Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-04-08
2001-01-30
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
Reexamination Certificate
active
06180834
ABSTRACT:
The present invention relates to a process for the extraction of the salts contained in the neutralized separation product obtained in the preparation of phenol by the oxidation of cumene.
More specifically, the present invention relates to a process for the reduction of water consumption in washing the neutralized separation product obtained in the production of phenol by the oxidation of cumene.
It is known that phenol can be prepared from cumene, as described in “Ullmann's Encyclopedia of Industrial Chemistry”, Fifth Edition, 1991, Vol. A 19, 302, according to a process which is substantially developed in two steps. The first relates to the oxidation of cumene to cumene hydroperoxide, the second relates to the separation of cumene hydroperoxide to phenol and acetone carried out in the presence of an acid catalyst. The separated product is then subjected to distillation to recover the phenol and acetone.
In the production process of phenol from cumene a large quantity of water is normally adopted, partly used as solvent of the chemical products which must be added to the main streams to obtain optimum process conditions, or for the recovery of phenol from organic streams from which it would be very difficult to obtain by distillation. Or, the water is used as such as solvent in washing operations whose purpose is to reduce as much as possible the concentration of saline compounds in the organic streams to be sent for distillation.
Examples of the first type of water use are aqueous solutions of Na
2
CO
3
(or NaOH) added to oxidation reactors to stabilize the pH; the aqueous solution of H
2
SO
4
added as catalyst to separation reactors of cumene hydroperoxide to phenol and acetone; the aqueous solution of NaOH used to salify the phenol contained in the hydrocarbon stream which is separated in the distillation section of the separated product.
Examples of the second type of water use are represented by the washing of the oxidated product, to eliminate the possible presence of Na
2
CO
3
(or NaOH) and sodium salts of the organic acids formed during the oxidation reaction or the washing of the neutralized separated product to eliminate possible traces of Na
2
SO
4
and the salts of organic acids dissolved therein, before it is sent to the distillation section for the recovery of the phenol and acetone.
The presence of water can also be found in other parts of the production process, for example in the liquid ring compressors or ejectors for effecting the vacuum necessary for the distillation columns.
Finally a certain quantity of water derives from the repeated flushing operations of the lines, the washing of the equipment and possible recovery of rain water, should this be polluted.
These aqueous streams form the process water whose overall amount corresponds more or less to the same quantity of phenol produced. They are subdivided into two main streams with an almost equal flow-rate, which are recovered from the oxidation section of cumene and from the separation section of cumene hydroperoxide, respectively.
The aqueous streams may contain organic compounds, in particular phenol and acetone, and must therefore be treated before being sent for biological purification to reduce the loss of high-quality products to the minimum. As a result, the greater the quantity of water fed/recovered in the plant, the more dilute will be the compounds to be recovered and the more expensive their recovery from the aqueous stream. It is therefore convenient for the quantity of water fed to the plant to be as small as possible.
The purpose of the present invention is to contribute to reducing the quantity of water used in the production process of phenol by the oxidation of cumene.
More specifically, the objective of the present invention is to reduce the flow-rate of the aqueous stream of the separation section of cumene hydroperoxide, by substituting the stream of fresh water used for washing the neutralized separated product, generally obtained by the demineralization of water coming from wells or running waters, with process water taken from another section of the production plant.
The present invention therefore relates to a process for the extraction of the salts contained in the neutralized separated product obtained in the preparation of phenol by the oxidation of cumene which comprises:
a) feeding the separated product essentially consisting of a stream of phenol and acetone in continuous to an extraction/washing with water section so as to obtain a first aqueous stream containing the extracted products and a first organic stream containing acetone, cumene, phenol and other organic products (for example &agr;-methylstyrene);
b) feeding said first organic stream, together with a second recycled aqueous stream containing acetone, to a mixing section;
c) feeding the stream leaving the mixing section to a first decanting system to obtain a second organic stream and a third aqueous stream;
d) feeding said third aqueous stream, substantially without acetone (about 10% by weight), to the washing section of step (a);
e) feeding said second organic stream to a distillation section to obtain a stream of heavy products essentially consisting of phenol and a stream of light products essentially consisting of water, acetone and hydrocarbons (cumene and &agr;-methylstyrene);
f) feeding the stream of light products to a second decanting system to obtain a third organic stream essentially consisting of acetone and hydrocarbons, and the second aqueous stream which is totally or partially recycled to the mixer of step (b).
REFERENCES:
patent: 2679535 (1954-05-01), Lavender
patent: 2734085 (1956-02-01), Adams
patent: 2881222 (1959-04-01), Joris
patent: 3180897 (1965-04-01), Sodomann
patent: 4973766 (1990-11-01), Penzo
patent: 5658437 (1997-08-01), Alessi et al.
patent: 5811598 (1998-09-01), Alessi et al.
patent: 0 717 024 (1996-06-01), None
patent: 743004 (1956-01-01), None
Alessi Vanni
Penzo Renzo
Enichem S.p.A.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Shippen Michael L.
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