Method for producing hydrogen peroxide

This invention provides a method for high efficiency, high concentration production of hydrogen peroxide wherein oxygen and hydrogen are reacted in the reaction medium in the presence of a catalyst comprising a metallic or carrier supported platinum group metal catalyst onto which an organic halogen compound which is insoluble in water, which compound excludes compounds which contain no halogen other than fluorine, has been adsorbed or a platinum group metal catalyst supported on a carrier in which a halogenated organic compound, which compound excludes compounds that contain no halogen other than fluorine, has been adsorbed to the carrier prior to supporting the platinum group metal. Since it is not necessary for halogen ions to be present in the reaction medium as it was in the prior art, the problems of deterioration due to the dissolution of the catalyst and of corrosion of the structural materials of the reaction vessel are alleviated.

FIELD OF UTILIZATION IN INDUSTRY 
The present invention relates to an improved method for reacting oxygen and 
hydrogen in the reaction medium in the presence of a catalyst and 
producing hydrogen peroxide. More particularly, it is a method for 
producing hydrogen peroxide wherein oxygen and hydrogen are directly 
reacted in the reaction medium in the presence of a catalyst comprising a 
metallic or carrier supported platinum group metal catalyst onto which an 
organic halogen compound which is insoluble in water, which compound 
excludes compounds which contain no halogen other than fluorine, has been 
adsorbed or a platinum group metal catalyst supported on a carrier in 
which a halogenated organic compound, except for the aforementioned 
fluorine compounds, has been adsorbed to the carrier prior to supporting 
the platinum group metal. 
DESCRIPTION OF THE PRIOR ART 
The main method presently used by industry for producing hydrogen peroxide 
is the autooxidation method using alkyl-anthraquinone as the reaction 
medium. The fact that the processes of reduction, oxidation, extraction, 
purification, and concentration are very complex and that equipment and 
operations costs are large are given as problem points of this method. 
Additionally, there are loss due to degeneration of alkyl-anthraquinone 
and problems of the degeneration of the hydrogenation catalyst. 
Several production methods other than the above method have been attempted 
in order to remedy these problems. One of these is a method for producing 
hydrogen peroxide directly from oxygen and hydrogen in the reaction medium 
in the presence of a catalyst. Already, methods for producing hydrogen 
peroxide from hydrogen and oxygen and using platinum group metals as 
catalysts have been proposed, and the production of moderate 
concentrations of hydrogen peroxide has been described (Please refer to 
Japanese Patent Publication No. 47121/1981, Japanese Patent Publication 
No. 18646/1980, Japanese Patent Publication No. 23401/1989, Japanese Laid 
Open Patent Application No. 156005/1988 and Japanese Laid Open Patent 
Application No. 258610/1990). All of these use aqueous solutions 
containing acid and/or inorganic salts as the reaction medium, and, in 
particular, due to the presence of halogen ions in the reaction medium, 
catalytic activity is inhibited, the decomposition of the produced 
hydrogen peroxide is suppressed, and a high concentration of hydrogen 
peroxide is obtained. For example, it has been shown in Japanese Laid Open 
Patent Application No. 156005/1988 that the selective production of a high 
concentration of hydrogen peroxide due to the presence of a halogen ion 
such as bromine ion in the reaction medium in a method for using a 
platinum group catalyst to produce a high concentration of hydrogen 
peroxide from hydrogen and oxygen under elevated pressure in an acidic 
aqueous solution is possible. Additionally, we have applied for a patent 
for a method of producing hydrogen peroxide by direct reaction of oxygen 
and hydrogen in the presence of a platinum group metal catalyst carried on 
a halogenated resin in a reaction medium which does not contain halogen 
ion (U.S. Ser. No. 07/763,166). 
PROBLEMS THE PRESENT INVENTION AIMS TO SOLVE 
Practically speaking, in prior art methods for the production of hydrogen 
peroxide by the catalytic reaction of hydrogen and oxygen in the reaction 
medium in the aforementioned manner, it is necessary for there to be a 
high concentration of acid and halogen ion present in the reaction medium 
in order to obtain a high concentration of hydrogen peroxide. In that 
case, there is a problem with the dissolution of the catalyst metal and 
the reaction vessel structural materials into the reaction medium before, 
during and after the reaction. Particularly, in a case such as that 
described above where there are halogen ions present, the amount of 
dissolution increases in proportion to the concentration of halogen ion. 
This is a very serious problem for the catalyst life when it is subjected 
to continuous long term use. Additionally, the selection of reaction 
vessel structural materials is also thereby limited, and, at the same 
time, such materials are necessarily very expensive. 
Moreover, since there are also halogen ions present in the hydrogen 
peroxide obtained after the reaction, depending upon the intended use of 
the hydrogen peroxide, there exists a substantial economic problem 
resulting from the necessity of such post production operations as a 
removal of halogen ions. 
MEANS FOR SOLVING THE PROBLEMS 
In regard to their method of producing hydrogen peroxide by the direct 
reaction of oxygen and hydrogen in the reaction medium, either in the 
presence or absence of an inert gas such as nitrogen that would not serve 
as an impediment to the reaction, the inventors of the present invention, 
as a result of continuing investigations into a production method to 
obtain high concentrations of hydrogen peroxide in a reaction medium which 
does not contain halogen ions, have discovered that it is possible to 
achieve this goal through the use of a catalyst comprising a metallic or 
carrier supported platinum group metal catalyst onto which an organic 
halogen compound which is insoluble in water, which compound excludes 
compounds which contain no halogen other than fluorine, has been adsorbed 
or a platinum group metal catalyst supported on a carrier in which a 
halogenated organic compound, which compound excludes compounds which 
contain no halogen other than fluorine, has been adsorbed to the carrier 
prior to supporting the platinum group metal. 
That is to say, the primary objective of the present invention is to offer 
a method of producing hydrogen peroxide where it is possible to obtain a 
high concentration of hydrogen peroxide by reacting oxygen and hydrogen in 
the presence of a catalyst using a neutral or acidic solution which does 
not contain halogen ions as the reaction medium. As such post production 
procedures as the removal of halogen ions from the hydrogen peroxide 
produced have become unnecessary, the second objective of the present 
invention is to offer a method for the production of hydrogen peroxide in 
which the purification process has been simplified. The third objective is 
to offer a method of producing hydrogen peroxide directly from oxygen and 
hydrogen in which commercial operation of large scale, very highly 
practical, economically advantageous production is facilitated. 
As the platinum group metal used in the present invention, concretely, 
ruthenium, osmium, rhodium, iridium, palladium, and platinum may be used 
either singly or in alloys or mixtures of two or more. Preferably, 
palladium or platinum may be used. 
The organic halogen compound which is insoluble in water in the present 
invention is an organic halogen compound which will not spontaneously mix 
with neutral or acidic water. With regard to the chemical structure of the 
organic halogen compound of this invention, outside of the presence of the 
halogen, there are no limitations with regard to such varieties as 
aromatic compounds, aliphatic compounds or functional groups However, 
since halogen compounds containing no halogen other than fluorine have 
very low selectivities in the present invention, they have been excluded 
from the scope of the present invention. As the organic halogen compound 
which is insoluble in water in the present invention, such compounds as 
halogen containing polymers, halogenated benzene or benzene derivatives, 
halogenated aliphatic carboxylic acids and halogenated organosilicon 
compounds may be employed. The halogenated organosilicon compounds 
referred to here are organosilicon compounds containing a halogen atom not 
directly bonded to a silicon atom. 
Concrete examples of organic halogenated compounds which are insoluble in 
water which may be employed include, for example, such compounds as 
bromobenzene, trichlorobenzene, chlorostyrene polymer, 2-bromo-n-caproic 
acid, chloromethyldimethylchlorosilane, 
bis(chloromethyl)tetramethyldisilazane, chloromethyldimethylvinylsilane, 
dichloromethyldimethylchlorosilane, chloroethyltrichlorosilane, 
dichloroethyltrichlorosilane, chloropropyltrimethoxysilane, 
chlorophenyltrimethoxysilane, bromomethyldimethylchlorosilane, 
dibromoethyltrichlorosilane, bromopropyltriethoxysilane, 
bromophenyldimethylvinylsilane, and dibromovinyltrimethylsilane. From 
among these, trichlorobenzene, bromobenzene, 2-bromo-n-caproic acid, 
chloromethyldimethylchlorosilane, dichloromethyldimethylchlorosilane, 
bromomethyldimethylchlorosilane and dibromoethyltrichlorosilane may be 
employed as particularly preferable. The form of the catalyst used in the 
present invention may be selected freely from among such forms as fine 
powder, grains, or pellets. 
Moreover, it is possible to use a catalyst supported on a carrier in the 
present invention, and, in the case where a catalyst carrier is used, it 
is possible to use ordinary organic resins and such prior art inorganic 
carriers as silica, alumina, and activated carbon. The basic 
characteristics of the carrier of the present invention are not limited. 
However, as normal characteristics of the carrier, a large surface area 
and the ability to effectively support the catalyst metal in a highly 
dispersed fashion are preferable. In addition, in cases where organic 
halogen compounds which do not contain reactive functional groups are 
used, the employment of an adsorbing resin as the carrier is particularly 
desirable. Adsorbing resins are insoluble crosslinked resins which have 
micropores, which have large specific surface areas, which adsorb various 
organic substances through Van der Waals forces and among which are 
included such polymers and copolymers as styrene-divinylbenzene copolymers 
and polymers and copolymers of acrylate esters, methacrylate esters, and 
vinylpyridine, etcetera . . . . 
The amount of catalyst metal supported on the above carrier in the present 
invention is normally about 0.1% to 10% of the weight of the carrier. 
Prior art methods may be used for the method of supporting the catalyst 
metal. 
The method of producing the catalyst of the present invention is not 
restricted. However, the simplest method for producing the catalyst of the 
present invention is to immerse a catalyst supported on a carrier or a 
metal powder catalyst into an organic solvent in which the organic halogen 
compound has been dissolved. After the solvent has been removed and the 
catalyst has been dried, it is ready for use. In the event that the 
dissolution of very small amounts of the organic compound when the 
catalyst is used over long periods of time becomes a problem, such methods 
as the use of an adsorbing resin as the carrier as described above, or 
methods of fixing the organic halogen compound to the catalyst surface, 
that is to say, such methods as adsorbing bromostyrene or chlorostyrene on 
the catalyst surface and then polymerizing them there by means of light or 
heat may be used. Additionally, the following methods are included among 
the methods of the present invention for preparing the catalyst. 
Specifically, methods of fixing halogenated organosilicon compounds 
containing reactive functional groups to the surface of the carrier by 
reacting them with such functional groups as hydroxyl groups contained in 
the carrier itself may be used. 
The amount of the organic halogen compound adsorbed in the present 
invention differs according to the amount of catalyst metal, the effective 
surface area of the metal and the type of the organic halogen compound. 
Accordingly, the amount supported must be optimized for each catalyst. As 
a normal supported amount, a range of about 0.01% to 50% for the 
percentage of the weight of the included halogen to the weight of the 
catalyst should be appropriate. 
With regard to the amount of the catalyst to be used in the production of 
hydrogen peroxide from oxygen and hydrogen in the present invention, there 
are no particular limitations. However, normally, more than one gram of 
catalyst per liter of reaction medium are used. In addition, it is 
possible to perform the reaction in slurry form by adding large amounts of 
the catalyst to the reaction medium. 
It is possible to use water as the reaction medium in the present 
invention. However, it is also possible to add substances which are shown 
to be usable as stabilizers with respect to hydrogen peroxide. For 
example, such prior art hydrogen peroxide stabilizers as inorganic acids, 
organic acids, amino acids, organic salts, chelating agents, and surface 
active agents may be used. The amount of stabilizer used differs according 
to the type of the stabilizer, its effect and the concentration of 
hydrogen peroxide required. The normal amount of stabilizer added is less 
than 0.1% by weight of the reaction medium and 100 ppm. or less is 
preferable. 
As concrete examples of stabilizers, other than such inorganic acids as 
phosphoric acid and nitric acid, such phosphoric acid salts as sodium 
pyrophosphate and such organic acids as aminotri(methylenephosphonic acid) 
may be employed. However, as particularly preferred stabilizers, 
aminotri(methylenephosphonic acid), 1-hydroxyethyledene-1,1-diphosphonic 
acid, ethylenediaminetetra(methylenephosphonic acid), the sodium salts of 
all of the preceding, or sodium pyrophosphate may be employed. 
The hydrogen peroxide production reaction of the present invention may be 
carried out either continuously or by batch, and, moreover, the reaction 
vessel used may be either a fixed bed type or an agitator type. In 
addition, the hydrogen peroxide production of the present invention may be 
carried out by bringing oxygen and hydrogen together with a catalyst in 
the reaction medium either in the presence or absence of an inert gas such 
as nitrogen which will not impede the progress of the reaction and under 
normal reaction conditions including a reaction pressure of 3 
kg./cm.sup.2.G-150 kg./cm.sup.2.G, a reaction temperature of between 
0.degree. C. and 50.degree. C. and a reaction time of 30 minutes to 6 
hours.

EXAMPLES 
Following is a further more concrete explanation of this invention made by 
means of Examples and Comparative Experiments. The analytical values of 
gas composition used in the Examples are values taken by gas 
chromatography. Moreover, the measurement of the concentration of hydrogen 
peroxide produced in the reaction mixture was performed by titration with 
sulphuric acid-potassium permanganate. 
Example 1 
Mitsubishi Kasei's aromatic adsorbing resin ("HP20": the trade name for a 
product of Mitsubishi Kasei Corporation, a styrene-divinylbenzene 
copolymer (standard product), grain size: 0.2 mm.-1 mm. diameter, specific 
surface area: 605 m.sup.2 /g., true specific gravity: 1.01, water content: 
about 56.3% by weight) was washed first with 30% by weight hydrogen 
peroxide and then with water after which it was dried. After swelling the 
resin with chloroform, it was impregnated with a palladium 
acetate/chloroform solution and then again dried. The palladium acetate 
impregnated into the HP20 resin was then reduced by hydrogen gas at 
100.degree. C. and washed with methanol and, after washing with methanol, 
was washed with water, and a 1% by weight palladium catalyst supported on 
HP20 was obtained. 
Again, the catalyst was dried and was impregnated with a 
trichlorobenzene/methanol solution in which the amount of trichlorobenzene 
was equal to 10% of the weight of the dried catalyst. After impregnating 
the catalyst with the solution, the solution was diluted by twice its 
volume of water. Subsequently, using an evaporator, the methanol was 
removed selectively, the catalyst was separated from the water by 
filtration, washed with water, and an HP20 supported 1% by weight 
palladium catalyst (water content: about 50% by weight) onto which 
trichlorobenzene was adsorbed in an amount equal to 10% of the weight of 
the catalyst was obtained. 
One hundred milliliters of an aqueous solution containing 12 ppm. 
phosphoric acid and 12 ppm. sodium pyrophosphate were placed in a 180 ml. 
volume glass vessel. Six grams of the above catalyst were added to this 
solution, and the glass vessel was then placed in a autoclave with a 300 
ml. capacity. After exchanging the air in the autoclave with a gaseous 
mixture consisting by volume of 4% hydrogen gas, 16% oxygen gas and 80% 
nitrogen gas, this same gaseous mixture was added to the autoclave until a 
pressure of 25 kg./cm.sup.2.G was achieved and maintained. A temperature 
of 10.degree. C. and stirring at a rate of 1000 rpm. were maintained for 1 
hour while introducing a flow of the same gaseous mixture at a rate of 0.8 
l./min. through the autoclave. After stirring for one hour, the 
concentration of hydrogen peroxide produced in the reaction mixture was 
0.45% by weight of the reaction mixture, and the hydrogen selectivity was 
55%. 
Hydrogen selectivity=.vertline.(the amount of hydrogen peroxide produced in 
the reaction in moles)/(the amount of all hydrogen consumed calculated 
from the change in gas composition in moles).vertline..times.100. 
In addition, after the reaction mixture containing the hydrogen peroxide 
was allowed to stand under atmosphere for 30 minutes after the termination 
of the reaction, the catalyst was separated from the reaction mixture by 
filtration. The results of measuring the amount of palladium dissolved 
into the reaction mixture by inductively coupled plasma emission 
spectroscopy using an SPS 1200 VR type spectrometer made by Seiko 
Instruments Inc. were that palladium concentration was less than 1 ppm. 
Moreover, the results of measurement of the amount of chlorine dissolved 
into the same reaction mixture using Mitsubishi Kasei Corporation's TSX-10 
chlorine.sulfur analysis instrument were that chlorine concentration was 
less than 1 ppm. It was observed that the amount of dissolution of 
palladium and halogen compounds from the catalyst into the reaction 
mixture was extremely small. 
Comparative Experiment 1 (Comparison with Example 1) 
Using Mitsubishi Kasei's HP20 aromatic adsorbing resin as the carrier, an 
HP20 supported 1% by weight palladium catalyst (water content: about 50% 
by weight) onto which was adsorbed trimethylbenzene in an amount equal to 
10% of the weight of the catalyst was obtained by the same methods as in 
Example 1. Upon reacting oxygen and hydrogen using this catalyst under the 
same reaction conditions as in Example 1, the concentration of hydrogen 
peroxide produced was 0.02% by weight of the reaction mixture, and the 
hydrogen selectivity was 1%. 
Comparative Experiment 2 (Comparison with Example 1) 
Upon reacting oxygen and hydrogen using the same catalyst as in Comparative 
Experiment 1 and under the same reaction conditions as in Comparative 
Experiment 1, except that 100 ml. of an aqueous solution containing 0.1 
mol./l. of hydrochloric acid was used in place of the aqueous solution of 
phosphoric acid--sodium pyrophosphate solution as the reaction medium, the 
concentration of hydrogen peroxide produced was 0.42% by weight of the 
reaction mixture, and the hydrogen selectivity was 51%. In addition, upon 
separating the catalyst from the reaction mixture by filtration and 
measuring the amount of palladium dissolved into the reaction mixture 
after allowing the reaction mixture to stand for 30 minutes exposed to the 
atmosphere in the same manner as in Example 1, the concentration of 
palladium in the reaction mixture was found to be 35 ppm. In order to 
obtain virtually the same results as were obtained in Example 1 using 
prior art methods in this way, the presence of high concentrations of acid 
and halogen ion in the reaction medium is necessary, and, as a result, the 
amount of dissolution of palladium increases considerably. 
Example 2 
Upon reacting oxygen and hydrogen using the same catalyst as in Example 1 
under the same reaction conditions as in Example 1, except that 100 ml. of 
pure water were used in place of the aqueous solution of phosphoric 
acid--sodium pyrophosphate solution as the reaction medium, the 
concentration of hydrogen peroxide produced was 0.20% by weight of the 
reaction mixture, and the hydrogen selectivity was 25%. 
Comparative Experiment 3 (Comparison with Example 2) 
Upon reacting oxygen and hydrogen using the same catalyst as in Comparative 
Experiment 1 under the same reaction conditions as in Example 1 except 
that 100 ml. of pure water were used in place of the aqueous solution of 
phosphoric acid--sodium pyrophosphate as the reaction medium, the 
concentration of hydrogen peroxide produced was 0.01% by weight of the 
reaction mixture, and the hydrogen selectivity was less than 1%. 
Example 3 
After washing Mitsubishi Kasei's HP20 aromatic adsorbing resin with 
methanol, with 30% by weight hydrogen peroxide and finally with water, it 
was impregnated with an aqueous solution of chloroplatinic acid and dried 
under vacuum. The resulting resin was reduced at 120.degree. C. using 
hydrogen gas and then washed again with methanol and then water to obtain 
an HP20 supported 0.5% by weight platinum catalyst. Again the catalyst was 
dried and was impregnated with an iodotoluene/methanol solution in which 
the amount of iodotoluene was equal to 10% of the weight of the dried 
catalyst. After impregnating the catalyst with the solution, the solution 
was diluted by twice its volume of water. Subsequently, the methanol was 
selectively removed by distillation at 80.degree. C. for 3 hours while 
adding water equal to the amount of methanol evaporated. Then, the 
catalyst was separated from the water by filtration, washed with water and 
an HP20 supported 0.5% by weight platinum catalyst (water content: about 
50% by weight) onto which iodotoluene was adsorbed in an amount equal to 
10% of the weight of the catalyst was obtained. 
One hundred milliliters of an aqueous solution containing 12 ppm. 
phosphoric acid and 12 ppm. sodium pyrophosphate were placed in a 180 ml. 
volume glass vessel. Three grams of the above catalyst were added to this 
solution, and the glass vessel was then placed in an autoclave with a 300 
ml. capacity. After exchanging the air in the autoclave with a gaseous 
mixture consisting by volume of 4% hydrogen gas, 40% oxygen gas and 56% 
nitrogen gas, this same gaseous mixture was added to the autoclave until a 
pressure of 25 kg./cm.sup.2.G was achieved and maintained. A temperature 
of 10.degree. C. and stirring at a rate of 1000 rpm. were maintained for 1 
hour while introducing a flow of the same gaseous mixture at a rate of 0.8 
l./min. through the autoclave. After stirring for one hour, the 
concentration of hydrogen peroxide produced in the reaction mixture was 
0.15% by weight of the reaction mixture, and the hydrogen selectivity was 
87%. 
Comparative Experiment 4 (Comparison with Example 3) 
Using Mitsubishi Kasei's HP20 aromatic adsorbing resin as the carrier, an 
HP20 supported 0.5% by weight platinum catalyst (water content: about 50% 
by weight) onto which trimethylbenzene was adsorbed in an amount equal to 
10% of the weight of the catalyst was obtained by the same methods as in 
Example 3. Upon reacting oxygen and hydrogen using this catalyst under the 
same reaction conditions as in Example 3, the concentration of hydrogen 
peroxide produced was 0.00% by weight of the reaction mixture, and the 
hydrogen selectivity was 0%. 
Example 4 
A commercially available palladium black catalyst was impregnated with a 
methanol solution of bromobenzene in which the amount of bromobenzene was 
equal to 15% of the weight of the catalyst. The bromobenzene was adsorbed 
to the catalyst by evaporating the solvent at 80.degree. C. while 
agitating the solution-catalyst mixture, and a palladium black catalyst to 
which bromobenzene was adsorbed in an amount equal to 15% of the weight of 
the catalyst was obtained. 
One hundred grams of an aqueous solution containing 0.1 mol./l. of 
sulphuric acid were placed in a 180 ml. volume glass vessel to serve as 
the reaction medium. One gram of the above catalyst was added to this 
solution, and the glass vessel was then placed in an autoclave with a 300 
ml. capacity. After exchanging the air in the autoclave with a gaseous 
mixture consisting by volume of 4% hydrogen gas, 40% oxygen gas and 56% 
nitrogen gas, this same gaseous mixture was added to the autoclave until a 
pressure of 25 kg./cm.sup.2.G was achieved and maintained. A temperature 
of 10.degree. C. and stirring at a rate of 2000 rpm. were maintained for 1 
hour while introducing a flow of the same gaseous mixture at a rate of 3.5 
l./min. through the autoclave. After stirring for one hour, the 
concentration of hydrogen peroxide produced in the reaction mixture was 
0.85% by weight of the reaction mixture, and the hydrogen selectivity was 
25%. 
Comparative Experiment 5 (Comparison with Example 4) 
Using a commercially available palladium black catalyst, a palladium black 
catalyst to which trimethylbenzene was adsorbed in an amount equal to 15% 
of the weight of the catalyst was obtained using the same methods as in 
Example 4. Upon reacting oxygen and hydrogen using this catalyst under the 
same reaction conditions as in Example 4, the concentration of hydrogen 
peroxide produced was 0.00% by weight of the reaction mixture, and the 
hydrogen selectivity was 0%. 
Example 5 
A commercially available platinum black catalyst was impregnated with a 
methanol solution of iodobenzene in which the amount of iodobenzene was 
equal to 10% of the weight of the catalyst. The iodobenzene was adsorbed 
onto the catalyst by evaporating the solvent at 80.degree. C. while 
agitating the solution-catalyst mixture, and a platinum black catalyst to 
which iodobenzene was adsorbed in an amount equal to 10% of the weight of 
the catalyst was obtained. Upon reacting oxygen and hydrogen using this 
catalyst and under the same reaction conditions as in Example 4, the 
concentration of the hydrogen peroxide produced was 0.58% by weight of the 
reaction mixture, and the hydrogen selectivity was 18%. 
Comparative Experiment 6 (Comparison with Example 5) 
Using a commercially available platinum black catalyst, a platinum black 
catalyst onto which trimethylbenzene was adsorbed in an amount equal to 
10% of the weight of the catalyst was obtained using the same methods as 
in Example 5. Upon reacting oxygen and hydrogen using this catalyst under 
the same reaction conditions as in Example 4, the concentration of 
hydrogen peroxide produced was 0.00% by weight of the reaction mixture, 
and the hydrogen selectivity was 0%. 
Example 6 
A commercially available alumina supported 1% by weight palladium catalyst 
was impregnated with an ethanol solution of 2-bromo-n-caproic acid in 
which the amount of 2-bromo-n-caproic acid was equal to 5% of the weight 
of the catalyst, and the ethanol solution-catalyst mixture was dried under 
vacuum at room temperature. Then, the catalyst was treated with hydrogen 
gas at 100.degree. C., and an alumina supported 1% by weight palladium 
catalyst onto which 2-bromo-n-caproic acid was adsorbed in an amount equal 
to 5% of the weight of the catalyst was obtained. 
Ten grams of an aqueous solution containing 0.1 mol./l. of sulphuric acid 
were placed in a 65 ml. volume glass vessel to serve as the reaction 
medium. 50 mg. of the catalyst treated by the above method were added to 
this solution, and the glass vessel was then placed in an autoclave with a 
100 ml. capacity. After exchanging the air in the autoclave with a gaseous 
mixture consisting by volume of 4% hydrogen gas, 40% oxygen gas and 56% 
nitrogen gas, this same gaseous mixture was added to the autoclave until a 
pressure of 50 kg./cm.sup.2.G was achieved and maintained. A temperature 
of 10.degree. C. was maintained and the reaction mixture was stirred at a 
rate of 2000 rpm. while the reaction was continued for 1 hour, and the 
above gas mixture was not supplemented during the reaction. After the 
reaction, the concentration of hydrogen peroxide produced in the reaction 
mixture was 0.30% by weight of the reaction mixture, and the hydrogen 
selectivity was 84%. 
Comparative Experiment 7 (Comparison with Example 6) 
Using a commercially available alumina supported palladium catalyst, an 
alumina supported 1% by weight palladium catalyst onto which 
perfluorodecalin was adsorbed in an amount equal to 5% of the weight of 
the catalyst was obtained using the same methods as in Example 6. Upon 
reacting oxygen and hydrogen using this catalyst under the same reaction 
conditions as in Example 6, the concentration of hydrogen peroxide 
produced was 0.00% by weight of the reaction mixture, and the hydrogen 
selectivity was 0%. 
Example 7 
A commercially available alumina supported 1% by weight palladium catalyst 
was impregnated with an methylene chloride solution of 4-bromostyrene in 
which the amount of 4-bromostyrene was equal to 10% of the weight of the 
catalyst, and the impregnated catalyst was dried at room temperature. 
Subsequently, the 4-bromostyrene adsorbed onto the catalyst was 
polymerized under nitrogen gas at 120.degree. C. and then treated with 
hydrogen gas at 100.degree. C., and an alumina supported 1% by weight 
palladium catalyst to which polybromostyrene was adsorbed in an amount 
equal to 10% of the weight of the catalyst was obtained. Upon reacting 
oxygen and hydrogen using this catalyst under the same reaction conditions 
as in Example 6, the concentration of hydrogen peroxide produced was 0.20% 
by weight of the reaction mixture, and the hydrogen selectivity was 20%. 
Comparative Experiment 8 (Comparison with Example 7) 
Using a commercially available alumina supported 1% by weight palladium 
catalyst and using styrene in place of the 4-bromostyrene of Example 7, an 
alumina supported 1% by weight palladium catalyst onto which polystyrene 
was adsorbed in an amount equal to 10% of the weight of the catalyst was 
obtained using the same methods as in Example 7. Upon reacting oxygen and 
hydrogen using this catalyst under the same reaction conditions as in 
Example 6, the concentration of hydrogen peroxide produced was 0.00% by 
weight of the reaction mixture, and the hydrogen selectivity was 0%. 
Example 8 
A commercially available silica supported 5% by weight palladium catalyst 
was impregnated with a solution composed of a mixture of a benzene 
solution of metaxylylene diisocyanate (a reagent manufactured by Takeda 
Chemical Industries, Ltd.) added where the amount of metaxylylene 
diisocyanate was equal to 8% of the weight of the catalyst and a benzene 
solution of 4-bromoresorcine (a reagent manufactured by Tokyo Kasei Kogyo 
Co., Ltd.) where the amount of 4-bromoresorcine is equal to 10% of the 
weight of the catalyst. After the solution-catalyst mixture was agitated 
for 30 minutes at room temperature, it was dried under vacuum at room 
temperature. Subsequently, polymerization was carried out under nitrogen 
gas at 120.degree. C. Then, the catalyst was treated with hydrogen gas at 
100.degree. C., and a silica supported 5% by weight palladium catalyst 
onto which polybromourethane was adsorbed in an amount equal to 18% of the 
weight of the catalyst was obtained. Upon reacting oxygen and hydrogen 
using this catalyst under the same reaction conditions as in Example 4, 
the concentration of hydrogen peroxide produced was 0.40% by weight of the 
reaction mixture, and the hydrogen selectivity was 30%. 
Comparative Experiment 9 (Compared with Example 8) 
Using a commercially available silica supported 5% by weight palladium 
catalyst and using resorcine in place of the 4-bromoresorcine of Example 
8, a silica supported 5% by weight palladium catalyst onto which 
polyurethane was adsorbed in an amount equal to 18% of the weight of the 
catalyst was obtained using the same methods as in Example 8. Upon 
reacting oxygen and hydrogen using this catalyst under the same reaction 
conditions as in Example 4, the concentration of hydrogen peroxide 
produced was 0.01% by weight of the reaction mixture, and the hydrogen 
selectivity was 1%. 
Example 9 
Using dehydrated toluene as the solvent, a solution of 
chloromethyldimethylchlorosilane (a reagent manufactured by Tokyo Kasei 
Kogyo Co., Ltd.) which is an organosilicon compound containing a halogen 
atom directly bonded to a silicon atom and a halogen atom not directly 
bonded to a silicon atom, was prepared in which the weight of the 
chloromethyldimethylchlorosilane was 5% of the weight of the toluene, and 
this solution was added to a commercially available silica supported 2% 
palladium catalyst. This solution-catalyst mixture was allowed to stand 
for 24 hours at room temperature to permit the reaction between the 
hydroxyl groups on the catalyst carrier and the reactive chlorines bonded 
directly to silicon atoms. After driving the reaction to completion by 
heating the mixture for two hours at 70.degree. C., the catalyst was 
separated from the solution by filtration and dried at 120.degree. C. 
Then, in order to remove the hydrochloric acid produced by the reaction, 
the catalyst was washed with methanol and then water, and silver nitrate 
solution was added to the washing water so that, until chlorine ion was no 
longer detected, washing with water was continued. Finally, the catalyst 
was washed with methanol and after air drying, was treated with hydrogen 
gas at 130.degree. C., and a silica supported 2% by weight catalyst which 
had been treated by the addition of chloromethylsilane was obtained. Upon 
reacting oxygen and hydrogen using this catalyst under the same reaction 
conditions as in Example 4, the concentration of hydrogen peroxide 
produced was 0.85% by weight of the reaction mixture, and the hydrogen 
selectivity was 45%. 
Comparative Experiment 10 (Comparison with Example 9) 
A commercially available silica supported 2% by weight palladium catalyst 
was treated by addition of trimethylsilane using the same methods as in 
Example 9 except that trimethylchlorosilane (a reagent manufactured by 
Tokyo Kasei Kogyo Co., Ltd.) which is an organosilicon compound where the 
only halogen atoms are reactive chlorine atoms bonded directly to a 
silicon atom was used in place of the chloromethyldimethylchlorosilane of 
Example 9. That is to say, a silica supported 2% by weight palladium 
catalyst which did not contain chlorine atoms was obtained. Upon reacting 
oxygen and hydrogen using this catalyst under the same reaction conditions 
as in Example 4, the concentration of hydrogen peroxide produced was 0.05% 
by weight of the reaction mixture, and the hydrogen selectivity was 5%. 
Example 10 
Using dehydrated toluene as the solvent, a bromomethyldimethylchlorosilane 
(a reagent manufactured by Tokyo Kasei Kogyo Co., Ltd.) solution was 
prepared so that the weight of bromomethyldimethylchlorosilane was 5% of 
the weight of the toluene. A commercially available silica supported 1% 
palladium catalyst which was dried for 24 hours at 200.degree. C. and 
impregnated with dehydrated toluene. Then, the 5% by weight 
bromomethyldimethylchlorosilane solution was added to the catalyst in such 
an amount that the weight of bromine added was equal to 0.05% of the 
weight of the catalyst, and this solution-catalyst mixture was allowed to 
stand for 24 hours at room temperature. After driving the reaction to 
completion by heating the mixture for two hours at 70.degree. C., the 
catalyst was separated from the solution by filtration and dried at 
120.degree. C. Then, in order to remove the hydrochloric acid produced by 
the reaction, the catalyst was washed with methanol and then water, and 
silver nitrate solution was added to the washing water and, until chloride 
ion was no longer detected, washing with water was continued. Finally, the 
catalyst was washed with methanol and after air drying, was treated with 
hydrogen gas at 130.degree. C., and a silica supported 1% palladium 
catalyst was obtained which had been treated by the addition of 
bromomethylsilane in such amount that the amount of bromine added was 
equal to 0.05% of the weight of the catalyst. 
Eighty grams of an aqueous solution containing 0.1 mol./l. of sulphuric 
acid were placed in a 180 ml. volume glass vessel to serve as the reaction 
medium. Four tenths of a gram of the above catalyst were added to this 
solution, and the glass vessel was then placed in an autoclave with a 300 
ml. capacity. After exchanging the air in the autoclave with a gaseous 
mixture consisting by volume of 4% hydrogen gas, 40% oxygen gas and 56% 
nitrogen gas, this same gaseous mixture was added to the autoclave until a 
pressure of 50 kg./cm.sup.2.G was achieved and maintained. A temperature 
of 10.degree. C. and stirring at a rate of 2000 rpm. were maintained for 1 
hour while introducing a flow of the same gaseous mixture at a rate of 1.0 
l./min. through the autoclave. After stirring for one hour, the 
concentration of hydrogen peroxide in the reaction mixture was 1.32% by 
weight of the reaction mixture, and the hydrogen selectivity was 74%. 
Comparative Experiment 11 (Comparison with Example 10) 
Using a commercially available silica supported 1% by weight palladium 
catalyst, a silica supported 1% by weight palladium catalyst was obtained 
which was treated by addition of trimethylsilane in such amount that the 
amount of silicon added was 1% of the weight of the catalyst using the 
same methods as in Example 10, except that trimethylchlorosilane (a 
reagent manufactured by Tokyo Kasei Kogyo Co., Ltd.) was used in place of 
the bromomethyldimethylchlorosilane of Example 10 and that the amount of 
trimethylchlorosilane was adjusted to provide the result of an added 
silicon weight of 1% of the weight of the catalyst. Upon reacting oxygen 
and hydrogen using this catalyst under the same reaction conditions as in 
Example 10, the concentration of hydrogen peroxide produced was 0.03% by 
weight of the reaction mixture, and the hydrogen selectivity was 4%. 
Example 11 
The catalyst was prepared by treating silica powder by the addition of 
bromomethyldimethylsilane before it is used to support palladium. That is 
to say, a dehydrated toluene solution of bromomethyldimethylchlorosilane 
where the amount of bromomethyldimethylchlorosilane is equal to 5% of the 
weight of the solution as in Example 10 was added in such amount that the 
weight of bromine added is equal to 0.05% of the weight of the silica 
powder to the silica powder which before addition of the solution had been 
impregnated with dehydrated toluene after being dried at 200.degree. C. 
for 24 hours. This mixture was left to stand for 24 hours, and, then, 
after driving the reaction to completion by heating it at 70.degree. C. 
for 2 hours, the treated silica powder was separated by filtration and 
dried at 120.degree. C. The treated silica powder was washed with methanol 
and then washed with water, and silver nitrate solution was added to the 
water so that, until chloride ion was no longer detected, washing was 
continued. Finally, the silica powder was washed with methanol, air dried, 
and dried under nitrogen at 120.degree. C., and a silica powder treated by 
the addition of bromomethyldimethylsilane in which the amount of bromine 
added was equal to 0.05% of the weight of the silica powder was obtained. 
The treated silica powder obtained in this manner was impregnated with a 
palladium acetate/chloroform solution in which the amount of palladium was 
equal to 1% of the weight of the treated silica powder. The impregnated 
treated silica powder was dried under vacuum and reduced at 100.degree. C. 
using hydrogen gas, and a 1% by weight palladium catalyst in which the 
palladium was supported on silica powder which had been treated by the 
addition of bromomethyldimethylsilane in such an amount that the weight of 
bromine added was equal to 0.05% of the weight of the catalyst carrier was 
obtained. Upon reacting oxygen and hydrogen using this catalyst and under 
the same reaction conditions as in Example 10, the concentration of 
hydrogen peroxide produced was 1.02% by weight of the reaction mixture, 
and the hydrogen selectivity was 70%. 
Examples 12, 13, and 14 
Using commercially available alumina supported 5% by weight palladium 
catalyst, titania supported 5% by weight palladium catalyst, and 
silica-magnesia supported 5% by weight palladium catalyst, and treating 
each of them by addition of bromomethyldimethylsilane in such amount that 
the weight of bromine added was 1% of the weight of the respective 
catalyst using the same methods as in Example 10, three palladium 
catalysts which were 5% palladium by weight were obtained. Eighty grams of 
an aqueous solution containing 0.1 mol./l. of sulphuric acid were placed 
in each of three 180 ml. volume glass vessels to serve as the reaction 
medium. Eighty milligrams of the each of the above catalysts were added to 
the solutions, one type of catalyst per solution, and the glass vessels 
were then placed in autoclaves with 300 ml. capacities. After exchanging 
the air in the autoclaves with a gaseous mixture consisting by volume of 
3.5% hydrogen gas, 20.5% oxygen gas and 76% nitrogen gas, this same 
gaseous mixture was added to the autoclaves until a pressure of 10 
kg./cm.sup.2.G was achieved and maintained. A temperature of 10.degree. C. 
and stirring at a rate of 2000 rpm. were maintained for 1 hour while 
introducing a flow of the same gaseous mixture at a rate of 0.7 l./min. 
through the autoclaves. After stirring for one hour, the following results 
were obtained: 
______________________________________ 
H.sub.2 O.sub.2 
H.sub.2 
Catalyst Conc. (wt %) 
Selectivity (%) 
______________________________________ 
Ex. 12 5% Pd/Al.sub.2 O.sub.3 
0.43 83 
Ex. 13 5% Pd/TiO.sub.2 
0.74 75 
Ex. 14 5% Pd/SiO.sub.2 --MgO 
0.55 76 
______________________________________ 
Comparative Experiments 12, 13, and 14 (Comparison with Examples 12, 13 and 
14) 
Using commercially available alumina supported 5% by weight palladium 
catalyst, titania supported 5% by weight palladium catalyst, and 
silica-magnesia supported 5% by weight palladium catalyst, and treating 
each of them by addition of trimethylsilane in such amount that the weight 
of silicon added was 2.0% of the weight of the respective catalyst using 
the same methods as in Example 11, three palladium catalysts which were 5% 
palladium by weight were obtained. Upon reacting oxygen and hydrogen using 
these catalysts under the same reaction conditions as in Example 10, the 
following results were obtained: 
______________________________________ 
H.sub.2 O.sub.2 
Catalyst Conc. (wt %) 
H.sub.2 Sel. (%) 
______________________________________ 
Comp. Ex. 12 
5% Pd/Al.sub.2 O.sub.3 
0.01 1 
Comp. Ex. 13 
5% Pd/TiO.sub.2 
0.00 0 
Comp. Ex. 14 
5% Pd/SiO.sub.2 --MgO 
0.00 0 
______________________________________ 
Example 15 
Upon reacting oxygen and hydrogen under the same reaction conditions as in 
Example 12 except that pure water was used as the reaction medium, and 
using a titania supported 5% by weight palladium catalyst which was 
treated by addition of bromomethyldimethylsilane using the same methods as 
in Example 13, the concentration of hydrogen peroxide produced was 0.30% 
by weight of the reaction mixture, and the hydrogen selectivity was 20%. 
Comparative Experiment 15 (Comparison with Example 15) 
Upon reacting oxygen and hydrogen under the same reaction conditions as in 
Example 12, except that pure water was used as the reaction medium, and 
using a titania supported 5% by weight palladium catalyst which was 
treated by addition of trimethylsilane using the same methods as in 
Comparative Experiment 13, the concentration of hydrogen peroxide produced 
was 0.00% by weight of the reaction mixture, and the hydrogen selectivity 
was 0%. 
Examples 16-21 
Using a commercially available silica supported 1% by weight palladium 
catalyst, and treating six separate portions of it with the respective 
addition of 1,3-bis(chloromethyl)tetramethyldisilazane (BCMTMDS) (a 
reagent manufactured by Tokyo Kasei Kogyo Co., Ltd.), 
1,2-dibromoethyltrichlorosilane (DBETCS), 
dichloromethyldimethylchlorosilane (DCMDMCS), 
3-chloropropyltrimethoxysilane (CPRTMS), 4-chlorophenyltrimethoxysilane 
(CPHTMS), and 3-bromopropyltriethoxysilane (BPRTES) (the preceding 5 
reagents were manufactured by Shin Etsu Chemical Co., Ltd.), one of the 
above compounds per each portion of catalyst, in place of the 
bromomethyldimethylchlorosilane of Example 10 in amounts necessary to 
produce respective halogen weight percentages shown below using the same 
methods as in Example 10, six silica supported 1% by weight palladium 
catalysts were obtained. Upon reacting oxygen and hydrogen using these 
catalysts under the same reaction conditions as in Example 10, the 
following results were obtained: 
______________________________________ 
Hal. H.sub.2 O.sub.2 
H.sub.2 
Ex. # Silane cont. (wt %) 
Conc. (wt %) 
Sel. (%) 
______________________________________ 
16 BCMTMDS Cl: 1.0 0.40 53 
17 DBETCS Br: 0.3 0.92 91 
18 DCMDMCS Cl: 0.2 0.80 76 
19 CPRTMS Cl: 0.1 0.43 45 
20 CPHTMS Cl: 0.1 0.30 40 
21 BPRTES Br: 0.1 0.78 74 
______________________________________ 
Comparative Examples 16-21 (Comparison with Examples 16-21) 
Using a commercially available silica supported 1% by weight palladium 
catalyst, and treating six separate portions of it with the respective 
addition of 1, 1, 1, 3, 3, 3-hexamethyldisilazane (HMDS), 
triethylchlorosilane (TECS), triphenylchlorosilane (TPCS), 
tertbutyldimethylchlorosilane (t-BDMCS) (the above 4 reagents were 
manufactured by Tokyo Kasei Kogyo Co., Ltd.), 3, 3, 
3-trifluoropropyltrimethoxysilane (TFPRTMS) and 3, 3, 4, 4, 5, 5, 6, 6, 
6-nonafluorohexylmethyldichlorosilane (NFHMDCS) (the preceding two 
reagents were manufactured by Shin Etsu Chemical Co., Ltd.), one of the 
above compounds per each portion of catalyst, in place of the 
bromomethyldimethylchlorosilane of Example 10 in amounts necessary to 
produce respective silicon and fluorine weight percentages shown below 
using the same methods as in Example 10, six silica supported 1% by weight 
palladium catalysts were obtained. Upon reacting oxygen and hydrogen using 
these catalysts under the same reaction conditions as in Example 10, the 
following results were obtained: 
______________________________________ 
Comp. Silane Si or F H.sub.2 O.sub.2 
H.sub.2 
Ex. # name (wt %) Conc. (wt %) 
Sel. (%) 
______________________________________ 
16 HMDS Si: 2.0 0.07 10 
17 TECS Si: 1.1 0.07 9 
18 TPHCS Si: 0.5 0.02 3 
19 t-BDMCS Si: 1.1 0.04 4 
20 TFPRTMS F: 1.0 0.07 6 
21 NFHMDCS F: 1.0 0.09 8 
______________________________________ 
Example 22 
Upon reacting oxygen and hydrogen using an alumina supported 5% by weight 
palladium catalyst, and which was treated with bromomethyldimethylsilane 
as in Example 13 and using the same reaction conditions as in Example 13 
except that a 70 ppm. aqueous solution of aminotri(methylenephosphonic 
acid) was used as the reaction medium instead of the sulphuric acid 
solution, the concentration of hydrogen peroxide produced was 0.70% by 
weight of the reaction mixture, and the hydrogen selectivity was 78%. 
EFFECTS OF THE PRESENT INVENTION 
In the Examples of the present invention, the hydrogen selectivities of the 
hydrogen peroxide production reactions were very high compared to those of 
the Comparative Experiments, and where organic halogen compounds which 
were insoluble in water, except for those containing only fluorine, were 
used, a high concentration of hydrogen peroxide was obtained. In this way 
it is possible to produce hydrogen peroxide relatively efficiently and in 
high concentration even where the halogen ions of the prior art are not 
present through the use of the catalysts of the present invention.