CA1292273C - Electrogenerative cell for the oxidation or halogenation of hydrocarbons - Google Patents

Abstract

ABSTRACT

An electrogenerative cell and a process for the oxidation or halogenation of hydrocarbons is disclosed wherein a cell body containing a permselective membrane which divides said cell body into anolyte and catholyte compartments containing a liquid electrolyte consisting respectively of anolyte and catholyte and a porous anode and a porous cathode. Anolyte and catholyte compartments are fed respectively with a mixture of a liquid electrolyte and an unsaturated hydrocarbon and a mixture of a liquid electrolyte and a halogen or oxygen, wherein said electrolytes are fed to said cell at ambient or elevated temperature and pressure. A
halogenated or oxygenated hydrocarbon is recovered and electrolytes, unsaturated hydrocarbon, halogen or oxygen are recycled to the cell.

34,467-F

Description

z~

ELECTROGENERATIVE CELL FOR THE OXIDATION OR
HALOGENATION OF HYDROCARBONS

The invention relates to the oxidation or halogenation of hydrocarbons by a process termed electrogenerative wherein the free energy of reaction iq partially converted directly into potentially useful electric energy while the main product of value is produced.

The halogenation of hydrocarbons, for instance the chlorination of ethylene to produce 1,2-dichloro-ethane ~hereinafter referred to as DCE), is carried out : in a chemical method by reacting anhydrous ethylene saturated with ferric chloride at a temperature of 50C.
~: ~ 15~ The yield of DCE (calculated -far chlorine reacted) : : ~ approaahes 100 percent. The chemical method for prepar1ng bCE involves a preliminary production o~
: ~ ~chlorine, a subsequent purification thereof, : compression, and thorough drying of the chlorine since ; 20 moisture impairs the process parameters by inactivating ; ferric chloride which is required to inhibit the substitutive chlorination of ethylene.
.

: :~ ~ ` ::: :

:~ 34,~67 :

Z~73 Also known i a method for preparing DCE
utilizing an electrolysis cell containing from 4 to 20 percent aqueous hydrochloric acid (HCl) as an electrolyte at a temperature between 20 to 70C with the simultaneous-supply of ethylene into the anodic space. A combination of ethylene and aqueous HCl is fed into the anodic space at such a rate that the amount of HCl fed into the solution is ten times higher than its stoichiometric amount. The current yield of DCE is from 20 to 4ll percent. This is equivalent to the yield calculated based upon reacted chlorine in the chemical method.

Prior art methods of electrogenerative halogenation of hydrocarbons is discussed in a thesis by Miller at the University of Wisconsin (1973).
Electrolytic oxidation and chlorination of ethylene are discussed by Kalinin et al in the ~ IL~
Chemistry, 19, No. 10-11 1045-1058 (Russian) (1946).
Electrogenerative processes are disclosed by Langer et al in Industrial En~ineering Chemistry and Process Desi~n Development, 18, No. 4 (1979), pages 567 to 578, and by Langer et al in the Journal of The Electrochemical SocietY, pages 510-511 (April 1970). A
~low-through electrochemical cell is disclosed in Kinoshita and Leach in the Journal of The Electrochemical Society, 129, No. 9, pag0s 1993-1997 (September 1982~.
In none of these references i3 the applicant's novel flow-through electrogenerative cell or process for the axidati~n or halogenation of hydrocarbons disclosed.

34,467-F -2-l.Z.~Z;2 73 A flow-through cell for use in producing halogenated hydrocarbons or oxidized hydrocarbons is disclosed wherein an electrogenerative cell having a cell body enclosing an anolyte compartment containing a porous anode and a catholyte compartment containing a porous cathode and separated by a permselective membrane i9 fed an anolyte in admixture with a hydrocarbon and a catholyte in admixture with either oxygen or a halogen gas at ambient temperatures and pressures. The electrogenerative cell can be operated at elevated tPmperatures and pressured to improve the efficiency thereof.
More particularly, the invention resides in an electrochemical cell operative at ambient or elevated temperature and pressure for the production of electric power and an oxidized or halogenated hydrocarbon product, comprising:
a cell body, a porous anode in electrical contact with a current collector in an anode compartment~ a porous cathode in electrical contact with a current collector in a cathode compartment, an anion permeable membrane or diaphragm separating said anode and cathode, a mixture of a first electrolyte and at least one unsaturated hydrocarbon in said anode compartment, and a mixture of a second electrolyte and a halogen or oxygen in said cathode compartment.
The present invention also resides in a process for the electrogenerative halogenation or oxidation of at least one unsaturated hydrocarbon in an electro-chemical cell having a porous anode and a porous cathode separated by a permselective membrane or 34,467-F -3-:1 i2 ~ 3 ;2 ;~ ~ 3 electrolyte permeable diaphragm comprising the steps o~ :
flowing a first liquid electrolyte and said unsaturated hydrocarbon to an anolyte compartment of said cell containing said anode, flowing a second liquid electrolyte and a halogen or oxygen gas to a catholyte compartment of said cell cont~ining said cathode;
reacting 3aid unsaturated hydrocarbon with said halogen or said oxygen at ambient or elevated temperatures and pressures;
recovering a halogenated or oxygenated hydrocarbon; and recycling said electrolytes, unsaturated hydrocarbon, and halogen or oxygen gas to said cell.
In Figure 1 there is shown a schematic drawing of the electrogenerative cell of the invention~
In Figure 2 there is shown the performance of one embodiment of the electrogenerative cell of the invention using ethylene as a feed gas.
Referring to Figure 1, the electrogenerative cell of the invention comprises a cell body 34 which encloses an anolyte compartment 22 and a catholyte compartment 24 separated by a permselective membrane 30. The membrane is held in place by the cell body 34 and sealed with an 0-ring 32. An anode 26 is provided : with current through a lead 10. A cathode 28 is electrically connected through a lead 12. Electrolyte at elevated temperature and pressure is fed through conduits 14 and 16 and exits respectively through conduits 20 and 18.
.

34,467-F _4_ -~ 73 _5.

The porous electrodes utilized in the electrogenerative cell of the invention can be any of the porous particulate carbon based electrodes bonded with a thermoplastic polymer, suçh as a halogenated hydrocarbon polymerO Electrodes characterized as gas diffusion electrodes can be used. These generally comprise an electrochemically active hydrophilic layer of particul~te carbon and ~ hydrophobic polymer binder.
The electrodes generally are in electrical contact with a current collector or current distributor which can be a metal mesh. The hydrophobic polymer can be a thermoplastic halocarbon polymer, such as polytetrafluoroethylene (PTFE), so as to provide a binder sufficiently resistant to the conditions of the ;- cell environment. Such halogenated hydrocarbons useful - in preparing halogenated polymers for use as the binder for the electrodes of the invention are the polymers of PTFE, fluorinated ethylene propylene, copolymers thereof having the moieties:

( -CX 1 X2-CX3CX4- ), ( ~Y1Y2-CY3Y4-)7 and homopolymers having the moieties:
( CI1Y2-CY3F-) wherein X1, X2, X3 X4, Y1~ Y2~ Y3~ and Y4 ar selected from fluorine, chlorine, and hydrogen, at least one of~said X and Y being fluorine. Preferably the halocarbon polymer is a fluorocarbon polymer : selected from at least one copolymers having an 34,467-F _5_ .~ t ll~
-6~ 7 ~ ~ O ~

ethylene moiety and a fluorocarbon moiety selected ~rom:

(-CFH-CH2-), (-CF2-cH2)~
(-CF2-CFH-), (~CF2 CF2-), and (-CH2-CC1F-).
.
Suitable hydrophobio polymers can generally include any polymer ha~ing a low surface energy which will remain stable under fuel cell or chloro-alkali electrolysis cell operating conditions. Such polymers include polymers of various halogen-substituted hydrocarbon monomers, particularly fluorine-substituted olefinic monomers; Halogen-containing polymers that can be employed include polymers of fluorocarbons and a substituted fluorocarbons wherein one or more fluorine atoms are replaced by hydrogen 9 chlorine, or bromine.
~: 20 Alternative halooarbon polymers include polytrifluoroethylene, polyvinyl fluoride, :~ polyvinylidene fluoride, polytrifluorochloroethylene, : : and copolymers of different ~luorocarbon monomers such as copolymers of tetrafluoroethylene and hexafluoropropylene.
In addition to the halocarbon polymers, various other hydrophobio polymers can be used including :
hydrocarbon polymers having a molecular wei~ght of from -50,000 to greater than 1~,000,000 and having a free sur~aoe energy close to or below that o~ polyethylene.
Representative~polymers include polymers and copo~ymers o~:ethylene, propylene, 3-ethyl-1-butene, 4-methyl~
:35~ pentene,-~and 4,4-dimethyl-1-pentene. Silicone polymers 34,~467-F -6-''~

t73 are also suitable as hydrophobic polymers for use in the preparation of the porous electrodes.
The conductive carbon utilized in the formation of the hydrophilic layer of the gas di~usion electrodes utilized can be any electrically conductive, particulate, hydrophilic carbon. For instance, acetylene black having a small particle size which is electrically conductive can be used. Certain other carbon blacks such as furnace black are also electrically conduative and can be used. The carbon used can be porous or non-porous. 5enerally, carbon blacks having a particle size ranging from 0.01 to 0.05 microns, and more usually within the range of from 0.01 to 0.03 microns are suitable. Methods ~f preparing gas diffusion electrodes are well known in the art and are disclosed in U.S. Patent Nos. 3,442,715; 4, 354, 958; and 4,456,521.
An electrochemically active catalyst can be admixed with the carbon black but the gas diffusion electrode is operative without the addition of a catalyst and in some reactions the catalyst can be poisoned by one of the reactants so as to deactivate the catalyst. Useful metals from which an electrochemically active catalysts can be selected are the precious metals such as silver, platinum, palladium, rhodium, and the like, or metal oxides such as combinations of nickel oxide and lithium oxide.
Additional metals from which to select an electrochemically active cataly~t are chromium, tungsten, molybdenum, cobalt, nickel, silver, copper, platinum, palladium, rhodium, iridium, and other metals such as marganese and inorganic compo~nds containin~
one or more o~ such metals, for instance, nickel oxide, 3~,467-F -7-~ ~ 2 ~ ~3 manganese oxide, cobalt molybdate, vanadium pentolde~
and the like.
The electrodes can also be selected from the carbon ~elt type porous electrodes described in the Kinoshita et al reference cited above. In this type of electrode~ carbon ~ibers, for instance, those having a diameter of 2.54 x 10~3 cm and a porosity of 0.86, are prepared by pressing so as to make an electrode having a thickness of 0.175 cm~ Generally the thickness of the anode and the cathode are identical to prevent a dif~erential pressure drop.
The electrodes can be directly connected to a current lead or they can be electrically attached to a current collector or current distribution such as a metal wire mesh. The metal wire mesh can be a woven mesh such as a 50 x 50 ~ 0.025 cm silver-plated nickel wire mesh. Preferably wire meshes havin~ less than 0.038 cm dimension wire strands and greater than 4 strands in each direction per cm are used. The wire mesh current collector caln be prepared from a metal selected from stainless s~teel, nickel, platinum group metals, valve metals, and mixtures thereof. Preferably the metal mesh is prepared from a metal selected from silver, silver-coated nickel, silver-coate~ steel7 and silver-coated valve metals.
Separating the anion and cation porous electrodes, there is used as an ion exchange permselective (permionic) membrane, generally an anion-exchange membrane. Examples of anion-exchange membranes are those containing an anion selectiYe group, sueh as a quaternary ammonium group, a secondary amine group, or a tertiary amine group. Exemplary 34,467-F _~_ ~2 ~ 3 _9_ anion selective permionic membranes include ammonium derivatives of styrene and styrene-divinyl benzene polymers, amine derivatives of styrene and styrene-divinyl benzene, condensation polymers of alkyl oxides with amines or ammonia, ammoniated condensation products of acrylic and methacrylic esters, and iminodiacetate derivatives of styrene and styrene-divinyl~enzene.
The electrogenerative cell o~ the invention is applicable to the oxidation of unsaturated hydrocarbons and the halogenation of unsaturated hydrocarbons in a direct reaction between the hydrocarbon and the oxygen or halogen gas present in the electrolyte while the cell is operated as an electrochemical cell. In operation, the cell is connected to an external electrical circuit and a mixture of an electrolyte and an unsaturated hydrocarbon are fed to the anolyte compartment at ambient temperatures and pressures.
Elevated pressure and temperature conditions can be used with certain hydrocarbon reactants to increase cell efficiency as compared to permissible operation at ambient temperatures and pressures. At the same time, a mixture of an electrolyte and oxygen or halogen are fed to the catholyte compartment of the cell at ambient or at elevated temperature and pressure conditions.
The depleted mixture of electrolyte and oxygen or ~alogen fed to the cathodes is made up to the original 3 concentration and recirculated to the cell. The mixture of unsaturated hydrocarbon and electrolyte fed to the anode of the cell is also made up to original concentration following depletion by reaction at the anode and recirculated to the cell subsequent to the ~ removal of the reaction product from this stream.
:::
34,467~F _g_ 22~3 More specifically, an unsaturated hydrocarbon such as ethylene is mixed with an aqueous solution of phosphoric acid, as an electrolyte, and circulated preferably under elevated temperature and pressure conditions to the anode of the electrogenerative cell of the invention while at the same time there is circulated to the cathode of ~he cell a mixture of an aqueous solution, preferably a saturated solution, of sodium chloride admixed with chlorine gas. The major product of the reaction is l,2-dichloroethane which is produced in a yield, based upon the c~lorine reacted~
of from 90 to 97 percent by weight. A minor by-product consisting of ethylene chlorohydrin is produced in an amount of from 3 to lO percent by weight. Concurrent with the production of the halogenated hydrocarbons, electrical power is produced by the reaction.
The electrogenerative cell of the invention is also suitable for the electrochemical oxidation of hydrocarbons. The electrolytic oxidation of ethylene is discussed in the above referenced article by Kalinin et al entitled "Electrolytic Oxidation and Chlori~ation of Ethylene." Following the procedures set out in this article, an electrolyte and ethylene are fed to the anolyte compartment and an electrolyte and oxygen mixture are fed to the catholyte compartment.
.
Other unsaturated ~ydrocarbon reactants can be 30 .used in addition to ethylene and propylene as reactant~. Far instance, l-butylene and 1,3-butadiene when utilized in the electrogenerative cell of the invention produce 1,2-dichlorobutane and cis-1,4-dichloro-2-butene, respectively. The most useful .

~ 34,467-F -10-" .

hydrocarbons for oxidation or halogenation are the olefins.
It has been found that the use of phosphoric acid as an electrolyte with water as the solvent in the form o~ the commonly available 85 percent pho~phoric acid aqueous solution has particular advantages as an electrolyte and solvent for the hydrocarbon, particularly ethylene. It has been found that the solubility of ethylene in 85 percent phosphoric ~cid increases as the prsssure is increased and decreases as the temperature i9 increased. Ethylene dissolved in variou~ electrolytes was utilized in the cell of the invention at various temperatures. It was found that the phosphoric acid 85 percent aqueous solution as an electrolyte was ~ar superior to the other electrolytes tested a~ indicated in Table 1.

.

34,467-F

- 1 2 ~ 2~73 ~1 N
E

C~
~ u~
_ O C-- O
V ~ o C

:~
~ ~ ~ o g ..
a~
.

, o E-l ~ a~
s:: 3 o o o o ~- ~
~ ~ 13 ~ o C~ Q) ~" ~ 3 ::s O s.,-- O ~
a~
v ~ ~ 3 E~
c~ ~ ~ ~r s.
a) ~ ~ o ¢l s~ ~, Z U~ u~
.,, " L~
~ tY- 3 ~r ~
: ~ ~. O O O
~ ll 0 N
Z ~ X
~:
.
3 4, 4 6 7 -F - 12 ~ 2`~3 The ~ollowing examples illustrate the various aspects of the invention but are not intended to limit its scope. Where not otherwise specified throughout this specification and claims, temperatures are given in degrees centigrade, and parts, percentages, and proportions are by weight.
Exam~le 1 .. ~ . . , ~
The flow-through electrogenerative cell was designed incorporating porous carbon electrodes. Each electrode consisted of three pads of WDF Graphite Felty 5.7 mm thick, as purchased from Union Carbide Corp., Carbon Products Division. Prior to cell assembly these electrode~ were activated by boiling in 70 percent nitric acid for two hours and rinsing in demineralized water. The electrodes were placed in two cell halves which were separated by a 0.05 mm thick fluorinated, glass reinforced, anion exchange rnembrane (Raipore, number 4035). The cell halves were constructed from 7.5 cm pipe flanges. Blind flanges were used for ends and open flanges for electrode reservoirs. Titanium was used for the cell half exposed to phosphoric acid and ethylene. The inner surface of the titanium blind flange was coated with Ru02, by thermal decomposition Qf a RuC14 solution, to provide an electrically conductive sur~ace through which current was conducted ~rom the electrode. A thin sheet of silver was placed on the inner surface of the (Hastelloy B) blind flange to provide electrical contact to the other electrode.
The 85 percent phosphoric acid anolyte, contained in an external reservoir at ambient temperature, was saturated with ethylene gas at a desired pressure which ranged from 45 to 75 psia (310 1* rfa~er~ k 34,467-F _13_ to 517 kPa). The pressure was held constant during each experiment by means of a regulated ethylene gas pressure in the anolyte reservoir. Likewise, a 20 percent brine catholyte was saturated with chlorine at ambient temperature and the pressure was held constant by regulated chlorine gas pressure over the catholyte.
The gas pressure in the catholyte was maintained identical to the pressure in the anolyt~ by means of a differential pressure controller to insure that a dif~erential pressure within the electrogenerati~e cell would not develop which could rupture the anion exchange membrane separator~
Flows of the ambient temperature, saturated and -5 pressurized, electrolytes were controlled at 40 cm3/min as they passed from the reservoirs through tubing to the bottom of the cell. The cell and portions of the tubing were sub~erged in a controlled temperature bath which was held at 75, 90, or 105C during each experiment. Adaquate tubing was used to insure that the electrolytes were at the desired temperature prior to entry into the cell. The electrolytes exited from the top of the cell and the pressures were reduced to ambient. Unreacted gas and products were allowed to escape. The electrolytes couLd be recycled which would be desired in a continuous operation, but were not during this experiment.
Samples of the anolyte and gaseous effl~ents from the hot anolyte were collected and analyzed by gas chromatographic techniques. The major product, gre2ter than 95 percent, was 1~2-dichloroethane.
The external electrical circuit consisted of copper wires connected to the two current collectors.

34~467-F -14-~q~2~73 ~ ~15-These wires were connected to an external high precision, one ohm resis.tor~ A high impedance volt meter was connected in parallel across the resistor and the voltage was measured. The current flowing through the external circuit was determined using Ohm's law and current densities were obtained by.dividing this current by the cross-sectional area of the electrodes which was about 64.5 cm2. . -Results of this experiment are shown in the following Table 2.

34,467-F -15-- 16 - :1.2~2~273 _ _ o o t o o o _ U~ ~ , ~ ~
1~7 In Ln ~
~r'S Q O O
3 ~7 O ~r .. ~ I ~
~ _ ~ _ _ - .
a O , O
O O O O
N _ ~ O O

_~ al r~ 1'7 C ~~ u~
_~ O O O
C , o o o ~ U~ ~ O C~
R ~ cn 1~ t~l _I U') 1~
C ~ _ '` O O O
~V
O ~ . E N ~1 u e u O O
O ~ ~ O O

N ~ N
E-~ u ,o ~ ~ O ~ u~
3) ~
N O
~ 1 ~ ~ I
S ~ _l U~ U~
~ O O' o O
~i ~ ' _ : U ~ E o o o U,l _ C
" ~ ~ ~ U- o o 2 ~U 'IJN O ~r 0N ~ Ul ~ ~ O C~
:: , :
O~ ^ ~
E ~1 u- o E~
: ' .

34, 467-F ~ 16 -::

--17~

~xample 2 -The cell described in Example 1 was assembled with new electrodes and operated in a like manner except that external electrical resistances and the pressures were varied during operation. The results of this experiment conducted at 90C are shown in Figure 2.
The data was collected over a period of a few weeks during which the cell was typically operated for eight hours a day at temperatures varying from 75 to 105C.
Results were consistent within experimental error during the test period.
Example 3 The cell of Example 1 was assembled with new electrodes and operated in a like manner except the anolyte was a 20 percent sodium chloride solution instead of 85 percent phosp,horic acid. Operating at 105C and 75 psia (517 kPa) with a one ohm external resistance, the cell produced 0.170 volts and 0.017 amp/in2 (0.00265 amp/cm2) which was significantly lower than results of 0.527 volts and 0.0527 amp in2 (0.0082 amp/cm2) which were previously obtained under identical conditions when an 85 percent phosphoric acid anolyte was used.
Example 4 The cell in Example 1 was assembled and operated in a like manner except platinized carbon felt electrodes were employed. Two procedures were used to platinize the carbon felt. The first procedure, reported by Baltzly in the Journal of the American ` '' Chemical Society, ~4, 4586, (1952), entailed submerging the electrode in a solution of 2.65 grams of 10 percent 34.467-F _17_ .

~ ~ Z ~'~3 -18~

H2PtC16, 1 drop of a 5 percent PdC12, and 30 ml of deionized water per gram of carbon while hydrogen gas was sparged though the room-temperature solution for 30 minutes. The solution was then poured off and the electrode was stored in methanol saturated with H2 until used. The second procedure, developed by Brown and Brown (Journal of the American Chemical Society, 84, 1494, 1962), comprised submerging the felt pad in a solution of 2.65 grams of 10 percent H2PtC6 solution mixed with 40 ml of ethanol per gr-am of electrode.
After purging with nitrogen, 3 grams of a 12 percent NaBH4 solution was rinsed 3 times with deionized water and then stored in methanol saturated with hydrogen until used. When removed from the methanol and allowed to ir-dry, these electrodes were pyrophoric, so they were rinsed in deionized water and kept damp during the cell assembly.

2~ Results of this experiment conducted at a temperature of 105C and at a pressure of 75 psia (527 kPa) with a one ohm external resistance were 0.486 volts and 0.0486 amp/in2 (0.0075 amp~cm2) for the first electrode and 0.628 volts and 0.0628 amp/in2 (0.00~7 amp/cm2) for the second electrode. The uncatalyzed - electrodes operated under similar conditions at 0.527 volts and 0.0527 amp/in2 (0.0082 amp/cm2). Therefore, the! hydrogen reduced platinized electrode showed no advantage whereas t~e electrode produced by the sodium

3 borohydride reduction showed a 19 percent increase in voltage and current.
.
While this invention has been described with reference to certain specific embodiments, it will be recognized by those skilled in the art that many variations are possible without departing from the 34,467-F -18-' 9 scope and spirit of the invention, and it will be understood that it is intended to cover all changes and modifications of the invention disclosed herein for the purpose of illustration which do not constitute departures from the spirit and scope of the invention.

-34,~67-F -19-

Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS
FOLLOWS:

1. An electrochemical cell operative at ambient or elevated temperature and pressure for the production of electric power and an oxidized or halogenated hydrocarbon product, comprising:
a cell body, a porous anode in electrical contact with a current collector in an anode compartment, a porous cathode in electrical contact with a current collector in a cathode compartment, an anion permeable membrane or diaphragm separating said anode and cathode, a mixture of a first electrolyte and at least one unsaturated hydrocarbon in said anode compartment r and a mixture of a second electrolyte and a halogen or oxygen in said cathode compartment.

2. The cell of Claim 1, wherein said porous cathode and porous anode are formed from materials selected from carbon felt and thermoplastic polymer bonded particulate carbon.

3. The cell of Claim 1, wherein said first electrolyte is an aqueous solution of phosphoric acid and an unsaturated hydrocarbon, and wherein said second 34,467-F

electrolyte is an aqueous solution of an alkali metal halide and a halogen gas.

4. The cell of Claim 1, wherein said unsaturated hydrocarbon is an olefin.

5. The cell of Claim 4, wherein said olefin is selected from the group consisting of ethylene and propylene, said alkali metal halide is sodium chloride, and said halogen is chlorine.

6. A process for the electrogenerative halogenation or oxidation of at least one unsaturated hydrocarbon in an electrochemical cell having a porous anode and a porous cathode separated by a permselective membrane or electrolyte permeable diaphragm comprising the steps of:
flowing a first liquid electrolyte and said unsaturated hydrocarbon to an anolyte compartment of said cell containing said anode, flowing a second liquid electrolyte and a halogen or oxygen gas to a catholyte compartment of said cell containing said cathode;
reacting said unsaturated hydrocarbon with said halogen or said oxygen at ambient or elevated temperatures and pressures;
recovering a halogenated or oxygenated hydrocarbon; and recycling said electrolytes, unsaturated hydrocarbon, and halogen or oxygen gas to said cell.

7. The process of Claim 6, wherein said first electrolyte is an aqueous solution of phosphoric acid and an unsaturated hydrocarbon, and wherein said 34,467-F

second electrolyte is an aqueous solution of an alkali metal halide and a halogen gas.

8. The process of Claim 7, wherein said first and second electrolytes are fed respectively to said porous anode and said porous cathode under a pressure of from 50 to 150 lb/in2 at a temperature of from 50 to 100°C.

9. The process of Claim 6, wherein said unsaturated hydrocarbon is an olefin.

10. The process of Claim 6, wherein said porous anode and cathode are formed of a particulate carbon material bonded with a thermoplastic polymer, and said permselective membrane is an anion permeable membrane.

11. The process of Claim 6, wherein said porous anode and cathode are formed of a carbon felt material, and said permselective membrane is an anion permeable membrane.

12. The process of Claim 9, wherein said olefin is selected from ethylene and propylene, said alkali metal halide is sodium chloride, and said halogen is chlorine.

34,467-F 22