Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2002-10-15
2004-01-27
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S727000
Reexamination Certificate
active
06683223
ABSTRACT:
The present invention provides fluidised bisphenol dust containing bisphenol dust and water, a process for preparing this and a process for preparing a bisphenol, wherein fluidised bisphenol dust is supplied to the process.
Bis(4-hydroxyaryl)alkanes, called bisphenols in the following, are important as starting materials or as intermediates for preparing a large number of commercial products. Bisphenols can be prepared by the condensation of phenols and carbonyl compounds. Substituted or unsubstituted phenols may be used.
The condensation product from the reaction between phenol and acetone, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A, BPA), is of particular industrial importance. BPA is used as the starting material for preparing many different types of polymer materials such as, for example, polyarylates, polyetherimides, polysulfones and modified phenol/formaldehyde resins. Preferred areas of application include the preparation of epoxy resins and polycarbonates.
Processes for preparing bisphenols by acid catalysed reaction of phenols with carbonyl compounds are known, for example, from U.S. Pat. No. 2,775,620 and EP-A-0 342 758.
Bisphenols of the general structure may be prepared by processes which are analogous to the processes for preparing BPA.
Bisphenols and in particular bisphenol A are advantageously converted into the form of so-called prills (prills are spherical solid particles which may be prepared by solidifying molten droplets in a stream of gas) or flakes. This enables simple storage, simple transport and simple handling procedures.
When producing bisphenol prills and bisphenol flakes or when otherwise handling bisphenols, a fine bisphenol dust is produced which consists of high purity bisphenol. The dust is tacky and difficult to handle. Handling this dust involves the risk of dust explosions. For this reason, the bisphenol dust is usually disposed of and, for example, incinerated, which entails a costly manual handling procedure and extensive safety precautions due to the risk of dust explosions. This has the disadvantage that disposal of the dust represents destruction of the valuable raw material bisphenol and in addition this procedure is not economically viable due to the high handling costs.
The present invention is therefore based on the object of providing a process for simplifying the handling of bisphenol dust and the possibility of making economic use of the dust.
This object is achieved by the provision of a process for fluidising bisphenol dust. This process enables the supply of bisphenol dust to the process for preparing bisphenols.
Thus, the invention provides a process for fluidising bisphenol dust, consisting of adding 0.1 to 10 parts by weight of water per 1 part by weight of bisphenol dust.
The invention also provides fluidised bisphenol dust containing 0.1 to 10 parts by weight of water per 1 part by weight of bisphenol dust.
The invention also provides a process for preparing a bisphenol, wherein fluidised bisphenol dust containing 0.1 to 10 parts by weight of water per 1 part by weight of bisphenol dust is supplied to the process before, during or after reaction of a phenol with a carbonyl compound.
Bisphenols in accordance with the invention are any bisphenols at all. Bisphenol A is preferred.
Phenols in accordance with the invention are any substituted phenols at all, unsubstituted phenol being preferred.
Carbonyl compounds in accordance with the invention are any carbonyl compounds at all. Acetone is preferred.
The amount of water used according to the invention is 0.1 to 10 parts by weight, preferably 0.15 to 1 part by weight, particularly preferably 0.2 to 0.4 parts by weight per 1 part by weight of bisphenol.
The fluidised bisphenol dust may preferably be supplied to the process for preparing a bisphenol without removing the water.
The fluidised bisphenol dust is preferably dissolved, preferably in a phenol, before being supplied to the process for preparing a bisphenol. This phenol is preferably the same phenol which is used in the process for preparing the bisphenol.
Supplying the fluidised bisphenol dust to the process for preparing a bisphenol may take place at any point during the process for preparing the bisphenol. Supply preferably takes place at the crystallisation stage in the process for preparing a bisphenol. Another preferred embodiment of the process is that in which supply of the fluidised bisphenol dust takes place at the mother liquor dewatering stage in the process for preparing the bisphenol.
In a preferred embodiment of the present invention, the bisphenol dust has a particle size of less than 1 mm, particularly preferably of less than 0.5 mm, very particularly preferably of less than 50 &mgr;m.
According to the invention, the particles which form the bisphenol dust may have any shape at all. They preferably have the form of fragments of geometric shapes, for example fragments of platelets or spheres.
According to the invention, fluidisation is understood to be production of the ability to flow. The ability to flow in this connection means, for example, that the fluidised bisphenol dust, under the effects of only the force of gravity, flows through a 50 cm long tube with a diameter of 20 cm at a sufficiently rapid rate, preferably at a rate greater than 300 kg per 10 minutes.
Bisphenol dust according to the invention preferably has a purity of greater than 95 wt. %.
Bisphenol dust according to the invention may also contain isomers and secondary products which are produced during the preparation of bisphenol.
In particular, so-called “start-up material”, which is produced in the form of a dust when starting up bisphenol A preparation, is also to be included within the expression bisphenol dust.
The process according to the invention for preparing a bisphenol, wherein fluidised bisphenol dust is supplied to the process before, during or after reaction of a phenol with a carbonyl compound, is preferably performed in such a way that the amount of bisphenol dust supplied to the process is substantially less than the amount of bisphenol produced overall by the process. The amount of bisphenol dust supplied is preferably less than 10% of the amount of bisphenol prepared by the process.
The process according to the invention has a number of advantages. The bisphenol dust fluidised with water does not emit any dust to the surrounding atmosphere when it is handled, as does the same non-fluidised bisphenol dust when it is handled. This means that there is no longer any risk of dust explosions. As a result of the possibility of supplying the fluidised bisphenol dust to the process for preparing bisphenol, difficult and expensive waste disposal of the dust is not required. The valuable raw material bisphenol is recovered.
The process according to the invention for preparing BPA is preferably based on the acid catalysed reaction of phenol and acetone, wherein there is preferably a ratio by weight of phenol to acetone in the reaction of greater than 5:1. The acid catalysts used may be homogeneous or else heterogeneous Brönsted acids or Lewis acids, that is, for example, strong inorganic acids such as hydrochloric acid or sulfuric acid. Gel-like or macroporous sulfonated cross-linked polystyrene resins (acid ion-exchangers) are preferably used. The following details refer to a process for preparation which makes use of acid ion exchangers as catalysts.
In order to produce higher selectivity, the reaction of phenol and acetone may be performed in the presence of suitable mercapto compounds as co-catalysts. These may either be homogeneously dissolved in the reaction solution or be fixed to the sulfonated polystyrene matrix via ionic or covalent bonds. The reaction unit is preferably a layer bed or a fluidised bed which is flowed through either upwards or downwards, or a column of the reactive distillation column type.
When reacting phenol and acetone in the presence of acid catalysts and mercapto compounds as co-catalysts, a product mixture is produced which contains, apart from unreacted phenol and optionally acetone, primar
Bödiger Michael
Heydenreich Frieder
Kostyszyn Nikolai
Lanze Rolf
Neumann Rainer
Gil Joseph C.
Preis Aron
Shippen Michael L.
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