Hydrogenation catalyst for the manufacture of hydrogen peroxide

Abstract

The present invention relates to an anthraquinone process (AO) for the manufacture of hydrogen peroxide, wherein the hydrogenation step is conducted with the aid of a catalyst comprising in addition to palladium (Pd) at least one other metal, and an amorphous catalyst support.

Description

[0001] Hydrogenation Catalyst for the Manufacture of Hydrogen Peroxide

[0002] TECHNICAL FIELD

[0003] The present invention relates to an anthraquinone process (AO) for the manufacture of hydrogen peroxide, wherein the hydrogenation step is conducted with the aid of a catalyst comprising in addition to palladium (Pd) at least one other metal, and an amorphous catalyst support.

[0004] TECHNICAL BACKGROUND

[0005] Hydrogen peroxide is one of the most important inorganic chemicals to be produced worldwide. Its industrial applications include textile, pulp and paper bleaching, organic synthesis (propylene oxide), the manufacture of inorganic chemicals and detergents, environmental and other applications.

[0006] Synthesis of hydrogen peroxide is predominantly achieved by using the Riedl-Pfleiderer process (originally disclosed in U.S. Pat. Nos. 2,158,525 and 2,215,883), also called anthraquinone loop process or AO (auto-oxidation) process.

[0007] This well-known cyclic process makes use typically of the auto-oxidation of at least one alkylanthrahydroquinone and / or of at least one tetrahydroalkylanthrahydroquinone, most often 2-alkylanthrahydroquinone, to the corresponding alkylanthraquinone and / or tetrahydroalkylanthraquinone, which results in the production of hydrogen peroxide.

[0008] The first step of the AO process is the reduction of the chosen quinone (alkylanthraquinone or tetrahydroalkylanthraquinone) into the corresponding hydroquinone (alkylanthrahydroquinone or tetrahydroalkylanthrahydroquinone) using hydrogen gas from any source and a catalyst in an organic solvent (generally a mixture of solvents). The catalyst used in the reduction step of the AO-process is usually a metal-based catalyst having a sufficient activity and selectivity to reduce the chosen quinone to the corresponding hydroquinone, e.g., 2-alklyanthraquinone to 2-alkyl-9,10-anthrahydroquinone. Numerous of metalbased catalysts have been developed to increase the catalyst’s activity and / or selectivity. Nowadays, in industry, Pd-catalysts including a catalyst support are mainly used. These catalysts usually have a high activity and selectivity to reduce the quinone to the corresponding hydroquinone. However, the production costs of monometallic Pd-based catalysts, and thus of the AO-process, are high due to the use of Pd as active metal component. Several efforts have been made to provide hydrogenation catalysts suitable for the AO-process, which shows the same or even improved activity and / or selectivity as monometallic Pd-catalysts, but which can be produced by low production costs. One approach is to replace at least partially Pd by unexpensive metals.

[0009] However, by replacing Pd with another metal there is the risk that the catalyst loses its high stable catalytic activity and selectivity. Therefore, there was the need to provide hydrogenation catalysts suitable for the AO-process that have at least the same good catalytic properties comparable to monometallic Pd- catalysts, but which can be produced at lower costs.

[0010] SUMMARY OF THE INVENTION

[0011] The invention relates to an anthraquinone process (AO) for the manufacture of hydrogen peroxide, wherein the hydrogenation step is carried out with a catalyst in the form of catalyst powder particles having a mean particle size between 100 pm and 200 pm, used in a slurry, and wherein the catalyst comprises palladium (Pd), at least one other metal, and an amorphous catalyst support comprising silicon dioxide and alumina (SiAlOx) in an aerogel -physical form, wherein the alumina is incorporated into the silicon dioxide structure at the molecular level.

[0012] DETAILED DESCRIPTION OF THE INVENTION

[0013] Before the process of the invention will be described in detail, it is to be understood that this invention is not limited to specific process conditions described herein, since such conditions may, of course, vary.

[0014] It is also to be understood that the terminology used herein is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0015] As used herein, the singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compound" means one compound or more than one compound.

[0016] The terms "containing", "contains" and "contained of as used herein are synonymous with "including", "includes" or " comprising", "comprises", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or process steps. It will be appreciated that the terms “containing”, “contains”, "comprising", "comprises" and "comprised of as used herein comprise the terms "consisting of, "consists" and "consists of.

[0017] Throughout this application, the term "about" is used to indicate that a value includes the standard deviation of error for the device or method being employed to determine the value.

[0018] As used herein, the term “average” refers to number average unless indicated otherwise.

[0019] As used herein, the terms “% by weight”, “wt.- %”, “weight percentage”, or “percentage by weight” are used interchangeably. The same applies to the terms “% by volume”, “vol.- %”, “vol. percentage”, or “percentage by volume”, or “% by mol”, “mol- %”, “mol percentage”, or “percentage by mol”.

[0020] The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1, 2, 3, 4 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of end points also includes the end point values themselves (e.g., from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all sub-ranges subsumed therein.

[0021] The term “amorphous” as used herein means a solid in which there is no long-range order of the positions of the atoms, in contrast to solids in which there is long-range atomic order which are called crystallized solids. The “amorphous” or “crystalline property” of a catalyst support, i.e., also of the catalyst support of the invention, may be shown by X-ray diffraction spectroscopy (XRD).

[0022] The term “aerogel” used herein means a solid and rigid material of a bonded, cross-linked macromolecule frame (network) obtained from corresponding monomers, for example a SiCh network, also called silica gel.

[0023] The term “anhydrous” as used herein means a substance which does not contain water. Thus, aluminium gel for example is hydrous not anhydrous. The anhydrous source may indeed be provided within a solution or a suspension but is nevertheless classed as anhydrous.

[0024] All references cited in the present specification are hereby incorporated by reference in their entirety. In particular, the teachings of all references herein specifically referred to are incorporated by reference.

[0025] Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

[0026] In the following passages, different alternatives, embodiments and variants of the invention are defined in more detail. Each alternative and embodiment so defined may be combined with any other alternative and embodiment, and this for each variant unless clearly indicated to the contrary or clearly incompatible when the value range of a same parameter is disjoined. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

[0027] Furthermore, the particular features, structures or characteristics described in present description may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and from different embodiments, as would be understood by those in the art.

[0028] The present invention relates to an anthraquinone process (AO) for the manufacture of hydrogen peroxide, wherein the hydrogenation step is carried out with a catalyst in the form of catalyst powder particles having a mean particle size between 100 pm and 200 pm, used in a slurry, and wherein the catalyst comprises Pd, at least one other metal, and an amorphous catalyst support comprising silicon dioxide and alumina (SiAlOx) in an aerogel-physical form, wherein the alumina is incorporated into the silicon dioxide structure at the molecular level.

[0029] In a preferred embodiment of the invention, the catalyst consists of Pd, at least one other metal, and an amorphous catalyst support comprising silicon dioxide and alumina (SiAlOx) in an aerogel -physical form, wherein the alumina is incorporated into the silicon dioxide structure at the molecular level.

[0030] The AO-process for the manufacture of hydrogen peroxide which has given particularly advantageous results in the presence of the catalyst according to the invention is described in particular in the work Ullmann’s Encyclopaedia of Industrial Chemistry, 5thEdition, 1989, vol. A13, p 443 et seq..

[0031] According to the invention, the catalyst is used in the form of catalyst powder particles in a slurry for the hydrogenation of a chosen quinone to the hydrogenated quinone. The catalyst powder particles have a mean particle size of between 100 and 200 pm determined by methods well known by a person skilled in the art, for example by sieving or determination by laser granulometry. Preferably, the catalyst powder particles have a mean particle size between 110 and 190 pm, more preferably between 120 and 180 pm, even more preferably between 130 and 170 pm.

[0032] The catalyst used in the AO-process of the invention comprises in addition to Pd at least one other metal, preferably selected from the group consisting of Fe, Cu, Co, Ni, Sn, Ga, Zn, Au, Ag, Pt, Bi and Ru, or a combination thereof. More preferably, the at least one other metal is Co, Ni, Au, Ru or mixture thereof.

[0033] Furthermore, it is preferred that the catalyst comprises in addition to Pd one, two, up to five other types of metal as active component, which are selected from the group as defined above. In particular, it is preferred that the catalyst comprises one, two or three other types of metal in addition to Pd. More preferably, the catalyst is a bimetallic catalyst, i.e., the catalyst comprises Pd and one other type of metal.

[0034] In the catalyst of the invention, the Pd as well as the at least one other metal can be in the elemental state or in the form of a compound, such as a salt or an oxide. The catalyst preferably comprises Pd and the at least one other metal in the elemental state.

[0035] The amount of Pd present in the catalyst is preferably of from 0.1 to 2.5 wt.- % based on the total amount of the catalyst. More preferably the amount is from 0.1 to 2.0, even more preferably from 0.2 to 1.5 wt.-%, most preferably 0.3 to 1.0 wt.-%, based on the total amount of the catalyst.

[0036] The at least one other metal is used in an amount in the catalyst of preferably from 0.01 wt.-% to 2.0 wt.-%, more preferably of from 0.05 to 1.5 wt.-% even more preferably of from 0.1 to 1.0 wt.-%, based on the total amount of the catalyst.

[0037] The amount of the metals presents in the catalyst used in the AO-process of the invention can be determined by any method known in the art, for example by using Inductively Couple Plasma Optical Emission Spectrometry (ICP-OES).

[0038] The catalyst used in the AO process of the invention is an amorphous supported catalyst. The carrier of the catalyst comprises silicon dioxide and alumina (SiAlOx) in an aerogel -physical form, wherein the alumina is incorporated into the silicon dioxide structure at the molecular level, i.e., the silicon dioxide forms a bonded, cross-linked macromolecule frame (network), also called silica gel, wherein the alumina is incorporated at the molecular level. Hence, the alumina is not only present on the exterior surface of the silica gel (for example as a coating) but also inside the silica gel. This structure can be determined by using transmission electron microscopy (TEM) and / or scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). Due to this structure the resulting catalyst support is homogenous, by the opposition to a carrier, in which a first oxide would have been deposited and / or precipitated on a second oxide.

[0039] Silica-based aerogels usually feature a mesoporous network, with interconnected pores of sizes typically ranging from 0.5 to 100 nm and average diameter between 5 and 40 nm. They have a low bulk density usually ranging from 0.03 to 0.8 g / cm3.

[0040] The amorphous catalyst support of the invention can be produced by any method known in the art, but, usually, the following two methods are used.

[0041] One method is described for example in US 2012 / 01223138 Al. In this variation of possible production processes, silicon dioxide is mixed with anhydrous source of alumina, for example sodium aluminate, at a pH level of above 11 and a temperature of 30 to 90 °C for forming a suspension. Afterwards, the suspension is optionally washed with water and the catalyst support is separated from water, dried and / or calcined. The such produced catalyst carrier comprises in addition to SiCE and alumina, also anions like Cl’, (CCE)2’, (SCU)2’; (NCE)’, in an amount not exceeding 10% by weight of the catalyst support, preferably, the amount of these anions is usually between 0.05 and 8 wt.-%, more preferably between 0.5 and 6 wt.-%, even more preferably between 1.0 and 3 wt.- %, based on the total weight of the support. The amount of the anions present in the catalyst support may be measured by any method known in the art, as for example described in US 2012 / 01223138 Al.

[0042] Another possible method to produce the catalyst support of the invention is the sol-gel process as described for example in the publication of C.M.R. Almeida et al., Advances in Colloid and Interface Science 282 (2020), 102189, pages 1-25. In this method, alumina and silica sols are prepared separately in the presence of a liquid, usually ethanol, and HC1 and NH4OH as common acid and alkaline catalysts. Afterwards, the two sols are brought together in the presence of an appropriate catalyst to obtain an alumina-silica gel. Subsequently, a silylation and drying step is carried out to obtain the desired amorphous catalyst support comprising silicon dioxide and alumina (SiAlOx) in an aerogel -physical form, wherein the alumina is incorporated into the silicon dioxide structure at the molecular level.

[0043] According to the invention, the amorphous catalyst support according to the invention preferably contains alumina in an amount of from 1 to 50 wt.-%, more preferably from 3 to 30 wt.-%, even more preferably from 5 to 10 wt.-%, based on the total weight of the amorphous catalyst support.

[0044] The catalyst support of the invention has preferably a spherical morphology.

[0045] Furthermore, the BET surface area of the amorphous catalyst support is preferably between 1 and 1000 m2 / g, more preferably between 50 and 800 m2 / g, even more preferably between 100 and 700 m2 / g determined by a porosity measurement.

[0046] In order to obtain the catalyst used in the AO-process of the invention, Pd and at least one other metal is deposited on the amorphous catalyst support as described above. This can be done by any suitable method known in the art. Preferably, the metals are deposited on the catalyst support by precipitation and / or impregnation, more preferably, both the at least one other metal and the Pd are deposited under precipitation conditions.

[0047] The source for Pd may be a palladium salt selected from chloride or acetate, preferably chloride, more preferably the source is EfcPdCU.

[0048] The source of the at least other metal is generally a salt selected from the group consisting of acetate, bromide, chloride, and nitrate.

[0049] The precipitation step is conducted preferably in basic medium having a pH in the range from 7 to 12, more preferably from 8 to 11. The basic medium therefore can be obtained by using for example sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, or ammonium carbonate.

[0050] Furthermore, it is preferred that the precipitation is carried out at a temperature of between 50 and 80 °C, more preferred between 55 and 75 °C, even more preferred between 60 and 70 °C.

[0051] The deposition of the Pd and the at least one other metal on the catalyst support can be carried out simultaneously or subsequently. According to the invention, it is preferred that in a first step the at least one other metal and subsequently Pd is deposited on the amorphous catalyst support.

[0052] In each case after precipitation deposition and / or after impregnation deposition the catalyst is filtered off, washed, preferably with demineralized water, optionally reduced to obtain the metals deposited on the catalyst support in elemental state, and dried. The reduction step can be carried out by any method known in the art. Preferably by using a reducing agent selected from the group consisting of molecular hydrogen, hydrazine, hydrate, hydrogen containing gas, ascorbic acid, formic acid, and formaldehyde. The reduction is carried out preferably at a temperature between 20 and 200 °C, more preferably between 20 and 100 °C.

[0053] In general, the deposited metals can have different locations on the amorphous catalyst support. The metals may be concentrated in a thin layer close to the external surface of the support, this may be referred to as an “egg-shell mode or “egg shell profile”. The metals may be concentrated in a thin layer below the surface, but not penetrating to the centre of the support, this may be referred to as an “egg-white mode (profile)”, the metals may be concentrated in a small zone near the centre of the support, this may be referred to as an “egg-yolk mode (profile)”, and the metals may be uniformly distributed throughout the support. According to the invention, Pd and the at least one other metal show usually an egg-shell profile as determined by STEM & SEM-EDX analysis.

[0054] The Pd and at least one other metal are preferably located on the amorphous catalyst support in the form of particles. These metal particles have preferably a size between 1 and 50 nm, more preferably between 3 to 45 nm, as determined by STEM & SEM-EDX analysis.

[0055] The catalyst of the invention generally has an activity of at least 100% relative to the activity of the same catalyst in which the at least one other metal is replaced with Pd. Preferably, the catalyst shows a relative activity of at least 110% or at least 120 %, i.e., shows an improved activity relative to the activity of the same catalyst in which the at least one other metal is replaced with Pd. The activity of the catalyst can be determined by measuring the rate of conversion of alkylanthraquinone into alkylanthrahydroquinone as for example described in US 2012 / 0123138 Al.

[0056] Furthermore, due to the replacement of Pd with at least one other metal it is possible to reduce the production costs of the catalyst, and thus of the AO process, without losing the high catalyst activity.

[0057] The present invention is further illustrated by the following examples. It should be understood that the following examples are for illustration purposes only and are not used to limit the present invention thereto.

[0058] EXAMPLES The SiAlOx catalyst support used in the examples, and which is in accordance with the teaching of the invention, was produced by one of the methods as described above.

[0059] Example 1 - Pd / Co / SiAlOxcatalyst

[0060] The catalyst was prepared in two steps. Firstly, 10 g of the SiAlOx support was added to 30 ml of demineralized water and stirred at 250 rpm. 2 g of Na2COs was added and the reaction mixture was heated to 70 °C. 5.25 ml of an acidic C0Q2.6H20 solution (20 g Co / 1) was added at a rate of 1 ml / min. The reaction mixture was stirred for 15 min. Afterwards, the mixture was decanted and washed 3 times with 30 ml of demineralized water. 30 ml of demineralized water was again added, and the mixture was heated to 50 °C at 250 rpm. 0.3 g formic acid (100%) was added. Afterwards the catalyst was again decanted and washed 3 times with 30 ml demineralized water. The catalyst was put in an oven at 110 °C to dry for 12 h. Secondly, the catalyst was again added to 30 ml of demineralized water, heated to 70°C and stirred at 250 rpm. 5.25 ml EfcPdCU solution (20 g Pd / 1) was added at 1.7 ml / min. The mixture was stirred for 15 min. Afterwards, it was decanted and washed 3 times with 30 ml demineralized water. 30 ml of demineralized water was again added, and the mixture was heated to 50 °C at 250 rpm. 0.3 g formic acid (100%) was added. Afterwards the catalyst was again decanted and washed 3 times with 30 ml demineralized water. The catalyst was put in an oven at 110 °C to dry for 12 h.

[0061] The concentration of metals deposited on the carrier SiAlOx was determined via ICP-OES. The Pd concentration was 1 wt.-% and the Co concentration was 0.35 wt.-%.

[0062] The determined activity of said catalyst was 107 % of the relative activity of a 1.0 wt.%-Pd catalyst. STEM & SEM-EDX analysis showed an egg-shell profile for both metals. The metal particles, Pd & Co had a size between 3 and 17 nm, and the catalyst powder particles have a mean particle size of 120 pm determined by laser granulometry.

[0063] Example 2 - Pd / Ni / SiAlOxcatalyst

[0064] The catalyst was prepared in two steps. Firstly, 10 g of the SiAlOx support was added to 30 ml of demineralized water and stirred at 250 rpm. 2 g of Na2COs was added and the reaction mixture was heated to 70 °C. 3.5 ml of an acidic NiNCh solution (20 g Ni / 1, NiNCh dissolved in diluted HC1)) was added at a rate of 1 ml / min. The reaction mixture was stirred for 15 min. Afterwards, the mixture was decanted and washed 3 times with 30 ml of demineralized water. 30 ml of demineralized water was again added, and the mixture was heated to 50 °C at 250 rpm. 0.3 g formic acid (100%) was added. Afterwards the catalyst was again decanted and washed 3 times with 30 ml demineralized water. The catalyst was put in an oven at 110 °C to dry for 12 h. Secondly, the catalyst was again added to 30 ml of demineralized water, heated to 70°C and stirred at 250 rpm. 5.25 ml FEPdCU solution (20 g Pd / 1) was added at 1.7 ml / min. The mixture was stirred for 15 min. Afterwards, it was decanted and washed 3 times with 30 ml demineralized water. 30 ml of demineralized water was again added, and the mixture was heated to 50 °C at 250 rpm. 0.3 g formic acid (100%) was added. Afterwards the catalyst was again decanted and washed 3 times with 30 ml demineralized water. The catalyst was put in an oven at 110°C to dry for 12h.

[0065] The concentration of metals deposited on the carrier SiA10xwas determined via ICP-OES. The Pd concentration was 1 wt.-% and the Ni concentration was 0.10 wt.-%.

[0066] The determined activity of said catalyst was 121 % of the relative activity of a 1.0 wt.%-Pd catalyst. STEM & SEM-EDX analysis showed an egg-shell profile for both metals. The metal particles, Pd & Co had a size between 5 and 41 nm, and the catalyst powder particles have a mean particle size of 120 pm determined by laser granulometry.

[0067] Example 3 - Pd / Au / SiAlOxcatalyst

[0068] The catalyst was prepared in two steps. Firstly, 10 g of the SiA10xsupport was added to 30 ml of demineralized water and stirred at 250 rpm. 2 g of Na2CC>3 was added and the reaction mixture was heated to 70 °C. 1.05ml of an acidic AuCh solution (20 g Au / 1)) was added at a rate of 1 ml / min. The reaction mixture was stirred for 15min. Afterwards, the mixture was decanted and washed 3 times with 30 ml of demineralized water. 30 ml of demineralized water was again added, and the mixture was heated to 50 °C at 250 rpm. 0.3 g formic acid (100%) was added. Afterwards the catalyst was again decanted and washed 3 times with 30 ml demineralized water. The catalyst was put in an oven at 110 °C to dry for 12 h. Secondly, the catalyst was again added to 30 ml of demineralized water, heated to 70°C and stirred at 250 rpm. 63 ml EfcPdCU solution (20 g Pd / 1) was added at 1.7 ml / min. The mixture was stirred for 15 min. Afterwards, it was decanted and washed 3 times with 30 ml demineralized water. 30 ml of demineralized water was again added, and the mixture was heated to 50 °C at 250 rpm. 0.3 g formic acid (100%) was added. Afterwards the catalyst was again decanted and washed 3 times with 30 ml demineralized water. The catalyst was put in an oven at 110 °C to dry for 12 h.

[0069] The concentration of metals deposited on the carrier SiA10xwas determined via ICP-OES. The Pd concentration was 1.2 wt.-% and the Au concentration was 0.068 wt.-%.

[0070] The determined activity of said catalyst was 155 % of the relative activity of a 1.4 wt.%-Pd catalyst. STEM & SEM-EDX analysis showed an egg-shell profile for both metals. The metal particles, Pd & Co had a size between 4 and 22 nm, and the catalyst powder particles have a mean particle size of 120 pm determined by laser granulometry.

[0071] Example 4 - Pd / Ru / SiAlOxcatalyst

[0072] The catalyst was prepared in two steps. Firstly, 10g of the SiA10xsupport was added to 30 ml of demineralized water and stirred at 250 rpm. 2 g of Na2CC>3 was added and the reaction mixture is heated to 70 °C. 1.05 ml of an acidic RuCh solution (20 g Ru / 1) was added at a rate of 1 ml / min. The reaction mixture was stirred for 15min. Afterwards, the mixture was decanted and washed 3 times with 30ml of demineralized water. 30 ml of demineralized water was again added, and the mixture was heated to 50 °C at 250rpm. 0.3 g formic acid (100%) was added. Afterwards the catalyst was again decanted and washed 3 times with 30 ml demineralized water. The catalyst was put in an oven at 110 °C to dry for 12 h. Secondly, the catalyst was again added to 30 ml of demineralized water, heated to 70°C and stirred at 250 rpm. 5.25 ml EfcPdCU solution (20 g Pd / 1) was added at 1.7 ml / min. The mixture was stirred for 15 min. Afterwards, it was decanted and washed 3 times with 30ml demineralized water. 30 ml of demineralized water was again added, and the mixture was heated to 50 °C at 250 rpm. 0.3 g formic acid (100%) was added. Afterwards the catalyst was again decanted and washed 3 times with 30 ml demineralized water. The catalyst was put in an oven at 110 °C to dry for 12 h. The concentration of metals deposited on the carrier SiA10xwas determined via ICP-OES. The Pd concentration was 1 wt.-% and the Ru concentration was 0.08 wt.-%.

[0073] The determined activity of said catalyst was 130 % of the relative activity of a 1.2 wt.%-Pd catalyst. STEM & SEM-EDX analysis showed an egg-shell profile for both metals. The metal particles, Pd & Co had a size between 5 and 41 nm, and the catalyst powder particles have a mean particle size of 120 pm determined by laser granulometry. The examples demonstrate that the activity of the supported bimetallic catalyst of the invention is in the same range or even better in comparison to the corresponding monometallic Pd-catalyst.

Claims

C L A I M S1. An anthraquinone process (AO) for the manufacture of hydrogen peroxide, wherein the hydrogenation step is carried out with a catalyst in the form of catalyst powder particles having a mean particle size between 100 and 200 pm, used in a slurry, and wherein the catalyst comprises Pd, at least one other metal, and an amorphous catalyst support comprising silicon dioxide and alumina (SiAlOx) in an aerogel-physical form, wherein the alumina is incorporated into the silicon dioxide structure at the molecular level.

2. The process according to claim 1, wherein the at least one other metal is selected from the group consisting of Fe, Cu, Co, Ni, Sn, Ga, Zn, Au, Ag, Pt, Bi and Ru, or a combination thereof.

3. The process according to claim 1 or 2, wherein the catalyst is a bimetallic catalyst.

4. The process according to any one of the preceding claims, wherein the catalyst comprises Pd in an amount of 0.1 to 2.5 wt.-%.

5. The process according to any one of the preceding claims, wherein the at least one other metal is present in an amount of 0.01 wt.-% to 2.0 wt.-%, based on the total amount of the catalyst.

6. The process according to any one of the preceding claims, wherein alumina is present in the amorphous catalyst support in an amount of 1 to 50 wt.- %, based on the total weight of the amorphous catalyst support.

7. The process according to any one of the preceding claims, wherein Pd and the at least one other metal is located on the amorphous catalyst support in egg-shell mode.

8. The process according to any one of the preceding claims, wherein the amorphous catalyst support has a surface area between 1 and 1000 m2 / g.

9. The process according to any one of the preceding claims, wherein the catalyst is produced by depositing Pd and at least one other metal by precipitation on the amorphous catalyst support.

10. The process according to claim 9, wherein in a first step at least one other metal and subsequently Pd is deposited on the amorphous catalyst support.