PROCESS TO OBTAIN HYDROGEN PEROXIDE, AND CATALYST AND CATALYSTS SUPPORTS FOR SAID PROCESS

Abstract

Catalyst support comprising a material functionalized with at least one acid group and at least one linear hydrophobic group. Catalyst comprising said support and process for the direct synthesis of hydrogen peroxide using said catalyst.

Claims

1. A catalyst support, comprising a support material having a surface, at least one acid group grafted on the surface, and at least one linear hydrophobic group grafted on the surface, wherein each of the at least one acid group and at least one linear hydrophobic group is part of a respective silane molecule, each of the respective silane molecules comprises a Si atom and four substituents per such Si atom, 3 of the four substituents are covalently bonded to the surface of the support material, the fourth of the four substituents of a respective one of the silane molecules is an organic substituent which comprises the at least one acid group, and the fourth of the four substituents of another of the respective the silane molecules is the at least one linear hydrophobic group.

2. The catalyst support according to claim 1, wherein the acid group is selected from the group consisting of sulfonic, phosphonic, carboxylic, and dicarboxylic acid groups.

3. The catalyst support according to claim 2, wherein the acid group is p-toluene sulfonic acid.

4. The catalyst support according to claim 1, wherein the linear hydrophobic group is an alkane having from 1 to 20 carbon atoms.

5. The catalyst support according to claim 1, wherein the catalyst support further comprises a halogenated group grafted to the surface of the support material, wherein the halogenated group is part of a silane molecule, that comprises a Si atom having four substituents per such Si atom, 3 of such substituents are covalently bonded to surface of the support material, and the fourth of such substituents is the halogenated group.

6. The catalyst support according to claim 1, wherein the respective silane molecules are derived from starting silane molecules that comprise 3 substituents selected from the group consisting of halogen atoms and methoxy groups.

7. The catalyst support according to claim 1, wherein the support material is a metal oxide preferably chosen from silica, alumina, aluminosilicates, and titanosilicates.

8. The catalyst support according to claim 7, wherein the support material is silicon oxide.

9. The catalyst support according to claim 8, wherein the at least one linear hydrophobic group is a butyl group and the at least one acid group is a p-toluene sulfonic acid group.

10. A catalyst comprising an element selected from groups 7 to 11 of the Periodic Table or a combination of at least two of such elements supported on a catalyst support according to claim 1.

11. The catalyst according to claim 10, wherein the element comprises a metal.

12. The catalyst according to claim 11, wherein the metal is present in an amount of between 0.001 and 10% by weight with respect to the weight of the catalyst support.

13. A process for producing hydrogen peroxide, comprising reacting hydrogen and oxygen in presence of the catalyst according to claim 10.

14. The process according to claim 13, wherein the catalyst is present in an amount effective to obtain a concentration of H.sub.2O.sub.2 of 0.01% to 15% by weight with respect to the weight of the solvent.

15. The process according to claim 13, wherein reaction of oxygen with hydrogen is performed at temperatures ranging from 0 C. to 50 C.

16. The catalyst support according to claim 4, wherein the linear hydrophobic group is a butyl group or an octyl group.

17. The catalyst support according to claim 5, wherein the halogenated group is a halogenophenyl group or a halogenopropyl group.

18. The catalyst support according to claim 9, further comprising propylbromide groups grafted on the silica support material.

19. The catalyst support according to claim 9, wherein residual OH groups, if any, of the silica support material are end-capped with branched molecules.

20. The catalyst according to claim 10, wherein the catalyst comprises palladium or an alloy of palladium with another noble metal supported on the catalyst support.

Description

EXAMPLE 1

Synthesis of Catalysts Supports

[0039] Catalyst supports were synthesized for catalysts 1 to 8 (which are according to the invention) and catalysts X and Y (which are not according to the invention) using the following methods:

Catalyst 1: Support Preparation

SiliaBond C1/Tosic acid (47% C1)

[0040] In a 500 mL three necks round bottomed flask equipped with a mechanical stirrer and fitted with a condenser, the silica gel (50 g) was placed in toluene (200 mL). To this mixture was added Trichloromethylsilane (2.55 g) and the reaction was stirred at 90 C. for 16 h. The silica was then filtered on Buchner and washed with toluene and methanol. The gel was dried under vacuum at room temperature for 16 h and at 65 C. for 1 h to yield the C1 gel as a white solid (Wt % C=2.94).

[0041] In a 500 mL three necks round bottomed flask equipped with a mechanical stirrer and fitted with a condenser, the C1 silica gel (50 g) was placed in dichloromethane (200 mL). To this mixture was added 2-(4-chlorosulfonylphenyl)-ethyltrichlorosilane (50% in toluene; 68 g) and the reaction was stirred at room temperature for 16 h. Trimethylchlorosilane (TMSCl5.66 g) was added to the reaction and the mixture was stirred at room temperature for an additional 2 h. The silica was filtered on Buchner and washed with dichloromethane and acetone. The gel was dried in vacuum at room temperature for 16 h and at 65 C. for 1 h to yield the C1/Tonsil chloride gel as a white solid (Wt % C=10.31; Wt % S=3.02).

[0042] In a 500 mL three necks round bottomed flask equipped with a mechanical stirrer and fitted with a condenser, the C1/Tonsil chloride gel (50 g) was placed in a mixture of water (150 mL) and acetone (150 mL). The reaction was stirred at 35 C. for 16 h. The silica was filtered on Buchner and washed with methanol. The gel was put in an 8/2 mixture (in volume) of methanol and water (300 mL) and stirred for 10 minutes at room temperature. The silica was filtered on Buchner and dried in vacuo at room temperature for 16 h and at at 65 C. for 1 h to yield the C1/Tosic acid gel as a white solid (Wt % C=7.01; Wt % S=1.77).

Catalyst 2: Support Preparation

SiliaBond C4/Tosic Acid (46% C4)

[0043] In a 500 mL three necks round bottomed flask equipped with a mechanical stirrer and fitted with a Dean-Stark condenser, the silica gel (50 g) was placed in toluene (250 mL) under an argon atmosphere. The mixture was refluxed to remove 50 mL of toluene/water via the Dean-Stark. The reaction was cooled to room temperature and pyrazine (2.97 g) and n-Butyltrichlorosilane (4.48 g) were added to the mixture. The reaction was stirred under an argon atmosphere at 60 C. for 16 h. The silica was then filtered on Buchner and washed with methanol, toluene and a second portion of methanol. The gel was put in an 8/2 mixture (in volume) of methanol and water (300 mL) and the mixture was stirred for 1 h at room temperature. The gel was filtered on Buchner, washed with methanol and dried in vacuum at room temperature for 16 h and at 65 C. for 1 h to yield the C4 gel as a white solid (Wt % C=2.69).

[0044] In a 500 mL three necks round bottomed flask equipped with a mechanical stirrer and fitted with a condenser, the C4 silica gel (50 g) was placed in dichloromethane (200 mL). To this mixture was added 2-(4-chlorosulfonylphenyl)-ethyltrichlorosilane (50% in toluene; 68 g) and the reaction was stirred at room temperature for 16 h. Trimethylchlorosilane (TMSCl5.66 g) was added to the reaction and the mixture was stirred at room temperature for an additional 2 h. The silica was filtered on Buchner and washed with dichloromethane and acetone. The gel was dried in vacuum at room temperature for 16 h and at 65 C. for 1 h to yield the C4/Tonsil chloride gel as a white solid (Wt % C=10.13; Wt % S=2.25).

[0045] In a 500 mL three necks round bottomed flask equipped with a mechanical stirrer and fitted with a condenser, the C4/Tonsil chloride gel (50 g) was placed in a mixture of water (150 mL) and acetone (150 mL). The reaction was stirred at 35 C. for 16 h. The silica was filtered on Buchner and washed with methanol. The gel was put in an 8/2 mixture (in volume) of methanol and water (300 mL) and stirred for 10 minutes at room temperature. The silica was filtered on Buchner and dried in vacuum at room temperature for 16 h and at at 65 C. for 1 h to yield the C4/Tosic acid gel as a white solid (Wt % C=8.17;Wt % S=1.89).

Catalyst 3: Support Preparation

SiliaBond C8/Tosic Acid (47% C8)

[0046] Catalyst 3 support was prepared according to the procedure for catalyst 2 support. n-Octyltrichlorosilane (5.79 g) was used in the preparation of the C8 gel. C8/Tosic acid gel was obtained as a white solid (Wt % C=9.04; Wt % S=1.41).

Catalyst 4: Support Preparation

SiliaBond C18/Tosic Acid (48% C18)

[0047] Catalyst 4 support was prepared according to the procedure for catalyst 2 support. n-Octadecyltrichlorosilane (9.07 g) was used in the preparation of the C18 gel. C18/Tosic acid gel was obtained as a white solid (Wt % C=12.55; Wt % S=1.20).

Catalyst 5: Support Preparation

Trifunctionalized Grafted 8% Propylbromide 17% C4/Tosic Acid

[0048] In a 500 mL three necks round bottomed flask equipped with a mechanical stirrer and fitted with a Dean-Stark condenser, the silica gel (50 g) was placed in toluene (250 mL) under an argon atmosphere. The mixture was refluxed to remove 50 mL of toluene/water via the Dean-Stark. The reaction was cooled to room temperature and pyrazine (0.375 g) and n-butyltrichlorosilane (0.5 g) were added to the mixture. The reaction was stirred under an argon atmosphere at 60 C. for 16 h. The silica was then filtered on Buchner and washed with methanol, toluene and a second portion of methanol. The gel was put in an 8/2 mixture (in volume) of methanol and water (300 mL) and the mixture was stirred for 1 h at room temperature. The gel was filtered on Buchner, washed with methanol and dried in vacuum at room temperature for 16 h and at 65 C. for 1 h to yield the C4 gel as a white solid (Wt % C=0.67).

[0049] In a 500 mL three necks round bottomed flask equipped with a mechanical stirrer and fitted with a condenser, the C4 silica gel (50 g) was placed in toluene (300 mL). To this mixture was added (3-Bromopropyl)-trimethoxysilane (0.6 g) and the reaction was stirred at 90 C. for 16 h. The silica was then filtered on Buchner and washed with toluene and methanol. The gel was put in methanol (300 mL) and the mixture was stirred for 1 h at room temperature. The gel was filtered on Buchner, washed with methanol and dried in vacuum at room temperature for 16 h and at 65 C. for 1 h to yield the Propylbromide/C4 gel as a white solid (Wt % C=3.36).

[0050] In a 500 mL three necks round bottomed flask equipped with a mechanical stirrer and fitted with a condenser, the Propylbromide/C4 silica gel (50 g) was placed in dichloromethane (200 mL). To this mixture was added 2-(4-chlorosulfonylphenyl)-ethyltrichlorosilane (50% in toluene; 68 g) and the reaction was stirred at room temperature for 16 h. Trimethylchlorosilane (TMSCl5.66 g) was added to the reaction and the mixture was stirred at room temperature for an additional 2 h. The silica was filtered on Buchner and washed with dichloromethane and acetone. The gel was dried in vacuo at room temperature for 16 h and at 65 C. for 1 h to yield the Propylbromide/C4/Tonsil chloride gel as a white solid (Wt % C=12.16; Wt % S=3.51).

[0051] In a 500 mL three necks round bottomed flask equipped with a mechanical stirrer and fitted with a condenser, the Propylbromide/C4/Tonsil chloride gel (50 g) was placed in a mixture of water (150 mL) and acetone (150 mL). The reaction was stirred at 35 C. for 16 h. The silica was filtered on Buchner and washed with methanol. The gel was put in an 8/2 mixture of methanol and water (300 mL) and stirred for 10 minutes at room temperature. The silica was filtered on Buchner and dried in vacuum at room temperature for 16 h and at at 65 C. for 1 h to yield the Propylbromide/C4/Tosic acid gel as a white solid (Wt % C=6.89; Wt % S=2.0).

Catalyst 6: Support Preparation

Trifunctionalized Grafted 15% Propylbromide 46% C4/Tosic Acid

[0052] Catalyst 6 support was prepared according to the procedure for catalyst 5 support. 12 g of n-butyltrichlorosilane were used in the C4 gel preparation. 0.72 g of (3-Bromopropyl)-trimethoxysilane was used in the Propylbromide/C4 gel preparation. Propylbromide /C4/Tosic acid gel was obtained as a white solid (Wt % C=9.06;Wt % S=1.99).

Catalyst 7: Support Preparation

Trifunctionalized Grafted 12% Propylbromide 27% C4/Tosic Acid

[0053] Catalyst 7 support was prepared according to the procedure for catalyst 5 support. 6 g of n-butyltrichlorosilane were used in the C4 gel preparation. 1.22 g of (3-Bromopropyl)-trimethoxysilane was used in the Propylbromide/C4 gel preparation. Propylbromide/C4/Tosic acid gel was obtained as a white solid (Wt % C=8.70; Wt % S=2.30).

Catalyst 8: Support Preparation

Trifunctionalized Grafted 10% Propylbromide 10% C4/Tosic Acid

[0054] Catalyst 8 support was prepared according to the procedure for catalyst 5 support. 0.25 g of n-butyltrichlorosilane was used in the C4 gel preparation. 0.60 g of (3-Bromopropyl)-trimethoxysilane was used in the Propylbromide/C4 gel preparation. Propylbromide/C4/Tosic acid gel was obtained as a white solid (Wt % C=9.32; Wt % S=2.86).

[0055] The characteristics of these supports figure below namely: their surface area, pore volume and content/nature of linear hydrophobic groups.

Catalyst 1: SiliaBond C1/Tosic Acid

[0056] 47% C1 [0057] Surface area: 500 m.sup.2/g [0058] Pore volume: 0.8 ml/g

Catalyst 2: SiliaBond C4/Tosic Acid

[0059] 46% C4 [0060] Surface area: 500 m.sup.2/g [0061] Pore volume: 0.8 ml/g

Catalyst 3: SiliaBond C8/Tosic Acid

[0062] 47% C8 [0063] Surface area: 500 m.sup.2/g [0064] Pore volume: 0.8 ml/g

Catalyst 4: SiliaBond C18/Tosic Acid

[0065] 48% C18 [0066] Surface area: 500 m.sup.2/g [0067] Pore volume: 0.8 ml/g

Catalyst 5: Trifunctionalized Grafted 8% Propylbromide17% C4

[0068] Surface area: 500 m.sup.2/g [0069] Pore volume: 0.8 ml/g

Catalyst 6: Trifunctionalized Grafted 15% Propylbromide46% C4

[0070] Surface area: 500 m.sup.2/g [0071] Pore volume: 0.8 ml/g

Catalyst 7: Trifunctionalized Grafted 12% Propylbromide/27% C4

[0072] Surface area: 500 m.sup.2/g [0073] Pore volume: 0.8 ml/g

Catalyst 8: Trifunctionalized Grafted 10% Propylbromide10% C4

[0074] Surface area: 500 m.sup.2/g [0075] Pore volume: 0.8 ml/g

Catalyst X: SiliaBond Tosic Acid

[0076] Surface area: 500 m.sup.2/g [0077] Pore volume: 0.8 ml/g

Catalyst Y: 6% propylbromide/Tosic Acid

[0078] Surface area: 500 m.sup.2/g [0079] Pore volume: 0.8 ml/g

EXAMPLE 2

Catalyst Preparation

[0080] 20 g of each selected grafted silica was put in a glass reactor of 1 liter equipped with a mechanical stirrer. 600 ml acetone high grade was added to the solid. The suspension was mechanically stirred at room temperature at around 250 rpm. 0.20 g of palladium acetate was dissolved at room temperature in 100 ml of acetone high grade (magnetic stirrer400 rpm). The Pd solution was added slowly to the suspension (around 1 ml/5 sec). The suspension was maintained under mechanical stirring during 24 hours at room temperature. The suspension was filtered under vacuum and washed with 100 ml acetone high grade. The solid was dried 24 hours at 90 C.

[0081] Catalyst X has additionally been reduced during 5 hours under a mixture of hydrogen and nitrogen at 150 C.

[0082] The characteristics of the several catalysts are shown in Table 1 below.

[0083] Pd concentration has been determined by ICP-OES (Inductively coupled plasma atomic emission spectroscopy). The S and the Br concentrations have been determined by ionic chromatography after mineralization of the samples by Wurzschmitt digestion.

TABLE-US-00001 TABLE 1 Pd, % Wt S, % Wt Br, % Wt Catalyst 1 0.45 2.00 0 Catalyst 2 0.33 2.20 0 Catalyst 3 0.16 1.50 0 Catalyst 4 0.29 1.25 0 Catalyst 5 0.50 NM 0.20 Catalyst 6 0.09 NM 0.78 Catalyst 7 0.24 NM 0.75 Catalyst 8 0.20 NM 0.26 Catalyst X 0.35 3.00 0 Catalyst Y 0.43 1.57 0.43 NM = not measured

EXAMPLE 3

Direct Synthesis of Hydrogen Peroxide

[0084] In a HC-22/250cc reactor, methanol (150 g) and catalyst (3.0 g) were introduced. Eventually, some HBr was added (10 l of an aqueous solution 12% Wt). The reactor was cooled to 5 C. and the working pressure was set at 50 bars (obtained by introduction of nitrogen). The reactor was flushed during the entire reaction with the following mixture of gases: Hydrogen (3.6% Mol)/Oxygen (55.0% Mol)/Nitrogen (41.4% Mol). The total flow was 2708 mIN/min. When the gas phase coming out of the reactor was stable (measured by GC (Gas Chromatography) on line), the mechanical stirrer was started and set at 1200 rpm. GC on line analyzed every 10 minutes the composition of the gas phase coming out of the reactor. Liquid samples were taken to measure their hydrogen peroxide and water concentration. Hydrogen peroxide concentration was measured by redox titration with cerium sulfate and water concentration was measured according to the Karl-Fisher method.

[0085] The experimental conditions used and the results obtained are detailed in Tables 2 to 6 below.

[0086] Table 2 shows the selectivity improvement attained through the addition of a C4 linear hydrophobic group to an acid functionalized support.

[0087] Table 3 shows the influence of the nature (length) of the hydrophobic group.

[0088] Table 4 shows the influence of the reaction temperature.

[0089] Table 5 shows the selectivity improvement attained through the addition of a C4 linear hydrophobic group to a bromo and acid functionalized support.

[0090] Table 6 shows the influence of the ratio between the different functional groups.

TABLE-US-00002 TABLE 2 Catalyst 2 X Methanol g 150.1 151.63 HBr ppm 10 9 Catalyst g 3.0281 2.9799 Temperature C. 5 5 Pressure bar 50 50 Hydrogen % Mol 3.6 3.6 Oxygen % Mol 55.0 55.0 Nitrogen % mol 41.4 41.4 Total flow mlN/min 2708 2708 Speed rpm 1200 1200 Contact time min 240 240 H.sub.2O.sub.2 fin % Wt 10.26 10.43 Water fin % Wt 4.01 4.55 Conversion fin % 53.4 52.2 Selectivity init % 75 58 Selectivity fin % 58 55

TABLE-US-00003 TABLE 3 Catalyst 1 2 3 4 Methanol g 152.9 150.1 150.05 150.79 HBr ppm 10 10 10 10 Catalyst g 2.9848 3.0281 2.9995 3.0039 Temperature C. 40 40 40 40 Pressure bar 50 50 50 50 Hydrogen % Mol 3.6 3.6 3.6 3.6 Oxygen % Mol 55.0 55.0 55.0 55.0 Nitrogen % mol 41.4 41.4 41.4 41.4 Total flow mlN/min 2708 2708 2708 2708 Speed rpm 1200 1200 1200 1200 Contact time min 240 240 240 240 H.sub.2O.sub.2 fin % Wt 7.14 8.50 7.72 4.28 Water fin % Wt 9.44 8.57 5.93 9.99 Conversion % 71.5 69.10 53.20 76.10 fin Selectivity % 48 67 66 58 init Selectivity % 29 35 41 19 fin

TABLE-US-00004 TABLE 4 Catalyst 2 2 Methanol g 150.1 150.1 HBr ppm 10 10 Catalyst g 3.0281 3.0281 Temperature C. 40 5 Pressure bar 50 50 Hydrogen % Mol 3.6 3.6 Oxygen % Mol 55.0 55.0 Nitrogen % mol 41.4 41.4 Total flow mlN/min 2708 2708 Speed rpm 1200 1200 Contact time min 240 240 H2O2 fin % Wt 8.50 10.26 Water fin % Wt 8.57 4.01 Conversion fin % 69.10 53.4 Selectivity init % 67 75 Selectivity fin % 35 58

TABLE-US-00005 TABLE 5 Catalyst 5 Y Methanol g 150.34 150.4 HBr ppm / / Catalyst g 3.0058 3.026 Temperature C. 5 5 Pressure bar 50 50 Hydrogen % Mol 3.6 3.6 Oxygen % Mol 55.0 55.0 Nitrogen % mol 41.4 41.4 Total flow mlN/min 2708 2708 Speed rpm 1200 1200 Contact time Min 240 240 Hydrogen peroxide % Wt 13.75 11.15 fin Water fin % Wt 3.33 3.04 Conversion fin % 60.6 60.1 Selectivity init % 81 66 Selectivity fin % 69 66

TABLE-US-00006 TABLE 6 Catalyst 6 7 5 8 Methanol g 150.15 151.71 150.34 149.61 HBr ppm / / / / Catalyst g 2.9942 2.9992 3.0058 2.9991 Temperature C. 5 5 5 5 Pressure bar 50 50 50 50 Hydrogen % Mol 3.6 33.6 3.6 3.6 Oxygen % Mol 55.0 55.0 55.0 55.0 Nitrogen % mol 41.4 41.4 41.4 41.4 Total flow mlN/ 2708 2708 2708 2708 min Speed rpm 1200 1200 1200 1200 Contact time min 240 240 240 240 H.sub.2O.sub.2 fin % Wt 3.03 5.81 13.75 8.13 Water fin % Wt 0.73 1.98 3.33 3.81 Conversion fin % 9.8 20.2 60.6 44.2 Selectivity init % 67 71 81 78 Selectivity fin % 67 64 69 53