Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B25/00—Phosphorus; Compounds thereof
  • C01B25/10—Halides or oxyhalides of phosphorus
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
  • B01D3/36—Azeotropic distillation
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B25/00—Phosphorus; Compounds thereof
  • C01B25/16—Oxyacids of phosphorus; Salts thereof
  • C01B25/26—Phosphates
  • C01B25/455—Phosphates containing halogen
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B7/00—Halogens; Halogen acids
  • C01B7/19—Fluorine; Hydrogen fluoride
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B7/00—Halogens; Halogen acids
  • C01B7/19—Fluorine; Hydrogen fluoride
  • C01B7/191—Hydrogen fluoride
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D15/00—Lithium compounds
  • C01D15/005—Lithium hexafluorophosphate

Definitions

• the present technology pertains to azeotropic or azeotrope-like compositions of phosphorus pentafluoride (PF 5 ) and hydrogen fluoride (HF). More particularly the invention pertains to such azeotropic and azeotropic-like compositions that are useful intermediates in the production of lithium hexafluorophosphate (LiPFe).
• PF 5 phosphorus pentafluoride
• HF hydrogen fluoride
• LiPF 6 is a highly conductive salt that is used in lithium ion batteries.
• a lithium ion battery is made up of an anode which is typically carbon, a cathode made of a metal oxide, a separator and an electrolyte which contains LiPF 6 .
• Lithium ion batteries have found use in personal electronics such as cell phones and laptop computers as well as in hybrid electric vehicles. Lithium ion batteries are ideal for these applications due to their high energy density. The higher the energy density, the smaller and lighter the battery for a given application. Lithium ion batteries also operate at higher voltage and have a longer shelf life than other common rechargeable batteries.
• LiPF 6 is manufactured by using lithium fluoride (LiF) and phosphorus pentafluoride PF 5 as starting materials.
• LiF lithium fluoride
• PF 5 phosphorus pentafluoride
• U.S. Patent No. 5,935,941 to Bonnet et al which involves reacting PF 5 gas, alone or accompanied by HC1, and a solution of LiF in HF.
• PF 5 is produced along with other reaction products, and must be purified prior to removing those other reaction products.
• a method of producing PF 5 more directly by reacting elemental phosphorus (P) and fluorine (F 2 ) is described in U.S. Patent Application Serial No. 12/722,390, filed on March 11, 2010.
• the present technology provides an azeotropic or azeotrope-like composition
• azeotropic or azeotrope-like composition comprising, consisting essentially of, or consisting of phosphorus pentafluoride (PF 5 ) and hydrogen fluoride (HF), and methods of producing such a composition.
• the composition consists essentially of phosphorus pentafluoride (PF 5 ) and hydrogen fluoride (HF)
• additional components may be present to the extent that they do not materially affect the azeotropic or azeotrope-like properties of the composition.
• an azeotropic or azeotrope-like composition that comprises HF and PF 5 .
• the HF is in an amount from about 0.01 weight percent to about 12 weight percent based on the total weight of the azeotropic or azeotrope-like composition
• the PF 5 is in an amount from about 88 weight percent to about 99.99 weight percent based on the total weight of the azeotropic or azeotrope-like composition
• the azeotropic or azeotrope-like composition has a boiling point of from about -13 °C to about 0 °C at a pressure of from about 268 psia to about 377 psia.
• a method of forming an azeotropic or azeotrope-like composition of HF and PF 5 includes providing HF from a source of HF, providing PF 5 from a source of PF 5 , and combining the HF and the PF 5 to form the azeotropic or azeotrope-like composition.
• Figure 1 provides a plot of the vapor pressures of the mixtures formed in Example 1 below, as measured at -13 °C, -10 °C, -5 °C and 0 °C.
• the present technology provides an azeotropic or azeotrope-like compositions that comprise, consist essentially of, or consist of, phosphorus pentafluoride (PF 5 ) and hydrogen fluoride (HF), and methods of producing such compositions.
• one method includes forming an azeotropic or azeotrope-like composition comprising, consisting essentially of, or consisting of HF and PF 5 by combining HF and PF 5 in amounts effective to form the azeotrope or azeotrope-like composition at a suitable temperature and a suitable pressure.
• azeotrope-like is intended in its broad sense to include both compositions that are strictly azeotropic and compositions that behave like azeotropic mixtures.
• azeotrope-like compositions can be compositions for which the bubble point curve remains relatively constant, dropping by less than about 2%, over the compositional range.
• thermodynamic state of a fluid is defined by pressure, temperature, liquid composition, and vapor composition.
• An azeotropic mixture is a system of two or more components in which the liquid composition and vapor composition are equal at the stated pressure and temperature. In practice, this means that the components of an azeotropic mixture are constant boiling and cannot be separated during distillation.
• Azeotrope-like compositions are constant boiling or essentially constant boiling.
• the composition of the vapor formed during boiling or evaporation (under substantially isobaric conditions) is identical, or substantially identical, to the original liquid composition.
• the liquid composition changes, if at all, only to a minimal or negligible extent.
• non-azeotrope-like compositions in which, during boiling or evaporation, the liquid composition changes to a substantial degree. All azeotrope-like compositions of the invention within the indicated ranges as well as certain compositions outside these ranges are azeotrope-like.
• azeotrope-like compositions there is a range of compositions containing these components in varying proportions that are azeotrope-like. All such compositions are intended to be covered by the term "azeotrope-like" as used herein.
• the boiling point of the liquid azeotropic or azeotrope-like composition is fixed and the composition of the vapor above the boiling liquid composition is essentially that of the boiling liquid composition, such that essentially no fractionation of the components of the liquid composition takes place.
• Both the boiling point and the weight percentages of each component of the azeotropic or azeotrope-like composition may change when the azeotrope or azeotrope-like liquid composition is subjected to boiling at different pressures.
• an azeotropic or azeotrope-like composition may be defined in terms of the relationship that exists between its components, in terms of the compositional ranges of the components, or in terms of weight percentages of each component of the composition characterized by a fixed boiling point at a specified pressure.
• One method of forming an azeotropic or azeotrope-like composition of HF and PF5 includes providing HF from a source of HF, providing PF5 from a source of PF5, and combining the HF and the PF5 to form the azeotropic or azeotrope-like composition.
• the HF and the PF5 can be provided in effective amounts from their respective sources.
• An effective amount each component is an amount that, when combined with the other component(s), results in the formation of an azeotropic or azeotrope-like composition of the components.
• Azeotropic or azeotrope-like compositions of the present technology can generally include HF in an amount from about 0.01 weight percent to about 12 weight percent based on the total weight of the azeotropic or azeotrope-like composition, and PF5 in an amount from about 88 weight percent to about 99.99 weight percent based on the total weight of the azeotropic or azeotrope-like composition.
• an azeotropic or azeotrope-like composition having a boiling point of about 0 °C, where the azeotropic or azeotrope-like composition comprises, consists of, or consists essentially of, HF in an amount of 0.5 ⁇ 0.4 weight percent based on the weight of the azeotropic or azeotrope-like composition and PF5 in an amount of 99.5 ⁇ 0.4 weight percent based on the weight of the azeotropic or azeotrope-like composition.
• an azeotropic or azeotrope-like composition can include HF in an amount from about 0.01 weight percent to about 12 weight percent, from about 0.01 weight percent to about 5 weight percent based on the total weight of the azeotropic or azeotrope-like composition, or from about 0.1 weight percent to about 1 weight percent based on the total weight of the azeotropic or azeotrope-like composition.
• the azeotropic or azeotrope-like composition can include PF5 in an amount from about 88 to about 99.99 weight percent based on the total weight of the azeotropic or azeotrope-like composition, from about 95 weight percent to about 99.99 weight percent based on the weight of the azeotropic or azeotrope-like composition, or form about 99 weight percent to about 99.9 weight percent based on the weight of the azeotropic or azeotrope-like composition.
• Azeotropic or azeotrope-like compositions of the present technology formed by combining HF and PF5 in amounts as described above, and such compositions can have a boiling point of from about -13 °C to about 0 °C at a pressure of from about 268 psia to about 377 psia.
• an azeotropic or azeotrope-like composition including HF and PF5 can have a boiling point of about -13 °C at a pressure of about 268 psia.
• an azeotropic or azeotrope-like composition including HF and PF5 can have a boiling point of about -10 °C at a pressure of about 289 psia. In another example, an azeotropic or azeotrope-like composition including HF and PF5 can have a boiling point of about -5 °C at a pressure of about 329 psia. In another example, an azeotropic or azeotrope-like composition including HF and PF5 can have a boiling point of about 0 °C at a pressure of about 377 psia.
• an azeotropic or azeotrope-like composition HF and PF5 can be formed during a PF5 production process.
• Such an example can include reacting a phosphorous (P) feed stream and a fluorine (F 2 ) feed stream to yield a reaction product that includes PF5, HF and by-products.
• the source of the PF5 and the HF can be the reaction product.
• the PF 5 in the reaction product can result from the reaction of phosphorous in the phosphorous (P) feed stream and fluorine in the fluorine (F 2 ) feed stream.
• the HF in the reaction product can result in several ways, including but not limited to impurities in the fluorine (F 2 ) feed stream and reactions of the PF 5 with moisture that may be present.
• F 2 is typically generated from HF, and a fluorine (F 2 ) feed stream can thus include some amount of HF, such as from about 0.1 weight percent to about 5 weight percent based upon the total weight of the fluorine (F 2 ) feed stream.
• the PF 5 in the reaction product is exposed to moisture, it will react to form HF and POF 3 .
• the by-products can include at least POF3.
• An azeotropic or azeotrope-like composition HF and PF5 can be formed by removing the by-products prior to combining the HF with the PF 5 to form the azeotropic or azeotrope-like composition.
• PF 5 can be purified by using HF to separate the PF 5 from a composition containing PF 5 and at least one additional compound.
• the at least one additional compound can be, for example, an impurity.
• the source of the PF 5 can be a composition containing PF 5 and at least one additional compound, and the HF can be provided in an amount sufficient to form an azeotropic or azeotrope-like composition of the PF 5 and the HF.
• the method can include separating the azeotropic or azeotrope-like composition from the at least one additional compound.
• a composition can be purified by utilizing PF 5 to remove HF from the composition.
• the source of HF can be a composition comprising HF and at least one additional compound, and the PF 5 can be provided in an amount sufficient to form an azeotropic or azeotrope-like composition of the PF 5 and the HF.
• the at least one additional compound can be any compound, including but not limited to POF 3 , LiF, LiPF 6 , a compound miscible with AsF 5 , or combinations thereof.
• the method can include separating the azeotropic or azeotrope-like composition from the at least one additional compound. Separating the azeotropic or azeotrope-like composition from the at least one additional compound can be accomplished in any suitable manner, including for example distillation, flash separation, or other art recognized separating methods. In one example, the at least one additional compound does not form an azeotropic or azeotrope-like composition with PF 5 , HF or a mixture of PF5 and HF. In another example, the at least one additional compound does form an azeotropic or azeotrope-like composition with PF5, HF or a mixture of PF5 and HF.
• Azeotropic or azeotrope-like compositions of PF5 and HF were formed by the following procedure.
• a vapor liquid equilibrium (VLE) cell was constructed of stainless steel which was fitted with two vapor ports. One vapor port was connected to a pressure transducer that had been previously calibrated with a dead weight tester. The other port was used to evacuate and fill the VLE cell. Before being put into service, the VLE cell it was exposed to 19% F 2 / 81% 2 at a pressure of about 30 psi and then evacuated to remove any organic impurities. The VLE cell was then completely evacuated. To start the procedure, 112.1 gm of degassed PF 5 was charged into the VLE cell. The VLE cell was immersed in a bath with a thermostat, which was maintained at temperature between -14 and 0°C until equilibrium was achieved.
• the pressure was recorded when equilibrium was achieved and the VLE cell was removed from the bath and frozen in liquid nitrogen. An initial charge of HF was then added to the frozen VLE cell in an amount of 0.46 gm. The VLE cell was allowed to warm to the bath temperature and was then placed back in the bath with the thermostat. HF was incrementally added and the equilibrium pressure was recorded after each addition. Due to the relatively high pressure of PF5, the mass of material in the vapor phase was not neglected. The mass of material in the vapor space was calculated from the known volume of the cell and the vapor density of PF5. The overall liquid composition was then corrected by subtracting the mass of HF and PF5 in the vapor space from the bulk amount added to the cell.
• the experimental data is shown in Figure 1.
• the scatter in the data at -13° C is due to variations in the bath temperature at that condition during the testing.
• the pressures at -13° C to 0° C reach a maximum, indicating that an azeotrope was formed.
• the azeotrope-like region extends to at least 12 wt% HF.
• a composition of LiPF 6 crystals can be purified by using PF5 to form an azeotropic or azeotrope-like composition with HF that adheres to the L1PF 6 crystals in the following manner.
• LiPF 6 can be prepared by bubbling PF 5 through a solution of LiF dissolved in HF. Approximately half of the HF evaporates and the crystals can be filtered from the solution. Because the crystals have a small amount of HF adhering to them, PF5 can be swept over the surface of the crystals. An azeotropic or azeotrope-like composition of HF and PF5 forms and can be removed from the system. The resulting L1PF6 crystals have a reduced HF content.
• Example 1 The experimental data in Example 1 was used to regress the vapor liquid equilibrium of HF and PF5 over a temperature range of -60 to 15°C.
• the azeotropic compositions at temperatures between -60 and 10°C are given in Table 1.

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• 2011
  • 2011-04-29 US US13/097,836 patent/US8883707B2/en not_active Expired - Fee Related
  • 2011-06-27 JP JP2013518515A patent/JP2013536144A/ja not_active Withdrawn
  • 2011-06-27 KR KR1020127033810A patent/KR20130114601A/ko not_active Withdrawn
  • 2011-06-27 EP EP11810081.7A patent/EP2595916A4/en not_active Withdrawn
  • 2011-06-27 WO PCT/US2011/041945 patent/WO2012012107A2/en not_active Ceased
  • 2011-06-27 CN CN2011800323676A patent/CN102958830A/zh active Pending

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