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

Definitions

• the present invention relates to a woven diaphragm for aqueous electrolytes such as alkali chloride solutions, hydrochloric acid solutions and for the water electrolysis of water mixed with acids and / or alkalis.
• non-woven fibers made of asbestos fibers have been used as diaphragms in alkali chloride electrolysis.
• the need to largely replace asbestos has already led to proposals to use fluorocarbon polymers for diaphragms in the form of fabrics or foils, possibly including inorganic fiber structures.
• PVC fabrics have been used in the diaphragm process for hydrochloric acid electrolysis.
• Polytetrafluoroethylene fiber fabrics which have been rendered hydrophilic by an acid and / or radiation treatment have already been proposed for water electrolysis.
• An ideal diaphragm must meet a variety of requirements, such as resistance to the electrolytes and the reaction products, sufficient porosity for the electrolyte passage, good separation properties for the reaction products and low ohmic resistance.
• the present invention now provides diaphragms which are characterized in particular by their weave.
• the present invention relates to a woven diaphragm for electrolytic processes, which is characterized in that both warp and weft threads consist of multifilament threads, at least the multifilament weft thread being untwisted or up to max. 200 tours, preferably up to max. 50 tours, twisted per meter.
• the warp multifilaments can have a twist of 0 to 400 turns per meter, preferably about 100 to 200 turns per meter.
• Warp and weft threads are preferably woven in plain weave, particularly preferably plain weave,.
• the essentially untwisted or low-speed twisted weft threads give the diaphragm a capillarity that is sufficient porosity for the electrolyte passage with a good separation effect for the electrolysis products.
• PVDF Polyvinylidene fluoride
• PPS polyphenylene sulfide
• Ryton trademark of Philipps Petroleum
• fluorocarbon polymers are polyethylene tetrafluoroethylene and copolymers, or polytetrafluoroethylene, especially for sodium chloride electrolysis.
• threads composed of continuous filaments are used in particular. If twisted threads are used as warp threads, these can also be constructed from staple fibers, weaving with spinning flake auxiliaries and, if appropriate, the auxiliary being subsequently removed. If untwisted continuous threads are used as warp threads, the multifilament must be treated with finishing or layering agents before weaving. A twisting with at least 100 tours / m eliminates the use of such means and the effort for their subsequent removal.
• Preferred diaphragms according to the invention have 4 to 28 wefts per cm, preferably 8 to 20 wefts per cm.
• the titer should be 280 to 1100 dtex, single or double, preferably 300 to 600 dtex, double.
• the individual thread is preferably composed of 20 to 70 individual filaments, preferably 35 to 55 individual filaments.
• the chain preferably consists of 25 to 100 warp threads per cm, particularly preferably 45 to 70 warp threads per cm.
• the titer is preferably also 280 to 1100 dtex, particularly preferably 350 to 700 dtex.
• the warp thread can also have a twist of 0 to 400 turns per meter, preferably 100 to 150 turns per meter.
• Warp and weft are preferably selected within the above limits so that the diaphragm has a density of 200 to 600 g / m 2 , particularly preferably 300 to 500 g / m l .
• the cloth After weaving, the cloth can be compacted by calendering.
• the voltage drop during electrolysis at the diaphragm is increased as a result, but a purer quality of the gaseous electrolysis products is achieved.
• the multifilament is woven in a grosgrain weave with 57 warp threads per cm and 11.5 weft threads twice per cm.
• the diaphragm is installed in a test electrolytic cell with graphite electrodes.
• the graphite electrodes have vertical slots in a known manner.
• the electrodes were 11 cm high and 7.3 cm wide. The distance between the electrodes was 4 mm.
• the diaphragm was clamped between the electrode frames with rubber seals. 23% hydrochloric acid is introduced into the electrode chambers separated by the diaphragm. Depleted 18% hydrochloric acid escapes on the cathode side together with hydrogen and on the anode side together with chlorine.
• the temperature of the hydrochloric acid was 85 ° C.
• the electrolysis was operated with a current density of 5 kA / m2. A voltage drop of 2.32 volts is measured between the electrodes. On the cathode side there was 2.7% chlorine in the hydrogen the purity of the chlorine on the anode side was 99.7%.
• Example 1 The diaphragm used in Example 1 was additionally calendered under heat and pressure. The electrolysis was carried out in the same manner as in Example 1. There was a voltage drop of 2.43 volts. The hydrogen produced on the cathode side had 0.7% chlorine, the purity of the chlorine produced on the anode was 99.5%.
• Example 1 A diaphragm as in Example 1 was used and the electrolysis was carried out in the same way as in Example 1. However, 1% orthodichlorobenzene was added to the hydrochloric acid as an organic impurity. The result was a voltage drop of 2.36 volts, a purity of the chlorine of 99.8% and contamination of the hydrogen gas with 1% chlorine.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)

Applications Claiming Priority (2)

Publications (3)

Family

ID=6201252

Family Applications (1)

Country Status (4)

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• 1983
  • 1983-06-11 DE DE19833321159 patent/DE3321159A1/de not_active Withdrawn
• 1984
  • 1984-05-30 DE DE8484106154T patent/DE3473302D1/de not_active Expired
  • 1984-05-30 EP EP84106154A patent/EP0131724B1/fr not_active Expired
  • 1984-06-06 US US06/617,691 patent/US4539082A/en not_active Expired - Fee Related
  • 1984-06-08 DD DD84263968A patent/DD222045A5/de not_active IP Right Cessation

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