Organic compounds -- part of the class 532-570 series – Organic compounds – Sulfur containing
Reexamination Certificate
2002-08-28
2004-04-20
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Sulfur containing
C502S109000
Reexamination Certificate
active
06723881
ABSTRACT:
FIELD OF THE INVENTION
This application relates to the conditioning and use of ion-exchangers for the production of bisphenols.
The present application relates, in particular, to the conditioning of monodisperse cation-exchangers and anion-exchangers and also to the use thereof as catalysts, in particular for the catalysis of condensation reactions.
BACKGROUND OF THE INVENTION
Condensation reactions, such as the synthesis of bisphenols, for example, which is generally undertaken by acid-catalysed conversion of phenols with carbonyl compounds, are known from the literature. The latter reaction is generally carried out in fixed-bed or fluidised-bed reactors, as well as in reagent columns.
For example, catalysts consisting of cross-linked sulfonated polystyrene resins (acidic ion-exchangers) are conventionally used in the synthesis of bisphenols.
These ion-exchangers may optionally be chemically modified by covalently or ionically bonded co-catalysts and are macroporous or gel-like (U.S. Pat. Nos. 4,191,843; 3,037,052). According to U.S. Pat. No. 5,233,096, jetted suspension-polymerised styrene copolymers that have been functionalised with strongly acidic functional groups are employed for the condensation reaction of phenol with aldehydes or ketones to form bisphenols.
In the commercial form the ion-exchangers contain 45 to 85 wt. % water. In order to avoid a competition of water relative to the feed materials at the catalytic points and consequently to avoid a decrease in the activity of the ion-exchanger, for use in the course of the production of technically important 2,2-bis(4-hydroxyphenyl)propane (BPA), for example, the water should be largely removed. Furthermore, by reason of their production process, standard commercial ion-exchangers are provided with certain amounts of acidic oligomer portions which, in the case of continuous flow, can be washed out with reaction solution and have a negative influence on the purity, thermostability and colour of products that are prepared with them.
With a view to improving the space-time yields and with a view to increasing the selectivities of production processes in which these ion-exchangers are employed as catalysts it is therefore necessary to condition the catalyst prior to initial use.
It is therefore an object of the present invention to condition ion-exchangers based on cross-linked sulfonated polystyrene resins in such a way that a contamination of the reaction product with acidic fragments in the course of condensation reactions is prevented. In the case of the synthesis of bisphenols which has already been described above, trouble-free starting with phenol/acetone mixtures is consequently to be guaranteed without activation losses occurring in the course of the transfer of the ion-exchanger which has been conditioned in this way into the reaction vessel and that the flows of material arising in the course of conditioning can be processed meaningfully and can optionally be recycled without unnecessary loss of material occurring.
In the case of the synthesis of bisphenols, various attempts to achieve this object have been described in the literature. For instance, a hydrous ion-exchanger can be dehydrated in the reaction vessel by rinsing with phenol, in which case water is entrained by flowing phenol. In this case a shrinkage of the ion-exchanger occurs which leads to an additional mechanical loading of the ion-exchanger and can consequently result in fracture of the grains. In addition, traces of oligomer are only removed inadequately with this procedure. Furthermore, this process is timeconsuming and the reaction vessel is not available for production during this period.
In U.S. Pat. No. 3,037,052 it is therefore recommended to dry the ion-exchanger at elevated temperatures (about 150° C.) prior to use for the synthesis of bisphenols. In this case, however, the rate of drying has to be controlled very precisely (cf. Zundel et al.
Physik. Chem. (Frankfurt), 59, 225 (1968)) and there is a risk of mechanical damage at the high temperatures.
The partial dehydration of the catalyst prior to decanting into the reactor is described in U.S. Pat. No. 5,146,007. 20 to 90% of the water is removed by vacuum drying or drying with a stream of carrier gas. Subsequently the catalyst is transferred into the reactor, and the residual water is removed by rinsing with phenol. With a procedure of this type, however, harmful water-soluble oligomer portions are not adequately removed. In EP-A-765 685 it is proposed firstly to wash the catalyst with water until a defined residual conductivity is attained, then to remove a part of the water by vacuum drying or carrier-gas drying and subsequently to reduce the water content down to <1% by continuous rinsing with phenol. Whilst this procedure provides for a separation of oligomer constituents, in practical implementation it is laborious, since special devices are necessary for the partial removal of water by vacuum technology or carrier-gas technology. Furthermore, large quantities of water and phenol accumulate which are contaminated with harmful catalyst constituents and cannot readily be returned to the process. In the case where washing with water and dehydration are implemented in the reactor container, production stoppages arise as a result of blockage of the container for the stated conditioning tasks.
In order to circumvent the disadvantages, described above, of the various conditioning processes, an integrated process for preparation of the catalyst is being developed that is suitable for the conditioning of ion-exchangers that are to be employed in condensation reactions.
DETAILED DESCRIPTION OF THE INVENTION
The application therefore provides a process for conditioning ion-exchangers, said process being characterised in that
a) the ion-exchanger which has been moistened with water is suspended in a unit (
1
) with oxygen-free, completely de-ionized water at 5 to 80° C., in particular 20 to 60° C., whereby in particular a volume ratio of 3 to 1.5 parts, preferably 2.5 to 2 parts, of ion-exchanger which has been moistened with water to 1 part of water is adjusted and whereby the content of dissolved oxygen in the completely de-ionized water which is employed is preferably no greater than 1 ppm, preferably no greater than 100 ppb, and whereby the content of dissolved or undissolved metallic ions in the completely de-ionized water which is used is preferably no greater than 1 ppm, preferably no greater than 0.5 ppm, for Fe, Co, Ni, Mo, Cr, Cu as individual components and is preferably no greater than 10 ppm, preferably no greater than 1 ppm, for the sum of the stated metals;
b) the suspension is agitated, preferably by stirring for between half an hour and 24 hours at 5 to 80° C., in particular 20 to 60° C., and subsequently an analysis of the supernatant aqueous solution in respect of its conductivity is carried out, in order to obtain an indication of the oligomer content of the ion-exchanger and the number of necessary washing cycles for step c);
c) the ion-exchanger is subjected to discontinuous washing with oxygen-free, completely de-ionized water until constant residual conductivity is attained; washing is effected preferably 5 to 50 times, in particular 10 to 25 times, depending on the conductivity, whereby, after discharge of the completely deionized water, in each instance 0.2 to 1.5 parts by volume of completely deionized water, relative to the ion-exchanger which has been moistened with water, are added, the mixture is agitated and the completely de-ionized water is discharged and the conductivity of the completely de-ionized water is examined at the outlet, whereby the conductivity at the end of the washing cycles is less than 100 microSiemens/cm, preferably less than 50 microSiemens/cm, in particularly preferred manner less than 20 microSiemens/cm, and whereby the content of dissolved oxygen in the completely de-ionized water which is employed is preferably no greater than 1 ppm, preferably no greater than 100 ppb, and whereby the content of dissolved or undissolved metalli
Bödiger Michael
Fennhoff Gerhard
Heydenreich Frieder
Klipper Reinhold
Neumann Rainer
Bayer Aktiengesellschaft
Gil Joseph C.
Mrozinski, Jr. John E.
Seng Jennifer R.
Shippen Michael L.
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