Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Patent
1998-06-11
2000-07-04
Bell, Mark L.
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
502338, 502353, 558318, 558319, 558320, 558325, B01J 2300, B01J 23745, C07C25300
Patent
active
060838698
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a new process for the preparation of mixed vanadium, antimony and iron oxides and to the use of these oxides as catalysts for the ammoxidation of alkanes.
Certain mixed oxides of vanadium and of antimony or of vanadium, of antimony and of other metals are known compounds which have been described, among many other mixed oxides, in Patent FR-A-2, 072,334.
A description is given, in U.S. Pat. No. 5,008,427, of a process for the ammoxidation of propane or of butane in the presence of a catalyst which can comprise, in particular, oxides of vanadium, of antimony and of iron or of titanium or of chromium or of gallium or of tin, and optionally of other metals. These catalysts exhibit the essential characteristic of having been calcined at a temperature equal to or greater than 780.degree. C.
A description has likewise been given, in Patent EP-A-0,558,424, of a process for the ammoxidation of alkanes which is catalysed by mixed oxides of vanadium, of antimony, of iron and/or of gallium and/or of indium. These mixed oxides are prepared by mixing aqueous suspensions of compounds of the various metals, heating with stirring and then evaporating the water, drying and calcining.
The present invention relates to a new process for the preparation of a mixed vanadium, antimony and iron oxide corresponding to the general empirical formula (I): of the other elements, one saturated alcohol or in water, into contact with an aqueous solution containing an ammonium salt, in order to precipitate the mixed oxide,
The vanadium, antimony and iron compounds used in the process must be soluble in a saturated alcohol or a mixture of saturated alcohols or in water.
In the present text, a compound is regarded as soluble when its solubility, measured at 25.degree. C., is at least 5 grams per liter of saturated alcohol or of water. These compounds can be introduced together; they can also, first of all, be dissolved separately in an alcohol, the various alcoholic solutions thus obtained then being mixed with each other. They can also, first of all, be dissolved separately in water, the various aqueous solutions thus obtained then being mixed with each other. Generally, but non-limitingly, an alcoholic solution or an aqueous solution is prepared by dissolving the various compounds, without intermediate preparation of solutions of each of the vanadium, antimony and iron compounds.
To prevent the decomposition or the precipitation of certain compounds, more particularly of the iron salts, it is preferable to use an acidic aqueous solution having a pH of less than or equal to 2, when the catalysts of the invention are prepared in water.
In this case, the acid used to prepare this acidic aqueous solution can be any strong inorganic or organic acid capable of giving a solution having a pH of less than or equal to 2 and preferably a pH of 0.5 to 1.
Mention may be made, as non-limiting examples of such acids, of, in particular, hydrochloric, hydrobromic, sulphuric, nitric and trifluoroacetic acids.
For convenience, it is preferable to use the acid corresponding to the iron salt used, without this being essential.
Use is often made of hydrochloric acid, generally in the form of aqueous solutions having a weight for weight concentration of 10 to 20%.
In the present text, the expression aqueous solution used in the context of the process for the preparation of the catalysts also covers, except when otherwise mentioned, the above acidic aqueous solutions.
Mention may be made, as examples of soluble vanadium compounds, of vanadyl acetylacetonate, vanadyl trichloride, vanadium trifluoride, vanadium tetrafluoride, vanadium pentafluoride, vanadium tribromide, vanadium dichloride, vanadium trichloride, vanadium tetrachloride or vanadium triiodide.
Mention may be made, as examples of soluble antimony compounds, of antimony pentachloride, antimony trichloride, antimony tribromide, antimony trifluoride, antimony triiodide, antimony trioxide or stibine.
Mention may be made, as examples of soluble iron compounds, of iron dichl
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Albonetti Stefania
Blanchard Gilbert
Burattin Paolo
Cavani Fabrizio
Trifiro Ferruccio
Bell Mark L.
Hailey Patricia L.
Rhodia Fiber and Resin Intermediates
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