| 摘要 |
An improved process was found for preparing a vanadium-containing catalyst wherein a tetravalent vanadium compound is provided from a pentavalent vanadium compound, comprising contacting the pentavalent vanadium compound with a phosphonate. The improved process is exemplified by the preparation of phosphorus-vanadium-oxygen catalysts, and particularly the preparation of phosphorus-vanadium-oxygen catalysts having a phosphorus to vanadium atom ratio of about 1:2 to about 2:1 comprising contacting a vanadium compound with a selected phosphonate, recovering a phosphorus-vanadium-oxygen precursor, and thereafter calcining the precursor to form the catalysts. The compound 1-hydroxy-1,1-ethylidene diphosphonic acid is preferred as the phosphonate.
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