V) in the state(W) was studied in connection with the activity, because only the state(W) was suitable for polymerization. The behavior of the activity was in fair agreement with that of the molybdenum(V) content in the state(W) and this content depedned on the amount of supported MoO<SUB>3</SUB> and on the extent of reduction. The amount of molybdenum(V) in the state(W) corresponded to the amount of chemisorbed hydrogen, which was a polymerization initiator. The chemisorption of oxygen on the catalyst caused a complete disappearance of both the activity and the molybdenum(V) content in the state(W). Therefore, it was concluded that the active center of the polymerization was molybdenum(V) in the state(W).

• 公益社団法人 日本化学会の論文

著者

• Tarama Kimio

  Department of Hydrocarbon Chemistry, Faculty of Engineering, Kyoto University

• Hashimoto Keizi

  The Osaka Municipal Technical Research Institute

• Watanabe Shozi

  The Osaka Municipal Technical Research Institute

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