Polyoxometallate catalysts and catalytic processes
AssigneeCalifornia Institute of Technology
InventorsMark E. Davis, Christopher J. Dillon, Joseph H. Holles, Jay A. Labinger, Axel Brait
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Abstract
An active and selective hydrocarbon partial oxidation catalyst comprises an activated partially-reduced polyoxometallate, preferably niobium polyoxomolybdate, that is prepared from a suitable polyoxoanion, which has been exchanged with a suitable cation and activated by heating to an activation effective temperature in the presence of a suitable reducing agent such as pyridinium. C3 and C4 hydrocarbons may be partially oxidized selectively to acrylic acid and maleic acid.
Claims24
An oxidation catalyst comprising an activated partially-reduced metal ion polyoxometallate containing a framework metal bonded through oxygen atoms to at least one heteroatom and charge balanced with at least one Group 3-13 reducible metal ion.
An oxidation catalyst comprising an activated partially-reduced niobium polyoxomolybdate.
An oxidation catalyst precursor comprising:
- a polyoxoanion
- {XxMmQqOy}−e
- wherein X is a Group 12-16 element, M is a Group 5-6 element, Q is a Group element, 0 is oxygen, e is the charge of the polyoxoanion, x is 1 to 5, m is 5 to 20, q is 0 to 10, and y is 18 to 62;
- and
- onto which has been exchanged a charge-balancing number of niobium and quaternary ammonium cations.
An oxidation catalyst precursor comprising:
- a polyoxometallate:
- AbCc{PxMmVnOy}
- wherein x=1 or 2;
- m=10-18.;
- n=0-4, and y=40-62, A is quaternary ammonium ion, C is one or more Group 3-13 reducible metal ions, and b and c are calculated to balance the charge of the polyoxoanion {PxMmVnOy}.
A method of making an oxidation catalyst comprising
- a. forming a polyoxoanion containing Mo, P, O, and optionally V;
- b. exchanging the polyoxoanion with charge balancing amounts of Nb and pyridinium to form a polyoxomolybdate;
- c. activating the exchanged polyoxomolybdate by heating to 400 to 450° C. in a non-oxidizing atmosphere for a time sufficient to form a catalytically active phase of niobium polyoxomolybdate.
Dependencies are inferred from the claim text.