Catalyst – solid sorbent – or support therefor: product or process – Solid sorbent – Free carbon containing
Patent
1992-06-03
1993-09-28
Konopka, Paul E.
Catalyst, solid sorbent, or support therefor: product or process
Solid sorbent
Free carbon containing
264 295, 502416, 502418, 502429, 502437, 95138, C01B 3110, C01B 3100, B01J 2020, B01D 5304
Patent
active
052486516
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a National Phase of PCT/EP 91/01796 filed Sep. 20, 1991 and based upon German National application P 4 031 580.0 filed Oct. 5, 1990 under the International Convention.
FIELD OF THE INVENTION
The invention relates to a process for producing carbon molecular sieves. More particularly, the invention relates to a process of this type in which finely ground hard coal particles are oxidized with air in a fluidized bed, the coal is shaped after water and binders have been added, carbonized, activated with steam and treated with carbon splitting hydrocarbons.
BACKGROUND OF THE INVENTION
From German Patent 36 18 426 and the therein mentioned German Patent 21 19 829 it is known to produce carbon molecular sieves for the separation of gases with small molecular size, particularly O.sub.2 and N.sub.2, in the following manner: finely ground hard coal is oxidized with air in a fluidized bed, after adding binders and water the coal is shaped and carbonized at temperatures up to 900.degree. C., subsequently activated with steam at temperatures of 800.degree.-900.degree. C. and the preliminary product of the low-level activation is treated with carbon splitting hydrocarbons at 750.degree.-850.degree. C.
The carbon molecular sieves produced this way are used for obtaining nitrogen from air in pressure swins processes. The operating costs of alternate pressure processes consist primarily of compression costs for the required air compression. The so-called specific air consumption, i.e. the ratio of the used amounts of air to the produced amount of nitrogen (m.sup.3 air/m.sup.3 nitrogen) should be as low as possible. This specific air consumption is directly related to the nitrogen adsorptivity of the carbon molecular sieve, which results from the difference between the diffusion rates of nitrogen and oxygen in the carbon molecular sieve.
OBJECT OF THE INVENTION
It is the object of the present invention to produce a carbon molecular sieve with improved oxygen adsorptivity, so that the costs related to energy consumption can be reduced during the separation of nitrogen from air.
DESCRIPTION OF THE INVENTION
This object is achieved by using starches as binding agents. These starches can be obtained by reacting agglutinated starches with sulphamates. These starches are described in EP 0 129 227 B1.
The carbon molecular sieves produced according to the invention have good mechanical strength, comparable to carbon molecular sieves using coaltar pitch as binders. The shock resistance (H. von Kienle, E. Bader; "Aktivkohle und ihre industrielle Anwendung"--"Activated Carbon and its Industrial Application"--published by F. Enke Verlag, Stuttgart 1980, Page 57) was 90%>0.5 mm., no matter whether coaltar pitch or starch were used for binders.
The oxygen adsorptivity of the carbon molecular sieve with respect to the separation of nitrogen and oxygen is determined by a test method which takes into account the differences in the diffusion rates of nitrogen and oxygen (1-minute test).
An adsorber (capacity 200 ml) filled with carbon molecular sieve to be tested is traversed for the duration of one minute by air supplied by an air pump under a pressure of 1013 mbar. During this time the carbon molecular sieve contained in the adsorber adsorbs gas due to its porous structure, whereby due to its high diffusion ratio the oxygen is preferentially adsorbed before the nitrogen. Most of the nitrogen passes the separating pores and exits the adsorber at the end. After one minute, this process is interrupted and the adsorber is evacuated in counterflow by means of a vacuum pump to 40 mbar. This way an oxygen-enriched gas is obtained, which is fed to a gasometer. The amount of desorbed considered with respect to the volume of the carbon molecular sieve CMS (Relative Volume RV=1 Gas/1 CMS), the maximum oxygen concentration as well as the average oxygen concentration of the desorption gas are measured. Both oxygen concentrations are higher than the oxygen concentration in the ai
REFERENCES:
patent: 4880765 (1989-11-01), Knoblauch et al.
patent: 5043310 (1991-08-01), Takeuchi et al.
patent: 5098880 (1992-03-01), Gaffhey et al.
Chemical Abstr. vol. 102, No. 20, May 1985 No. 169053, Japan Oxygen Co., Porous Carbon Molecular Sieve, p. 135.
Bongartz Wolfgang
Degel Josef
Henning Klaus D.
Knoblauch Karl K.
Wybrands Klaus
Bergwerksverband GmbH
Dubno Herbert
Konopka Paul E.
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