Hydrogen peroxide purification process and hydrogen peroxide

Abstract

A hydrogen peroxide purification process, including supplying a starting stream containing hydrogen peroxide at a content above 50 wt %, as well as at least one stabilizer; a single step of purification of the starting stream, the single step having purification by reverse osmosis; collecting a purified stream at the end of said single purification step, in which purification by reverse osmosis includes: passing the starting stream over a first membrane; collecting a permeate and a retentate from the first membrane; passing the permeate from the first membrane over a second membrane; collecting a permeate and a retentate from the second membrane, the purified stream having the permeate from the second membrane.

Claims

1. A hydrogen peroxide purification process, comprising: supplying a starting stream, wherein the starting stream comprises hydrogen peroxide at a content above 50 wt %, and at least one stabilizer; purifying the starting stream by reverse osmosis, wherein the purifying consists essentially of: passing the starting stream over a first membrane; collecting a permeate and a retentate from the first membrane; passing the permeate from the first membrane over a second membrane; and collecting a permeate and a retentate from the second membrane, wherein the purified stream consists of the permeate from the second membrane, and wherein the purification process excludes the presence of ion exchange steps.

2. The process as claimed in claim 1, wherein the starting stream is prepared by a process comprising passing the starting stream over an adsorption resin.

3. The process of claim 1, wherein the starting stream comprises at least 55 wt % of hydrogen peroxide.

4. The process of claim 1, wherein the stabilizer is selected from phosphate or pyrophosphate salts, tin salts, organophosphorus compounds and phosphonates, carboxylic acids, borates, nitrates and combinations of the latter.

5. The process of claim 1, wherein the first membrane is of the polyamide, polypiperazine, polyacrylonitrile or polysulfone type.

6. The process of claim 1, wherein the purified stream comprises: less than 100 mg/kg of total organic carbon; less than 5 mg/kg of phosphorus; less than 0.04 mg/kg of iron; and less than 0.1 mg/kg of the sum of chromium and nickel.

7. The process of claim 1, wherein the first membrane and the second membrane are used for greater than or equal to 1 week.

8. The process of claim 1, wherein the purification process form a solution comprising at least 55 wt % of hydrogen peroxide, at least one stabilizer, less than 100 mg/kg of total organic carbon; less than 5 mg/kg of phosphorus; less than 0.04 mg/kg of iron; and less than 0.1 mg/kg of the sum of chromium and nickel.

9. The process of claim 8, wherein the stabilizer is selected from phosphate or pyrophosphate salts, tin salts, organophosphorus compounds and phosphonates, carboxylic acids, borates, nitrates and combinations of the latter.

10. The process of claim 8, wherein the content of stabilizer is between 5 and 50 mg per kg of solution.

11. The process of claim 1, comprising supplying the starting stream directly from a hydrogen peroxide production unit.

12. The process of claim 11, wherein the starting stream is passaged over an adsorption resin in the hydrogen peroxide production unit before being supplied to the hydrogen peroxide purification process.

13. The process of claim 1, wherein the starting stream is passaged over an adsorption resin in a hydrogen peroxide production unit before being supplied to the hydrogen peroxide purification process.

Description

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(1) The invention will now be described in more detail in the following nonlimiting description.

(2) Unless stated otherwise, all the concentrations or contents mentioned are values by weight.

(3) The invention specifies supplying a starting stream containing hydrogen peroxide at a content above 50 wt %. This starting stream has preferably come directly from a hydrogen peroxide production unit, and has not undergone prior purification other than optionally passage over adsorption resin during its production. It is an aqueous solution of hydrogen peroxide.

(4) The invention is advantageously applied to starting streams containing at least 52%, at least 55%, at least 58%, at least 60%, at least 62% or at least 65% of hydrogen peroxide.

(5) The starting stream contains at least one stabilizer. This stabilizer is generally added directly at the outlet of the production unit. The stabilizer content varies from 1 to 400 mg/kg, preferably from 5 to 300 mg/kg.

(6) As stabilizer, we may use for example phosphate or pyrophosphate salts, tin salts, organophosphorus compounds and notably phosphonates, carboxylic acids, borates, nitrates or combinations of the latter. The preferred stabilizer is a mixture of sodium pyrophosphate and sodium stannate containing 1 to 150 mg of each stabilizer per kg of product, preferably from 15 to 100 mg of each stabilizer per kg of product, preferably from 20 to 110 mg of each stabilizer per kg of product, preferably from 25 to 120 mg of each stabilizer per kg of product.

(7) The invention specifies a single step of purification of the starting stream, which is a reverse osmosis purification step. Thus, the invention excludes the presence of steps of purification by another technique, such as steps of distillation, ion exchange, exposure to ozone or to ultraviolet radiation, ultrafiltration or nanofiltration, etc.

(8) The reverse osmosis purification step may comprise a single passage over a reverse osmosis membrane, or a succession of several passages over reverse osmosis membranes, notably a succession of two or three passages over reverse osmosis membranes.

(9) The succession of several passages over reverse osmosis membranes may be carried out by arranging reverse osmosis units in series. Of course, it is also possible to arrange reverse osmosis units in parallel, depending on the desired flow rate.

(10) The reverse osmosis membranes used in the context of the invention are semipermeable membranes of the polyamide, polypiperazine, polyacrylonitrile or polysulfone type, and preferably are polyamide membranes on a polysulfone support.

(11) Each step of passage over a reverse osmosis membrane makes it possible to collect a permeate and a retentate, the permeate being the fraction depleted of contaminants. Passage over the membrane is forced by applying a suitable pressure.

(12) The retentate, enriched in contaminants, may also be utilized, for example in the form of hydrogen peroxide corresponding to lower specifications. If only part of the starting stream is purified, it is thus possible to mix the retentate with the other part (not submitted to purification) of the starting stream.

(13) The permeation stream may for example be between 10 and 200 L/h.Math.m.sup.2, preferably between 20 and 180 L/h.Math.m.sup.2, preferably between 50 and 150 L/h.Math.m.sup.2. The pressure may for example be between 10 and 80 bar, preferably between 15 and 70 bar, preferably between 25 and 40 bar. The VCF (Volume Concentration Factor, calculated as the ratio of the feed flow rate to the retentate flow rate) may for example be between 1 and 10, preferably between 1.2 and 8, preferably between 1.5 and 5, preferably between 2 and 4.

(14) One problem that arises in the reverse osmosis purification of hydrogen peroxide streams is that hydrogen peroxide has a tendency to attack the membranes chemically, especially when it is present at a high concentration. Thus, document U.S. Pat. No. 4,879,043 teaches the use of reverse osmosis only for streams containing less than 50% of hydrogen peroxide.

(15) The present inventors found that the life of certain membranes in the presence of a stream containing more than 50% of hydrogen peroxide does not exceed a few hours or days. However, certain membranes have a higher resistance to hydrogen peroxide and may be used continuously for at least 1, 2, 3 or even 4 weeks.

EXAMPLES

(16) The following example illustrates but does not limit the invention.

(17) This example compares the content of various contaminants in a solution S containing 60% of hydrogen peroxide stabilized with 110 mg of sodium pyrophosphate and 30 mg of sodium stannate (expressed as Na.sub.2SnO.sub.3.3H.sub.2O) per kg of solution, before and after purification by reverse osmosis (in a single step or in two steps, notation OI) using a KOCH TFC-XR reverse osmosis membrane, in the following operating conditions: pressure: 35 bar, temperature: 22 C., VCF: 2.5, permeation stream: 70 L/h.Math.m.sup.2. The starting solution tested S has specifications typical of a mass-produced hydrogen peroxide. The solution S was prepared by a process comprising passage over adsorption resin.

(18) Specifications commonly used for producing peracetic acid are also indicated. The results are given in the following table (TOC denotes: total organic carbon).

(19) The contents of metals were determined by the methods described in standards NF EN ISO 17294-2 and NF EN ISO 11885; TOC was determined by the method described in standard NF EN 1484.

(20) TABLE-US-00001 S + 1 step S + 2 steps Example of S OI OI specifications TOC (mg/kg) 240 100 40 <100 P (mg/kg) 45 9 2 <5 Fe (mg/kg) 0.3 0.05 0.03 <0.04 Sn (mg/kg) 13.5 0.7 0.03 Cr + Ni 0.15 <0.1 <0.1 <0.1 (mg/kg)