Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Halogen or compound containing same
Reexamination Certificate
2001-02-15
2003-02-25
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Halogen or compound containing same
C502S226000, C502S227000, C502S228000, C502S229000, C502S231000
Reexamination Certificate
active
06524990
ABSTRACT:
BACKGROUND OF THE INVENTION
There is a need in the industry for scaleable processes that are capable of generating electrophilic fluorination (F
+
) agents with sufficient F
+
character, or alternatively, F
+
power, to affect electrophilic fluorination reactions of a wide variety of organic substrates with high selectivity, and are also safe and economical to produce and use.
Examples of F
+
agents which possess sufficient F
+
power and selectivity in fluorination reactions with organic substrates include bis(fluoroxy)difluoromethane (BDM) and fluoroxytrifluoromethane (FTM.) BDM and FTM can be produced in a cesium fluoride (CsF)-catalyzed reaction between fluorine and carbon dioxide or fluorine and carbonyl fluoride, as shown in the reaction schemes below.
The preparation and handling of the CsF catalyst is critical to its effectiveness as a catalyst. The CsF must be rigorously dried and totally free of water and hydrogen fluoride. Even a minimum exposure of the bulk catalyst bed to either water or hydrogen fluoride can result in an immediate and irreversible loss of catalytic activity.
One of the major problems in using a CsF catalyst is preparing CsF in an anhydrous condition, and subsequently loading a vessel with the dry material while preserving the anhydrous condition. A known method for preparing the CsF catalyst is to melt CsF at 800° C. and then allow the molten material to cool and solidify in a moisture-free glovebox. The solidified material is then finely ground using a combination of mortar/pestle and electric grinder. The catalyst material so prepared is transferred, inside the dry atmosphere of a glovebox, to the reactor.
A problem with the above method of catalyst preparation is the fine powder form of the activated catalyst material. When loaded into the catalyst vessel, the fine powder can create an unacceptable pressure drop across the vessel. This becomes especially problematic at the high gas flow rates that are required in large scale BDM and FTM technologies. Another problem arises when performing the above described catalyst preparation procedure on the scale required for commercial scale use. Commercial scale catalyst vessels can be too large and unwieldy to be handled in a conventional drybox. A further problem with the above described catalysts is the potential for channeling which compromises efficiency of the catalyst bed.
Other fluorides, such as potassium fluoride and sodium fluoride, have been shown to catalyze specific fluorination reactions.
Examples of processes for producing BDM and FTM using fluoride catalysts are described in the following publications:
Frederick A. Hohorst and Jean'ne M. Shreeve (
Journal of the American Chemical Society,
V.89, (1967), pages 1809-1010,) describe the static fluorination of carbon dioxide with a large (305%) molar excess of fluorine in the presence of a large (18 mmoles) molar excess of cesium fluoride to prepare BDM.
Ronald L. Cauble and George H. Cady (
Journal of the American Chemical Society,
V. 89 (1967), page 1962) describe a preparation of BDM in which carbon dioxide was reacted with nearly 100% excess fluorine in the presence of pulverized CsF as the catalyst.
Max Lustig, et al. (
Journal of the American Chemical Society, V.
89 (1967) pages 2841-2843) describe a low temperature preparation of fluoroxy compounds, including BDM, by catalytic fluorination of carbonyl halides and fluoroalkyl acid fluorides. Finely ground cesium fluoride was used in the examples.
U.S. Pat. No. 3,394,163 (Kroon, 1968) discloses preparation of BDM by treating an alkali metal oxalate with fluorine in the presence of an alkali metal fluoride or an alkaline earth metal fluoride catalyst.
U.S. Pat. No. 4,499,024 (Fifolt, 1985) discloses a continuous reaction for preparing BDM by reacting carbon dioxide and fluorine in the presence of CsF catalyst. The reactants are passed through a reactor, such as a nickel or nickel-lined tube containing particles or powder of cesium fluoride. In the examples, a 4:1 mole ratio of fluorine:carbon dioxide is used.
Michael J. Fifolt, et al. (
Journal of Organic Chemistry,
V.50 (1985) pages 4576-4582) disclose the production of BDM and FTM by the reaction of fluorine with carbon dioxide and carbon monoxide, respectively, using a cesium fluoride catalyst. It is reported that preparation of cesium fluoride by fusion and subsequent grinding under anhydrous conditions is critical for the reaction to occur.
U.S. Pat. No. 2,689,254 (Cady and Kellogg, 1954) discloses a process for preparing FTM by reacting carbon monoxide and fluorine in the presence of a catalyst comprising a copper ribbon coated with silver fluoride.
R. Craig Kennedy and George H. Cady (
Journal of Fluorine Chemistry,
V.3 (1973/74), pages 41-54,) report on the use of several fluoride catalysts, such as sodium fluoride, ammonium fluoride, and barium fluoride, in the preparation of FTM. Except for the fluorides prepared in the reactor, each catalyst was ground to a fine powder before it was added to the reactor.
The need remains for an effective catalyst that can be used in large scale fluorination processes; for example, a catalyst that will not create a large pressure drop across a vessel used in large scale production of BDM or FTM.
BRIEF SUMMARY OF THE INVENTION
This invention is directed to new active fluoride catalysts that are useful in producing electrophilic fluorination agents. The new active fluoride catalysts are especially useful in producing BDM from the reaction of fluorine with carbon dioxide and FTM from the reaction of fluorine with carbonyl fluoride. The fluoride catalyst comprises a mixture of two or more fluorides selected from a transition metal fluoride, an alkali metal fluoride and an alkaline earth metal fluoride. Alternately, the fluoride catalyst is one or more fluorides, such as alkali metal fluorides, alkaline earth metal fluorides, and/or transition metal fluorides, deposited on an inert support, such as a zirconium oxide (ZrO
2
) support. The catalysts of this invention are in the form of particles or pellets such that the surface area is preferably at least about 0.1 m
2
per gram.
In an embodiment of this invention, the active fluoride catalysts are formed by depositing an aqueous mixture of one or more of an alkali metal salt, an alkaline metal salt, and/or a transition metal salt on an inert support, heating the supported salts to evaporate the water, thoroughly drying the supported salts under dry nitrogen, and activating the salts by passing fluorine or fluorine-containing gas over the supported material to convert the salt to a fluoride.
In another embodiment of this invention, the active fluoride catalysts are formed by mixing together, in an aqueous medium, a transition metal salt, preferably a fluoride, and one or more of an alkali metal salt, alkaline earth metal salt, and/or another transition metal salt, heating the mixture to evaporate the water, extruding the dried mixture, breaking the extrudate into particles or pellets, thoroughly drying the particles under dry nitrogen, and activating the salts by passing fluorine or fluorine-containing gas over the supported material to convert the salt to a fluoride.
In another embodiment of this invention the above catalysts are used in fluorination reactions in which BDM is formed from the reaction of fluorine and carbon dioxide or FTM is formed from the reaction of fluorine and carbonyl fluoride.
In another embodiment of this invention, the above catalysts are formed in situ prior to reacting fluorine and carbon dioxide to form BDM or fluorine and carbonyl fluoride to form FTM.
The fluorination catalysts prepared by the method of this invention provide the following advantages compared to known catalysts:
eliminates the need for large scale melting and grinding equipment in making the catalyst;
the size of the catalyst particles prevents high pressure gradients in large scale fluorination reactors;
the catalysts can be made and activated in situ prior to using them in a fluorination reaction;
use of the cataly
Campion Beth Ann
Fowler Donald Elson
Henderson Philip Bruce
Syvret Robert George
Wilheim Frederick Carl
Air Products and Chemicals Inc.
Bell Mark L.
Bongiorno Mary E.
Hailey Patricia L.
LandOfFree
Active fluoride catalysts for fluorination reactions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Active fluoride catalysts for fluorination reactions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Active fluoride catalysts for fluorination reactions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3165471