Method for producing hydrogen peroxide

Abstract

An object of the present invention is to provide a method by which hydrogen peroxide can be produced at a satisfactory level from an industrial and economical viewpoint without causing the load of purification to be large and without needing too large facilities for production. The present invention is directed to a method for producing hydrogen peroxide, which comprises reacting hydrogen and oxygen in a reaction medium in the presence of a noble metal catalyst and a radical scavenger.

Claims

1. A method for producing hydrogen peroxide, comprising reacting hydrogen and oxygen in a reaction medium in the presence of a noble metal catalyst and a radical scavenger to produce hydrogen peroxide, wherein the reaction medium is free of halogen ions, and wherein the radical scavenger is capable of capturing OH radicals generated from decomposition of the hydrogen peroxide and forming a radical scavenger-OH adduct and is a nitrone compound of formula (1), (2), or (3), a nitroso compound of formula (4), a dithiocarbamate derivative of formula (5), or a compound of formula (6): ##STR00005## wherein, in formula (1), R.sub.1 and R.sub.2 are each independently an alkyl group having 1 to 10 carbon atoms and optionally having a branch, a phosphoric acid group, or a phosphate group, and R.sub.3 and R.sub.4 are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms and optionally having a branch, an alkyl group having 1 to 10 carbon atoms optionally having a branch and optionally being substituted with a hydroxyl group or an amino group, a 2-oxo-1-pyridylmethyl group, or an amino group, in formula (2), R.sub.5 is an alkyl group having 1 to 10 carbon atoms and optionally having a branch, and R.sub.6 to R.sub.10 are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms and optionally having a branch, in formula (3), R.sub.11 is an alkyl group having 1 to 10 carbon atoms and optionally having a branch, and R.sub.12 to R.sub.15 are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms and optionally having a branch, in formula (4), R.sub.16 is an alkyl group having 1 to 10 carbon atoms and optionally having a branch, or an aryl group having 6 to 20 carbon atoms and optionally being substituted with an alkyl group having 1 to 10 carbon atoms and optionally having a halogen, a sulfonic acid group, or a branch, and in formula (5), R.sub.17 and R.sub.18 are each independently an alkyl group having 1 to 10 carbon atoms optionally having a branch and optionally being substituted with a hydroxyl group, or a carboxyalkyl group having 1 to 10 carbon atoms and optionally having a branch, and X.sup.+ is a cation.

2. The method according to claim 1, wherein the radical scavenger is a nitrone compound of formula (1).

3. The method according to claim 1, wherein, in formula (1), R.sub.1 and R.sub.2 are methyl groups, and R.sub.3 and R.sub.4 are each independently a methyl group, hydrogen, a 2-oxo-1-pyridylmethyl group, or an amino group, in formula (2), R.sub.5 is a methyl group, an ethyl group, an isopropyl group, a n-propyl group, a cyclopropyl group, a n-butyl group, a sec-butyl group, a tert-butyl group, or a cyclobutyl group, and R.sub.6 to R.sub.10 are hydrogen, in formula (3), R.sub.11 is a tert-butyl group, and R.sub.12 to R.sub.15 are hydrogen, in formula (4), R.sub.16 is a tert-butyl group, a 3,5-dibromo-1-sulfophenyl group, or a 2,3,5,6-tetramethylphenyl group; and in formula (5), each of R.sub.17 and R.sub.18 is independently a methyl group, an ethyl group, or a carboxymethyl group, and X.sup.+ is a sodium ion.

4. The method according to claim 1, wherein the radical scavenger is 5,5-dimethyl-1-pyrroline N-oxide or N-tert-butyl--phenylnitrone.

5. The method according to claim 1, wherein an amount of the radical scavenger is from 0.01 to 0.05 part by weight, relative to 100 parts by weight of the reaction medium.

6. The method according to claim 1, wherein the noble metal catalyst is a catalyst comprising silica, alumina, silica-alumina, titanium oxide, or zirconia oxide having supported thereon at least one metal selected from the group consisting of platinum, palladium, silver, and gold.

7. The method according to claim 3, wherein an amount of the radical scavenger is from 0.01 to 0.05 part by weight, relative to 100 parts by weight of the reaction medium.

8. The method according to claim 4, wherein an amount of the radical scavenger is from 0.01 to 0.05 part by weight, relative to 100 parts by weight of the reaction medium.

9. The method according to claim 3, wherein the noble metal catalyst is a catalyst comprising silica, alumina, silica-alumina, titanium oxide, or zirconia oxide having supported thereon at least one metal selected from the group consisting of platinum, palladium, silver, and gold.

10. The method according to claim 4, wherein the noble metal catalyst is a catalyst comprising silica, alumina, silica-alumina, titanium oxide, or zirconia oxide having supported thereon at least one metal selected from the group consisting of platinum, palladium, silver, and gold.

11. The method according to claim 5, wherein the noble metal catalyst is a catalyst comprising silica, alumina, silica-alumina, titanium oxide, or zirconia oxide having supported thereon at least one metal selected from the group consisting of platinum, palladium, silver, and gold.

12. The method according to claim 7, wherein the noble metal catalyst is a catalyst comprising silica, alumina, silica-alumina, titanium oxide, or zirconia oxide having supported thereon at least one metal selected from the group consisting of platinum, palladium, silver, and gold.

13. The method according to claim 8, wherein the noble metal catalyst is a catalyst comprising silica, alumina, silica-alumina, titanium oxide, or zirconia oxide having supported thereon at least one metal selected from the group consisting of platinum, palladium, silver, and gold.

14. The method according to claim 1, wherein the radical scavenger is a nitrone compound of formula (2).

15. The method according to claim 1, wherein the radical scavenger is a nitrone compound of formula (3).

16. The method according to claim 1, wherein the radical scavenger is a nitroso compound of formula (4).

17. The method according to claim 1, wherein the radical scavenger is a dithiocarbamate derivative of formula (5).

18. The method according to claim 1, wherein the radical scavenger is a compound of formula (6).

Description

EXAMPLES

(1) Hereinbelow, the present invention will be described in more detail with reference to the following Examples and Comparative Examples, which should not be construed as limiting the scope of the present invention to Examples.

(2) In the following Examples and Comparative Examples, various evaluations including the yield of hydrogen peroxide were conducted as follows.

(3) (1) The rate of the reaction of hydrogen was determined from the following formula.
Rate of reaction of hydrogen=(Amount of the hydrogen consumed)(Total amount of the hydrogen fed)

(4) The amount of the hydrogen consumed was determined by measuring the amount of the hydrogen remaining unreacted by gas chromatography (apparatus used: trade name: GC-8A; manufactured by Shimadzu Corporation), and subtracting the measured amount from the total amount of the hydrogen fed.

(5) (2) The selectivity for hydrogen peroxide was determined from the following formula.
Selectivity for hydrogen peroxide=[(Mole of the hydrogen peroxide generated by the reaction)(Theoretical mole of the generated hydrogen peroxide calculated from the amount of the hydrogen consumed)]

(6) The mole of the hydrogen peroxide formed was determined by taking out a portion of the reaction solution after completion of the synthesis reaction of hydrogen peroxide, and measuring the mole using titanyl sulfate as a color former for hydrogen peroxide with use of an ultraviolet-visible spectrophotometer (trade name: V-550; manufactured by JASCO Corporation).

(7) (3) The yield of hydrogen peroxide was determined from the following formula.
Yield of hydrogen peroxide=(Rate of reaction of hydrogen)(Selectivity for hydrogen peroxide)

(8) The results of the above evaluations made with respect to the Examples and Comparative Examples are shown in Table 1 below.

Example 1

(9) To 200 ml of a mixed solvent of ethanol and water (water:ethanol=1:1) was added 2 g of oxalic acid, and the resultant mixture was stirred. To the mixture were added 10 g of titania manufactured by Sakai Chemical Industry Co., Ltd., 0.05 g of HAuCl.sub.4, and 0.12 g of PdCl.sub.2, and the resultant mixture was refluxed at 80 C. using a Liebig condenser for one hour.

(10) After a lapse of one hour, the resultant suspension was transferred to a 300 ml beaker, and heated to remove the solvent. Then, the resultant solids were dried in a dryer at 85 C. for 2 days, and controlled in particle size so as to have a size of 0.5 to 1.8 mm, and used in the experiment.

(11) In the experiment, to a 270 ml autoclave lined with Teflon (registered trademark), having a stirrer and a gas feeding pipe, were added 1.125 g of the above-produced Au/Pd-supported titania catalyst and 270 ml of a reaction solution (which contains 0.5 mM phosphoric acid and 2 mM DMPO (5,5-dimethyl-1-pyrroline N-oxide), and uses water as a reaction medium).

(12) While controlling the temperature in the autoclave at 10 C. and feeding gas into the autoclave at a rate of 150 ml/min (hydrogen: 4%; oxygen: 19.5%; nitrogen: 76.5%), the pressure was adjusted to 1 MPa, and a reaction was effected for 2 hours while stirring at a rotational speed of 800 rpm.

Example 2

(13) An Au/Pd-supported titania catalyst was produced in the same manner as in Example 1.

(14) In the experiment, to a 270 ml autoclave lined with Teflon (registered trademark), having a stirrer and a gas feeding pipe, were added 1.125 g of the above-produced Au/Pd-supported titania catalyst and 270 ml of a reaction solution (which contains 0.5 mM phosphoric acid and 2 mM PBN (N-tert-butyl--phenylnitrone), and uses water as a reaction medium).

(15) While controlling the temperature in the autoclave at 10 C. and feeding gas into the autoclave at a rate of 150 ml/min (hydrogen: 4%; oxygen: 19.5%; nitrogen: 76.5%), the pressure was adjusted to 1 MPa, and a reaction was effected for 2 hours while stirring at a rotational speed of 800 rpm.

Example 3

(16) An Au/Pd-supported titania catalyst was produced in the same manner as in Example 1.

(17) In the experiment, to a 270 ml autoclave lined with Teflon (registered trademark), having a stirrer and a gas feeding pipe, were added 1.125 g of the above-produced Au/Pd-supported titania catalyst and 270 ml of a reaction solution (which contains 0.5 mM phosphoric acid and 4 mM DMPO, and uses water as a reaction medium).

(18) While controlling the temperature in the autoclave at 10 C. and feeding gas into the autoclave at a rate of 150 ml/min (hydrogen: 4%; oxygen: 19.5%; nitrogen: 76.5%), the pressure was adjusted to 1 MPa, and a reaction was effected for 2 hours while stirring at a rotational speed of 800 rpm.

Example 4

(19) An Au/Pd-supported titania catalyst was produced in the same manner as in Example 1.

(20) In the experiment, to a 270 ml autoclave lined with Teflon (registered trademark), having a stirrer and a gas feeding pipe, were added 1.125 g of the above-produced Au/Pd-supported titania catalyst and 270 ml of a reaction solution (which contains 0.5 mM phosphoric acid and 2 mM DMPO, and uses ethanol as a reaction medium).

(21) While controlling the temperature in the autoclave at 10 C. and feeding gas into the autoclave at a rate of 150 ml/min (hydrogen: 4%; oxygen: 19.5%; nitrogen: 76.5%), the pressure was adjusted to 1 MPa, and a reaction was effected for 2 hours while stirring at a rotational speed of 800 rpm.

Comparative Example 1

(22) An Au/Pd-supported titania catalyst was produced in the same manner as in Example 1.

(23) In the experiment, to a 270 ml autoclave lined with Teflon (registered trademark), having a stirrer and a gas feeding pipe, were added 1.125 g of the above-produced Au/Pd-supported titania catalyst and 270 ml of a reaction solution (which contains 0.5 mM phosphoric acid, and uses water as a reaction medium).

(24) While controlling the temperature in the autoclave at 10 C. and feeding gas into the autoclave at a rate of 150 ml/min (hydrogen: 4%; oxygen: 19.5%; nitrogen: 76.5%), the pressure was adjusted to 1 MPa, and a reaction was effected for 2 hours while stirring at a rotational speed of 800 rpm.

Comparative Example 2

(25) An Au/Pd-supported titania catalyst was produced in the same manner as in Example 1.

(26) In the experiment, to a 270 ml autoclave lined with Teflon (registered trademark), having a stirrer and a gas feeding pipe, were added 1.125 g of the above-produced Au/Pd-supported titania catalyst and 270 ml of a reaction solution (which contains 0.5 mM phosphoric acid and 2 mM NaBr, and uses water as a reaction medium).

(27) While controlling the temperature in the autoclave at 10 C. and feeding gas into the autoclave at a rate of 150 ml/min (hydrogen: 4%; oxygen: 19.5%; nitrogen: 76.5%), the pressure was adjusted to 1 MPa, and a reaction was effected for 2 hours while stirring at a rotational speed of 800 rpm.

(28) The results of the various evaluations including the yield of hydrogen peroxide made with respect to the above Examples and Comparative Examples are shown in Table 1 below.

(29) TABLE-US-00001 TABLE 1 Decomposition Rate of H.sub.2 Selectivity for Yield of inhibitor reaction H.sub.2O.sub.2 H.sub.2O.sub.2 (Concentration) (%) (%) (%) Example 1 DMPO 63.7 63.8 40.6 (2 mM) Example 2 PBN 68.7 56.9 39.1 (2 mM) Example 3 DMPO 68.6 65.4 44.8 (4 mM) Example 4 DMPO 92.5 40.8 37.7 (2 mM) Comparative None 63.1 23.0 14.5 example 1 Comparative Br.sup. 49.2 96.5 47.5 example 2 (2 mM)

(30) As is apparent from the results shown in Table 1, by the method for producing hydrogen peroxide of the present invention using a radical scavenger (Examples 1 to 4), hydrogen peroxide can be efficiently produced without using a halogen as an inhibitor of decomposition. Accordingly, an increase of the cost due to necessity of purification for removing the halogen can be suppressed, and industrial significance was acknowledged on the present invention.