Patent Application
20220324710
The present invention is in the field of a method for obtaining high purity hydrogen peroxide, as well as a production unit for obtaining high purity hydrogen peroxide. In principle the present method and production unit are applicable to further chemical species as well, such as those that dissolve well in water.
Hydrogen peroxide is a chemical compound with the formula H2O2. It has many applications, such as for bleaching, as an oxidizer, and as an antiseptic. Concentrated hydrogen peroxide is difficult to obtain. For chemical purposes typically se is made of the unstable peroxide bond. As a consequence, hydrogen peroxide slowly decomposes.
Hydrogen peroxide can be produced through various chemical routes, wherein it is typically extracted in a final step of the process. Hydrogen peroxide is typically available as a solution in water, hence diluted. For consumers it is usually available in low concentrations (˜5 wt. %). For laboratories higher concentrations (˜30 wt. %) may be used. Commercial grades above 70% may also be available, but these pose certain risks. Therefore, most production relates to a concentration of 70% or less.
There are various process and production units that achieve higher concentrations, such as up to 95% or more. These may involve distillation units, membranes, chemicals, desiccants, sorbents for water, low pressures of typically <10 kPa, elevated temperatures, and combinations thereof. The obtained hydrogen peroxide is typically prone to some extent of disintegration and/or reaction.
Production of hydrogen peroxide, and purification thereof typically makes use of expensive systems and processes, such as in terms of energy consumption, e.g. at an elevated temperature, chemical consumption, such as catalyst consumption, high pressures, use of a resin, use of a membrane, complex installations, and so on. In addition, thereto also expensive systems and processes are used, possibly in addition to the above. the concentration of the obtained hydrogen peroxide is typically rather low, such as up to 70% or so. Thereto also Such is a concentration is acceptable for many applications, but the present invention is aimed at achieving much higher concentrations.
So prior art methods for concentrating hydrogen peroxide employ complex concentration techniques. For instance, membranes for filtration process, active reagents, external sources of energy, such as temperature and pressure, and other chemical catalysts are used, sometimes in conjunction. Hence these processes require a series of complex steps and vast amounts of infrastructure to set up. These methods can also sometimes take long to achieve the increased hydrogen peroxide levels, such as longer than 48 hours, and are often limited to a maximum concentration of 80%. These complex methods take a lot of resources and development to get implement in an efficient scale and take a large stationary production facility for it to be cost effective and viable. Once produced, this concentrated hydrogen peroxide must be then transported to the required facilities which possess additional hazards arising from the highly flammable nature and instability issues with concentrated hydrogen peroxide. Due to the complex nature of the current methods, sometimes the yield obtained of the concentrated product is low per unit volume input, and hence is inefficient. The usage of these complex processes is also harmful to the environment due to exhaust gasses formed from the various reactions during the concentration products. If membranes, catalysts, reagents or other chemicals are used in the concentration process, there is copious amounts of waste material that needs to expelled and these wastes can be reactive with the environment and hence will need treatment themselves to make them less potent. This introduces additional costs and complexities into the production process. The current methods can also be dangerous to the labour forces that are concentrating the solution as higher concentrations are more likely to corrode complex equipment over repeated use and may cause harmful leakages or explosions. Concentration techniques that require an external source of energy such as temperature, lead to instabilities of the hydrogen peroxide and hence can also cause leakages or explosions.
An example thereof is DE 36 32 245 A1. Therein a method is recited for concentrating aqueous solutions from production processes and an apparatus is disclosed for carrying out the method. The method steps comprise the particular aqueous solution flowing through at least one tank in the course of a circulation and the surface of the volume of solution situated in the tank being exposed to an air stream which is heated, i.e. energy is supplied, by so-called heat accumulated at the top in closed chambers. The apparatus comprises a plurality of flat tanks stacked one above the other, to which an aqueous solution is fed from a main vessel by a feed pump. The solution flows by gravity back into the main vessel and on passing through the tanks is exposed to an air stream which is generated by a fan and is heated by the heat accumulated at the top. The air stream serves as a heat source for vaporising the solution and for transporting away the evaporated portions of the solution. The document is silent on the hydrogen peroxide solutions, as it relates to salt solutions, and no results are given. As mentioned, heated air is used, the air not being an inert gas.
WO 2005/113428 A1 recites methods for concentrating hydrogen peroxide solutions. The methods utilize a polymeric membrane separating a hydrogen peroxide solution from a sweep gas or permeate. The membrane is selective to the permeability of water over the permeability of hydrogen peroxide, thereby facilitating the concentration of the hydrogen peroxide solution through the transport of water through the membrane to the permeate. By utilizing methods in accordance with the invention, hydrogen peroxide solutions of up to 85% by volume or higher may be generated at a point of use without storing substantial quantities of the highly-concentrated solutions and without requiring temperatures that would produce explosive mixtures of hydrogen peroxide vapors.
Some methods include using complex reagents, such as magnesium chlorate, and sodium salts to concentrate and purify the aqueous solution. These might lead to some impurities in the concentrated hydrogen peroxide.
The present invention therefore relates to an improved method for economical and simplified in-situ concentration of >90 wt. % hydrogen peroxide, which solves one or more of the above problems and drawbacks of the prior state-of-the-art, providing reliable results, without jeopardizing functionality and advantages.
It is an object of the invention to overcome one or more limitations of the methods of the prior art and at the very least to provide an alternative thereto. In a first aspect, the invention relates to a method for obtaining high purity hydrogen peroxide comprising of providing an open container with an aqueous fluid comprising hydrogen peroxide, putting the open container with the aqueous fluid in a closed space, at ambient conditions providing an inert gas flow over and in contact with the aqueous fluid, removing water from the aqueous fluid at said ambient conditions by said gas flow, and thereby concentrating the H2O2. The term “inert gas” is used in its normal meaning, namely a gas that does not undergo chemical reactions under a set of given conditions; for the present invention this is the contact with either water or hydrogen peroxide. The term “high purity” [chemical] is used in its normal meaning, namely a chemical compound with virtually no impurities, and thus a purity of typically at least 90%, and if possible of at least 99%, and often at least 99.5% or more. It has been found that with said method concentration of hydrogen peroxide is obtained in relatively short time periods, under ambient condition, and to very high concentrations, of >90 wt. % hydrogen peroxide, and typically to >98 wt. % hydrogen Peroxide and more, in an economical, simple, fast, user-friendly, and accurate manner. Such can be done in the absence of further features, such as chemicals. The present invention leaves the purity of the feedstock unaltered, making the desired purity a function of the initial feedstock.
An advantage of the present invention is that it can be used for any mixture of chemicals. Nitrogen is inert and can be extracted from the atmosphere. Since the gas is inert it can be released back into the atmosphere without any problem. No chemicals, no membrane, and no heat, are used in the process. Therefore the purity of the chemical is unaltered. A direct interaction between the inert gas and the surface of the chemical solution is provided, without any medium in between (e.g. no membranes). It is noted that using dry-air would cause the chemical surface to react with the oxygen, and other gasses to react with the H2O2, which can lead to decomposition of H2O2 to lower concentrations and can even lead to explosions. It is noted that H2O2 is highly sensitive to foreign particles and impurities, hence dry air can not being used.
In a second aspect the present invention relates to a production unit comprising a concentration chamber 4, in the reaction chamber an open container 3 for receiving aqueous fluid, an aqueous fluid supply 5 in fluid connection with a source of aqueous fluid and the open container in the reaction chamber, an aqueous fluid outlet 6 in fluid connection with a fluid receiver and the open container in the reaction chamber, a gas supply in fluid connection with a source of inert gas 1 and the reaction chamber, a valve 2 for regulating an inflow of inert gas, optionally at least one valve 8 for regulating an outflow of inert gas, and optionally a controller 7. So, with a very simple production unit an economical, simple, fast, user-friendly, and accurate manner, and typically portable, and stand-alone, way of obtaining highly concentrated hydrogen peroxide is provided. The production unit and present method provide the availability of hydrogen peroxide for any small/medium scale research project, as well as a quick route to obtaining the chemical for larger companies.
This invention relates to a method of concentrating hydrogen peroxide in a simplified, safe, economical and portable manner, particularly, an innovative way to concentrate hydrogen peroxide from e.g. 10% to 98% or above within a duration of e.g. 45 hours. The invention uses an inert gas to cause removal of water from an aqueous solution of hydrogen peroxide, thereby concentrating the hydrogen peroxide solution. It typically uses no active input of energy in terms of pressure, temperature, electrical voltage, catalysts, membranes, reagents, chemicals or force. From an aqueous solution of hydrogen peroxide, which implies, a solution of hydrogen peroxide and water, the water molecules are extracted leaving behind the hydrogen peroxide, hence concentrating it. In an example the invention (
So, the present invention provides a radical way to concentrate hydrogen peroxide using minimal external resources and in a safe user environment. As no chemical reagents, external heat, high-pressure environment, or purification/distillation is required, the present method provides an entirely new approach for concentration of hydrogen peroxide. Prior art methods struggle to obtain concentrations higher than 75% to 85%, and hence the present method provides a radical new way to reach concentrations even higher than 95%. Such concentrations of hydrogen peroxide can be used in pesticide products, pharmaceutical industry, clothing industry, chemical industry, cosmetics, food processing, medicine, insecticides, pesticides, packaging, space industry, and defence industry, such as a rocket propellant. The results of hypergolicity and fuel ignition using the oxidizer and fuel combinations were obtained, applicable for multiple space missions, including defence. The results achieved by using the invention allowed to obtain hydrogen peroxide to concentrations in excess of 98% in a period less than 45 hours, as seen in
Advantages of the present description are detailed throughout the description.
In an exemplary embodiment of the present method the inert gas may be >95% pure, preferably >99% pure, more preferably >99.5% pure, such as >99.8% pure, e.g. having less than 10 ppm impurities. Therewith a stable solution of concentrated hydrogen peroxide is obtained.
In an exemplary embodiment of the present method the inert gas may be selected from nitrogen, a noble gas, such as He, and Ar, carbon dioxide, and combinations thereof. Therewith a stable solution of concentrated hydrogen peroxide is obtained.
In an exemplary embodiment of the present method the aqueous fluid may comprise 1-99 wt. % water, preferably 5-98 wt. % water, more preferably 10-97 wt. % water, even more preferably 20-96 wt. % water, such as 50-95 wt. % water.
In an exemplary embodiment of the present method the aqueous fluid may comprise 1-85 wt. % hydrogen peroxide, preferably 2-50 wt. % hydrogen peroxide, more preferably 3-40 wt. % hydrogen peroxide, even more preferably 4-30 wt. % hydrogen peroxide, such as 10-20 wt. % hydrogen peroxide.
The present aqueous fluid typically comprises water and hydrogen peroxide, together typically forming >90 wt. % of the fluid, preferably >95 wt. %, such as >99 wt. %, and only small or tiny amounts of further compounds, typically inevitable, such as impurities, such as <2 wt. %, preferably <1 wt. %, such as <0.2 wt. %.
So, with relatively low amounts of hydrogen peroxide, and likewise high amounts of water, the present method and production unit are capable of increasing the hydrogen peroxide concentration significantly, by removing said water, such as by evaporation. It is noted that prior art methods typically are limited to a maximum of 70% hydrogen peroxide, and sometimes with extreme efforts higher concentrations might be obtained.
In an exemplary embodiment of the present method the water may be removed during a period of 1-1000 hours, preferably 2-350 hours, more preferably 3-170 hours, such as 20-40 hours. Such is much quicker than typical prior art methods. The present method does require some time to remove most or all of the water, but this is considered acceptable as during the method a system or production unit in use can be left alone.
In an exemplary embodiment of the present method ambient conditions may be at a temperature of below 45° C., preferably 10-40° C., more preferably 15-30° C., such as 16-24° C. No heating is required, and hence costs of energy are minimal.
In an exemplary embodiment of the present method ambient conditions may be at a pressure of 15-700 kPa, preferably 35-500 kPa, more preferably 70-400 kPa, such as 100-300 kPa. The gas flow may be provided at a slight under-pressure, at about ambient pressure (100 kPa), or at a slightly elevated pressure. Such may be controlled and regulated by one or more valves.
In an exemplary embodiment of the present method ambient conditions may be in the absence of a catalyst.
In an exemplary embodiment of the present method ambient conditions may be in the absence of a voltage.
In an exemplary embodiment of the present method ambient conditions may be in the absence of a membrane.
In an exemplary embodiment of the present method ambient conditions may be in the absence of a reagent.
In an exemplary embodiment of the present method ambient conditions may be in the absence of a driving force.
In an exemplary embodiment of the present method ambient conditions may be in the absence of addition of thermal energy.
In an exemplary embodiment the method may be in-situ.
Other than many prior art methods for the present method only an open container, typically of glass, a closed space, such as a vessel, some valves, and inert gas are used.
In an exemplary embodiment the present method may be a combination of the above and/or below.
In an exemplary embodiment of the present method for a volume of 1-10 litre aqueous fluid the flow of inert gas may be 1-1000 ccm/min, preferably 10-500 ccm/min, such as 100-200 ccm/min.
In an exemplary embodiment of the present method flow of inert gas may be controlled by at least one valve.
In an exemplary embodiment of the present method flow of gas may be provide over a surface of the aqueous fluid, wherein said surface has a surface area of >100 cm2.
In an exemplary embodiment of the present method a surface of the fluid (m2):volume of the fluid (m3) ratio may be >10−3/m, preferably >10−2/m, such as >0.1/m.
In an exemplary embodiment of the present method hydrogen peroxide may be concentrated to a purity of >90 wt. %, which is already higher than disclosed in the prior art, preferably to >95 wt. %, more preferably to >97 wt. %, such as >98 wt. %. Typically concentrating may be perfumed at a rate of 50-1000 ccm/sec inert gas per 100 cm2 hydrogen peroxide solution surface, preferably 70-500 ccm/sec, more preferably 100-300 ccm/sec, for a period of 1-96 hours, preferably 2-48 hours, more preferably 4-24 hours.
In an exemplary embodiment the present production unit is stand-alone.
The invention will hereafter be further elucidated through the following examples which are exemplary and explanatory of nature and are not intended to be considered limiting of the invention. To the person skilled in the art it may be clear that many variants, being obvious or not, may be conceivable falling within the scope of protection, defined by the present claims.
a-b, and 3-6 show experimental details of the present invention.
In the figures:
Below is a short list of components used:
Nitrogen Gas generator, producing 99.5% pure N2, operating pressure: 2.5 Bar, operating Temperature: 20 degrees Celsius; Feedstock aqueous Hydrogen Peroxide, Hydrogen Peroxide 30%, EMSURE, ISO Sigma-Aldrich, CAS Number: 7722-84-1; concentration Dish 3 of Borosilicate glass, tubes of polypropylene, External Dynamic Air Environment Chamber 9 made of Poly-acetic acid.
Inventors have now obtained H2O2 concentrations of up to 99.5%+, and would now like to include this in the patent application. They have updated the concentration and time graphs as shown in
Experiment
Description of Production Unit Operation (
This production unit comprises at least two main inputs, one for aqueous hydrogen peroxide (5), and one for an inert gas supply (1). The production unit is for purifying (hence concentrating) H2O2. The input of the feedstock hydrogen peroxide was provided at an initial concentration, which might be as low as 5 to 10% H2O2 aqueous solution) and volume that is required to be concentrated. This aqueous H2O2 in an amount of e.g. 2 is introduced into the concentration chamber (shown by 4 in
From graphs 2a and 2b a total time required for a required concentration can be obtained. It is noted that these graphs pertain to a particular and given flow rate of inert gas (140 ml/sec). This flow rate is considered optimal for the present production unit. For a shorter duration of the concentration procedure, a fast flow rate of the inert gas could be used. But this faster flow rate could affect the percent yield of the final concentrated H2O2. In order to significantly improve the final yield, the flow rate may typically be optimised. This will lead to larger amounts of final concentrated H2O2, based on the optimised flow rate selected.
Testing
Two methods were used in different qualities to characterize the concentration of the solution. These are:
Quantitatively: refractive index with the use of Abbe refractometer in controlled conditions (20° C., 1 atm). This optical approach is used to monitor H2O2 concentration. In this method the following procedure was followed; the varied concentration range of H2O2 produced by the present invention was evaluated through refractive index of H2O2 droplets using an Abbe refractometer. Using this technique one can measure the concentrations of H2O2. First the Abbe refractometer device was calibrated with a distilled H2O droplet followed by H2O2 concentrations ranging from 10% to 99.6%. Water has a refractive index of 1.33, and 100% pure H2O2 has a refractive index of 1.41 (at visible wavelengths of light), with aqueous solutions of H2O2 and water lying in between these values. As the concentration of H2O2 in the solution increases, it follows that the refractive index will increase, and by measuring the refractive index, it is possible to determine a concentration of H2O2 in a H2O2 aqueous solution.
Qualitatively: recording of decomposition temperature of the solution through fast recording data acquisition system (55 Hz) with k-type thermocouples. The process was initiated trough thermal activation of the solution. Monitoring the concentration of H2O2 in H2O2 aqueous solution through electrochemical redox reaction, where in the heat energy of the exothermic reaction increases with increasing H2O2 concentration. For this qualitative method, small amount of external source of temperature was used to increase the rate of decomposition of H2O2 aqueous solution.
Decomposition of concentrated H2O2 solutions: This approach helps to predict qualitatively the varied H2O2 concentrated solution decomposition with minimum input activation energy in terms of temperature. For qualitative evaluation of concentration, a H2O2 concentration from 80% and above have been investigated.
Evaluation 1—Decomposition Input Temperature (TMin): The process was initiated with thermal activation of the H2O2 aqueous solution by providing a minimum input activation energy to initiate decomposition. In this evaluation experiment, single drops of varied concentrations of H2O2 (from 80% to 95%) were released over a thermal heating plate from a height of 17 cm. H2O2 droplets of 0.13 mL of volume were generated through an electronic syringe pump. As soon as the concentrated H2O2 droplet comes in contact with the heating plate, it undergoes rapid exothermic decomposition followed by release of energy in terms of temperature. With increase in H2O2 concentration (from 80% to 95% pure) the minimum input energy (TMin) needed for decomposition decreases as seen in
Ignition of concentrated H2O2 aqueous solution with fuel (Ethanol): Recording of ignition of the H2O2 droplet (concentration from 80% to 95%) once it comes in contact with a fuel ethanol (C2H5OH) droplet done using a photron high speed camera at 6400 fps. The reaction starts with minimum activation thermal energy supply of 250° C. via a heating plate to the H2O2 droplet (0.13 mL volume) at different concentrations (80% to 95% pure) and subsequent addition of an ethanol (99.5% pure) droplet from a height of 17 cm to initiate ignition. A electronic syringe pump was used to generate H2O2 and Ethanol droplet. With an increase in H2O2 concentration, it is expected that the ignition temperature increases followed by a decrease in ignition delay time (time between first contact and the start of ignition). This is due to increased energetic content with increased H2O2 concentration. This trend can be seen in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2024229 | Nov 2019 | NL | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/NL2020/050653 | 10/22/2020 | WO |
