Chemical process
View Patent ↗The invention relates to a process for the production of alkali metal chlorate comprising: providing an electrochemical cell comprising an anode and a cathode in separate anode and cathode compartments; contacting the cathode with an electrolyte comprising at least one organic mediator and one or more organic or mineral acids; reacting the organic mediator at the cathode to form at least one reduced form of the mediator; reacting the at least one reduced form of the mediator with oxygen to form hydrogen peroxide; contacting the anode with an anolyte comprising alkali metal chloride; reacting chloride at the anode to form chlorine that is hydrolyzed; and, reacting the hydrolyzed chlorine to form chlorate.
1. Process for the production of alkali metal chlorate comprising:
providing an electrochemical cell comprising an anode and a cathode in separate anode and cathode compartments;
contacting the cathode with an electrolyte comprising at least one organic mediator and one or more organic or mineral acids;
reacting the organic mediator at the cathode to form at least one reduced form of the mediator;
reacting the at least one reduced form of the mediator with oxygen to form hydrogen peroxide;
contacting the anode with an anolyte comprising alkali metal chloride;
reacting chloride at the anode to form chlorine that is hydrolyzed; and,
reacting the hydrolyzed chlorine to form chlorate,
wherein the electrolyte is a continuous liquid phase further comprising from about 20 wt % to about 99 wt % of an at least partially organic salt, comprising at least one kind of organic cation and/or organic anion.
2. Process as claimed in claim 1 , wherein the concentration of chloride ions in the anolyte is from about 30 to about 300 g/l, calculated as sodium chloride.
3. Process as claimed in claim 1 , wherein the pH in the bulk of the anolyte is from about 4 to about 10.
4. Process as claimed in claim 1 , wherein the electrochemical cell comprises at least one compartment between the anode- and cathode compartments.
5. Process as claimed in claim 1 , wherein the organic mediator is selected from the group consisting of quinones, flavoquinones, pyridine derivates, and ketones.
6. Process as claimed in claim 5 , wherein the organic mediator is selected from the group consisting of quinones containing a (benzo)quinone-moiety.
7. Process as claimed in claim 6 , wherein the organic mediator is selected from the group consisting of anthraquinones, tetrahydro anthraquinones, naphtoquinones, benzoquinones and derivates thereof.
8. Process as claimed in claim 1 , wherein the content of organic mediator, including the reduced forms, in the catholyte is at least about 1 wt %.
9. Process as claimed in claim 1 , wherein the content of the at least partially organic salt in the catholyte is from about 40 wt % to about 95 wt %.
10. Process as claimed in claim 1 , wherein the at least partially organic salt is present together with a neutral co-solvent and the weight ratio salt to co-solvent is from about 1:1 to about 1000:1.
11. Process as claimed in claim 1 , wherein a neutral co-solvent is present in the catholyte in an amount up to about 50 wt %.
12. Process as claimed in claim 1 , wherein the at least partially organic salt that in itself or in combination with a neutral co-solvent forms a liquid phase at atmospheric pressure below about 130° C.
13. Process as claimed in claim 1 , wherein the at least partially organic salt at 100° C. has a partial pressure below about 10 kPa.
14. Process as claimed in claim 1 , wherein the at least partially organic salt comprises a cation selected from the group consisting of 1-alkyl-3-methyl imidiazolium, 1-butyl-3-methyl imidazolium [BMIM], 1-ethyl-3-methyl imidazolium [EMIM], 1,2,3-trimethyl imidazolium, N-alkylpyridinium, N-butyl pyridinium [BPY], pyrrolidinium, guanidinium and alkyl guanidinium, isouronium, PR 4 + , NR 4 + , SR 3 + , tetramethylammonium, choline, cocomonium, and mixtures thereof, R being, independently of each other, optionally substituted alkyl, alkenyl or aryl, or hydrogen.
15. Process as claimed in claim 1 , wherein the at least partially organic salt comprises a cation selected from the group consisting of substituted quinones.
16. Process as claimed in claim 1 , wherein the at least partially organic salt comprises an anion selected from the group consisting of hexafluorophosphate [HFP], tetrafluoroborate [TFB], fluorosulfonate, hexafluoroantimonate hexafluoroarsenate, chloroaluminate, bromoaluminate, bis(trifluoromethylsulfonyl)imide, tris(trifluoromethylsulfonyl)methide, tricyanomethide, dicyanamide, nonafluorobutanesulfonate, trifluoromethane sulfonate, 2,2,2-trifluororethanesulfonate, nitrate, sulphate, phosphate, RPO 4 2− , R 2 PO 4 − , R 2 PO 2 − (e.g. a dialkylphosphinate), perchlorate, actetate, alkylsulphonate, bis(2-ethylhexyl)sodium sulfosuccinate, diethyleneglycolmonomethylethersulfate, alkyloligoethersultfate, pivalate, tetraalkylborate, propionate, succinate, saccharinate, glycolate, stearate, lactate, malate, tartrate, citrate, ascorbate, glutamate, benzoate, salicylate, methanesulfonate, toluenesulfonate, and mixtures thereof, R being, independently of each other, optionally substituted alkyl, alkenyl or aryl, or hydrogen.
17. Process as claimed in claim 1 , wherein the at least partially organic salt comprises an anion selected from the group consisting of substituted quinones.
18. Process as claimed in claim 1 , wherein the at least partially organic salt comprises a cation selected from the group consisting of [1,3-dialkyl imidazolium], [trialkylammonium], [tetraalkylammonium], [trialkylphosphonium], [tetraalkylphosphonium], [alkylpyridinium], [choline], [Q-NR 3 + ] and [Q-PR 3 + ] and an anion selected from the group consisting of [sulphate], [phosphate], [alkyl sulphate], [alkyl sulphonate], [dialkyl phosphate], [alkyl phosphonate], [Q-(O)—SO 3 − ] and [Q-(O)—PO 3 R − ], where Q is a quinone, (O) is an optional oxygen and R is, independently of each other, optionally substituted alkyl, alkenyl or aryl, or hydrogen.