Chemical process

Abstract

The invention relates to a process for the production of hydrogen peroxide comprising: providing an electrochemical cell comprising an anode and a cathode; contacting the cathode with an electrolyte comprising at least one organic mediator dissolved in an at least partially organic continuous liquid phase comprising an at least partially organic salt and a neutral co-solvent, said salt comprising at least one kind of organic cation and/or organic anion, said continuous liquid phase having an electrical conductivity under process conditions of at least about 0.1 S/m; reacting the organic mediator at the cathode to form at least one reduced form of the mediator; and, reacting the at least one reduced form of the mediator with oxygen to form hydrogen peroxide.

1 . Process for the production of hydrogen peroxide comprising: 
 providing an electrochemical cell comprising an anode and a cathode;    contacting the cathode with an electrolyte comprising at least one organic mediator dissolved in an at least partially organic continuous liquid phase comprising an at least partially organic salt and a neutral co-solvent, said salt comprising at least one kind of organic cation and/or organic anion, said continuous liquid phase having an electrical conductivity under process conditions of at least about 0.1 S/m;    reacting the organic mediator at the cathode to form at least one reduced form of the mediator; and,    reacting the at least one reduced form of the mediator with oxygen to form hydrogen peroxide.    
   
   
       2 . Process as claimed in  claim 1 , wherein a neutral co-solvent is present in the at least partially organic continuous liquid phase of the electrolyte in an amount up to about 50 wt %.  
   
   
       3 . Process as claimed in  claim 2 , wherein a neutral co-solvent is present in the at least partially organic continuous liquid phase of the electrolyte in an amount from about 1 to about 20 wt %.  
   
   
       4 . Process as claimed in  claim 1 , wherein the co-solvent is water.  
   
   
       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 at least partially organic continuous liquid phase 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 continuous liquid phase is from about 20 wt % to about 99 wt %.  
   
   
       10 . 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.  
   
   
       11 . Process as claimed in  claim 1 , wherein the at least partially organic salt at 100° C. has a partial pressure below about 10 kPa.  
   
   
       12 . 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.  
   
   
       13 . Process as claimed in  claim 1 , wherein the at least partially organic salt comprises a cation selected from the group consisting of substituted quinones.  
   
   
       14 . Process as claimed in any  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.  
   
   
       15 . Process as claimed in any  claim 1 , wherein the at least partially organic salt comprises an anion selected from the group consisting of substituted quinones.  
   
   
       16 . 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.  
   
   
       17 . Process as claimed in  claim 1 , wherein the electrochemical cell comprises separate anode and cathode compartment.  
   
   
       18 . Process as claimed in any one of the claims  1 - 17 , wherein the electrolyte in the cathode compartment, or cell if no separate cathode compartment is present, contains a single liquid phase.  
   
   
       19 . Process as claimed in  claim 1 , wherein molecular oxygen is added to the at least partially organic phase of the electrolyte comprising reduced mediator, resulting in formation of hydrogen peroxide in the electrolyte.  
   
   
       20 . Process as claimed in  claim 19 , wherein at least part of the oxygen is added to the at least partially organic phase of the electrolyte comprising reduced mediator as a gas directly into the electrochemical cell.  
   
   
       21 . Process as claimed in  claim 1 , wherein hydrogen peroxide is evaporated from the at least partially organic phase of the electrolyte.  
   
   
       22 . Process as claimed in  claim 1 , wherein hydrogen peroxide is extracted from the at least partially organic liquid phase.