Method for purifying hydrogen peroxide

Abstract

The present invention relates to a new process configuration for purifying aqueous hydrogen peroxide (H2O2) solutions containing organic impurities.

Description

[0001] This application claims priority from European application number 22216112.7 filed on December 22, 2022. Technical Field

[0002] The present invention relates to a new process configuration for purifying aqueous hydrogen peroxide (H2O2) solutions containing organic impurities. Background Art

[0003] Hydrogen peroxide is one of the most important inorganic chemicals produced worldwide. Its industrial applications include textiles, pulp and paper bleaching, organic synthesis (propylene oxide, caprolactam), the manufacture of inorganic chemicals and detergents, and environmental and other applications.

[0004] The synthesis of hydrogen peroxide is primarily achieved by using the Riedl-Pfleiderer process (originally disclosed in US Pat. Nos. 2,158,525 and 2,215,883), also known as the anthraquinone cycle process or the AO (auto-oxidation) process.

[0005] A well-known method is the circulation method of dissolving the organic anthraquinone in a solvent and circulating this "working solution - WS" mixture around the equipment.

[0006] The first step of the AO process is to chemically reduce two main organic substances (useful quinone(s)) (2-alkylanthracene-9,10-dione and / or 6-alkyl-1,2,3,4-tetrahydroanthracene-9,10-dione) to the corresponding hydroquinone(s) (2-alkylanthracene-9,10-diol and / or 6-alkyl-1,2,3,4-tetrahydroanthracene-9,10-diol) using hydrogen and a catalyst. The mixture of organic solvent, hydroquinone, and quinone substance is then separated from the catalyst and oxidized using oxygen, air, or oxygen-enriched air to regenerate the quinone(s) while simultaneously forming hydrogen peroxide.

[0007] The organic solvent is typically a mixture of two solvents, one being a good solvent for dissolving one or more quinones (usually a non-polar solvent, such as a mixture of aromatic compounds) and the other being a good solvent for dissolving one or more hydroquinones (usually a polar solvent, such as a long-chain alcohol). The hydrogen peroxide is then typically extracted with water in an extraction column and recovered as a crude aqueous hydrogen peroxide solution, and the working solution is returned to the hydrogenator to complete the loop. Thus, the typical layout of a standard hydrogen peroxide plant can be summarized as starting with a hydrogenator, followed by an oxidation column, and then an extraction column. The hydrogen peroxide is typically extracted from the working solution in a demineralized water stream from the extraction column.

[0008] Although extraction methods are highly effective in separating the aqueous phase containing hydrogen peroxide from the organic phase containing quinones, solvents, and degradation agents, some of those organic substances remain in the aqueous phase and are generally undesirable to the end user due to their impact on final product quality and yield. Typically, the concentration of these organic impurities in aqueous hydrogen peroxide solutions with a concentration of 20% to 70% by weight ranges from hundreds or tens of milligrams per kilogram. These organic impurities are typically measured and referred to as total organic carbon (TOC).

[0009] Several operations are described in the prior art in order to reduce the organic content of the aqueous phase, which operations can be used alone or in combination with, for example, distillation, gas stripping, reverse osmosis, resin adsorption, etc.

[0010] EP 0930269 A1 describes a purification process in which a reverse osmosis membrane is used to remove most of the contaminants from hydrogen peroxide. In this case, the permeate from the reverse osmosis operation exhibits a low TOC content, but a retentate stream with a concentrated TOC is inherently generated, which is undesirable for the end customer and requires further treatment to reduce the TOC.

[0011] In the prior art, a common solution for purifying hydrogen peroxide produced by the AO-process is to use adsorption resins due to the reliability of the performance of such resins and the low operating costs associated with their potential regeneration once saturated.

[0012] For example, EP 1520839 A1 relates to a method for purifying hydrogen peroxide by using a combination of reverse osmosis and adsorption resins. However, this method does not take into account the regeneration of the resin used, and therefore the method provides an undesirably large amount of resin waste.

[0013] U.S. Patent No. 6,896,867 discloses a method for producing purified aqueous hydrogen peroxide solution using an adsorption resin and regenerating it. In this case, the resin is regenerated in the same vessel, resulting in time loss, quality loss, and potentially dangerous and undesirable mixing of peroxide with the regeneration agent.

[0014] CN 208554226 discloses a device for purifying electronic grade hydrogen peroxide, wherein an adsorbent resin is used in one container and regenerated with a regenerant in a separate container. This method allows for continuous operation of the process. However, one of the problems with this method is that hydrogen peroxide and / or regenerants may accumulate in the macroporous resin structure. In addition, the transfer of the resin from the purification container to the regeneration container is carried out under vacuum. Vacuum transfer carries the risk of air entering the system, which leads to an undesirable safety risk scenario in which typical regenerant (e.g., methanol) vapor mixes with air in a confined space and thus causes an explosion. It is well known in the art that a mixture of organic vapor (also known as fuel) and air / oxygen (oxidant) that forms a flammable mixture may cause a fire or explosion when in a confined space. In addition, the hydrogen peroxide (oxidant) and regenerant that accumulate in the macroporous resin structure may cause an explosive mixture to form in the confined space and thus cause an explosion.

[0015] In other words, it is difficult to reduce the TOC level of hydrogen peroxide solutions with the help of adsorption resins due to the inherent reactivity of hydrogen peroxide when it comes into contact with resins and the hazardous conditions when hydrogen peroxide comes into contact with organic regenerants. For this reason, it is of paramount importance not only to ensure the production performance of the purification process but also to ensure its safe implementation.

[0016] It was therefore an object of the present invention to provide a process for the purification of hydrogen peroxide solutions from an auto-oxidation (AO) process which overcomes the disadvantages of the processes known in the art, in particular to provide a process for the purification of hydrogen peroxide solutions from an AO process using adsorption resins which has improved production properties, i.e. provides hydrogen peroxide solutions with a low TOC content, and which can additionally be carried out safely. Summary of the Invention

[0017] The present invention relates to a method for purifying an aqueous hydrogen peroxide solution containing organic impurities, the method comprising the following steps:

[0018] (a) contacting an aqueous hydrogen peroxide solution with an adsorption resin in an adsorption vessel to remove at least a portion of organic impurities and obtain a purified aqueous hydrogen peroxide solution, and collecting the purified aqueous hydrogen peroxide solution outside the adsorption vessel,

[0019] (b) subsequently adding a liquid, preferably demineralized water, to the adsorption vessel so that the suspension of resin flows out of the adsorption vessel through the first line into the regeneration vessel at a higher pressure in the adsorption vessel and the first line than outside the adsorption vessel and the first line;

[0020] (c) treating the resin in the regeneration vessel with an organic regeneration agent to obtain regenerated resin,

[0021] (d) returning the regenerated resin to the adsorption vessel through the second line by using a liquid, preferably demineralized water, at a higher pressure in the regeneration vessel and the second line than outside the regeneration vessel and the second line. DETAILED DESCRIPTION

[0022] Before the purification methods of the present invention are described in detail, it is to be understood that this invention is not limited to the particular method conditions described herein, as such conditions may, of course, vary.

[0023] It is also to be understood that the terminology used herein is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0024] As used herein, the singular forms "a," "an," and "the" include both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compound" means one compound or more than one compound.

[0025] As used herein, the terms "containing / contains / contained of" are synonymous with "including / includes" or "comprising / comprises" and are inclusive or open-ended and do not exclude additional, unrecited members, elements, or method steps. It will be understood that the terms "containing / contains," "comprising / comprises," and "comprised of" as used herein include the term "consisting of / consists / consists of."

[0026] Throughout this application, the term "about" is used to indicate that a value includes the standard deviation of error for the device or method being employed to determine the value.

[0027] As used herein, the term "average" refers to the number mean unless otherwise indicated.

[0028] As used herein, the terms "% by weight," "wt.-%," "weight percent," or "percent by weight" are used interchangeably. The same applies to the terms "% by volume," "vol.-%," "vol. percent," or "percent by volume," or "% by mole," "mol-%," "molar percent," or "percent by mole."

[0029] Numerical ranges recited by endpoints include all integers and, where appropriate, fractions contained within the range (e.g., 1 to 5 when referring to, for example, the number of elements, may include 1, 2, 3, 4, and when referring to, for example, a measurement, may also include 1.5, 2, 2.75, and 3.80). Endpoint recitations also include the endpoint values ​​themselves (e.g., 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all subranges contained therein.

[0030] Unless otherwise defined, all terms used in disclosing the present invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. By way of further guidance, term definitions are included to better understand the teachings of the present invention.

[0031] Should the disclosure of any patents, patent applications, and publications conflict with the description of this application to the extent that a term may be unclear, this description shall take precedence.

[0032] In the following paragraphs, different alternatives, embodiments and variants of the present invention are defined in more detail. Each alternative and embodiment thus defined can be combined with any other alternative and embodiment when the value ranges for the same parameter are separated, and this applies to each variant, unless clearly indicated to the contrary or clearly incompatible. In particular, any feature indicated as being preferred or advantageous can be combined with any other feature or features indicated as being preferred or advantageous.

[0033] Furthermore, in one or more embodiments, the specific features, structures, or characteristics described in this specification can be combined in any suitable manner, as will be apparent to those skilled in the art from this disclosure. Furthermore, although some embodiments described herein include some features (in addition to other features included in other embodiments), combinations of features from different embodiments are intended to be within the scope of the present invention and from different embodiments, as will be understood by those skilled in the art.

[0034] In order to overcome the disadvantages of the purification methods for aqueous hydrogen peroxide containing organic impurities as known in the prior art and discussed above, the present invention provides a method comprising the following steps:

[0035] (a) contacting an aqueous hydrogen peroxide solution with an adsorption resin in an adsorption vessel to remove at least a portion of organic impurities and obtain a purified aqueous hydrogen peroxide solution, and collecting the purified aqueous hydrogen peroxide solution outside the adsorption vessel,

[0036] (b) subsequently adding a liquid, preferably demineralized water, to the adsorption vessel so that the suspension of resin flows out of the adsorption vessel through the first line into the regeneration vessel at a higher pressure in the adsorption vessel and the first line than outside the adsorption vessel and the first line;

[0037] (c) treating the resin in the regeneration vessel with an organic regeneration agent to obtain regenerated resin,

[0038] (d) returning the regenerated resin to the adsorption vessel through the second line by using a liquid, preferably demineralized water, at a higher pressure in the regeneration vessel and the second line than outside the regeneration vessel and the second line.

[0039] The process of the invention thus comprises four main process steps: a purification step, a transfer step, a regeneration step and a recycling step, whereby the resin adsorption takes place in one vessel, the resin regeneration takes place in another, separate vessel and the resin is transferred in the form of a slurry by means of two lines between the two vessels at a pressure in the vessels and the lines that is higher than the pressure outside these vessels and the lines.

[0040] According to the present invention, it is preferred that the purification vessel and the regeneration vessel have almost similar volumes, more preferably the same volumes.

[0041] exist Figure 1 A flow chart is presented in which schematically illustrates a process configuration according to the present invention;

[0042] legend:

[0043] DMW: demineralized water;

[0044] H2O2: hydrogen peroxide inlet;

[0045] H2O2 product: hydrogen peroxide outlet;

[0046] V-1: adsorption vessel;

[0047] V-1 effluent: hydrogen peroxide and demineralized water effluent;

[0048] MeOH: regenerant inlet;

[0049] Used MeOH: outlet for used regenerant;

[0050] V-2 effluent: regenerant and demineralized water effluent;

[0051] A-1: density analysis point in V-1;

[0052] A-2: Density analysis point in V-2.

[0053] The hydrogen peroxide purification container (V-1) used in the method of the present invention is preferably a tubular column, which comprises a purification column body, and a purification column upper head and a purification column lower head arranged at the upper and lower ends of the purification column body.

[0054] The purification column body has an upper part, which is preferably provided with a filter, a membrane and / or a liquid distributor. More preferably, the filter, the membrane and / or the liquid distributor are located directly below the purification column upper head. The purification upper head preferably has a demineralized water ( Figure 1 DMW) inlet, and the hydrogen peroxide solution product for purification ( Figure 1 The inlet and outlet are each connected to a delivery pipeline. In one embodiment of the present invention, Figure 1 As depicted in FIG, the inlet and outlet of the purification column upper head can be the same, and therefore the purification column upper head is connected to only one transfer line, which is divided into two transfer lines outside the container (column), one for transferring demineralized water and one for transferring purified hydrogen peroxide product.

[0055] In addition, the purification column body has a lower part, which is preferably provided with a filter, a membrane and / or a liquid distributor. More preferably, the filter, the membrane and / or the liquid distributor are located directly above the purification column lower head. The purification lower head preferably has a filter for the hydrogen peroxide solution to be purified ( Figure 1 of H2O2), and for the mixture of hydrogen peroxide and demineralized water effluent obtained in the washing step described below ( Figure 1 The inlet and outlet are each connected to a delivery line. In an embodiment of the present invention, Figure 1 As depicted in FIG, the inlet and outlet of the purification column lower head can be the same, and therefore the purification column lower head is connected to only one transfer line, which is divided into two transfer lines outside the container (column), one for transferring hydrogen peroxide and one for transferring a mixture of hydrogen peroxide and demineralized water effluent.

[0056] Regeneration container ( Figure 1 V-2) is preferably also a tubular column, which includes a regeneration column body, and a regeneration column upper head and a regeneration column lower head arranged at the upper and lower ends of the regeneration column body.

[0057] The regeneration column body has an upper portion provided with a filter, a membrane and / or a liquid distributor, more preferably the filter, the membrane and / or the liquid distributor are located directly below the upper end of the regeneration column. The upper end of the regeneration column preferably has demineralized water ( Figure 1DMW) inlet, and for regeneration agent ( Figure 1 The two inlets are each connected to a delivery line. In an embodiment of the present invention, Figure 1 As depicted in , the regeneration column upper head may have only one inlet, and therefore the regeneration column upper head is connected to only one transfer line, which is divided into two transfer lines outside the container (column), one for delivering demineralized water and one for delivering regenerant.

[0058] Furthermore, the regeneration column has a lower portion which is preferably provided with a filter, a membrane and / or a liquid distributor, more preferably the filter, the membrane and / or the liquid distributor are located directly above the lower head of the regeneration column. The lower head of the regeneration column preferably has a container for the spent regeneration agent ( Figure 1 outlet for the spent MeOH) and for the mixture of regenerant and demineralized water effluent obtained in the washing step described below ( Figure 1 The two outlets are each connected to a delivery pipeline. In an embodiment of the present invention, Figure 1 As depicted in the figure, the regeneration column lower head can have only one outlet and is therefore connected to only one transfer line, which is divided into two transfer lines outside the container (column), one for transferring the spent regenerant and one for transferring the mixture of regenerant and demineralized water effluent.

[0059] The presence of filters, membranes and / or liquid distributors in the container as described above ensures that the adsorption resin used in the process of the invention remains in the container for as long as is necessary to fully carry out the purification and regeneration steps.

[0060] Furthermore, according to the present invention, the adsorption container is provided with a pipeline (first pipeline) connecting the adsorption container and the regeneration container. This pipeline is preferably attached to the purification column body just above the filter, membrane, and / or liquid distributor located in the lower portion of the purification column body, and is preferably attached to the regeneration column body just below the filter, membrane, and / or liquid distributor located in the upper portion of the regeneration column body.

[0061] Furthermore, according to the present invention, a second line is used, which also connects the two containers. The second line is preferably attached to the regeneration column body just above the filter, membrane, and / or liquid distributor located in the lower part of the regeneration column body, and is preferably attached to the purification column body just below the filter, membrane, and / or liquid distributor located in the upper part of the purification column body.

[0062] All inlets, outlets and lines used in the container configuration of the present invention as described above are equipped with valves to control the flow rates of the liquid streams used in the purification process of the present invention.

[0063] In a preferred embodiment of the invention, at the end of each process stage a washing step with demineralized water is performed followed by a concentration analysis, which ensures that no hydrogen peroxide or regeneration agent is transferred between the two vessels.

[0064] One of the essential features of the present invention is the improved ability to remove impurities from aqueous hydrogen peroxide solutions (step (a) of the process according to the invention). These contaminants may, for example, be generated during the production of hydrogen peroxide. In the case of an auto-oxidation (AO) process for the production of hydrogen peroxide, the contaminants may be organic hydrocarbon compounds containing functional groups, such as alcohols, aldehydes, and carboxylic acids, as well as alkylated aromatic compounds. Diisobutylcarbinol would be a typical alcohol, and tetramethylbenzene would be a typical alkylated aromatic compound.

[0065] The adsorption resin used in the present invention is preferably a nonion exchange adsorbent, particularly a cross-linked polymeric styrene resin with divinylbenzene, which preferably does not contain components that can be washed off, such as monomers and polymerization adjuvants. Usually, nonion exchange adsorbents absorb and release ionic species through hydrophobic and polar interactions, that is, they have high affinity to hydrophobic organic substances, but to hydrophilic materials such as water or H O There is low affinity. The cross-linked polymeric styrene resin with divinylbenzene preferably used in the method of the present invention can be obtained by vinylbenzene and divinylbenzene suspension polymerization, and has nonionic functional groups, and their adsorption characteristics are derived from macroporous network structure, pore size range, large surface area and this surperficial aromatic compound property. Thus, non-ion exchange adsorbents, in particular styrene-divinylbenzene copolymer adsorbents, differ significantly in this respect from cation and anion exchange resins, which, due to their functional groups, are very sensitive to oxidation and therefore must be handled with extreme care when used to purify hydrogen peroxide (e.g., by operating at low temperatures, such as 5° C. to 10° C., and low hydrogen peroxide concentrations, such as 25 wt.% to 35 wt.%). In contrast, non-ion exchange adsorbents are stable to oxidation and can even be used at normal ambient temperatures, such as, for example, 15° C. to 35° C., most preferably 20° C. to 25° C. Typically, they are stable at a pH of 0 to 14 and at temperatures up to 250° C.

[0066] The styrene-divinylbenzene copolymer adsorbents preferably used in the present invention have a white or light yellow color, a bead shape, and are insoluble in the treatment medium. Typical characteristics of these styrene-divinylbenzene copolymer adsorbents are an average particle size of 0.5 mm to 1.3 mm, a water content of 45% to 65%, a specific gravity of 1.01 to 1.07, and a viscosity of 700 m³. 2 / g up to 1300m 2 / g, most preferably higher than 1000m 2Such styrene-divinylbenzene copolymers are commercially available, for example, from Rohm & Haas under the trademark "Amberlite". or Sold or marketed by Sunresin under the trademark "Seplite" Other commercially available non-ion exchange adsorbents that can be used in the process of the present invention are acrylic resins, such as Diaion and Diaion

[0067] According to the present invention, it is preferred that, before the adsorption resin is used in the purification process according to the present invention, the resin is washed in order to release from it impurities or preservatives arising during production which could degrade or otherwise affect the quality of the hydrogen peroxide solution. This can be carried out by any method known in the art; for example, such a washing step can be carried out with the aid of water, preferably demineralized water, and / or a lower alcohol, preferably pure methanol.

[0068] By using a non-ion exchange adsorbent in the process according to the invention, hydrogen peroxide solutions having a hydrogen peroxide concentration of up to 55 wt.-% can be purified. Preferably, the solution to be treated has a hydrogen peroxide concentration of between 35 wt.-% and 55 wt.-%, more preferably between 40 wt.-% and 53 wt.-%, even more preferably between 45 wt.-% and 52 wt.-%.

[0069] The method step (a) of the present invention is preferably a continuous flow method step, wherein the hydrogen peroxide solution to be purified passes through an adsorption vessel. The vessel is preferably a bed column filled with an adsorption resin, in particular when the density of the hydrogen peroxide solution is higher than the density of the adsorption resin. The hydrogen peroxide solution is preferably introduced into the vessel at the lower end of the purification column and preferably flows through the vessel (purification column body) at a feed pressure of between 0.5 barg and 5 barg, more preferably between 0.1 barg and 3 barg, and preferably at a flow rate of 0.5 to 8 bed volumes (BV) / hour, more preferably 1 to 3 bed volumes / hour, to leave the purification vessel at the upper end of the purification column. The bed volume (BV) depends on the bed height of the vessel (column) and the cross-sectional area of ​​the column body and is calculated by the following formula:

[0070]

[0071] By carrying out step (a) of the process according to the invention, the content of organic impurities, which is typically between 100 mg / kg and 400 mg / kg, can be reduced to a maximum of 25 mg / kg (measured as total organic carbon (TOC), determined using a combustion catalytic oxidation method as commonly used in the art of the present invention and described in the examples below). Preferably, the purified hydrogen peroxide solution product has a TOC content of between 25 mg / kg and 150 mg / kg, more preferably between 40 mg / kg and 100 mg / kg, and most preferably between 50 mg / kg and 80 mg / kg, measured using the combustion catalytic oxidation method. If desired, for a fixed peroxide flow rate, it will be possible to further reduce the impurities by increasing the amount of resin used.

[0072] Once the resin has been saturated, i.e., the purified hydrogen peroxide solution stream leaving the adsorption vessel has a constant TOC content as defined above, the flow of hydrogen peroxide solution into the vessel is stopped, and demineralized water is passed through the vessel (purification column body), preferably from the top of the purification column of the vessel, until no detectable amount of hydrogen peroxide is present in the vessel, which is typically after 80 minutes to as long as 100 minutes. Preferably, the washing step is carried out at a temperature between 10° C. and 50° C., more preferably between 15° C. and 35° C. In addition, the pressure used in the washing step is preferably 0.01 barg to 10 barg, 0.05 barg to 8 barg, more preferably 0.1 barg to 5 barg. The demineralized water is passed through the packed bed vessel at a flow rate of 2 to 5 bed volumes per hour, preferably 3 to 4 bed volumes per hour.

[0073] The amount of hydrogen peroxide present in the container can be determined by measuring the density of the effluent mixture containing hydrogen peroxide and demineralized water, which mixture leaves the container at the lower end of the purification column (see Figure 1 , A-1). It is well known that different materials have different densities, and the density of a mixture of multiple components is the result of a combination of the different densities of these components. For example, at 20°C, methanol has a density of 791.4 kg / m 3 Density of water: 998.2 kg / m 3 The density of 100% hydrogen peroxide is 1448.0 kg / m 3 density.

[0074] If the measured density of the mixture of hydrogen peroxide and demineralized water leaving the vessel at the lower head of the purification column corresponds to the density of demineralized water, i.e. the density is preferably 998.2 kg / m3 at 20° C. 3 ±0.1kg / m 3 , the "mixture" leaving the container no longer contains hydrogen peroxide. Therefore, there is no longer any hydrogen peroxide inside the container.

[0075] At this point, the adsorption resin, along with the demineralized water, is transferred from the adsorption vessel to the regeneration vessel via the first line, which connects the two vessels as described above. This transfer in step (b) of the process according to the invention is carried out at a higher pressure inside the adsorption vessel and the first line than outside the adsorption vessel and the first line, i.e., the transfer of the resin in slurry form is carried out at a positive pressure, preferably a pressure above ambient pressure (i.e., above 1.01 bara). According to the invention, this pressure is preferably between 1.5 and 3 bara. This pressure is generated by using a flow rate of demineralized water introduced into the adsorption vessel of between 2 and 6 bed volumes / hour, more preferably between 3 and 5 bed volumes / hour.

[0076] The use of positive pressure avoids the ingress of air into the system. Furthermore, due to the washing step of the adsorption vessel as described above, hydrogen peroxide is not undesirably transferred to the regeneration vessel.

[0077] In the prior art, adsorption resins are generally capable of regeneration. Typical regeneration agents used in the regeneration process step (process step (c)) of the present invention are lower alcohols, such as methanol, ethanol, or isopropanol. In a preferred embodiment of the present invention, methanol is used as the regeneration agent.

[0078] Once the adsorption resin with demineralized water is completely transferred to the second container, the resin, preferably packed in a bed in the regeneration column body, is regenerated with a regenerant, preferably passed from the regeneration column head through the container (regeneration column body) to the regeneration column head. The amount of organic regenerant used in step (c) is at least 1 bed volume, preferably at least 1.5 bed volumes.

[0079] According to the present invention, it is preferred that the regenerant be used in the form of an aqueous solution. The solution is transferred from the upper end of the regeneration column to the lower end of the regeneration column at a flow rate of 1 to 4 bed volumes / hour, preferably 2 to 3 bed volumes / hour. The regeneration process step is performed for at least 60 minutes, preferably at least 90 minutes.

[0080] The regenerant can be reused after use by separating the impurities by suitable techniques such as distillation. Thus, the spent regenerant is collected for distillation and reused in one or more continuous cycles (see Figure 1 of used MeOH).

[0081] Once the adsorption resin is regenerated, i.e., substantially free of adsorbed organic matter (this is typically after 80 minutes, preferably after 60 minutes), the introduction of regenerant into the regeneration vessel is stopped and demineralized water is passed downwardly through the vessel (regeneration column) until the density of the mixture is that of demineralized water, ensuring that no regenerant remains in the vessel, i.e., the density of the "mixture" is 998.2 kg / m at 20°C. 3 ±0.1kg / m 3 , and is a mixture containing regenerant and demineralized water effluent ( Figure 1 The used MeOH) is measured after leaving the regeneration vessel at the lower head of the regeneration column (see Figure 1 , A-2). The washing step is preferably carried out at a temperature between 10° C. and 50° C., more preferably between 15° C. and 35° C. Furthermore, the pressure used in the washing step is preferably 0.01 barg to 10 barg, 0.05 barg to 8 barg, more preferably 0.1 barg to 5 barg.

[0082] At this stage of the process according to the invention, the regenerated adsorbent resin is transferred to the first vessel along with demineralized water via a second line, which connects the two vessels as described above. The resin is then ready for contact with hydrogen peroxide again. This transfer step (step (d) of the process according to the invention) is carried out at a higher pressure inside the regeneration vessel and the second line than outside the regeneration vessel and the second line. This means that the transfer of the resin in slurry form is carried out under positive pressure, preferably above ambient pressure, i.e., above 1.01 bara, preferably between 1.5 and 3 bara. This pressure is generated by using a flow rate of demineralized water introduced into the regeneration vessel of between 2 and 6 bed volumes / hour, more preferably between 3 and 5 bed volumes / hour.

[0083] The process of the present invention can be carried out in batch mode or continuous mode. If the process is carried out in continuous mode, at least two sets of adsorption vessels and regeneration vessels as described above for carrying out the process are used, i.e., the process of the present invention is carried out in these two sets of adsorption and regeneration vessels in a staggered manner to ensure a continuous process.

[0084] The present invention is further illustrated by the following examples. It should be understood that the following examples are for illustrative purposes only and are not intended to limit the present invention thereto.

[0085] Examples

[0086] Example 1

[0087] At 20° C., an aqueous solution of hydrogen peroxide having a concentration of 50% by weight and 295 mg TOC / kg was continuously fed into a vessel containing 268 g of polymerized styrene-divinylbenzene resin. The resin used was Seplite from Lanxiao Technology. At a feed pressure of 0.2 barg, a flow rate of 1.7 L / h (or 4 bed volumes / hour, 4 BV / h) was passed upward through the packed bed until the resin was saturated to an average TOC value of 67 mg / kg. A total of 66.6 kg of purified hydrogen peroxide was collected.

[0088] Thereafter, demineralized water at a flow rate of 4 BV was passed downwardly through the packed bed for 80 minutes to eliminate hydrogen peroxide hold-up until the density measurement of the outlet stream was that of demineralized water.

[0089] The resin was then transferred to a vessel of similar volume using demineralized water at a flow rate of 4 BV / h through a connected line until the first vessel was free of resin.

[0090] Thereafter, methanol at a flow rate of 2 BV / h was passed downward through the packed bed for 60 minutes to regenerate the resin.

[0091] Thereafter, demineralized water at a flow rate of 4 BV was passed downwardly through the packed bed for 90 minutes to eliminate menthol holdup until the density measurement of the outlet stream was that of demineralized water.

[0092] The resin was then transferred to the first vessel through the connected line using demineralized water at a flow rate of 4 BV / h until the exiting vessel was free of resin.

[0093] The mixture of methanol, organic impurities and demineralized water was collected for methanol reuse. The mixture was separated using a batch distillation system consisting of 15 theoretical plates to obtain methanol with a purity of 99% by weight, which could be reused in the next resin regeneration.

[0094] Example 2-20

[0095] Examples 2-20 were carried out in the same manner as Example 1, i.e. the entire cycle was repeated 19 times. All examples showed similar performance:

[0096]

[0097] Table 1

[0098]

[0099] Table 2

[0100] TOC content is measured using a combustion catalytic oxidation method commonly used in the technical field of the present invention. In this method, the sample to be used for TOC determination is heated to 680°C in an oxygen-rich environment within a TC combustion tube filled with a platinum catalyst. This decomposes the organic carbon impurities present in the sample and converts them into carbon dioxide. The generated carbon dioxide is detected using an infrared gas analyzer. The total carbon (TC) concentration in the sample is determined by comparison with a calibration curve.

Claims

1. A method for purifying an aqueous hydrogen peroxide solution containing organic impurities, the method comprising the following steps: (a) contacting the aqueous hydrogen peroxide solution with an adsorption resin in an adsorption vessel to remove at least a portion of the organic impurities and obtain a purified aqueous hydrogen peroxide solution, and collecting the purified aqueous hydrogen peroxide solution outside the adsorption vessel, (b) subsequently adding liquid to the adsorption vessel so that the suspension of the resin flows out of the adsorption vessel through the first line into the regeneration vessel at a pressure within the adsorption vessel and the first line that is higher than the pressure outside the adsorption vessel and the first line; (c) treating the resin in the regeneration vessel with an organic regeneration agent to obtain a regenerated resin, (d) returning the regenerated resin to the adsorption vessel through the second line by using a liquid at a pressure in the regeneration vessel and the second line that is higher than the pressure outside the regeneration vessel and the second line; wherein after step (a) and / or after step (c), the container or containers used therein are washed with demineralized water until no detectable amount of hydrogen peroxide and / or regeneration agent is present in the container.

2. The method of claim 1 , wherein the liquid added to the adsorption vessel in step (b) so that the suspension of the resin flows out of the adsorption vessel through the first line into the regeneration vessel is demineralized water.

3. The process of claim 2, wherein the liquid used in step (d) to return the regenerated resin to the adsorption vessel through the second line is demineralized water.

4. The process of claim 1 , wherein the liquid used in step (d) to return the regenerated resin to the adsorption vessel through the second line is demineralized water.

5. The method according to claim 1, wherein After step (a), the adsorption vessel is washed with demineralized water until no detectable amount of hydrogen peroxide is present in the adsorption vessel.

6. The method according to claim 5, wherein: The presence of hydrogen peroxide in the adsorption vessel is measured by analyzing the density of the wash liquid exiting the adsorption vessel.

7. The method according to claim 5, wherein: The washing is carried out at a temperature of 10 to 50° C. and a pressure of 0.01 to 10 barg.

8. The method of claim 1, wherein: After step (c), the regeneration vessel is washed with demineralized water until no detectable amount of adsorbent is present in the adsorption vessel.

9. The method of claim 8, wherein: The washing is carried out at a temperature of 10 to 50° C. and a pressure of 0.01 to 10 barg.

10. The method of claim 1, wherein: After step (a) and after step (c), the container used therein is washed with demineralized water until no detectable amount of hydrogen peroxide and regeneration agent is present in the container.

11. The method according to claim 10, wherein: The washing is carried out at a temperature of 10 to 50° C. and a pressure of 0.01 to 10 barg.

12. The method of claim 1, wherein: After step (a) or after step (c), the container used therein is washed with demineralized water until no detectable amount of hydrogen peroxide or regeneration agent is present in the container.

13. The method of claim 12, wherein: The washing is carried out at a temperature of 10 to 50° C. and a pressure of 0.01 to 10 barg.

14. The method according to any one of claims 1 to 13, wherein The aqueous hydrogen peroxide solution contains organic impurities in an amount of 100 mg / kg to 400 mg / kg as measured by using a combustion catalytic oxidation method before its purification.

15. The method according to any one of claims 1 to 13, wherein The amount of organic impurities in the purified aqueous hydrogen peroxide solution is 25 mg / kg to 150 mg / kg.

16. The method according to any one of claims 1 to 13, wherein These organic impurities are selected from organic hydrocarbon compounds containing functional groups, such as alcohols, aldehydes, carboxylic acids and alkylated aromatic compounds.

17. The method of claim 16, wherein: The alkylated aromatic compound is diisobutyl carbinol and / or tetramethyl benzene.

18. The method of any one of claims 1 to 13, wherein Step (a) is carried out at a temperature of 15°C to 35°C.

19. The method of claim 18, wherein: Step (a) is carried out at a temperature of 20°C to 25°C.

20. The method of any one of claims 1 to 13, wherein The amount of hydrogen peroxide in the aqueous hydrogen peroxide solution is 40 to 55 wt.-%.

21. The method of any one of claims 1 to 13, wherein The adsorption resin is selected from non-ion exchange adsorbents.

22. The method of claim 21, wherein: The adsorption resin is selected from polymerized styrene resins cross-linked with divinylbenzene.

23. The method of any one of claims 1 to 13, wherein The pressure used in step (b) is 0.1 barg to 1 barg.

24. The method of claim 23, wherein: The pressure used in step (b) was 0.5 barg.

25. The method of any one of claims 1 to 13, wherein The regeneration agent used in step (c) is selected from alcohols such as methanol, ethanol, isopropanol, or a combination thereof.

26. The method of any one of claims 1 to 13, wherein The organic regeneration agent is used in step (c) in an amount of at least 1 bed volume.

27. The method of any one of claims 1 to 13, wherein The spent regenerant is collected for distillation and optionally reused in one or more cycles of continuous purification.

28. The method of any one of claims 1 to 13, wherein The process is carried out in a continuous mode by using at least two sets of adsorption vessels and regeneration vessels for carrying out the process.

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