Preparation of amines from olefins over boron beta-zeolites

Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing

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564395, 564408, 564445, C07C20900

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061439347

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BRIEF SUMMARY
This application is a 371 of PCT/EP96/03634 filed Aug. 19, 1996.
The present invention relates to a process for preparing amines by reacting ammonia or primary or secondary amines with olefins at elevated temperatures and pressures in the presence of boron BETA-zeolites.
CA-A-2 092 964 discloses a process for preparing amines from olefins in which aluminum BETA-zeolites, which are defined as crystalline aluminosilicates of a definite composition and having a pore size of more than 5 .ANG., are used.
These catalysts leave something to be desired in terms of yield or space-time yield or rapid deactivation.
It is an object of the present invention to provide a solution to the above disadvantages.
We have found that this object is achieved by a novel and improved process for preparing amines of the general formula I ##STR4## where R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6 are hydrogen, C.sub.1 -C.sub.20 -alkyl, C.sub.2 -C.sub.20 -alkenyl, C.sub.2 -C.sub.20 -alkynyl, C.sub.3 -C.sub.20 -cycloalkyl, C.sub.4 -C.sub.20 -alkylcycloalkyl, C.sub.4 -C.sub.20 -cycloalkylalkyl, aryl, C.sub.7 -C.sub.20 -alkylaryl or C.sub.7 -C.sub.20 -aralkyl, C.sub.3 -C.sub.9 -alkylene chain and -C.sub.200 -alkenyl or together are a divalent C.sub.2 -C.sub.12 -alkylene chain, ##STR5## where R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are as defined above, with ammonia or primary or secondary amines of the general formula III ##STR6## where R.sup.1 and R.sup.2 are as defined above, at from 200 to 350.degree. C. and pressures of from 100 to 300 bar in the presence of a zeolitic catalyst, wherein the zeolitic catalyst used is a boron BETA-zeolite.
The process of the present invention can be carried out as follows:
The olefin II and ammonia or the primary or secondary amine III can be reacted at from 200 to 350.degree. C., preferably from 220 to 330.degree. C., particularly preferably from 230 to 320.degree. C., and pressures of from 100 to 300 bar, preferably from 120 to 300 bar, particularly preferably from 140 to 290 bar, in the presence of a boron BETA-zeolite as catalyst, for example in a pressure reactor, and the amine obtained is preferably separated off and the unreacted starting materials are recirculated.
The present invention gives a very good yield at high selectivity and at high space-time yield. In addition, the deactivation of the catalyst has been suppressed.
The boron BETA-zeolites have, especially for this type of reaction (direct amination of olefins), a particularly favorable arrangement of the acid centers in combination with the characteristic size of the micropore system. This gives a high activity and a high operating life. The deactivation of the catalysts which is frequently found when using aluminum zeolites is attributed to the high acidity of the aluminum zeolites. For the same number of acid centers, boron zeolites have a significantly lower acid strength. The use of boron BETA-zeolite thus allows the advantages of the BETA-zeolite pore structure to be linked with the desired acidity.
Even with a low excess of ammonia or amine, the process of the present invention achieves a high selectivity of desired reaction product and dimerization and/or oligomerization of the olefin used is avoided.
One embodiment of the process comprises feeding ammonia and/or amines III mixed with the olefin II in a molar ratio of from 1:1 to 5:1 into a fixed-bed reactor and reacting the starting materials in the gas phase or in a supercritical state at a pressure of from 100 to 300 bar and at from 200 to 350.degree. C.
The desired product can be obtained from the reactor output by means of known methods, for example distillation or extraction, and if necessary brought to the desired purity by means of further separation operations. Preference is generally given to recirculating the unreacted starting materials to the reactor.
It is possible to use monounsaturated or polyunsaturated olefins II, in particular those having from 2 to 10 carbon atoms, or their mixtures or polyolefins as starting materials. Owing to their less pronounced

REFERENCES:
Chemical Abstract 1987:600919, Hoelderich et al; abstract of de3634247, Jul. 1987.

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