Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Patent
1997-04-04
1998-07-07
O'Sullivan, Peter
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
423387, 564300, C07C23900, C07C23908, C01B 2114
Patent
active
057771634
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/EP95/03771 filed 23 Sep. 1995.
The present invention relates to an improved process for the preparation of hydroxylamines from ammonia or the corresponding amines, hydrogen and oxygen using a certain oxidation catalyst.
Multistage industrial processes are known for the preparation of hydroxylamine starting from ammonia. The disadvantage of these processes is that they bind the resulting hydroxylamine in the form of ammonium salts, which subsequently, for example when used in processes for the preparation of caprolactam, inevitably lead to considerable amounts of ammonium sulfate salts.
A salt-free process based on ammonia and hydrogen peroxide is described in EP-A 522 634, but the use of expensive hydrogen peroxide makes this process uneconomical.
It is an object of the present invention to provide an easily prepared and efficient oxidation catalyst for the preparation of hydroxylamines from ammonia or the corresponding amines and a corresponding process which no longer has the disadvantages of the prior art and is capable of producing hydroxylamines in salt-free form from ammonia or the corresponding amines, hydrogen and oxygen.
We have found that this object is achieved by a process for the preparation of hydroxylamines from ammonia or the corresponding amines, hydrogen and oxygen, wherein the starting materials are reacted under heterogeneous catalysis using an oxidation catalyst based on a titanium or vanadium silicalite having a zeolite structure and containing from 0.01 to 20% by weight of one or more platinum metals selected from the group consisting of ruthenium, rhodium, palladium, osmium, iridium and platinum, the platinum metals each being present in at least two different bond energy states.
Such oxidation catalysts are disclosed in German Patent Application P 44 25 672.8.
For the purpose of the present invention, it is of decisive importance that, before it is used, the oxidation catalyst contains the platinum metals in the stated special modification comprising the mixture of different bond energy states. The different bond energy states correspond formally to different oxidation states of the metals. In a preferred embodiment, two, three, four or five different bond energy states are present.
Where two different bond energy states are present, this may correspond, for example, to a mixture of species of oxidation states 0 and +1, 0 and +2, 0 and +3 or 0 and +4. The two species are usually present in a ratio of from 5:95 to 95:5, in particular from 10:90 to 90:10.
Where three different bond energy states are present, this corresponds, for example, to a mixture of species of oxidation states 0, +1 and +2 or 0, +2 and +3, or 0, +2 and +4 or 0, +1 and +3 or 0, +1 and +4 or 0, +3 and +4. The three species are usually present in a ratio of (0.05-20):(0.05-20):1, in particular (0.1-10):(0.1-10):1.
Mixtures of four or more different oxidation states may also be present, for example of 0, +1, +2 and +3 or 0, +1, +2 and +4, or 0, +2, +3 and +4 or 0, +1, +3 and +4 or 0, +1, +2, +3 and +4. Here, the species are present in weight ratios which are similar to those in the case of the mixtures of 2 or 3 different oxidation states.
Palladium is preferred among platinum metals. In a particularly preferred embodiment, the palladium is present in two or three different bond energy states.
The bond energy states at the surface of the catalyst can most easily be characterized by X-ray photoelectron spectroscopy (XPS). For example, in a typical mixture of three palladium species, the corresponding values for the energies of the Pd-3d.sub.5/2 state is 335.0-335.4 eV, 336-336.6 eV and 337.1-337.9 eV, which formally corresponds to the oxidation states Pd.sup.0, Pd.sup.1+ and Pd.sup.2+.
In the case of the oxidation catalysts described, it is particularly advantageous to apply the platinum metals in such a way that no metal-metal bonds are effective and metal-zeolite bonds predominate. In particular, X-ray fine structure investigations (EXAFS) reveal that, with the presence of palladium
REFERENCES:
patent: 3960954 (1976-06-01), Russell et al.
Heineke Daniel
Muller Ulrich
BASF - Aktiengesellschaft
O'Sullivan Peter
LandOfFree
Preparation of hydroxylamines from ammonia or the corresponding does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Preparation of hydroxylamines from ammonia or the corresponding , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Preparation of hydroxylamines from ammonia or the corresponding will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1207751