GENERAL METHOD TO INCORPORATE METAL NANOPARTICLES IN ZEOLITES AND ZEOTYPES

Abstract

Disclosed herein is a method for producing a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure.

Claims

1. A method for producing a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure, the method comprising: a) treating a zeolite, zeolite-like or zeotype structure with an alkaline solution in the presence of a surfactant thereby obtaining a zeolite, zeolite-like or zeotype structure having a partly dissolved structure; b) heating the partly dissolved zeolite, zeolite-like or zeotype structure to an elevated temperature between 110-200 C., thereby obtaining a zeolite, zeolite-like or zeotype structure with an additional porosity situated inside the structure; c) impregnating the zeolite, zeolite-like or zeotype structure with the additional porosity situated inside the structure with a solution comprising at least one transition metal precursor selected from nitrates, carbonates, acetates, sulphates, chlorides, carbonyls or formats thereby obtaining a transition metal precursor containing zeolite, zeolite-like or zeotype structure; and d) obtaining the zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure by: i. subjecting the transition metal precursor containing zeolite, zeolite-like or zeotype structure to a reactive atmosphere selected from a stream of hydrogen gas (H.sub.2), a stream of oxygen gas (O.sub.2), a stream of hydrogen sulfide gas (H.sub.2S), a stream of methane gas (CH.sub.4), or a stream of ammonia gas (NH.sub.3) at an elevated temperature, or ii. decomposing the transition metal precursor containing zeolite, zeolite-like or zeotype structure by thermal treatment, wherein the transition metal, metal oxide or metal sulphide nanoparticle particles are selectively positioned inside the zeolite, zeolite-like or zeotype structure.

2-15. (canceled)

16. The method according to claim 1, wherein the alkaline solution in step a) is selected from bicarbonates, carbonates, ammonia hydroxide, sodium hydroxide, or potassium hydroxide.

17. The method according to claim 1, wherein the surfactant in step a) is selected from anionic, cationic, zwitterionic or nonionic surfactants, or C8-C18 alkyltrimethylammonium bromides, phencyclidine hydrochloride (P123), polyoxyethylene 20 cetyl ether (Brij-58), or polyoxypropylene-polyoxyethylene block polymer polyglycol (F127).

18. The method according to claim 1, wherein heating the partly dissolved zeolite, zeolite-like or zeotype structure to an elevated temperature in step b) is done in an autoclave.

19. The method according to claim 1, wherein the elevated temperature in step b) is between 110-190 C., or between 110-180 C., or between 120-170 C., or between 120-160 C., or between 130-150 C., or between 135-145 C.

20. The method according to claim 1, wherein the zeolite, zeolite-like or zeotype structure with an additional porosity situated inside the structure obtained in step b) is dried prior to the impregnation in step c).

21. The method according to claim 1, wherein the transition metal precursor in step c) comprises one or more metal(s) selected from the group consisting of group 4 elements, group 6 elements, group 7 elements, group 8 elements, group 9 elements, group 10 elements, group 11 elements and group 12 elements or mixtures thereof.

22. The method according to claim 1, wherein the transition metal precursor in step c) comprises: one or more metal(s) selected from the group consisting of manganese, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, cadmium, molybdenum, zinc, vanadium, chrome, and titanium or mixtures thereof; or one or more metal alloys(s) selected from the group consisting of molybdenum-cobalt, molybdenum-nickel, molybdenum-platinum, iron-ruthenium, iron-cobalt, iron-nickel, ruthenium-cobalt, ruthenium-copper, ruthenium-platinum, cobalt-palladium, cobalt-platinum, cobalt-gold, nickel-platinum, iridium-platinum, palladium-platinum, palladium-copper, palladium-gold, platinum-gold, and silver-gold.

23. The method according to claim 1, wherein the thermal treatment in step d)ii is performed in the temperature range from 200 to 800 C., from 200 to 600 C. or from 200 to 500 C.

24. The method according to claim 1, wherein the zeolite, zeolite-like or zeotype structure has a framework type selected from BEA, FAU, MFI, MEL MOR, CHA or MTW.

25. A transition zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure obtained by the method according to claim 1.

26. The zeolite, zeolite-like or zeotype structure according to claim 25 wherein: the zeolite, zeolite-like or zeotype structure has micropores with a pore size between 0-2 nm, or mesopores with a pore size between 2-50 nm, or macropores with a pore size between 50-100 nm; the transition metal, metal oxide or metal sulphide nanoparticles have a particle size between 0-40 nm, or between 1-30 nm, or between 1-20 nm, or between 1-10 nm, or between 1-5 nm, or between 2-3 nm; the transition metal, metal oxide or metal sulphide nanoparticles are distributed selectively on internal surfaces of the zeolite zeolite, zeolite-like or zeotype, and any two consecutive transition metal, metal oxide or metal sulphide nanoparticles inside the zeolite, zeolite-like or zeotype has an internal distance d between them, wherein the nearest neighbour index between any different two consecutive transition metal, metal oxide or metal sulphide nanoparticles inside the zeolite, zeolite-like or zeotype is at least 1.

27. A method of using the zeolite, zeolite-like or zeotype structure prepared according to claim 1 comprising: providing the zeolite, zeolite-like or zeotype structure prepared according to claim 1; and using said zeolite, zeolite-like or zeotype structure in one or more of the following: as catalytic material for chemical reactions; for hydroisomerization, cracking and reforming of petrochemicals; for the synthesis of liquid hydrocarbons from synthesis gas by means of the Fisher-Tropsch process or Mobile process; for production of substitute natural gas from synthesis gas by methanation; for in-situ generation of hydrogen peroxide (H.sub.2O.sub.2) from hydrogen (H.sub.2) and oxygen (O.sub.2) for epoxidation of propylene; for epoxidation of propylene, for selective oxidations and hydrogenations; for catalytic exhaust and/or flue-gas cleaning; for conversion of ammonia to N.sub.2O, NO.sub.x and N.sub.2; for selective oxidations and hydrogenations; for the synthesis of olefins in methanol to olefins reactions (MTO); for the synthesis of methanol to hydrocarbons reactions (MTH); or for the synthesis of methanol to gasoline reactions (MTG).

Description

BRIEF DESCRIPTION OF THE FIGURES

[0033] FIG. 1 shows a schematic illustration of the method for producing zeolite, zeolite-like or zeotype encapsulated metal nanoparticles/clusters.

[0034] FIGS. 2a-d show the TEM images of four different silicalite-1 (S1) base zeolites; a traditionally synthesised gold (Au) impregnated zeolite of the type Au/S1 shown in FIG. 2a, a gold impregnated meso-zeolite (Au/meso-S1) in FIG. 2b, a gold impregnated APS-zeolite (Au/APS-S1) in FIG. 2c, and a gold impregnated recrystallized zeolite (Au/recryst-S1) according the invention in FIG. 2d.

[0035] FIG. 2e shows two high-angle annular dark-field imaging scanning transmission electron microscope (HAADF-STEM) images of the Au/recryst-S1 zeolite according to the invention.

[0036] FIGS. 3a-d show a particle size histogram and the normal distribution of the gold particles impregnated in the Au/S1 zeolite structure of FIG. 2a displayed in FIG. 3a, the Au/meso-S1 zeolite structure of FIG. 2b displayed in FIG. 3b, the Au/APS-S1 zeolite structure of FIG. 2c displayed in FIG. 3c, and the Au/recryst-S1 zeolite structure of FIG. 2d displayed in FIG. 3d.

[0037] FIGS. 4a-d show X-ray Photoelectron Spectroscopy (XPS) measurements of the Au/S1 zeolite (FIG. 4a), the Au/meso-S1 zeolite (FIG. 4b), the Au/APS-S1 zeolite (FIG. 4c), and the Au/recryst-S1 zeolite (FIG. 4d).

[0038] FIGS. 5a-d show X-ray powder diffraction (XRPD) analysis of the Au/S1 zeolite (FIG. 5a), the Au/meso-S1 zeolite (FIG. 5b), the Au/APS-S1 zeolite (FIG. 5c), and the Au/recryst-S1 zeolite (FIG. 5d).

[0039] FIGS. 6 and 7a-d show bio-ethanol oxidation to acetaldehyde/acetic acid/CO.sub.2 using the four zeolites shown in FIGS. 2a-d.

[0040] FIGS. 8a-d show the nitrogen N.sub.2 physisorption using the Au/S1 zeolite (FIG. 8a), the Au/meso-S1 zeolite (FIG. 8b), the Au/APS-S1 zeolite (FIG. 8c), and the Au/recryst-S1 zeolite (FIG. 8d).

[0041] In FIG. 9, the Barrett-Joyner-Halenda (BJH) pore size distributions derived from the desorption branch of the nitrogen physisorption isotherms.

[0042] FIGS. 10a-b show the TEM images of two different silicalite-1 (S1) base zeolites; a traditionally synthesised palladium (Pd) impregnated zeolite of the type Pd/S1 (FIG. 10a) and a palladium impregnated recrystallized zeolite (Pd/recryst-S1) according the invention (FIG. 10b).

[0043] FIG. 11 show the yield from the hydrogenation of mesityl oxide and isophorone performed at room temperature and under 1 bar of H.sub.2 using Pd/Recryst-S1 as hydrogenation catalyst.

[0044] FIGS. 12a-b show the TEM images of two different silicalite-1 (S1) base zeolites; a traditionally synthesised nickel (Ni) impregnated zeolite of the type 1 wt % Ni/Si is shown in FIG. 12a, and a nickel impregnated recrystallized zeolite (Ni/Recryst-S1) according the invention is shown in FIG. 12b.

DETAILED DESCRIPTION OF THE INVENTION

[0045] In the following detailed description of the invention, reference is made to the examples, including tables and figures.

[0046] Throughout the description, when zeolites are mentioned this is meant to comprise zeolites, zeolite-like materials and zeotypes unless otherwise specifically mentioned.

[0047] By zeolite, zeolite-like and zeotype particle is meant zeolite, zeolite-like and zeotype crystal or zeolite, zeolite-like and zeotype material.

[0048] By the term zeolite-like is meant non-silicon comprising material. Examples of zeolite-like materials are non-silicon comprising materials such as aluminum phosphate (AIPO4) molecular sieves, known as AIPO's. The phosphorous compound can be selected from the group consisting of phosphoric acid, phosphate salts and mixtures thereof. By the term phosphate salts is meant salts of phosphates, monohydrogen phosphates and dihydrogen phosphates.

[0049] In this application a new method for producing zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure is presented according to a first aspect of the invention.

[0050] The method according to the first aspect of the invention comprises a number of steps including a first step of treating a zeolite, zeolite-like or zeotype structure with an alkaline solution in the presence of a surfactant thereby obtaining a zeolite, zeolite-like or zeotype structure having a partly dissolved structure.

[0051] In one or more embodiments, the alkaline solution is selected from bicarbonates, carbonates, ammonia hydroxide, sodium hydroxide, and potassium hydroxide.

[0052] In one or more embodiments, the surfactant is selected from anionic, cationic, zwitterionic and nonionic surfactants. These surfactants may include C8-C18 alkyltrimethylammonium bromides, phencyclidine hydrochloride (P123), polyoxyethylene 20 cetyl ether (Brij-58), and polyoxypropylene-polyoxyethylene block polymer polyglycol (F127).

[0053] In one or more embodiments, the surfactant is cetyl trimethylammonium bromide (CTAB).

[0054] The method according to the first aspect of the invention further comprises the step of heating the partly dissolved zeolite, zeolite-like or zeotype structure to an elevated temperature between 110-200 C. thereby obtaining a zeolite, zeolite-like or zeotype structure with an additional porosity situated inside the structure. By heating the structure, the surfactant is removed.

[0055] In one or more embodiments, heating the partly dissolved zeolite, zeolite-like or zeotype structure to an elevated temperature is done in an autoclave.

[0056] In one or more embodiments, the elevated temperature is between 110-190 C.

[0057] In one or more embodiments, the elevated temperature is between 110-180 C.

[0058] In one or more embodiments, the elevated temperature is between 120-170 C.

[0059] In one or more embodiments, the elevated temperature is between 120-160 C.

[0060] In one or more embodiments, the elevated temperature is between 130-150 C.

[0061] In one or more embodiments, the elevated temperature is between 135-145 C.

[0062] The method according to the first aspect of the invention further comprises the step of impregnating the zeolite, zeolite-like or zeotype structure with the additional porosity situated inside the structure with a solution comprising at least one transition metal precursor thereby obtaining a transition metal precursor containing zeolite, zeolite-like or zeotype structure.

[0063] In one or more embodiments, the transition metal precursor comprises one or more metal precursors selected from nitrates, carbonates, acetates, sulphates, chlorides, carbonyls or formates.

[0064] In one or more embodiments, the transition metal precursor comprises one or more metal(s) selected from the group consisting of group 4 elements, group 6 elements, group 7 elements, group 8 elements, group 9 elements, group 10 elements, group 11 elements or group 12 elements or mixtures thereof. The group elements are defined by the new IUPAC numbering.

[0065] In one or more embodiments, the transition metal precursor comprises one or more metal(s) selected from the group of manganese, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, cadmium, molybdenum, zinc, vanadium, chrome, titanium or mixtures thereof.

[0066] In one embodiment or more embodiments, the metal is selected from the group of manganese, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, and gold.

[0067] In one embodiment or more embodiments, the metal is selected from the group of iron, cobalt, nickel, palladium, platinum, copper, silver and gold.

[0068] In one embodiment or more embodiments, the metal is gold.

[0069] In one or more embodiments, the transition metal precursor comprises one or more metal alloys(s) selected from the group of molybdenum-cobalt, molybdenum-nickel, molybdenum-platinum, iron-ruthenium, iron-cobalt, iron-nickel, ruthenium-cobalt, ruthenium-copper, ruthenium-platinum, cobalt-palladium, cobalt-platinum, cobalt-gold, nickel-platinum, iridium-platinum, palladium-platinum, palladium-copper, palladium-gold, platinum-gold, or silver-gold. One of the metals in the metal alloy may be present in an amount of from 1 to 50%. The optimal weight ratio between the metals in the alloy depends on the metal alloy.

[0070] The metal or mixture of metal precursors might form into the respective oxides or nitrates. This can happen either during the manufacturing process or in the end product.

[0071] The method according to the invention may prior to impregnation of the zeolite, zeolite-like or zeotype structure with an additional porosity situated inside the structure be dried. The drying is performed in order to improve the impregnation of the recrystallized material. The drying can be achieved by keeping the calcined materials in a dry atmosphere or by separately drying the material prior to the impregnation by other means. The drying may be performed at elevated temperatures, preferably under reduced pressure or in a flow of dry gas.

[0072] The method according to the first aspect of the invention subsequently comprises the step of obtaining the zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure by either: i) reducing the transition metal precursor containing zeolite, zeolite-like or zeotype structure in a reactive atmosphere, or ii) decomposing the transition metal precursor containing zeolite, zeolite-like or zeotype structure by thermal treatment.

[0073] This causes the transition metal, metal oxide or metal sulphide nanoparticle particles to be selectively positioned inside the zeolite, zeolite-like or zeotype structure.

[0074] In one or more embodiments, the reactive atmosphere in alternative i) is a stream of hydrogen gas (H.sub.2), a stream of oxygen gas (O.sub.2), a stream of hydrogen sulfide gas (H.sub.2S), a stream of methane gas (CH.sub.4), or a stream of ammonia gas (NH.sub.3).

[0075] In one or more embodiments, the reactive atmosphere in alternative i) is a stream of hydrogen gas (H.sub.2) and the transition metal precursor forms metal nanoparticles.

[0076] The term metal nanoparticles used throughout this application also includes mixtures of metals nanoparticles. By metal nanoparticles is also meant metal oxide nanoparticles and metal sulfide nanoparticles.

[0077] In one or more embodiments, the reactive atmosphere in alternative i) is a stream of oxygen gas (O.sub.2) and the transition metal precursor forms metal oxides.

[0078] In one or more embodiments, the reactive atmosphere in alternative i) is a stream of hydrogen sulfide gas (H.sub.2S) and the transition metal precursor forms metal sulfides.

[0079] In one or more embodiments, the reactive atmosphere in alternative i) is a stream of methane gas (CH.sub.4) and the transition metal precursor forms metal carbides.

[0080] In one or more embodiments, the reactive atmosphere in alternative i) is a stream of ammonia gas (NH.sub.3) and the transition metal precursor forms metal nitrides.

[0081] In one embodiment the flow of the stream of gas is applied for around 1-7 hours, 4-6 hours, or 2-3 hours. This holds true for all of the above mentioned examples of gaseous compounds, but depends on the metal type.

[0082] In one or more embodiments, the thermal treatment in alternative ii) is performed in the temperature range from 200 to 800 C.

[0083] In one or more embodiments, the thermal treatment in alternative ii) is performed in the temperature range from 200 to 600 C.

[0084] In one or more embodiments, the thermal treatment in alternative ii) is performed in the temperature range from 200 to 500 C.

[0085] The method according to the first aspect of the invention is illustrated schematically in FIG. 1. In FIG. 1, the zeolite, zeolite-like or zeotype structure 102 is first re-crystallised by treating it with an alkaline solution in the presence of a surfactant thereby obtaining a zeolite, zeolite-like or zeotype structure having a partly dissolved structure. The partly dissolved zeolite, zeolite-like or zeotype structure is afterwards heated to an elevated temperature, normally between 110-200 C., thereby obtaining a recrystallized zeolite, zeolite-like or zeotype structure 104 with an additional porosity 106 situated inside the structure. The additional porosity 106 inside the zeolite structure is illustrated as a number of boxes for illustrative purposes, but is in no way limited to having such a shape.

[0086] After obtaining the zeolite structure 104 with the additional porosity 106, the zeolite structure 104 is impregnated with a solution comprising at least one transition metal precursor 108 thereby obtaining a transition metal impregnated zeolite, zeolite-like or zeotype structure. The transition metal impregnated zeolite, zeolite-like or zeotype structure is either reduced or decomposed to yield the final transition metal, metal oxide or metal sulphide nanoparticle containing zeolite, zeolite-like or zeotype structure 110 as depicted as the last structure in FIG. 1.

[0087] As is illustrated in FIG. 1, the impregnation of the zeolite structure with the additional porosity 106 ensures that the transition metal, metal oxide or metal sulphide particles and/or clusters 108 are selectively positioned inside the zeolite, zeolite-like or zeotype structure, i.e. on internal surfaces of the transition metal, metal oxide or metal sulphide nanoparticle containing zeolite, zeolite-like or zeotype structure. Thus, no transition metal oxide or metal sulphide particles/clusters are observed on the external surfaces of the transition metal particle, i.e. on the outside of the transition metal particle.

[0088] When the steps involved in the recrystallization of the zeolite structure (steps a and b) are omitted, transition metal, metal oxide or metal sulphide particles/clusters are also observed on the outside of the zeolite, zeolite-like or zeotype structure as is discussed in connection with FIGS. 2 and 3. Thus, the recrystallization process ensures that a selective positioning of the transition metal, metal oxide or metal sulphide particles is obtained. An explanation for this observation may be that i) the alkaline treatment causes the formation of intra-particle voids and defects that is filled up with the transition metal precursor solution, and ii) that the confined space of the zeolite framework provide ideal conditions for the preparation of small and disperse nanoparticles inside the zeolite crystal. Furthermore, the recrystallization process may remove defects that prevent the formation of nanoparticles on the external surface of the zeolite.

[0089] Independently of what mechanism/combination of processes or chemical substances that ensures the selective positioning of the transition metal particles inside of the zeolite structure, the selectivity has a number of advantages.

[0090] The encapsulation of metal nanoparticles within the zeolite structure inhibits sintering, thereby preserving their high surface area required for the effective catalytic activity. The increase in catalytic properties of the transition metal, metal oxide or metal sulphide nanoparticle containing zeolite, zeolite-like or zeotype is clearly seen and discussed in connection with FIG. 4.

[0091] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has a framework type selected from BEA, FAU, MFI, MEL MOR, CHA or MTW. Alternative frameworks can also be imagined.

[0092] In one or more embodiments, the zeolite, zeolite-like or zeotype structure is silica based. Possible silica sources for zeolites may be bulk silica of different quality and alumina contamination, including pure silica, fumed silica, sodium silicate or other soluble silicate salts, precipitated silica, tetraethyl orthosilicate and other alkoxy-silicates, silicic acid, etc.

[0093] In one or more embodiments, the zeolite, zeolite-like or zeotype structure is aluminium based. Possible aluminium sources for zeolites may be aluminium nitrate, aluminium sulphate, aluminium phosphate, sodium aluminate and more.

[0094] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has micropores with a pore size between 0-2 nm.

[0095] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has micropores with a pore size between 0.5-2 nm.

[0096] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has micropores with a pore size between 1-2 nm.

[0097] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has mesopores with a pore size between 2-50 nm.

[0098] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has mesopores with a pore size between 10-40 nm.

[0099] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has mesopores with a pore size between 15-30 nm.

[0100] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has mesopores with a pore size between 20-30 nm.

[0101] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has mesopores with a pore size between 40-50 nm.

[0102] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has mesopores with a pore size between 2-15 nm.

[0103] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has macropores with a pore size between 50-100 nm.

[0104] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has macropores with a pore size between 60-90 nm.

[0105] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has macropores with a pore size between 70-80 nm.

[0106] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has macropores with a pore size between 50-60 nm.

[0107] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has macropores with a pore size between 50-70 nm.

[0108] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has macropores with a pore size between 70-100 nm.

[0109] In one or more embodiments, the zeolite, zeolite-like or zeotype structure has macropores with a pore size between 80-90 nm.

[0110] Depending on the application, the transition metal, metal oxide or metal sulphide nanoparticles may vary in size quit significantly. Thus, in one or more embodiments, the transition metal, metal oxide or metal sulphide nanoparticles may have a particle size between 0-40 nm.

[0111] In one or more embodiments, the transition metal, metal oxide or metal sulphide nanoparticles may have a particle size between 1-30 nm.

[0112] In one or more embodiments, the transition metal, metal oxide or metal sulphide nanoparticles may have a particle size between 1-20 nm.

[0113] In one or more embodiments, the transition metal, metal oxide or metal sulphide nanoparticles may have a particle size between 1-10 nm.

[0114] In one or more embodiments, the transition metal, metal oxide or metal sulphide nanoparticles may have a particle size between 1-5 nm.

[0115] In one or more embodiments, the transition metal, metal oxide or metal sulphide nanoparticles may have a particle size between 2-3 nm.

[0116] The transition metal, metal oxide or metal sulphide nanoparticles may be distributed selectively inside the zeolite zeolite, zeolite-like or zeotype.

[0117] In one or more embodiments, the transition metal, metal oxide or metal sulphide nanoparticles may be evenly distributed inside the zeolite zeolite, zeolite-like or zeotype such that any two consecutive transition metal, metal oxide or metal sulphide nanoparticles inside the zeolite, zeolite-like or zeotype has an internal distance d between them, wherein the nearest neighbour index between any different two consecutive transition metal, metal oxide or metal sulphide nanoparticles inside the zeolite, zeolite-like or zeotype is at least 1.

[0118] By nearest neighbour index is meant the ratio of the observed distance between any two different nanoparticles divided by the expected distance, where the expected distance is the average distance between neighbours in a hypothetical random distribution.

[0119] In one or more embodiments, the wherein the nearest neighbour index between any different two consecutive transition metal, metal oxide or metal sulphide nanoparticles inside the zeolite, zeolite-like or zeotype is between 1-10, or between 2-5.

[0120] The transition metal, metal oxide or metal sulphide nanoparticle containing zeolite, zeolite-like or zeotype have increased thermal stability and resistance against sintering.

[0121] By impregnating transition metal, metal oxide or metal sulphide nanoparticle in a zeolite, zeolite-like or zeotype zeolite matrix, shape selective catalysis is possible as described in the introduction.

[0122] In one embodiment the size of the zeolite crystals are in the range of 0.1 to 5 micrometer, or 0.1 to 2 micrometer, or 0.1 to 0.5 micrometer.

[0123] In one or more embodiments the amount of transition metal, metal oxide or metal sulphide nanoparticles are in the range of 0.1-25 wt %, 0.5-20 wt %, 0.5-10 wt %, 0.5-5%, 1.0-5 wt %, 1-2 wt %, or around 1 wt %.

[0124] In one embodiment the zeolite, zeolite-like or zeotype particle has a Vp value in the range of 0.1 to 0.4 cm.sup.3/g, or 0.2 to 0.4 cm.sup.3/g.

[0125] In one embodiment the zeolite, zeolite-like or zeotype particle has a BET surface area of 200 to 500 m.sup.2/g or 350 to 400 m.sup.2/g or around 375 m.sup.2/g.

[0126] FIGS. 2a-d show the TEM images of four different silicalite-1 (S1) base zeolites. In FIG. 2a, the TEM image of a traditionally synthesised gold (Au) impregnated zeolite of the type Au/S1 is shown, where no re-crystallization step has been performed prior to impregnating the zeolite with gold. In FIG. 2b, the TEM image of a gold impregnated meso-zeolite (Au/meso-S1) is showagain re-crystallization has been omitted when synthesising this structure. In FIG. 2c, the TEM image of a gold impregnated (3-aminopropyl)trimethoxysilane modified (APS) zeolite (Au/APS-S1) is shown. Again, no re-crystallisation has been used. In FIG. 2d, the TEM image of a gold impregnated recrystallized zeolite (Au/recryst-S1) according the invention is shown.

[0127] As can be seen in FIGS. 2a and 2b, the traditional zeolite/meso-zeolite structures impregnated with gold have gold particles positioned on the internal surfaces inside the zeolite/meso-zeolite structure and on the outer surface of the zeolite. The outer gold particles can be seen as the larger particles which have formed larger particles with a smaller total surface area.

[0128] The Au/APS-S1 structure shown in FIG. 2c also shows an uneven distribution in the size of the metal particles compared to the Au/rectryst-S1 structure according to the invention shown in FIG. 2d. This implies that metal particles are also distributed on the outer surface of the Au/APS-S1 structure shown in FIG. 2c and not only on the internal surfaces as is observed in Au/recryst-S1 in FIG. 2d.

[0129] FIG. 2e shows two high-angle annular dark-field imaging scanning transmission electron microscope (HAADF-STEM) images of the Au/recryst-S1 zeolite according to the invention. In these images, the even distribution of the gold particles inside in the zeolite can be seen clearly.

[0130] FIGS. 3a-d show a particle size histogram and the normal distribution of the gold particles impregnated in the Au/S1 zeolite structure of FIG. 2a displayed in FIG. 3a, the Au/meso-S1 zeolite structure of FIG. 2b displayed in FIG. 3b, the Au/APS-S1 zeolite structure of FIG. 2c displayed in FIG. 3c, and the Au/recryst-S1 zeolite structure of FIG. 2d displayed in FIG. 3d. From FIGS. 3a-d, it can clearly be seen that the particles in the Au/recryst-S1structure have a much more narrow distribution in size and further have a smaller average size compared to the other structures.

[0131] FIGS. 4a-d show X-ray Photoelectron Spectroscopy (XPS) measurements of the Au/S1 zeolite structure of FIG. 2a displayed in FIG. 4a, the Au/meso-S1 zeolite structure of FIG. 2b displayed in FIG. 4b, the Au/APS-S1 zeolite structure of FIG. 2c displayed in FIG. 4c, and the Au/recryst-S1 zeolite structure of FIG. 2d displayed in FIG. 4d. The XPS measurements show that gold is the presence of gold on the outer surface of the Au/Si zeolite in FIG. 4a. However, no gold was observed on the outer surface of the Au/recryst-S1 zeolite according to the invention shown in FIG. 4d. This observation supports the observations form the TEM images in FIGS. 2a-d showing that the gold particles are positioned selectively on the inside of the zeolite only for the zeolite structure synthesised according to the method of the invention.

[0132] FIGS. 5a-d show X-ray powder diffraction (XRPD) analysis of the Au/S1 zeolite structure of FIG. 2a displayed in FIG. 5a, the Au/meso-S1 zeolite structure of FIG. 2b displayed in FIG. 5b, the Au/APS-S1 zeolite structure of FIG. 2c displayed in FIG. 5c, and the Au/recryst-S1 zeolite structure of FIG. 2d displayed in FIG. 5d.

[0133] FIGS. 6 and 7a-d shows the measurement of the bio-ethanol oxidation to acetaldehyde/acetic acid/CO.sub.2 using the four zeolites shown and described in FIGS. 2a-d. In FIG. 6, Au/S1 is represented as line A, Au/meso-S1 as line B, Au/APS-S1 as line C, and Au/recryst-S1 as line D. The mole fraction indicates the amount of bio-ethanol in the solution normalised to the starting concentration of bio-ethanol.

[0134] As can be seen in FIG. 6, below approximately 150 C., bio-ethanol oxidation to acetaldehyde only occurs when using the Au/APS-S1 zeolite (line C). However, once the temperature exceeds 180 C., the Au/recryst-S1 zeolite according to this invention (line D) is by far the most efficient catalyst for the bio-ethanol oxidation.

[0135] FIGS. 7a-d show the product distribution (bio-ethanol, acetaldehyde, acetic acid, and CO.sub.2) as a function of the reaction temperature for the catalysts Au/S1 (FIG. 7a), Au/meso-S1 (FIG. 7b), Au/APS-S1 (FIG. 7c), and Au/recryst-S1 (FIG. 7d).

[0136] The Au/S1 catalyst shown in FIG. 7a is highly selective toward the formation of acetaldehyde and reaches 50% conversion of ethanol around 280 C.

[0137] The Au/Meso-S1 catalyst shown in FIG. 7b is more active and reaches 50% conversion around 250 C. Only small amounts of CO.sub.2 and acetic acid are observed at temperatures above 250 C. The slightly higher activity of the Au/Meso-S1 catalyst compared to the Au/S1 catalyst may be related to the increased external surface area, which results in a better dispersion of the Au nanoparticles.

[0138] The surface-functionalized Au/APS-S1 catalyst shown in FIG. 7c is more active than both Au/S1 and Au/Meso-S1 shown in FIGS. 7a and 7b, respectively, and reaches 50% conversion of ethanol around 210 C. At temperatures above 240 C., however, the catalyst results in large amounts of acetic acid and CO.sub.2, which significantly decreases the acetaldehyde yield.

[0139] The Au/recryst-S1 catalyst according to the invention and shown in FIG. 7d is the most active catalyst and reaches 50% conversion of ethanol with 98% selectivity toward acetaldehyde around 200 C. Above 200 C., the selectivity toward acetaldehyde starts to decrease because of the formation of acetic acid. At 270 C., both acetaldehyde and acetic acid are formed in 50% yield. Thus, at 270 C. a complete oxidation of bio-ethanol to acetaldehyde and acetic acid is observed for the Au/recryst-S1 zeolite according to the invention, whereas less than 20% of the bio-ethanol is oxidised to acetaldehyde when using the Au/S1 zeolite (FIG. 7a and line A in FIG. 6). Surprisingly, no CO.sub.2 is formed when using the Au/recryst-S1 catalyst even at 300 C.

[0140] In conclusion, FIGS. 6 and 7a-d show that the zeolite according to the invention shows significantly better catalytic properties than the other zeolites.

[0141] FIGS. 8a-d show the nitrogen N.sub.2 physisorption using the Au/S1 zeolite (FIG. 8a), the Au/meso-S1 zeolite (FIG. 8b), the Au/APS-S1 zeolite (FIG. 8c), and the Au/recryst-S1 zeolite (FIG. 8d).

[0142] In FIG. 9, the Barrett-Joyner-Halenda (BJH) pore size distributions derived from the desorption branch of the nitrogen physisorption isotherms. Please note that the peak at 4 nm for the Au/Recrys-S1 zeolite may be an artefact be caused by theso-called tensile strength effect.

[0143] The results from the N.sub.2 physisorption measurements are summarized in table 1 below.

TABLE-US-00001 TABLE 1 Results from N.sub.2 physisorption analysis. S.sub.BET S.sub.ext V.sub.micro V.sub.tot Catalyst (m.sup.2/g).sup.[a] (m.sup.2/g).sup.[b] (cm.sup.3/g).sup.[b] (cm.sup.3/g).sup.[c] HF.sup.[d] Au/S1 313 65 0.116 0.192 0.13 Au/Meso-S1 353 139 0.100 0.304 0.13 Au/APS-S1 333 80 0.118 0.201 0.14 Au/Recryst-S1 374 102 0.124 0.232 0.15 .sup.[a]Calculated by the BET method. .sup.[b]Calculated by the t-plot method. .sup.[c]Determined from the isotherm adsorption branch at around P/P0 = 0.95. .sup.[d]Hierarchy factor calculated by HF = (S.sub.ext/S.sub.BET)(V.sub.micro/V.sub.tot).

[0144] FIGS. 10a-b show the TEM images of two different silicalite-1 (S1) base zeolites. In FIG. 10a, a TEM image of a traditionally synthesised palladium (Pd) impregnated zeolite of the type Pd/S1 is shown, where no re-crystallization step has been performed prior to impregnating the zeolite with palladium. In FIG. 10b, a TEM image of a palladium impregnated recrystallized zeolite (Pd/recryst-S1) according to the invention is shown.

[0145] In FIG. 10a it can be seen that the Pd/S1 catalyst seem to have lengths of 250 nm and uniform coffin-shapes. As the images show, most of the Pd nanoparticles are distributed at the edges of the zeolite crystals. They vary in sizes from about 5-25 nm in diameter, which indicate a relative broad size distribution similar to that observed for Au/S1 in FIG. 2a. Some particles must have been subject of sintering, especially at the edges where the largest Pd nanoparticles are present. It is clear that these zeolite crystals contain the impregnated Pd nanoparticles, but the microporous structure limits the diffusion of the Pd precursor and the formation of Pd nanoparticles within the zeolite crystal.

[0146] In FIG. 10b it can be seen that the prepared recrystallized S1 crystals are similar In length and shape to the nonrecrystallized, but the TEM images reveal some bright areas indicating a broad distribution of intracrystalline voids and mesopores. It also appears like the external morphology is unchanged. Pd nanoparticles appear to be located within the zeolite crystals in the mesopores and less sintering seems to have happened. The size distribution of Pd nanoparticle is more narrow with sizes about 2-10 nm in diameter. Thus, a similar trend in regards to size distribution is observed for Pd zeolites as for the Au zeolites.

[0147] Large Pd nanoparticles of sizes about 25 nm due to sintering seem to have been avoided by the implementation of mesopores through the recrystallization according to the invention.

[0148] FIG. 11 show the yield from the hydrogenation of mesityl oxide and isophorone performed at room temperature and under 1 bar of H.sub.2 using Pd/Recryst-S1 as hydrogenation catalyst. These preliminary results indicate that zeolite encapsulated metal nanoparticle may be promising bifunctional catalyst for acid catalysed aldol condensations and subsequent hydrogenations into valuable products, such as the direct conversion of acetone into mesityl isobutyl ketone or dihydroisophorone.

[0149] FIGS. 12a-b show the TEM images of two different silicalite-1 (S1) base zeolites; a traditionally synthesised nickel (Ni) impregnated zeolite of the type 1 wt % Ni/S1 is shown in FIG. 12a, and a nickel impregnated recrystallized zeolite (Ni/Recryst-S1) according the invention is shown in FIG. 12b. Again it is clearly seen in FIG. 12a, that the metal particles are distributed evenly inside the zeolite structure in the recrystallized version according to the invention, whereas the metal particles form large particles mainly on the outside of the zeolite in the non-recrystallized version seen in FIG. 12a.

[0150] The invention also relates to the use of a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure according to the invention as catalytic material for chemical reactions.

[0151] The invention further relates to the use of a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure as defined above for the synthesis of liquid hydrocarbons from synthesis gas by means of the Fisher-Tropsch process or Mobile process.

[0152] The invention additionally relates to the use of a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure as defined above for in-situ generation of hydrogen peroxide (H.sub.2O.sub.2) from hydrogen (H.sub.2) and oxygen (O.sub.2) for epoxidation of propylene.

[0153] The invention further relates to the use of a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure as defined above for catalytic exhaust and/or flue-gas cleaning.

[0154] The invention further relates to the use of a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure as defined above for synthesis of olefins in methanol to olefins reactions (MTO).

[0155] The invention further relates to the use of a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure as defined above for synthesis of methanol to hydrocarbons reactions (MTH).

[0156] The invention further relates to the use of a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure as defined above for the synthesis of methanol to gasoline reactions (MTG).

[0157] The invention further relates to the use of a zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure as defined above for conversion of ammonia to N.sub.2O, NO.sub.x and N.sub.2.

[0158] Additional use applications of the zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure may include fluid catalytic cracking, hydrocracking, hydroconversion, paraffin isomerisation, paraffin aromatisation, olefin oligomerisation, aromatic alkylation, aromatic disproportionation, aromatic isomerisation, hydration, hydrogenation, benzene hydroxylation, phenol hydroxylation, DeNOx stationary sources, and synthesis of fine chemicals.

[0159] The zeolite, zeolite-like or zeotype structure with selective formation of metal, metal oxide or metal sulphide nanoparticles and/or clusters inside the zeolite, zeolite-like or zeotype structure of the present invention may also be used in shape-selective catalysis. The different shape-selective catalysis options described in the introduction part are for example reactant shape selectivity, product shape selectivity, and restricted transition-state shape selectivity.

Experimental Details

Materials

[0160] Commercial carbon black particles (Black Pearls 2000, Carbot Corporation) with an average particle diameter of around 12 nm were used as carbon-template for the synthesis of mesoporous silicalite-1. The carbon black particles were dried at 110 C. for 24 h prior to use. All other reagents were of reagent grade and used without further purification or pretreatment: HAuCl.sub.4 (Sigma-Aldrich), tetraethylorthosilicate (TEOS, Sigma-Aldrich), tetrapropylammonium hydroxide (TPAOH, 1M aqueous solution, Sigma-Aldrich), (3-aminopropyl)trimethoxysilane (APS, Sigma-Aldrich), toluene (Sigma-Aldrich), cetyl trimethylammonium bromide (CTAB, Sigma-Aldrich), ethanol (absolute, Sigma-Aldrich), deionized water and Formier gas (10% H.sub.2 in N.sub.2, Air Liquide).

[0161] Synthesis

[0162] The zeolites discussed in this application may be prepared by the following methods:

[0163] Silicalite-1 (S1)

[0164] TEOS (4.465 ml) was added dropwise to TPAOH (7.265 ml) under stirring in a Teflon beaker. The mixture was stirred for 1 hour and then transferred to a Teflon-lined stainless steel autoclave (130 ml). The autoclave was heated to 180 C. for 24 h under autogeneous pressure. The product was thoroughly washed with water, collected by filtration and washed again several times (until neutral pH). The product was dried at room temperature overnight and then calcined for 20 hours at 550 C. (heating 5 C./min) to give a fine white powder.

[0165] Au/S1

[0166] Silicalite-1 (0.9900 g) was impregnated with an aqueous solution of HAuCl.sub.4.3H.sub.2O (0.0199 g) to incipient wetness. The material was dried at room temperature overnight at then reduced in Formier gas for 2 h at 350 C. (heating 5 C./min) to give the final gold nanoparticle catalyst.

[0167] Au/Meso-S1

[0168] Pre-dried carbon black (2 g) was put in a Teflon beaker, impregnated with TPAOH (7.265 ml) and dried at room temperature overnight. The material was then impregnated with TEOS (4.465 ml) and dried at room temperature overnight once more. The Teflon beaker was placed inside a Teflon-lined stainless steel autoclave (130 ml) containing enough water to produce saturated steal (15 ml) and heated to 180 C. for 72 hours. The product was thoroughly washed with water, collected by filtration and washed again several times (until neutral pH). The product was dried at room temperature overnight and then calcined for 20 hours at 550 C. (heating 5 C./min) to give a fine white powder. The mesoporous zeolite was impregnated and reduced according to the general synthetic procedure described for the synthesis of Au/S1.

[0169] Au/APS-S1

[0170] Silicalite-1 (1 g) and toluene (100 ml) was added to a round-bottom flask equipped with a Liebig condenser. APS (1 ml) was added dropwise under stirring and the mixture was heated to 111 C. and refluxed for 4 hours. After cooling to room temperature, the product was precipitated by addition of ethanol and collected by filtration. The surface functioinalized zeolite was dried overnight and then impregnated and reduced according to the general synthetic procedure described for the synthesis of Au/S1.

[0171] Au/Recryst-S1

[0172] CTAB (0.7 g) was dissolved in an aqueous ammonia solution (100 ml, 2.5 wt %). Silicalite-1 (1 g) was added and the suspension was stirred for 3 hours at room temperature. The mixture was then transferred to a Teflon-lined stainless steel autoclave and heated to 140 C. for 24 hours. The product was collected by filtration, dried overnight and calcined at 550 C. for 5 hours to remove the surfactant. The obtained material was then impregnated and reduced according to the general synthetic procedure described for the synthesis of Au/S1.

[0173] Pd/Recryst-S1

[0174] The recryst-S1 zeolite was impregnated with the palladium precursor by incipient wetness impregnation. For this 0.99 g of the recrystallized zeolite S1 was first pre-dried under vacuum at 50 C. A solution of 0.0250 g (0.094 mmol) palladium(II)nitrate dihydrate (aq) in 0.30 mL of H.sub.2O was added to the recrystallized S1. It was dried at 25 C. and then reduced with 10% hydrogen/90% nitrogen by gradual heating at a rate of 5 C./min to the set temperature of 350 C. for 120 min to give the final palladium nanoparticle catalyst.

[0175] Ni/Recryst-S1

[0176] The recryst-S1 zeolite was impregnated with the nickel precursor by incipient wetness impregnation. For this 0.99 g of the recrystallized zeolite S1 was first pre-dried under vacuum at 50 C. A solution of 0.0495 g (0.170 mol) nickel(II)nitrate hexahydrate (aq) in 0.30 mL of H.sub.2O was added to the recrystallized S1. It was dried at 25 C. and then reduced with 10% hydrogen/90% nitrogen by gradual heating at a rate of 5 C./min to the set temperature of 350 C. for 120 min to give the final nickel nanoparticle catalyst.

[0177] Methods for CharacterisationTransmission Electron Microscopy (TEM)

[0178] TEM was performed on a FEI Tecnai microscope operated at 200 kV with the samples dispersed directly on holey carbon grids. The mean diameter and standard deviation of the nanoparticles was calculated by measurements of 250 particles.

[0179] Methods for CharacterisationPhysisorption Analysis

[0180] Argon gas physisorption analysis was performed at 77 K on a Micromeritics ASAP 2020. The samples were outgassed in vacuum at 300 C., 16 h prior to measurement. The (apparent) total surface areas were calculated according to the BET method. Pore size distributions were calculated by the BJH method. External surface area, micropore area and micropore volume were determined by t-plot methods using the desorption branch of the isotherm.