Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-11-09
2001-07-03
Padmanabhan, Sreeni (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S835000, C568S836000
Reexamination Certificate
active
06255533
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the production of cyclohexanone. More specifically, the present invention relates to the recovery of cyclohexanone and cyclohexanol from distillation bottoms containing unknown by-products of cyclohexanone production.
BACKGROUND AND SUMMARY OF THE INVENTION
Cyclohexanone is a commercially important starting compound for the production of caprolactam. The production of cyclohexanone typically involves the oxidation of cyclohexane which yields cyclohexanol and cyclohexanone as the principal oxidation products. (See, U.S. Pat. No. 3,946,076, the entire content of which is expressly incorporated hereinto by reference). The production process also generates substantial quantities of by-products which have higher boiling points than cyclohexanone.
It has been proposed in the past that some of these by-products of cyclohexanone production, especially multi-cyclic ketones, can be thermally cracked into cyclohexanone and cyclohexanol. (See, U.S. Pat. No. 4,173,586, the entire content of which is incorporated hereinto expressly by reference.) It is also known that cyclohexanediols can be catalytically cracked at elevated temperatures and pressures to produce cyclohexanone and cyclohexanol. (See, U.S. Pat. No. 5,874,651, the entire content of which is incorporated hereinto expressly by reference.)
It has now been discovered that organic by-products having higher boiling points than cyclohexanone (usually obtained from the bottoms of a distillation operation to separate cyclohexanone from other reaction products during cyclohexanone production) can be converted to recoverable cyclohexanone and cyclohexanol using a catalyst having high aluminum oxide concentrations.
These, and other, aspects and advantages will become more clear after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof.
DETAILED DESCRIPTION OF THE INVENTION
The feed stream employed in the practice of the present invention includes organic by-products having higher boiling points than cyclohexanone. The preferred by-products are typically obtained from the bottoms of a distillation operation to separate cyclohexanone from other reaction products in the production of cyclohexanone by the oxidation of cyclohexane. One preferred feed stream is EP-310 ANON HEAVIES commercially available from BASF Corporation, Freeport, Tex., having the following distillation range:
Initial (@ 13.5 kPa)
110° C.
10 vol. % (@ 13.5 kPa)
135° C.
20 vol. % (@ 10 kPa)
142° C.
50 vol. % (@ 4.7 kPa)
147° C.
Final (75 vol. %) (@ 3.3 kPa)
183° C.
The preferred feed stream may includes at least about 40 wt. %, and typically between about 41.2 to about 51.0 wt. %, of higher oxidation products (i.e., organic products having a higher boiling point than cyclohexanone). Usually, the feed stream will contain between about 8.3 to about 11.8 wt. % of unknown organic constituents. In addition, the preferred feed stream may have the following components: dicyclohexylether (between about 7.8 to about 17.4 wt. %); pentyl cyclohexyl ether (between about 1.4 to about 4.4 wt. %); 1.1-bicyclohexylether (between about 0.9 to about 2.3 wt. %); 2-cyclohexylidene cyclohexanone (between about 10.0 to about 16.9 wt. %); other ketones (between about 1.2 to about 1.7 wt. %); cyclohexanol (between about 1.2 to about 7.7 wt. %); diols (between about 3.8 to about 5.6 wt. %); higher oxidation products (between about 8.0 to about 13.0 wt. %); cyclohexanone dimer (between about 1.6 to about 2.7 wt. %); and dicyclohexyloxy methane (between about 0.4 to about 0.6 wt. %).
The feed stream is brought into contact with an amount of a catalyst with a high aluminum oxide concentration suffice to convert a substantial proportion of unknown organic components in the feed stream into cyclohexanone and/or cyclohexanol. In this regard, the preferred catalyst is one which has an aluminum oxide (Al
2
O
3
) content of at least about 95 wt. %, and more preferably greater than about 99 wt. %. One particularly preferred catalyst is BASF Catalyst D 10—10 commercially available from BASF Corporation, Geismar, Louisiana, which is substantially entirely aluminum oxide with minor (i.e., less than 0.1 wt. %) of each of Na, K and Fe impurities.
According to the present invention, only relatively small, but effective amounts of the aluminum oxide-rich catalyst need to be brought into contact with the feed stream. In this regard, it is preferred that the catalyst be employed in a maximum of amount of about 10 wt. %, or more preferably about to about 2 wt. %, based on the total weight of the feed stream, and a minimum amount of about of about 0.1 wt. %, and preferably about 0.5 wt. %, based on the total weight of the feed stream.
The cyclohexanone and cyclohexanol that are obtained by the process of the present invention can be recovered conveniently by conventional distillation techniques, crystallization, or other separation processes well known to those in this art.
It is hypothesized that the increased yield is due to the increased conversion of enyl anone and other compounds to cyclohexanone and cyclohexanol. A comparison of the analysis of the feed and products from the reaction is shown below:
EP-310
No catalyst
Invention Product
Compound
(Feed)
Product
(D 10-10 Catalyst)
Enyl Anone
12.97 wt %
1.81 wt %
1.17 wt %
trans 1,2-
1.49 wt %
1.55 wt %
1.17 wt %
cyclohexanediol
RT 21.40 min
9,105
7,491
6,250
RT 25.17 min
1,314
1,258
705
RT 25.31 min
1,439
382
nd
RT 25.99 min
1,605
279
nd
RT 29.27 min
1,211
573
nd
RT 29.50 min
1,183
304
nd
The units of measure for the compounds noted above identified by their gas chromatograph retention times (RT) are in area counts. The decrease in area counts of the RT compounds above indicates that the addition of the aluminum oxide-rich (D10—10) catalyst promotes a reaction which consumes some or all of the RT compound.
REFERENCES:
patent: 3726888 (1973-04-01), Hatten et al.
patent: 3946076 (1976-03-01), Paasen et al.
patent: 3974221 (1976-08-01), Duggan
patent: 4082788 (1978-04-01), Mims
patent: 4173586 (1979-11-01), Payne et al.
patent: 4271315 (1981-06-01), Cywinski
patent: 4272326 (1981-06-01), Hertzog et al.
patent: 4306944 (1981-12-01), Murthy et al.
patent: 4316775 (1982-02-01), Nash
patent: 4994152 (1991-02-01), Kaibel et al.
patent: 5015787 (1991-05-01), Van Peppen
patent: 5168983 (1992-12-01), Tan et al.
patent: 5874651 (1999-02-01), McNabb et al.
McNabb Andrew J.
Williams Deirdre R.
BASF Corporation
Nixon & Vanderhye P.C.
Padmanabhan Sreeni
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