Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B13/00—Diaphragms; Spacing elements
  • C25B13/04—Diaphragms; Spacing elements characterised by the material
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B3/00—Electrolytic production of organic compounds
  • C25B3/20—Processes
  • C25B3/25—Reduction

Definitions

• the present invention relates to a method for electrochemical production of alkali alcoholates and an electrolytic cell to be used for this purpose.
• the inventions are directed to such Production method in which aqueous salt solutions on the anode side can be used.
• Alkaline alcoholates (Na / KOMe / OEt etc.) are among the Standard products of the chemical industry, whereby especially those with alcohol components up to 4 Contains carbon atoms, valuable chemicals in the represent organic synthesis.
• DE3346131 also proposes an electrochemical Procedure in which using a Cation exchange membrane as separator material
• a Cation exchange membrane as separator material
• Akali metal ions from alcoholic salt solutions on the anode side are produced by the membrane in the cathode compartment migrate in which, under the evolution of hydrogen, alcohols are converted into their anions.
• US5,425,856 discloses a continuous one electrochemical process for the production of Alkaline alcoholates based on alcoholic salt solutions. This method has the disadvantage that in the anode compartment process-related chlorinated alcohol compounds as By-products arise, some of which are more pathogenic Character is well known.
• DE19603181 also proposes an electrochemical process for the preparation of alkali alcoholates.
• PCT / EP00 / 08278 describes a process for the production presented by alkali metals.
• you put in An anode solution an aqueous solution of an alkali metal salt and separates this compartment helium-tight from e.g. a cathode compartment having a steel cathode.
• Liquid electrolyte on the cathode side becomes a molten salt proposed. It is clear that with this method a Mixing of anolyte and catholyte under all circumstances must be avoided. Therefore, as a separator Solid electrolyte proposed that only the considered cations and in particular diffusion completely prevented by water into the cathode compartment.
• separators resistant to aqueous systems only coated ion-conducting solid electrolytes proposed.
• the object of the present invention was another electrochemical process for the production of To show alkali alcoholates, which has the disadvantages of Helps overcome the state of the art.
• this process from an economic and ecological point of view technical scale to be very well applicable. That is, that Method according to the invention while avoiding the emission pathogenic substances a cost-efficient representation of the should ensure desired products.
• the voltage used lower relative to the prior art methods be kept, which is a less expensive manufacture of the Alkaline alcoholates allowed.
• the catholyte Conductive salt e.g. the alkali alcoholate to be produced, in Orders of magnitude of ⁇ 5% by weight, preferably ⁇ 4% by weight, more preferably ⁇ 3% by weight and very particularly preferably ⁇ 2 % By weight are added.
• ion-conducting solid electrolytes that are possible for the person skilled in the art for the stated purpose can be used, provided they meet the above-mentioned requirements. Suitable solid electrolytes should also have a conductivity which is as selective as possible for the specific alkali ion and a specific resistance which is as low as possible. Solid electrolytes of this type are mentioned inter alia in GB 1155927, the disclosure of which in this regard is also included here.
• a solid electrolyte of the ⁇ -alumina type is preferably used.
• the solid electrolyte has the approximate composition Alk 2 O 11 Al 2 O 3 , where Alk is preferably sodium, potassium or lithium, depending on which alkali metal alcoholate is to be produced.
• the solid electrolyte can optionally also be equipped with the ion-conducting coatings described in PCT / EP00 / 08278. In this regard, the disclosure of PCT / EP00 / 08278 is considered to be included here.
• a variant according to the invention is preferred in which the Solid electrolyte on one or both sides with one or several ion-permeable electrically conductive layers is coated.
• the ion-permeable electrically conductive layer on the solid electrolyte evaporated or as an immersion layer on its surface fired.
• Manufacturing process for such coated Solid electrolytes can in principle be found in the literature (Edelmetall-Taschenbuch, ed. Degussa Ag, 2nd ed. Hüthig-Verlag Heidelberg; Thick film technology: a user's sorry. London, Andy. Cermalloy Div., Heraeus Inc., West Conshohocken, PA, USA.
• the solid electrolyte can all be familiar to the person skilled in the art Shapes such as sleeves, disks or tubes. However, preference is given to the two accessible surfaces in the form of a solid electrolyte a plane-parallel plate, preferably a disc, used.
• these are metal powders in the catholyte space of any kind, provided that under the circumstances are sufficiently stable and do not lead to contamination the alkali alcoholates when performing the process.
• Preferred powders to be used are nickel, tungsten, To name titanium, copper or steel powder. Especially the use of Hastelloy powders is preferred.
• Another powder that can be used is graphite. This can alone or in combination with those just described Metal powders or modified based on DE19802013 be used.
• Alcohol is the catholyte in electrolysis used, which is to form the alkali alcoholate.
• an anolyte one has larger ones with regard to the salt solutions to be used Freedoms. Such salts are preferably used Use electrolysis, which can be obtained inexpensively can.
• the concentration of the salt solution should be as possible be high. Saturated solutions of are therefore preferred Carbonates, chlorides, sulfates, sulfites, hydroxides etc. used. The use of. Is very particularly preferred Carbonates, sulfates and chlorides.
• the saline Anolyte solution should depend on the use of the solid electrolyte have such a pH at which this has maximum stability. Since it is the Solid electrolytes preferably around oxides of aluminum which is higher in the basic pH range have chemical stability, the anolyte is complete particularly preferred for pH values> 7, extremely preferred> 8 adjust.
• the current characteristic and thus the sales with a to achieve such procedures is very strong temperature dependent.
• the temperature should therefore be off Efficiency reasons are kept as high as possible.
• boiling of the anolyte or catholyte solutions can be avoided. Still can one above the boiling point of the one used Solutions work if you put them under pressure.
• the pressure resistance of each used solid electrolyte the amount of pressure one natural border.
• the temperature of the Anolytes during electrolysis in an interval of> -10 ° C, preferably> -5 ° C, to ⁇ + 0 ° C, preferably ⁇ -1 ° C, calculated from the boiling point of the anolyte.
• the temperature of the catholyte during electrolysis especially with a continuous feed in one Interval from> -45 ° C, preferably> -20 ° C, to ⁇ -5 ° C, preferably ⁇ -10 ° C, calculated from the boiling point of the catholyte set.
• the temperature of the catholyte is about 1 - 2 degrees higher than in the anolyte.
• a disk as a solid electrolyte with two electrolyte spaces, which in turn have an inlet and outlet, it is possible to design the process continuously.
• a washer with a diameter of 70 mm is fixed between two half-shells using an appropriate sealing system.
• the sealing system seals both cavities (anolyte and catholyte space) airtight and thus prevents the electrolyte solutions from crossing into one another.
• the electrolyte spaces (approx. 25 ml) can be flowed through in a defined manner using peristaltic pumps.
• the volume flow is advantageously chosen for the aqueous anolyte sols in a range from 0.1 l / h to 10 l / h, preferably 1 l / h to 2 l / h.
• the anolyte can be heated using a thermostat in order to adjust the temperature. If the anolyte compartment is filled with powder, a separator system (filter) should be connected upstream of the outlet line. With this procedure, the catholyte solution is also pumped through the catholyte compartment and optionally separated from entrained powder by means of a filter insert before leaving the catholyte compartment.
• the catholyte should not be continuously heated, and cooling may be provided. Only at the beginning of the experiment should the catholyte be run in the temperature range specified above in order to quickly obtain the desired reaction rate.
• its flow rate can be increased accordingly.
• the volume flow can be between 1 and 10 l / h, preferably in the range 2 to 5 l / h.
• the continuous cycle procedure causes the resulting gaseous products to be removed from the electrolyte compartments.
• the intermediate containers which were used as a pump template and for thermostatting can be equipped with nitrogen-blanketed reflux coolers which are open at the top.
• the anode material to be used in the process in question is familiar to the person skilled in the art.
• the materials listed in PCT / EP00 / 08278 are to be used for this purpose.
• a material as mentioned above for filling the anode space is also used as the anode material. The same must be stated for the cathode material.
• the Invention with an electrolytic cell comprising a Anode compartment containing at least one aqueous solution an alkali metal salt as anolyte Cathode compartment and a solid electrolyte as Membrane through which the anode compartment and the Cathode compartment are separated from each other, wherein the solid electrolyte is no further ion-conducting layer having.
• an electrolytic cell comprising a Anode compartment containing at least one aqueous solution an alkali metal salt as anolyte Cathode compartment and a solid electrolyte as Membrane through which the anode compartment and the Cathode compartment are separated from each other, wherein the solid electrolyte is no further ion-conducting layer having.
• Preferred electrolysis cells are otherwise based the preferred ones set out above for the process Embodiments.
• Another embodiment of the invention relates on the use of the invention Electrolytic cell for the production of alkali alcoholates. It is also a use analogous to PCT / EP00 / 08278 conceivable.
• the expression permeable to ions understood that due to Porosity and not due to defects (as with the Ion conduction) in the material ions through this material can diffuse.
• An arrangement of the solid electrolyte is designed so that an outsourcing of a sleeve (tube open at the top) in aqueous solutions is possible.
• This is the interior tightly sealed with a seal and glass top.
• the Glass top is with an outlet valve for pressure equalization and equipped for sampling.
• the sleeve is in one thermostable vessel fixed that in turn with a saturated soda solution is filled.
• the sleeve itself will filled with 30% sodium methylate solution.
• the Aging test is carried out at a temperature of 60 ° C carried out.
• the resistance of the solid electrolyte will by weekly determination of the water content in the Alcoholate solution checked. After 3 months the trial can be started be stopped without being in the alcoholate solution increased water content can be demonstrated.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
• Electrodes For Compound Or Non-Metal Manufacture (AREA)

Applications Claiming Priority (2)

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• 2002
  • 2002-10-02 EP EP02022077A patent/EP1312700A3/fr not_active Withdrawn
  • 2002-10-04 DE DE10246375A patent/DE10246375A1/de not_active Withdrawn
  • 2002-10-29 US US10/282,252 patent/US20030106805A1/en not_active Abandoned
  • 2002-10-30 JP JP2002316607A patent/JP2003193279A/ja active Pending

Patent Citations (6)

Non-Patent Citations (2)

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