Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D15/00—Lithium compounds
  • C01D15/08—Carbonates; Bicarbonates
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/14—Fuel cells with fused electrolytes
  • H01M8/144—Fuel cells with fused electrolytes characterised by the electrolyte material
  • H01M8/145—Fuel cells with fused electrolytes characterised by the electrolyte material comprising carbonates
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/14—Fuel cells with fused electrolytes
  • H01M2008/147—Fuel cells with molten carbonates
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0048—Molten electrolytes used at high temperature
  • H01M2300/0051—Carbonates
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/50—Fuel cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the present invention relates to an improved process for obtaining highly pure eutectic Li 2 CO 3 /LiKCO 3 , preferably for use in molten carbonate fuel cells.
• Patent US 7,060,219 describes equipment and a process for the continuous production of a eutectic mixture consisting of Li 2 CO 3 /LiKCO 3 in a molar ratio of 1:3.
• the production method comprises, among others, the steps of mixing Li 2 CO 3 and K 2 CO 3 , melting the mixture obtained, maintaining the mixture at a temperature greater than that of the melting point, cooling the mixture in a crucible, breaking up the block of carbonates obtained, pulverising and sieving the powder in order to obtain the desired granulometry.
• the above described process includes a step of melting the mixture of carbonates, and processing, following cooling of the molten carbonates, thus making the method costly and laborious .
• Patent WO 2005/096429 describes a process for obtaining a eutectic Li 2 CO 3 /LiKCO 3 mixture in a molar ratio of 1:3 consisting of mixing Li 2 CO 3 and K 2 CO 3 in powder form and grinding them in a ball mill for periods of time comprised of between 20 and 28 hours .
• this process has the advantage of not having the steps of melting the mixture of carbonates and processing, following cooling, of the molten carbonates and, thus being a faster and less costly method.
• the problem that has been dealt with by the inventors, and that lies at the heart of the present invention, is thus that of providing an improved method for preparing a highly pure eutectic Li 2 CO 3 /LiKCO 3 mixture in a molar ratio of 1:3, preferably a eutectic mixture where the content of K 2 CO 3 and hydrated K 2 CO 3 is below the X-ray analysis detection threshold.
• Said problem is resolved by an improved process for preparing a highly pure eutectic Li 2 CO 3 /LiKCO 3 mixture in a molar ratio of 1:3, as described in the appended claims .
• the starting potassium carbonate is K 2 CO 3 -3/2H 2 O.
• the potassium carbonate and lithium carbonate are mixed in a ball mill, preferably for a period of time greater than or equal to 90 hours.
• both the grinding spheres and the mill are made of alumina .
• Li 2 CO 3 and K 2 CO 3 starting salts are mixed in a ball mill in such a stoichiometric ratio as to obtain, by means of mechanical processing, the 62/38 Li 2 CO 3 /K 2 CO 3 eutectic mixture in which Li 2 CO 3 and the corresponding LiKCO 3 fusion compound are present in a ratio of 1:3.
• Li 2 CO 3 and K 2 CO 3 will be mixed in stoichiometric ratios comprised of between 3:1 and 1:1, preferably in a ratio of 1.7:1.
• water soluble K 2 CO 3 is absent, whilst LiKCO 3 , which has greatly reduced water solubility, is present.
• the high purity, of the eutectic mixture of the present invention allows its use in the production of a homogeneous electrolytic mixture to be used in molten carbonate fuel cells, wherein the carrier solution is a mixture of water with one or more organic solvents, according to the description in WO 2005/096429.
• the carrier solution is a mixture of water with one or more organic solvents, according to the description in WO 2005/096429.
• Example 2 shows a comparison example (example 3) wherein the eutectic mixture is produced by following the above described process, but using anhydrous potassium carbonate. Again in this case, it may be observed that the eutectic mixture obtained, despite mixing being carried out for 96 hours, contains potassium carbonate impurities .
• Table 1 also shows a comparison example (example 4) wherein the eutectic mixture is produced by following the above described process, but using a different purity of lithium carbonate (the RE and RPE-ACS codes indicated in table 1 refer to salts with different purity, as indicated in the Carlo Erba catalogue) .
• the RE and RPE-ACS codes indicated in table 1 refer to salts with different purity, as indicated in the Carlo Erba catalogue.
• potassium carbonate and anhydrous potassium carbonate are absent from the eutectic mixture obtained, and hence, mixing is complete. This shows that the desired eutectic mixture is attained when any kind of lithium carbonate is used with hydrated potassium carbonate .
• grinding times greater than 80 hours, preferably greater than 90 hours, and the use of hydrated potassium carbonate, preferably K 2 CO 3 -3/2H 2 O, are essential for obtaining the eutectic mixture of the invention.
• Table 2 shows a series of experiments preparing the eutectic mixture, performed by using the above described process, wherein various different -potassium carbonates (all hydrated) have been used.
• K 2 CO 3 MERCK, hydrated in the laboratory
• K 2 CO 3 Carlo Erba RPE-ACS, hydrated in the laboratory
• K 2 CO 3 -3/2H 2 O SIGMA-ALDRICH, purchased in sesquihydrate form

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Inorganic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
• Analysing Materials By The Use Of Radiation (AREA)

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• 2007
  • 2007-05-28 EP EP07736870A patent/EP2162393A1/de not_active Withdrawn
  • 2007-05-28 WO PCT/IT2007/000367 patent/WO2008146312A1/en active Application Filing

Non-Patent Citations (1)

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