Chemistry of inorganic compounds – Oxygen or compound thereof – Peroxide
Patent
1998-08-26
2000-08-22
Dunn, Tom
Chemistry of inorganic compounds
Oxygen or compound thereof
Peroxide
502 60, 502 64, 502 74, 549531, 564300, 564301, C01B 15029
Patent
active
061067970
DESCRIPTION:
BRIEF SUMMARY
This application is the national stage of International Application No. PCT/EP97/00804 filed Feb. 20, 1997.
The present invention relates to a gauze catalyst based on titanium or vanadium zeolites and inert gauze fabrics and its use for accelerating oxidation reactions. The present invention further relates to corresponding processes for preparing epoxides, hydrogen peroxide and hydroxylamines.
Titanium zeolites are known to be suitable for use as catalysts for oxidation reactions. For instance, EP-A 100 119 (1) discloses a process whereby propene can be epoxidated in the presence of a solvent with aqueous hydrogen peroxide to propylene oxide over titanium zeolites. The preparation of cyclohexanone oxime from cyclohexanone by reaction with ammonia and hydrogen peroxide over titanium silicalites is taught in EP-A 208 311 (2) and the hydroxylation of aromatics with hydrogen peroxide over synthetic zeolites is known from GB-A 2 116 974 (3). The oxidation of saturated aliphatic hydrocarbons with hydrogen peroxide over titanium silicalites is described in EP-A 376 453 (4).
The synthesis route for preparing propylene oxide starting from propene, hydrogen and oxygen is described in DE-A 44 25 672 (5) and the publications cited in (5). Functionalized zeolites are used as catalysts.
The abovementioned publications (1)-(5) do not mention gauze fabrics as supports. However, gauze catalysts without zeolites are known from other applications as described herein. Furthermore, EP-A 511 739 (6) describes membranes comprising aluminum oxide supports having films of zeolitic crystal bodies applied thereon for use in separation processes. In Microp. Mater. 5 (1995), 245-253 (7), Yamazaki and Tsutsumi describe the preparation and the properties of membranes made of mordenite (zeolite structure) supported on stainless steel or polytetrafluoroethylene. Zeolites supported on copper wire gauzes for use as reduction catalysts in the cleaning of exhaust gases (DeNox) are known from Calis et al., Chem.-Ing.-Tech. 67 (1995), 777-780 (8). However, the zeolites mentioned in (6)-(8) do not contain titanium or vanadium.
Since alkali metal, even if only present in trace amounts, may destroy the catalytic activity of titanium and vanadium zeolites in oxidation reactions, the ways of supporting described in (6)-(8) are unsuitable for the particular purposes of oxidation processes. In (7) and (8), for example, alkali metal-containing zeolite synthesis gels are used as starting materials.
It is an object of the present invention to provide improved catalysts, in particular for the preparation of epoxides from olefins, without the disadvantages of the prior art. In particular, the catalysts should be very easy to produce and highly efficient.
We have found that this object is achieved by a gauze catalyst based on titanium or vanadium zeolites and inert gauze fabrics.
Inert gauze fabrics, ie. gauze supports, especially wire gauzes, are preferably made of metal such as stainless steel, copper, silver, aluminum or nickel or alloys such as brass or kanthal (iron/chromium/aluminum/cobalt), plastic such as polytetrafluoroethylene, aluminum oxide such as .alpha.-aluminum oxide, glass fiber, carbon fiber or graphite. It is also possible to use a combination of two or more of the abovementioned gauze fabric materials.
Since alkali metals, even if only present in trace amounts, may destroy the catalytic activity of the titanium and vanadium zeolites in oxidation reactions, the alkali metal content (in particular sodium and/or potassium in this case) is preferably less than 500 ppm, in particular less than 100 ppm, especially less than 40 ppm, in each case based on the weight of the titanium or vanadium zeolites. Alkali metal contents as low as this can be achieved by appropriate preparation methods.
Zeolites are known to be crystalline aluminosilicates having ordered channel and cage structures, whose pore openings are in the micropore region of less than 0.9 nm. The framework of such zeolites is composed of SiO.sub.4 and AlO.sub.4 tetrahedra joined tog
REFERENCES:
patent: 5843392 (1998-12-01), Jansen et al.
patent: 5912367 (1999-06-01), Chang
patent: 6008388 (1999-12-01), Dessau et al.
S. Yamazaki, et al., Microporous Materials, vol. 5, pp. 245-253, "Synthesis of a Mordenite Membrane on a Stanless-Steel Filter And Polytetrafluoroethylene Plate Substrates", Jul. 15, 1995.
Hans Peter Calis, et al., Chem.-Ing.-Tech., No. 67, No. 6, pp. 777-780, "Anwendung Von Zeolithen Bei Der Selektiven Katalytischen Reduktion Von, No.sub.x In Industrieabgasen", 1995.
Brocker Franz Josef
Grosch Georg Heinrich
Harder Wolfgang
Muller Ulrich
Putter Hermann
BASF - Aktiengesellschaft
Dunn Tom
Ildebrando Christina
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