Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Reexamination Certificate
1996-12-19
2001-03-13
Niebling, John F. (Department: 2812)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
C502S353000
Reexamination Certificate
active
06200926
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to the preparation of mixed oxides based on vanadium, on antimony and, optionally, on tin and/or on titanium and/or on iron and/or on other metals deposited onto a support therefor and to the use of such supported mixed oxides as catalysts for the ammoxidation of alkanes.
2. Description of the Prior Art
Certain mixed oxides of vanadium and antimony, or of vanadium, antimony and other metals, are known compounds which have been described, among many other mixed oxides, in FR-A-2,072,334.
U.S. Pat. No. 5,008,427 describes the ammoxidation of propane or butane in the presence of a catalyst which can, in particular, comprise 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 have the essential characteristic of having been calcined at a temperature equal to or greater than 780° C.
Similarly, EP-A-0,558,424 describes the ammoxidation of alkanes in the presence of a mixed oxide catalyst 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 calcination.
The aforesaid patent literature provides no specific advice regarding the reactor technology associated with the catalysts for the ammoxidation of alkanes which they describe.
However, for the type of reaction represented by the ammoxidation of alkanes, it transpires that employing a fluidized bed or moving bed reactor is more advantageous. Due to the high exothermicity of the reactions involved in the ammoxidation of alkanes, the possibility of using one or a number of stationary bed reactors (multitubular reactors) on an industrial scale does not appear very realistic, indeed excluded, in particular if it is desired to achieve high productivities. In fact, it would be necessary, in order to dissipate the heat evolved, to use a multitubillar reactor of very large size or an entire battery of multitubular reactors, which is not feasible from an economic standpoint.
In comparison with the stationary bed reactor, fluidized or moving bed reactors have a greater ability to dissipate the heat evolved and appear, for this reason, better suited for the ammoxidation reaction of alkanes. This better ability to transfer heat would permit enhancing productivity by increasing the alkane content in the feedstream mixture. Such an operation is not possible in the case of a stationary bed reactor because the limitations with respect to heat transfer (which can be detected by the existence of a hot spot in the reactor) dictate the use of relatively low alkane contents, to avoid any danger of explosiveness or flammability of the gas mixture.
SUMMARY OF THE INVENTION
The present invention features the production of a catalyst for a fluidized bed or moving bed reactor comprising an active catalyst phase having the empirical formula (I):
VSb
a
Sn
b
Ti
c
Fe
d
E
e
O
x
(I)
in which E is an element providing an oxide of rutile structure or an element which, in combination with V, Sb, Sn, Ti, Fe and/or with another element E, provides a phase of rutile or trirutile structure, or a solid solution of rutile structure; a is a whole or fractional number equal to or greater than 0.5; b, c, d and e, independently, are each a whole or fractional number ranging from 0 to 100; and x is a whole or fractional number determined by the oxidation number of the other elements; deposited onto a solid and porous oxide support.
The process for the production of the above catalyst comprises (a) impregnating the solid support with a solution in at least one saturated alcohol of the respective compounds of vanadium, of antimony and, optionally, of tin and/or of titanium and/or of iron and/or of element E, (b) contacting the impregnated solid support with an aqueous buffer solution at a pH of from 6 to 8, (c) separating the resulting solid and drying same, and (d) calcining the solid in two stages, first at a temperature of 300° C. to 350° C. and then at a temperature of 400° C. to 800° C.
DETAILED DESCRIPTION OF BEST MODE AND SPECIFIC/PREFERRED EMBODIMENTS OF THE INVENTION
More particularly according to the present invention, the elements E are advantageously selected from among germanium, manganese, ruthenium, niobium, tantalum, gallium, chromium, rhodium, nickel, molybdenum, aluminum, thorium, calcium, tungsten and magnesium. There may be a number of elements E in the formula (I) and it will be appreciated that the expression “element E,” as intended herein, connotes one or more elements E.
The compounds of vanadium, of antimony, of tin, of titanium, of iron and of the element E employed in the subject process must be soluble in a saturated alcohol or a mixture of saturated alcohols.
Consistent herewith, a compound is regarded as soluble when its solubility, measured at 25° C., is at least 5 grams per liter of saturated alcohol. These compounds can be introduced together. They can also be first dissolved separately in an alcohol, the different alcoholic solutions thus obtained then being mixed with one another. Generally, the alcoholic solution is prepared by dissolving the different compounds of vanadium, of antimony and, if appropriate, of tin, of titanium, of iron and of element E, without the intermediate preparation of solutions of each of the compounds.
Suitable soluble vanadium compounds include vanadyl acetylacetonate, vanadyl trichloride, vanadium trifluoride, vanadium tetrafluoride, vanadium pentafluoride, vanadium tribromide, vanadium dichloride, vanadium trichloride, vanadium tetrachloride or vanadium triiodide.
Suitable soluble antimony compounds include antimony pentachloride, antimony trichloride, antimony tribromide, antimony trifluoride, antimony triiodide, antimony trioxide or stibine.
Suitable soluble tin compounds include stannic chloride, stannous chloride or stannous bromide.
Suitable soluble titanium compounds include titanium dichloride, titanium tetrachloride, titanium trichloride, titanium tribromide, titanium tetrabromide, titanium tetrafluoride or titanium diiodide.
And suitable soluble iron compounds include iron dichloride, iron trichloride, iron dibromide, iron tribromide, iron diiodide, ferrous nitrate, ferrous sulfate, ferric sulfate, ferrous thiosulfate, ferric formate, ferric acetate, ferric acetylacetonate, ferric benzoate, ferric oleate, ferrous lactate or ferric lactate.
The saturated alcohols employed in the process of the invention are advantageously alkanols and cycloalkanols, preferably those having a boiling point that is not excessively high, in order to facilitate the operations of separation or of recycling by distillation or evaporation. Thus, alkanols having from 1 to 6 carbon atoms, such as methanol, ethanol, n-propanol, 2-propanol, n-butanol, 2-butanol, tert-butanol, pentanols and hexanols, and cyclohexanol, are preferred.
The solid support is characteristically an oxide, such as an alumina, a silica, a silica/alumina, a zirconia, a cerite, a mixed oxide of cerium and of zirconium, a magnesia, a titanium oxide, a niobium oxide or a lanthanum oxide.
The size of the particles of the solid support generally ranges from 10 &mgr;m to 1,000 &mgr;m and preferably from 20 &mgr;m to 300 &mgr;m.
Another important characteristic of the solid support is its ability to be impregnated by a solution of the compounds of the metals of the active phase. Thus, supports are generally used having a total pore volume of at least 0.1 cm
3
/g and preferably of at least 0.15 cm
3
/g.
The quality of the fluidization of the catalytic bed can also depend on other parameters such as the relative density of the support, the void content of the support or the gas flow rate. The desired fluidization of the catalyst, in particular for application in the ammoxidation of alkanes, can be carried out under optimum conditions by one skilled in this art, taking account of these various param
Blanchard Gilbert
Burattin Paolo
Cavani Fabrizio
Masetti Stéfano
Trifiro Ferruccio
Burns Doane Swecker & Mathis L.L.P.
Ghyka Alexander G.
Niebling John F.
R. P. Fiber & Resin Intermediates
LandOfFree
Ammoxidation catalysts for fluidized/moving bed reactors does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ammoxidation catalysts for fluidized/moving bed reactors, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ammoxidation catalysts for fluidized/moving bed reactors will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2454085