FR2677010A1 - Process for purifying hydrogen peroxide - Google Patents

Abstract

The invention relates to a process for purifying hydrogen peroxide in aqueous solution, in accordance with which such a solution is first of all caused to pass through a strongly cationic resin mass in the acid form, it is then cooled to a temperature between 0 DEG C and the freezing point of the solution and caused to pass through an anionic resin mass of average strength in the basic form, the said mass being cooled so that the temperature of the solution before and during passing through the anionic resin remains constant and, finally, the said solution is caused to pass through an adsorbing resin and, if appropriate, filtered.

Description

PROCESS FOR THE PURIFICATION OF HYDROGEN PEROXIDE

  The present invention relates to a process for the purification of aqueous solutions of hydrogen peroxide obtained by synthesis, to remove cations, anions and organic compounds therefrom. Hydrogen peroxide for industrial uses, for example in the field of electronics, must as far as possible be free of cations, anions and organic compounds, and it must have the resistivity

as high as possible.

  The most commonly used process is that of subjecting aqueous hydrogen peroxide solutions to vacuum distillation, whereby sufficiently high purity values (almost all for barely sufficient selectivity towards certain

  organic compounds) are not reached.

  In addition, the decomposition reaction of hydrogen peroxide is helped, outside of a high temperature, by contact with easily oxidizable organic substances or with catalytic ions, in particular heavy metal ions and their oxides, in an environment

basic in particular.

  In accordance with French patent FR-A-1 484 127, a process has been proposed for the purification of aqueous solutions of hydrogen peroxide in order to remove the impurities in ionic form thereof, by adsorption of hydrogen peroxide on exchange resins of ions in salified form, therefore not binding such ions: the hydrogen peroxide must then be extracted from the resin by

the water.

  In accordance with American patent US-A-2 676 923, a method is proposed for the purification of aqueous solutions of hydrogen peroxide in order to remove the cations only, in particular those of heavy metals, by cationic resins polymer with sulfonic group in acid form. In accordance with British Patent GB-A-924,625, a purification process is proposed according to which hydrogen peroxide is caused to pass over an anionic resin in the form of hydroxide or salt, the temperature (in the only example , namely example 1, in which it is mentioned, it is indicated as being of + 25 C) being substantially ambient temperature, consequently such as to cause violent decomposition reactions of hydrogen peroxide, in particular if the resin is in basic form: it follows that the contact times of the solution with the resin must be extremely short (a few seconds, in accordance with the examples; preferably, less than 1 minute, as specified in lines 82- 87 of page 1 of the patent), so that such a process cannot have any industrial use. French patent FR-A-1,539,843 shows the purification of aqueous hydrogen peroxide to remove organic substances therefrom using macroreticular copolymer adsorbent resins, among which several resins are mentioned, marketed by Rohm and Haas under the name dl "Amberlite" (among which the resin

"Amberlite XAD 2" is cited).

  Finally, American patent US Pat. No. 3,074,782 relates to a process for the purification of aqueous solutions of hydrogen peroxide, according to which such a solution is first brought into contact with an anionic resin having a quaternary ammonium group in the form salified, then heated to 110 ° C 210 ° C to remove acids

  carboxylic present as impurities.

  According to this method, the first purification step on an anionic resin must necessarily be carried out on said resin in salified form, since the cations present in the solution would cause a violent decomposition of the hydrogen peroxide, the resin being in basic form , by combining with the hydroxyl groups of said resin Another remark which can be formulated is that the heating of hydrogen peroxide to a very high temperature and under pressure is a moderate process which can also prove to be dangerous. The main objectives of the present invention are to provide a process which allows the substantial purification of aqueous solutions of hydrogen peroxide obtained by synthesis, in order to remove anions, cations and organic substances therefrom, making it possible to obtain minimal decomposition of hydrogen peroxide and obtain purified solutions of hydrogen peroxide

  having a very high resistivity.

  These and other objectives are also achieved by a process in which the hydrogen peroxide solution is first passed over a strong cationic resin in acid form, then such a solution is cooled to a temperature situated in the range from OC to the freezing point of the solution, then said cooled solution is caused to pass over an anionic resin of medium strength in basic form, by extracting heat so as to maintain the temperature of the solution issuing of the treatment with the anionic resin at substantially the same value as the temperature of said incoming solution and, finally, said solution is brought into contact with an adsorbent resin having a macroreticular structure, all the resins having a

  matrix in styrene-divinylbenzene copolymer.

  Preferably, the effluent solution resulting from the treatment with the adsorbent resin is subjected to a

final filtration treatment.

  More preferably, the temperature to which the solution is cooled, before and during the treatment with the anionic resin, is less than -8 o C. To better understand the characteristics of the process according to the present invention, two embodiments preferred thereof are described below,

  which are given by way of example, not limiting.

EXAMPLE 1

  Suppose that it is desired to purify an aqueous solution of hydrogen peroxide obtained by synthesis, having a concentration of 40% by weight of hydrogen peroxide, a resistivity of 300,000 0 / cm, a density of 1.137, a freezing point of -40 C, and containing 350 ppb (1 ppb equals 1 pg / kg) of Al cations, 6000 ppb of Na cations, 1700 ppb of Sn cations, 20 ppb of Ca, 10 ppb of K, Ba and Bi, 25 ppb of V, 5 ppb of Fe, Zn, Mg, Co, Ni, Mn, Cd, Cr, Cu, Ag, Sr, Pb, Au and Mo and 1 ppb of Li, above 700 ppb chloride anions, 20,000 ppb nitrate anions, 3,000 ppb sulfate anions, 15,000 ppb phosphate anions and 200 ppm (1

  ppm is equal to 1 mg / kg) of organic compounds.

  For the purification of the solution,

  resins having a styrene copolymer matrix-

  divinylbenzene, which are the most resistant resins

oxidizing agents.

  Cationic resins are high strength, acidic, and are available in gel or macroreticular form; the most suitable anionic resins are of the basic type of medium strength and are in macroreticular form; and resins

  adsorbents are macroreticular resins.

  It can first of all be emphasized that it is essential to subject the solution to the treatment with the cationic resin before that with the anionic resin, because otherwise the oxides, released by the anionic resin in basic form, combining themselves with the cations still present, would form strong bases, with the consequence of the decomposition of hydrogen peroxide; in the treatment of the solution with the cationic resin in acid form, a

such problem does not occur.

  1 of aqueous hydrogen peroxide solution having the characteristics indicated above are brought to pass, at room temperature and with an elution speed of 10 1 / h, in a column uniformly filled with 1 1 of resin particles cationic (having a microporous structure and a diameter between 0.3 mm and 1.25 mm) in acid form, of the type marketed by BAYER under the trademark S-100 or of the Dowex HCR-S / E type by DOW

CHEMICAL.

  The solution is then cooled to -10 ° C. and passed through a column containing i 1 of anionic resin in basic form, of the Dowex MWA 1 type from DOW CHEMICAL, ensuring cooling so that the temperature during the treatment does not 'not raise above -100 C; in particular, the incoming solution and that resulting from the treatment with the anionic resin must have the same temperature, which thus makes it possible to significantly reduce the

  kinetics of decomposition of hydrogen peroxide.

  It goes without saying that the kinetics of degradation of hydrogen peroxide decreases with temperature and that very significant variations are no longer obtained at -10 C This allows the contact time between the

solution and anionic resin.

  The solution resulting from the treatment with the anionic resin is caused to pass over 0.5 l of adsorbent resin, formed, for example, of a resin of the Amberlite XAD-2 type from Rohm and Haas (the temperature having no importance), then the solution is filtered on a 0.2 micron membrane to

  remove any suspended particles.

  As a result, the time required for the treatment of the 200 liters of solution was approximately hours, and, in the end, a solution of hydrogen peroxide was obtained, containing 10 ppb of Na and Sn ions, less ppb from Ba, Mo and Bi, 50 ppb from Al, 1 ppb from Li, less ppb from Fe, Co, Ni, Mn, K, Cd, Zn, Cr, Cu, Ag, Sr, Pb, Ca , Mg and Au, 100 ppb of chlorides, 300 ppb of nitrates, 100 ppb of phosphates, 1000 ppb of sulfates, having a resistivity of 1 MQ / cm, with a residue of less than 10 ppm and having a TOC

  (total organic carbon content) of 60 ppm.

  The characteristics of the hydrogen peroxide solution thus obtained are suitable for industrial use, also in the field of electronics. It can be emphasized that the phase of the treatment with the cationic resin corresponds to that described in the American patent US-A-2 676 923, that the phase of the treatment with the adsorbent resin corresponds to that described in the French patent FR-A- 1,539,843, while the particular phase of the treatment with anionic resin and the sequence of the various phases of treatment are completely new, the treatment on the cationic resin having to precede that with the anionic resin for the reasons already explained.

EXAMPLE 2

  Using the same solution of hydrogen peroxide, the same resins and the same processes as those described in Example 1, but treating 200 l of the solution with 2 l of the cationic resin, then with 1 l of anionic resin and by 0.5 l of adsorbent resin, at a speed of 1 / h, the quality of the hydrogen peroxide obtained is further enhanced and its cation content (in particular that in

  A1) is less than that described in Example 1.

Claims (3)

  1 Method for purifying an aqueous hydrogen peroxide solution, characterized in that the hydrogen peroxide solution is first of all passed through a strong cationic resin in acid form, then cooled to a temperature included between OC and the freezing point of the solution, then, said cooled solution is caused to pass over an anionic resin of medium strength, in basic form, by extracting heat so as to maintain the temperature of the solution resulting from the treatment with the anionic resin at substantially the same value as the temperature of said incoming solution, and finally, said solution is brought into contact with an adsorbent resin having a macroreticular structure,   all resins having a styrene copolymer matrix-   divinylbenzene. 2 Method according to claim 1, characterized in that the temperature to which said solution is cooled before and during the treatment with the anionic resin is less than -80 C.   3 Method according to one of claims 1 and 2, characterized in that the solution is subjected to a   filtration treatment after treatment with the adsorbent resin.