US3567617A - Process for the production of olefin oxides - Google Patents

Process for the production of olefin oxides Download PDF

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Publication number
US3567617A
US3567617A US674783A US3567617DA US3567617A US 3567617 A US3567617 A US 3567617A US 674783 A US674783 A US 674783A US 3567617D A US3567617D A US 3567617DA US 3567617 A US3567617 A US 3567617A
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anode
cathode
compartment
olefin
diaphragm
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US674783A
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English (en)
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Walter Kronig
Peter Konrad
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Bayer AG
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Bayer AG
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D301/00—Preparation of oxiranes
    • C07D301/02—Synthesis of the oxirane ring
    • C07D301/03—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
    • C07D301/14—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with organic peracids, or salts, anhydrides or esters thereof
    • 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
    • C25B3/23—Oxidation

Definitions

  • This invention relates to a process for the production of olefin oxides.
  • olefin oxides can be produced from olefins by an electrochemical process in which an aqueous solution of a metal halide is electrolysed in an electrochemical system.
  • the olefin is introduced into the reaction in the proximity of the anode, followed by dehydrolialogenation of the halohydrin initially formed in an electrochemical system to form the olefin oxide (cf. Belgian patent specification No. 637,691 and French patent specification No. 1,375,973).
  • the electrolyte is transferred from the anode compartment through a diaphragm into the cathode compartment, olefin halohydrin being formed from the olefin introduced into the anode compartment under the electrochemical effect.
  • the olefin halohydrin, dissolved in the electrolyte passes through the diaphragm and is converted into the olefin oxide in the cathode compartment under the effect of the alkaline conditions prevailing therein.
  • This process is of particular importance in cases where the starting materials used are olefins which are present in gas form in the anode compartment under the reaction conditions selected, irrespective of whether the olefins used are themselves gaseous under the temperature and pressure conditions selected, or whether an inert gas is added which reduced the vapour pressure of the olefin to be reacted to such an extent that it is gaseous under the reaction conditions.
  • the gaseous olefin is intorduced into the zone between the anode and the cathode or, where the diaphragm usually required is present, in the zone between the anode and the diaphragm.
  • the gaseous olefins may be introduced into the zone described, for example at the lower end of the ver tical anode, although they are preferably supplied to this zone through the anode itself by providing the anode in a porous condition, in which case the anode may be positioned other than vertical.
  • the gasiform olefin is introduced into the current-line field between the anode and the Patented Mar. 2, 1971 cathode.
  • the desired electrochemical reaction may be carried out to good effect with systems such as these.
  • the gaseous olefin is not introduced into the intermediate zone between the anode and the cathode, but is introduced outside this intermediate zone into the anode zone which is on the side of the anode directed away from the cathode, i.e. the anode backside compartment. It has surprisingly been found that the electrochemical reaction also proceeds satisfactorily outside the current-line field.
  • the olefin is introduced as a gas and is converted into the olefin halohydrin in the space outside the intermediate zone be tween the anode and the cathode, with the olefin halohydrin thus formed passing into the zone between the anode and the cathode, or the diaphragm, in solution in the electrolyte.
  • Subsequent dehydrohalogenation of the halohydrin may be carried out in different ways.
  • the electrolyte may be passed from the intermediate compartment through the diaphragm into the cathode compartment where the halohydrin is then dehydro halogenated into the olefin oxide.
  • the anolyte containing the halohydrin with the catholyte outside the cell so that the olefin halohydrin is converted into the olefin oxide there. It has surprisingly been found that, despite the absence of the gaseous olefins in the intermediate zone between the anode and the cathode, the halohydrin passing through it does not undergo any undesirable changes.
  • One particular advantage of the novel arrangement is that the volt-age dro between the anode and the cathode is lower than it is in the conventional arrangement where the olefin gas is introduced between the anode and the cathode.
  • the interval between the anode and diaphragm in the new arrangement of this invention can be reduced to between one third and one sixth of the clearance required in the conventional system.
  • the drawing shown is an electrolytic cell 1 With anode 2 and a cathode 3 facing one another and with a diaphragm 4 between the electrodes.
  • an intermediate compartment or zone 5a anode/diaphragm
  • an anode backside compartment or zone 5b anode/ back wall of the cell.
  • the two zones 5a and 5b are interconnected, suitably by slots 6 in the anode.
  • the upper slot may be provided with a deflector 7 for purposes to be described below.
  • An aqueous metal halide solution is supplied to the anode backside compartment 5b through a pipe 8.
  • the catholyte leaves the cell through a pipe 9.
  • the olefin is introduced into the anode backside compartment 512 through a pipe 10, for example, by way of a frit, and rises upwards through it.
  • the excess, unreacted gas leaves the anode backside compartment 5b through a pipe 11 after it has been separated from the electrolyte in the upper part of the anode backside compartment.
  • Another empty space is provided above the cathode zone 3a through which the cathode gas is exhausted, for example by way of a pipe 12.
  • the catholyte leaving the system through the pipe 9 is resolved to separate further quantities of cathode gas from the catholyte which cathode gas leaves the system through a pipe 13 and which catolyte leaves the system through a pipe 14.
  • the gaseous olefins may be introduced into the anode compartment in various ways.
  • the olefinic gas may be introduced into the anode compartment filled with electrolyte on the side of the anode remote from the cathode, i.e. the anode backside compartment.
  • the upward flow of the gas in the anode backside compartment is used for internally cycling the anolyte, in which case the anolyte rises with the gas in the anode backside compartment and, following separation of most of the unreacted olefinic gas, flows downwards in the now largely gas-free intermediate compartment between the anode and the diaphragm.
  • the unreacted gas is separated for example at the upper liquid level of the anolyte by allowing the gas flowing through the liquid to pass over into a gas zone located above the liquid level, from which it can be removed for further processing.
  • a gas zone located above the liquid level, from which it can be removed for further processing.
  • the arrangement in terms of apparatus should be such that no more than about and preferably less than about 3 of the anode gas passes into the intermediate zone between the anode and the cathode or diaphragm.
  • connections be tween the anode zone and the intermediate zone.
  • These connections may be arranged in the cell itself, although it is also possible to provide them outside the cell. In general, it is of advantage to arrange these connections at the lower and upper ends of the anode.
  • the electrodes are advantageously arranged vertically and the olefin gas to be converted is introduced into the anode backside compartment at the lower end thereof, for example, through screens, frits or similar devices, in such a way that the olefin is not introduced into the region between the anode and cathode, but only into that region of the anode compartment which is remote from the cathode, i.e.
  • the anode backside compartment it is possible, for example in cases where titanium anodes are used, to use titanium anodes of the kind that are hollow over their entire area.
  • the part of the anode facing the cathode is made non-porous and coated with a noble metal, while the part of the anode which is remote from the cathode is porous and not coated with a noble metal.
  • solid anodes, impervious to the electrolyte and coated with a noble metal are used to carry out the process according to the invention, it is advisable to provide the noble metal coating on that side of the anode which faces the cathode. Accordingly, the gas flows upwards along that part of the anode which is not coated, while the anolyte, largely free of gas, flows downwards along that part of the anode which is coated with noble metal.
  • the anode surface may be regularly divided up into regions which are permeable and impermeable to the electrolyte. If anodes with a noble metal coating are used in an arrangement of this kind, the noble metal may be applied to that side of the anode facing the cathode and/or to that side of the anode remote from the cathode and, if desired, to those areas between the faces of the anode that are accessible to the electrolyte.
  • the anode is preferably arranged upright and the gas to be reacted is introduced into the anode backside compartment remote from the cathode.
  • vertical circulation of the anolyte may be dispensed with because the anolyte naturally has a free path to the cathode through the openings in the anode.
  • Internal streams may of course also flow between the anode backside zone and the intermediate zone through the openings in the anode.
  • the anodes with openings for the passage of the electrolyte may differ widely in shape.
  • Anodes which are advantageously in plate form may be provided with slots or holes.
  • Wire gauze anodes may also be used. It is of particular advantage to use anodes of expanded metal, in which case steps are preferably taken to ensure that the largest possible effective surface is also present between the two faces of the anode.
  • Suitable anode materials include, for example, graphite or platinum-coated titanium or other conventional materials. Titanium anodes in which the titanium surface is coated either wholly or in part with a noble metal, are particularly suitable for the present purpose. The titanium should be provided with a protective oxidic layer over those areas that are not coated with the noble metal. Although platinum is particularly suitable for use as the noble metal, it is also possible to use mixtures of platinum with other noble metals, particularly iridium and/ or rhodium, for the present purpose. Wire gauzes of iron or stainless steel are advantageously used as the cathode. The cathode and anode preferably have substantially the same surface area.
  • Gaseous mono-olefins such as ethylene, propylene and butylenes, and halogenated mono-olefins such as allyl chloride, for example, are particularly suitable starting materials for producing the olefin oxides.
  • the olefins may of course contain inert constituents such as, for example, ethane, propane or butane.
  • Aqueous solutions of metal halides such as for example sodium or potassium chloride or mixtures thereof are suitable electrolytes.
  • the salt concentration of the electrolyte may amount for example to between 2% and 20% and, preferably, to between 3% and 15%.
  • the aqueous electrolyte is introduced into the anode compartment and then transferred through the diaphragm and the cathode into the cathode compartment a rate of between about 10 and cc. per minute of electrolyte per 1 drn. of cathode area is suitable.
  • the catholyte issuing from the cathode compartment may then have the olefin oxide present in it removed by conventional means, such as by distillation for example, after which the catholyte may be returned to the anode compartment, thus completing the circuit.
  • the electrolyte from which the olefin oxide has been removed may be returned to the anode or cathode compartment.
  • the flow rate of electrolyte through the anode compartment may for example amount to between about 4 and 80 cc. per minute per dm. of anode area. If secondary products, which may be formed during electrolysis, have accumulated to a certain extent in the ciriculating electrolyte, it is advantageous to at least periodically remove a portion of the electrolyte from the circuit and to replace it with fresh electrolyte.
  • the throughput of olefin through the anode compartment may for example be selected in such a way that some 5% to 95% is reacted in a single passage.
  • Suitable diaphragms for the process according to the invention are made from inert materials such as, for example, asbestos, polyfluorohydrocarbons, polyolefins such as, for example, polypropylene, polyethylene, polybutylenes, polystyrenes, polyacrylonitrile, polyvinyl compounds such as, for example, polyvinyl chloride or copolymers of vinyl chloride and vinylidene chloride and others.
  • the materials may be used in the form of pervious or porous plates or films, or as fibres in the form of woven or non-woven fabrics. Fabrics woven from polyacrylonitrile fibres whose pore size has preferably been reduced by heat and/or pressure treatment, for example by calendering, have inter alia proved to be particularly suitable.
  • An anode and a cathode were arranged upright facing one another in an electrolytic cell (cf. figure).
  • the anode consisted of a 2 mm. thick sheet of solid titanium which was provided on the side facing the cathode with a layer of noble metal (platinum/iridium 70:30), and with a protective oxidic skin over those areas not coated with the noble metal.
  • the cathode consisted of a wire gauze of stainless steel.
  • a diaphragm of a polypropylene fabric 0.3 mm. thick was provided covering the cathode on the anode directed side thereof.
  • the anode was arranged in the cell in such a way as to provide an anode compartment defined by the anode and the rear wall of the cell, and an intermediate compartment defined by the anode and the diaphragm.
  • the gap between the anode and the diaphragm was 3.5 mm. wide.
  • the two regions were connected together by two mm. tall slots in the anode arranged above and below the platinum coating.
  • the upper slot was provided with a deflecting baffle.
  • the electrolytic cell was filled with a 5% aqueous potassium chloride solution. Four litres/hour of this solution were delivered into the anode compartment and from there through the diaphragm into the cathode compartment. The electrolyte was regenerated after leaving the cell.
  • the temperature of the electrolyte in the cell was 52 C.
  • the cell worked at atmospheric pressure. 45 litres/hour of a C -fraction containing 93% by weight of propylene (the rest being mostly propane) were introduced into the anode compartment through a frit arranged in the lower part of the anode/rear cell wall region in such a way that the gas flowed upward in this region. The excess unreacted gas left the electrolytic cell after it had been separated from the analyte through the gas zone situated at the upper end of this region.
  • the anode consisted of a 1.5 mm. thick expanded titanium plate of 1.75 dm. surface area which was arranged at a distance of 3.5 mm. from the diaphragm and which did not have any additional slots.
  • the anode had a noble metal coating of a 70:30 platinum/iridium mixture coated on the side remote from the cathode and between the two faces, while the side facing the cathode or diaphragm was not platinised.
  • Propylene gas to be reacted was introduced into the anolyte in the lower part of the anode/rear cell wall region as described in Example 1a.
  • the direct current flowing over a period of 4 hours at a DC. voltage of 3.55 volts corresponded to a current density of 10.9 amps per dm. of anode area.
  • the current yields of gaseous and liquid reaction products are set out in the following table:
  • EXAMPLE 2 The electrochemical system described in Example 1a was used with the modification that the anode which consisted of a 2 mm. thick sheet of solid titanium coated on the side facing the cathode with a 70:30 platinum/ iridium layer, was arranged at a distance of 3.5 mm. from the diaphragm covering the cathode and directly against the rear wall of the cell so that, in this case, the anode/ rear cell wall region did not exist.
  • the propylene gas to be reacted was introduced into the anolyte in the intermediate zone through a frit at the lower end of the space between the anode and the diaphragm in such a way that the gas flowed upwards in this space.
  • EXAMPLE 3 The electrochemical system described in Example lb was used with the modification that the expanded titanium plate used as the anode was covered on all sides with a thin layer of platinum.
  • the diaphragm lying on top of the cathode consisted of a 1.0 mm. thick blue asbestos paper.
  • a 4.3% aqueous sodium chloride solution was used as the electrolye.
  • the direct current flowing over a period of 4 hours at a DC. voltage of 3.7 volts corresponded to a current density of 11.5 amps/dm. of anode area.
  • the amounts of reaction products present in the cathode and the excess anode gas and in the catholyte were as follows in percentages of the current used:
  • An electrochemical system of the kind described in Example 1a was used with the modification that the anode and cathode each had an area of 7.5 dm. for a width of 100 mm. and a height of 750 mm.
  • the interval between the anode and the diaphragm was 5 mm.
  • the connecting slots between the regions of the anode compartment were mm. tall.
  • the electrolytic cell was filled with a 5% aqueous potassium chloride solution of which 17.5 litres/hour were delivered into the anode compartment and from there through the diaphragm into the cathode compartment.
  • the temperature of the electrolyte in the cell was 52 C.
  • the cell operated at atmospheric pressure. 90 litres/hour of a C -fraction containing 48% of ethylene (the rest being mostly ethane) were introduced into the anode/rear cell wall region of the anode compartment. 85% of the ethylene introduced was reacted on passing through the anode compartment.
  • a DC. voltage of 3.6 volts across the electrodes By applying a DC. voltage of 3.6 volts across the electrodes, a direct current with a current density of 11.1 amps/dm. flowed for a period of 4 hours.
  • the gaseous and liquid reaction products leaving the cell in the cathode and the excess anode gas and in the catholyte were analysed and used to calculate the current yield:
  • the electrolytic system for reacting the olefin was retained, except that the diaphragm of the cell was replaced by a 1.1 mm. thick asbestos paper diaphragm.
  • the apparatus was supplemented by a 120 cm. tall, 2.5 cm. diameter dehydrohalogenation column filled with 4-mm. glass Raschig rings which was provided with a brine-cooled receiver and whose bottom end was indirectly heated. Both anolyte from the anode compartment and the catholyte from the cathode compartment of the cell were introduced into the middle of the column through pump lines and, following separation of the reaction products, were returned to the electrolytic cell through a pH, a density and a temperature control system.
  • the electrolytic cell was filled with a 5% aqueous potassium chloride solution of which 2 litres/hour were introduced free of gas into the dehydrohalogenation column from the anode/ rear cell wall region and from the cathode zone of the cell, and, following separation of the volatile products from the bottom of the column kept at boiling temperature, were returned from the dehydrohalogenation column in equal parts to the cathode and anode compartment of the cell by way of the control systems.
  • pH-control involved the addition of hydrochloric acid to the electrolyte in such a way that the recycle electrolyte had a pH-value of between 7 and 8.
  • Density control regulated the potassium chloride content by the addition of water to the recycle electrolyte.
  • Temperature control regulated the temperature of the recycle electrolyte in such a way that the temperature of the electrolyte in the electrolytic cell amounted to 52 C.
  • the cell operated at atmospheric pressure and the dehydrohalogenation column at mm. Hg 45 litres/hour of a C -fraction containing 93% by weight of propylene (the rest being mostly propane) were delivered through the frit into the anode/rear cell wall region of the anode compartment described in detail in Example 1b. 20% of the propylene introduced was reacted on passing through the anode compartment. A DC. voltage of 3.6 volts was applied across the electrodes of the electrolytic cell so that a direct current with a current density of 11.0 amps/dm.
  • An improved electrolytic cell for the production of olefin oxides from olefins comprising a cell casing, an anode in said casing, a cathode in said casing, a diaphragm in said casing between said anode and said cathode, means defining an anode backside zone between said casing and the side of said anode directed away from said cathode, means defining an intermediate zone between said diaphragm and the side of said anode directed toward said cathode, inlet means for introducing gaseous olefin reactant only into said anode backside zone, and means for substantially preventing gaseous olefin reactant introduction into said intermediate zone.
  • deflection means associated with said anode adapted to substantially prevent the passage of gasiform olefin from said anode backside zone to said intermediate zone.

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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)
US674783A 1966-10-14 1967-10-12 Process for the production of olefin oxides Expired - Lifetime US3567617A (en)

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DEF50440A DE1290926B (de) 1966-10-14 1966-10-14 Verfahren zur Herstellung von Olefinoxiden

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AT (1) AT271410B (de)
BE (1) BE705084A (de)
DE (1) DE1290926B (de)
ES (1) ES346066A1 (de)
GB (1) GB1201928A (de)
NL (1) NL6713812A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4574037A (en) * 1983-04-12 1986-03-04 Kanegafuchi Kagaku Kogyo Kabushiki Kaisha Vertical type electrolytic cell and electrolytic process using the same

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5527436A (en) * 1994-11-21 1996-06-18 Arco Chemical Technology, L.P. Akylene oxide production

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4574037A (en) * 1983-04-12 1986-03-04 Kanegafuchi Kagaku Kogyo Kabushiki Kaisha Vertical type electrolytic cell and electrolytic process using the same

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NL6713812A (de) 1968-04-16
AT271410B (de) 1969-06-10
DE1290926B (de) 1969-03-20
GB1201928A (en) 1970-08-12
ES346066A1 (es) 1968-12-01
BE705084A (de) 1968-04-16

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