CN101448980B

CN101448980B - Producing hydrogen peroxide

Info

Publication number: CN101448980B
Application number: CN2007800180939A
Authority: CN
Inventors: 内森·C·布朗; 方超英
Original assignee: Dyson Ltd
Current assignee: Dyson Technology Ltd; Dyson Ltd
Priority date: 2006-04-11
Filing date: 2007-04-02
Publication date: 2011-08-24
Anticipated expiration: 2027-04-02
Also published as: US20090272654A1; WO2007128961A2; WO2007128961A3; EP2004878A2; CN101448980A; GB0607277D0; TW200806573A; GB2437956A

Abstract

An electrolytic cell (1) is arranged to generate hydrogen peroxide and includes a reservoir (12) for storing hydrogen peroxide generated by the cell. A controller (19) is arranged to activate the cell and introduce stored hydrogen peroxide from the reservoir to the cell. This permits the concentration of a store of hydrogen peroxide to be refreshed as required, by introducing the stored hydrogen peroxide as the electrolyte in the cell. This counteracts the natural decay of the stored hydrogen peroxide. The pH of the hydrogen peroxide is controlled so that it is below a predetermined value. It has been found that hydrogen peroxide having a low pH, close to neutral, decays much slower than hydrogen peroxide having a more strongly alkaline pH.

Description

Produce hydrogen peroxide

Technical field

The present invention relates to a kind of equipment and method that is used for producing hydrogen peroxide, and be particularly related to a kind of equipment that is set to for example in automatic dishwasher, produce hydrogen peroxide by electrolyzer.

Background technology

In traditional automatic dishwasher, adopt sanitising agent to produce cleaning liquid, to use on the foul that in being positioned over dishwasher, is used to clean.But when cleaning liquid was released in the environment, this sanitising agent can decompose and produce pollution substance.

Proposed in automatic dishwasher, to use superoxol as scavenging solution.The advantage of hydrogen peroxide is that it only can resolve into water and hydrogen, and the two is harmless and can bring problem to environment.

The problem that hydrogen peroxide may run into is that it is unstable and can not prolonged preservation and do not decompose.These character have reduced the magnetism of utilizing hydrogen peroxide, and particularly the use of hydrogen peroxide is relatively frequent and/or consumption is very little in the family expenses environment.

Because these problems have proposed to produce in use hydrogen peroxide.The method and apparatus that is used for electrolytically producing hydrogen peroxide is disclosed in US6, in 767,447.Electric energy is used to produce electrochemical reaction, i.e. the electrolysis of water.Chemical reaction by control cathode of electrolytic tank place produces hydrogen peroxide.But this process need is wanted several hours for a long time usually, and this has reduced its ease for use as family expenses peroxide solution source.

Summary of the invention

Thereby, the invention provides a kind of equipment that is used to produce hydrogen peroxide, comprise the electrolyzer that is set to produce hydrogen peroxide, be used to store the reservoir of the hydrogen peroxide that produces by electrolyzer and the controller that is set to start electrolyzer and stored hydrogen peroxide is fed to electrolyzer from reservoir.

By with stored hydrogen peroxide as the electrolytic solution in the electrolyzer, the storage concentration that the present invention allows hydrogen peroxide is to reach maximum at needs.This has offset the natural decomposition of stored hydrogen peroxide.

Advantageously, controller is set to monitor the stored hydrogen peroxide time span in the reservoir Already in, and depends on that the time span of this storage starts electrolyzer through after a while.

Preferably, the pH Be Controlled of hydrogen peroxide is so that it is lower than preset value.Have been found that hydrogen peroxide has low pH, when neutral, to compare decomposition slower with having more the hydrogen peroxide of strong basicity pH.

The present invention is specially adapted to use in automatic dishwasher converges.Concentration at pre-washing stage hydrogen peroxide can reach maximum.

Description of drawings

Present invention is described for example that now will be by with reference to the accompanying drawings, wherein:

Fig. 1 is the synoptic diagram of electrolyzer;

Fig. 2 is the synoptic diagram of system that is used for the electrolyzer electroconductibility of control chart 1;

Fig. 3 is the figure that electric current changes in the electrolyzer of Fig. 1;

Fig. 4 is the figure of the change in concentration of hydrogen peroxide in the electrolyzer of Fig. 1;

Fig. 5 is the typical rate figure of hydrogen peroxide decomposition;

Fig. 6 is the figure that three times of concentration of hydrogen peroxide change in the electrolyzer of Fig. 1 under different starting point concentrations;

Fig. 7 stores for constructed according to the invention being used for and the synoptic diagram of the system of the hydrogen peroxide of the electrolyzer of additional Fig. 1; With

Fig. 8 is the biopsy cavity marker devices skeleton view of utensil cabinet of having incorporated the system of the electrolyzer of Fig. 1 and Fig. 2 and 7 into.

Similar Reference numeral refers to similar parts in whole specification sheets.

Embodiment

Fig. 1 shows electrolyzer, and it is usually by Reference numeral 1 expression.This be purely synoptic diagram and shown in feature can not be used for measuring.Only show an electrolyzer 1 in the figure for clear, but in fact can be connected in series a plurality of electrolyzers.Electrolyzer 1 comprises two

chambers

2,3, and the two is divided into the anode chamber 2 with anode 5 and has the cathode chamber 3 of negative electrode 6 by ion-exchange membrane 4.Electrolyzer 1 also comprises air chamber 7.Negative electrode 6 is the electrode of carbon cloth type, and it separates cathode chamber 3 and air chamber 7.Pump 8 is set, so that air is pumped in the air chamber 7, so that air is maintained in the chamber 7 with certain pressure from surrounding environment.Pressure makes air be forced into carbon-cloth cathode 6, so that provide oxygen to negative electrode.Oxygen is necessary for produce hydrogen peroxide in cathode chamber 3.

Anode 5 and negative electrode 6 are connected to the power supply of DC power supply 9 forms.This power supply can obtain from primary source, and the DC power supply 9 with suitable electric current and voltage can suitably be changed and be rectified into to this primary source.Electrolyzer 1 starts by apply electromotive force between anode 5 and negative electrode 6, with ion in the

generation chamber

2,3 and the inside chemical reaction between the electrode.If ion is the positively charged ion of positively charged, then they flow and are reduced towards negative electrode 6.If ion is electronegative negatively charged ion, then they flow also oxidized towards anode 5.

Chemical reaction at negative electrode 6 places can be expressed as simply:

2H ⁺+O ₂+2e ^-→H ₂O ₂

This reaction comprises by hydrogen ion and electronics makes the oxygen from air chamber 7 carry out cathodic reduction, and described hydrogen ion and electron production are transferred in the cathode chamber 3 in anode chamber 2 and via film 4.By controlling this reaction, in cathode chamber 3, produce hydrogen peroxide.

The

chamber

2,3 of electrolyzer 1 has different separately electrolytic solution therein.The electrolytic solution relevant with cathode chamber 3 is called as catholyte 10.The electrolytic solution relevant with anode chamber 2 is called anolyte 11.

In the past, the electrolyzer that produces hydrogen peroxide used a kind of electrolytic solution, and anode chamber and cathode chamber are shared, and this electrolytic solution sodium chloride solution normally for convenience.But, in the electrochemical reaction at anode place, can produce chlorine, chlorine has high toxicity and got rid of the possibility that allows this electrolyzer use in the home appliances such as automatic dishwasher.Proposed to use other electrolytic solution, but these electrolytic solution are more expensive than sodium chloride solution usually, and must replenish when in cathode chamber, making electrolytic solution depleted when producing hydrogen peroxide.

This device allows the user to select only electrolytic solution based on the consideration of user's safety, cost, availability and effect aspect at each electrode.

Before electrolyzer 1 was activated, catholyte 10 comprised sodium chloride solution.This is that the convenient of catholyte selected, and this especially electrolyzer is used for automatic dishwasher.This dishwasher has the chamber of depositing the salt that washes the dishes usually.Usually, this salt has been used to keep the effectiveness of water-softening agent in the dishwasher.This storage of salt and water are supplied the convenient source that has constituted sodium chloride solution from local water source.

Anolyte 11 is a solution of metal sulfates, as sodium sulfate.The remollescent tap water also can be used as anolyte.In electrochemical reaction process, 5 places only produce oxygen at anode, and oxygen can harmlessly be discharged into the atmosphere or reuse in electrolyzer.In the electrolysis production process of hydrogen peroxide, anolyte 11 can not be used up and therefore not need to replenish.

Anode 5 can not consumed by the electrochemical reaction in the anode chamber.Suitable anode material is the titanium oxide screen cloth that is coated with iridium oxide.Conventional electrolyzer must adopt the minimized anode material of the generation that can make chlorine, for example platinum.Platinum is very expensive, than expensive many of the anode that contains iridium oxide.Adopt this equipment, can select anolyte to make and not produce chlorine, and allow to use more cheap material at the anode place.Further advantage is that the electrolyzer that contains iridium oxide is compared with platinum and had lower resistance, and this can improve the generation speed of hydrogen peroxide.

Electrically contact between the

electrolytic solution

10,11 that ion-exchange membrane 4 allows in each

chamber

2,3, but do not allow electrolytic solution to mix.

Electrolyzer 1 is very little, and it is wide approximately to have several centimetres.Therefore, typical electrolyzer only can produce a spot of hydrogen peroxide.Can obtain bigger output by a plurality of this electrolyzer that employing is connected in series.Other the means that are used for improving output are at electrolyzer and are maintained between the catholyte reservoir of catholyte storage tank 12 and circulate catholyte 10, as shown in Figure 2.Catholyte storage tank 12 has the capacity of several liters, about 5 liters usually.In use, hydrogen peroxide produces in cathode chamber 3, and this hydrogen peroxide is pumped in the catholyte tank 12 by catholyte liquid pump 13, to be replenished by more catholyte.When catholyte circulated between the cathode chamber 3 of electrolyzer 1 and catholyte tank 12, the concentration of hydrogen peroxide in catholyte increased gradually.By the chemical reaction at control cathode 6 places, and, can produce 5 liters of a collection of superoxols with desired concn by allowing catholyte between electrolyzer 1 and hold-up vessel 12, circulate.In typical home and light industry application, have been found that about 0.35% concentration is enough to be used in most of purpose.

Similarly, provide a kind of anolyte hold-up vessel 14 that is used to hold the reservoir of anolyte 11.Anolyte tank 14 has littler capacity, is typically about 1 liter.Pump 15 is used for circulating anolyte 11 between anode chamber 2 and anolyte hold-up vessel 14, so that up-to-date a collection of ion is fed in the electrolyzer 1.In the electrochemical reaction at anode 5 places, anolyte 11 can not used up.Anolyte 11 only needs to replenish by the water that comes autonomous supply department 16 occasionally, so that the anolyte that evaporates from hold-up vessel 14 is replenished.

In order to increase the speed of response of electrolyzer 1, and therefore increase the generation speed of hydrogen peroxide, in electrolyzer, need enough current densities.This current density need be stable, so that keep required generation speed.The reservoir 17 of metal salt solution is set up and Be Controlled, so that inject catholyte 10 with this salts solution, so that make the conductivity level of electrolyzer reach desired level apace.In the present embodiment, the metal salt solution that remains in the reservoir 17 is sodium chloride solution, just salt solution.

Current sensor 18 is arranged to and detects the electric current that flows through electrolyzer 1.This electric current has been represented the electroconductibility of electrolyzer 1.In the present embodiment, current sensor 18 comprises current transducer, and this transverter produces the strength of current of having represented the controller that flows to associative processor 19.Treater 19 periodically compares this signal and predetermined current value, and comes the pump 20 of control linkage to brinish reservoir 17 according to the difference between tested current value and the predetermined current value.If the electric current that is detected by transmitter 18 is lower than preset value, then treater is set to start brinepump so that distribute a certain amount of salt solution.The salt solution that comes from reservoir 17 enters into static mixer 21, and this agitator forces salt solution to mix with catholyte from catholyte tank 12 pumps to electrolyzer 1.Be present in the middle change effect that mixing liquid in the agitator 21 enters in the electrolyzer 1 subsequently and plays electroconductibility.

The detected electric current of transducer changes Fig. 3 in typical electroconductibility control process in order to show.Predetermined current is horizontally placed to 16 amperes.Increase the concentration of metal ion by (in-line) online in the above described manner, the electroconductibility of electrolyzer sharply increases, so that electrolyzer reaches required levels of current in several minutes.By regulating and cycle monitoring electric current and the adding of controlling salts solution subsequently, levels of current is held in the process of a collection of hydrogen peroxide of generation, has less relatively deviation on levels of current.Thus, the electroconductibility of electrolyzer 1 dynamically changes, but can not be subjected to the influence of the running status of battery itself, as the air pressure at negative electrode place, the change of service voltage, the temperature of electrolytic solution and the water quality of water supply.

Treater 19 can be set to write down the conductivity data that is used for Monitoring systems.Have mistake in abnormal change indication equipment of electroconductibility, and therefore data can be used to send the problem alarm to user or technician.

Fig. 4 shows the speed of the hydrogen peroxide that produces by electrolyzer 1 when catholyte 10 circulates between catholyte tank 12 and electrolyzer.Generation speed is stable and hydrogen peroxide reached desired concn in two hours.

Although it is this is the comparatively faster speed of the controlled generation of hydrogen peroxide, still lower for some are used.For example, in the family expenses automatic dishwasher, must wait for two hours for the user and produce the purpose that enough hydrogen peroxide clean tote that this is very inconvenient.Catholyte tank 12 is set to store a collection of hydrogen peroxide that produces by electrolyzer.But hydrogen peroxide can decompose among a couple of days.Therefore, if this a collection of hydrogen peroxide is using in this time, then it is understood deterioration and becomes unavailable.

According to the present invention, by to electrolyzer 1 energising and in battery, circulate the content of catholyte tank 12, whether reach required concentration up to consequent hydrogen peroxide, making needs a collection of hydrogen peroxide all to make the concentration that is stored in the hydrogen peroxide in the catholyte tank 12 reach fixed point.By with existing the catholyte of superoxol to begin the hydrogen peroxide production process, and to compare as catholyte with fresh water, a collection of hydrogen peroxide with desired concn can be produced quickly.

Treater 19 is set to monitor the time span that has been maintained at the stored hydrogen peroxide in the jar 12.Fig. 5 is the TYPICAL DECOMPOSITION velocity diagram that is used for hydrogen peroxide.For example, if hydrogen peroxide has been stored five days, then it will decompose, and makes its concentration reduce about 0.225% from about 0.4%.When a collection of hydrogen peroxide of needs, treater 19 is set to start electrolyzer 1, so that make concentration get back to desired level.Fig. 6 for when the concentration of electrolyzer hydrogen peroxide by the time with the startup of different starting point concentration over time.For example, if starting point concentration is 0.225%, then approximately need to draw in one hour to make concentration get back to 0.4%, this is than producing the many of a collection of required two hours new weak points with pure water.These data can be used by treater, produce the required time of hydrogen peroxide to determine electrolyzer 1 by simple calculations, have a collection of of predetermined concentration so that produce.

This system schematically is shown among Fig. 7, is applied to the utensil of domestic bowl-washing form, as shown in Figure 8.Dishwasher 22 comprises the outer cabinet 23 of the insulation with basin 24, and the antetheca of this basin can pivot around its bottom margin, can be near the door 25 of this basin to provide one.Bowl, other potteries, tableware and the utensil that forms tote is placed on the shelf in the basin.A shelf 26 is in the top of basin 24 as shown in Figure 8.Typically, another shelf is arranged on the bottom of basin 24.Water is splashed on the bowl from

injector

27,28, and this injector drives by impeller pump, and this pump rotates by the motor power supply.Pump and motor do not show in the figure.The parts of electrolyzer 1, hold-up

vessel

12,14 and peroxidation hydrogen-generating apparatus can be contained in the rotine positioning of utensil, for example are arranged in the compartment of cabinet below or the partitioned portion of sidewall.

During operation, the door 25 open and form machine tote the bowl etc. be inserted in the shelf.The exercisable controller 29 of user is arranged on the front panel 30 and is operable as the startup cleaning.Machine is by water-filling and start heating unit 31.When water temperature was enough to allow tote fully clean, motor rotation and pump were urged to sputter

nozzle

27,28 with hot water, to start pre-wash step.

In Fig. 7, the basin of dishwasher is with 24 indications and be connected to family expenses main suit 16.For clear, the controller of associative processor 19 does not show in the figure.Controller is arranged to the electrolyzer in control pump, valve and the dishwasher.When dishwasher 22 is activated, flow distributor 32 will directly be assigned to the tank that is used for dishwasher from the water with the main suit 16 embedded water softening apparatuss that are connected 33.This initialize pre-wash step, this is used to the article that will be cleaned flushings food particles or other fouls from basin 24.When pre-wash step was carried out, the peroxide solution that has been stored in the catholyte tank 12 was passed through electrolyzer 1 pumping, and electrolyzer is by transformation that obtains from primary source and rectifier power source power supply.Thus, the process that produces hydrogen peroxide can not started from scratch, but alternatively begins from the residual concentration that has the solution that stores.This process continues, and up to a collection of hydrogen peroxide that produces desired concn, this moment, dishwasher was set to start its main cleaning step.

In main cleaning step, the water discharge valve 34 that is connected to catholyte tank 12 is activated, so that a collection of peroxidation device solution that holds wherein is assigned in the tub 24 of dishwasher 22.The hydrogen peroxide sanitising agent that acts on article in the tub 24.Have been found that hydrogen peroxide is particularly suitable for cleaning glass article, glass article is exposed to conventional sanitising agent and can scratches and blur.Another advantage of hydrogen peroxide is that it resolves into the oxygen G﹠W, and can not produce pollution in being discharged into environment the time.

And this main cleaning step is when taking place, and catholyte tank 12 is used for from the main suit 16 fresh softening water and replenishes.The hydrogen peroxide production process begins once again, up to a collection of hydrogen peroxide that produces desired concn.This a collection of being stored in subsequently in the catholyte tank 12 is moved once more up to dishwasher, and treater 19 is determined the time span that superoxide have stored and calculate electrolyzer 1 thus to need the time of operation with the alternative hydrogen peroxide that decomposes at this moment.This time can be apprised of the user of dishwasher, for example by the visual display unit on control panel 30.

When main cleaning was finished, basin 24 was cleared via wet-pit 35 and fills fresh water again, and water is heated so that wash tote.After flushing, basin is draining once more.Also drying step can be arranged.Preferably, drying step comprises the of short duration blowing of high velocity air, leaves recess in the bowl to force residual water, as the bottom of the cup of tipping.The slow air flow process that is used for dry bowl subsequently.Air can be heated.

Can be embodied as the further measure that minimizing produces the time of a collection of hydrogen peroxide again and comprise the speed that reduces its decomposition.By the speed of reduce decomposing, a collection of hydrogen peroxide that has stored a very long time can have than obtainable higher residual concentration so far.This can realize by the pH value of control cathode electrolytic solution.Have been found that the pH value makes a collection of hydrogen peroxide have slower decomposition rate less than 8.5.It is 8.11 o'clock typical decomposition in the pH value that Fig. 5 shows hydrogen peroxide.Concentration eases down to about 0.225% from about 0.4% approximately needs five days.But, if the pH value greater than 8.5, the speed of decomposition is faster.Usually, be a collection of hydrogen peroxide that produced at the negative electrode place in 8.64 o'clock from concentration in the pH value be 0.4% to be decomposed into 0.225% and to need half a day.

The pH value of catholyte can controlled a kind of mode be by controlling the pH value of anolyte, changing because any variation of the pH value of catholyte can produce the pH value of anode electrode electrolytic solution pro rata.The preferred value of the pH value of anolyte is between 1 and 2.This can realize as anolyte by using metabisulfite solution.Alternatively, can adopt softening water.

In the start-up course of electrolyzer 1, anolyte can not used up, but usually for example because evaporation can small loss.Compare with the total amount of anolyte in remaining on jar, replenish anolyte 11 by the water that uses relatively small amount, the variation of the pH value of anolyte is held minimum.In Fig. 7, a kind of anolyte tank valve 36 is provided, be set to the moisture from the main suit is fitted on anolyte tank 14.More substantial if desired water then adds a spot of water, with the pH value stabilization that allows anolyte 11 between the water of doses.The further stability of the pH value of anolyte 11 can be exposed to air by the restriction anolyte and realize, for example, makes anolyte tank 14 airtight, so that anolyte does not need to fill it up with very continually.

Invention has been described with reference to the automatic dishwasher that adopts hydrogen peroxide to wash the dishes.But the present invention has more applications.For example, the present invention can be used for other cleaning operation, as floor cleaning device tool and particularly carpet cleaner.In incorporating steam washing machine of the present invention or steam generating iron into, hydrogen peroxide is heated, and this is considered to increase the effect of its bleaching.

Therefore hydrogen peroxide has sterilization effect, and the present invention can be used for family expenses and industrial use, with to utensil, working-surface sterilization, to treat sick and wounded and to infect and as the dispensers of hand washer.Other application of the present invention are apparent to those skilled in the art.

Claims

1. equipment that is used to produce hydrogen peroxide, comprise the electrolyzer that is set to produce hydrogen peroxide, be used to store the reservoir of the hydrogen peroxide that produces by described electrolyzer and be set to start described electrolyzer and stored hydrogen peroxide is incorporated into the controller of described electrolyzer from described reservoir, this controller also is set to control the pH value that is fed to described electrolyzer and comprises the electrolytic solution of the hydrogen peroxide that is produced by described electrolyzer and is lower than preset value.

2. equipment as claimed in claim 1, wherein, described controller also is set to monitor the time span in the Already in described reservoir of stored hydrogen peroxide, and is set to depend on that the time span of this storage starts described electrolyzer through the scheduled time.

3. equipment as claimed in claim 1 also comprises the pump that is configured such that hydrogen peroxide circulates between described reservoir and electrolyzer.

4. equipment as claimed in claim 1 wherein, is controlled the pH value that is fed to described electrolyzer and comprises the electrolytic solution of the hydrogen peroxide that is produced by this electrolyzer by the pH value of controlling the electrolytic solution in the described electrolyzer and is lower than preset value.

5. equipment as claimed in claim 4, wherein, the electrolytic solution in the described electrolyzer is associated with the anode of described electrolyzer.

6. equipment as claimed in claim 4, wherein, the electrolytic solution in the described electrolyzer is stored in the tight tank.

7. equipment as claimed in claim 4 wherein, replenishes electrolytic solution in the described electrolyzer by adding water.

8. equipment as claimed in claim 7 wherein, is compared the water that adds relatively small amount with the amount of electrolytic solution in the described electrolyzer.

9. equipment as claimed in claim 4, wherein, the electrolytic solution in the described electrolyzer is softening water.

10. equipment as claimed in claim 9, wherein, water is supplied from local main suit.

11. equipment as claimed in claim 4, wherein, the electrolytic solution in the described electrolyzer is metabisulfite solution.

12. each described device that is used to produce the equipment of hydrogen peroxide among combination such as the claim 1-11.

13. any one described automatic dishwasher that is used to produce the equipment of hydrogen peroxide in combination such as the claim 1 to 11.

14. automatic dishwasher as claimed in claim 13, be set to produce pre-wash step at being placed on the article that are used in the dishwasher clean with described controller, described controller is set to start described electrolyzer and in described pre-wash step hydrogen peroxide is incorporated into described electrolyzer from described reservoir.

15. automatic dishwasher as claimed in claim 13, wherein, hydrogen peroxide is applied on the article that will be cleaned from described reservoir in cleaning step.

16. automatic dishwasher as claimed in claim 15, wherein, when the hydrogen peroxide of described reservoir was cleared, described electrolyzer was activated to produce hydrogen peroxide and to be stored in the described reservoir.

17. method that in comprising the equipment of electrolyzer, produces hydrogen peroxide, described electrolyzer is configured to produce hydrogen peroxide, described method comprises: start described electrolyzer and stored hydrogen peroxide is incorporated into the pH value that described electrolyzer and control is fed to described electrolyzer and comprises the electrolytic solution of the hydrogen peroxide that is produced by described electrolyzer from reservoir and be lower than preset value.

18. a method of cleaning vessel comprises the step that applies hydrogen peroxide to described vessel, described hydrogen peroxide produces by the described method of claim 17.

19. method as claimed in claim 18 wherein, produces hydrogen peroxide in pre-wash step, wherein water is applied to the vessel that will be cleaned.

20. method as claimed in claim 18, wherein, hydrogen peroxide is applied to vessel from described reservoir in main cleaning step.

21. method as claimed in claim 20, wherein, when the hydrogen peroxide of described reservoir was cleared, described electrolyzer was activated to produce hydrogen peroxide and to be stored in the described reservoir.